INITIAL COMMIT (again)

2 files changed, 801 insertions, 1229 deletions

diff --git a/src/main.rs b/src/main.rs
index dd0041c..8933c96 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,11 +2,15 @@ mod parser;
 use crate::parser::*;
 
 use base64::prelude::*;
+use rand::distr::{Alphanumeric, SampleString};
 use yaml_rust2::parser::Parser;
 use yaml_rust2::Event;
 use std::collections::HashMap;
 use std::ops::Range;
 use std::sync;
+use std::io::Read;
+use std::io::Seek;
+use std::io::Write;
 
 fn help(cmd: &str) {
     println!(
@@ -28,29 +32,17 @@ enum AuthMethod {
 impl AuthMethod {
     fn from_header(header: &ureq::http::HeaderValue) -> Option<Self> {
         let header_str = header.to_str().unwrap();
-        let (parse, _) = parse_challenge(&header_str.chars().collect::<Vec<char>>(), 0).unwrap();
+        let parse = parse_authenticate_header(header_str).unwrap();
 
         if &header_str[parse.scheme.clone()] == "Basic" {
             return Some(AuthMethod::Basic);
         }
 
         if &header_str[parse.scheme.clone()] == "Bearer" {
-            let mut realm_param = None;
-            let mut scope_param = None;
-            let mut service_param = None;
-            for param in parse.params {
-                match &header_str[param.key.clone()] {
-                    "realm" => realm_param = Some(param),
-                    "scope" => scope_param = Some(param),
-                    "service" => service_param = Some(param),
-                    _ => {},
-                }
-            }
-
             return Some(AuthMethod::Bearer{
-                realm: header_str[realm_param.unwrap().value].to_string(),
-                scope: header_str[scope_param.unwrap().value].to_string(),
-                service: header_str[service_param.unwrap().value].to_string(),
+                realm: header_str[parse.realm.unwrap()].to_string(),
+                scope: header_str[parse.scope.unwrap()].to_string(),
+                service: header_str[parse.service.unwrap()].to_string(),
             });
         }
 
@@ -66,7 +58,6 @@ struct AuthInfo {
 
 enum AuthStage {
     Idle,
-    Unauthorized,
     Authorized(String),
 }
 
@@ -104,60 +95,56 @@ impl AuthState{
         return req
     }
 
-    fn attempt_authorization(&mut self, response: &ureq::http::Response<ureq::Body>) -> Result<(), ()> {
-        if let AuthStage::Idle = self.stage {
-            if let Some(auth_header) = response.headers().get("www-authenticate") {
-                let auth_header = AuthMethod::from_header(auth_header);
-                match auth_header {
-                    Some(AuthMethod::Basic) => {
-                        let basic_auth = format!("Basic {}", BASE64_STANDARD.encode(format!("{}:{}", self.info.username, self.info.password)));
-                        self.stage = AuthStage::Authorized(basic_auth);
-
-                        return Ok(());
-                    },
-                    Some(AuthMethod::Bearer{realm, scope, service}) => {
-                        let basic_auth = format!("Basic {}", BASE64_STANDARD.encode(format!("{}:{}", self.info.username, self.info.password)));
+    fn authenticate(&mut self, response: &ureq::http::Response<ureq::Body>) -> Result<(), String> {
+        match self.stage {
+            AuthStage::Authorized(_) => 
+                // The token must have expired
+                self.stage = AuthStage::Idle,
+            AuthStage::Idle => {},
+        }
 
-                        let url = format!("{}?service={}&scope={}", realm, service, scope);
+        let auth_header = response.headers().get("www-authenticate").unwrap();
+        match AuthMethod::from_header(auth_header) {
+            Some(AuthMethod::Basic) => {
+                let basic_auth = format!("Basic {}", BASE64_STANDARD.encode(format!("{}:{}", self.info.username, self.info.password)));
+                self.stage = AuthStage::Authorized(basic_auth);
 
-                        let body = ureq::get(url)
-                            .config().http_status_as_error(false).build()
-                            .header("Authorization", basic_auth)
-                            .call();
+                return Ok(());
+            },
+            Some(AuthMethod::Bearer{realm, scope, service}) => {
+                let basic_auth = format!("Basic {}", BASE64_STANDARD.encode(format!("{}:{}", self.info.username, self.info.password)));
 
-                        dbg!(&body);
+                let url = format!("{}?service={}&scope={}", realm, service, scope);
 
-                        let body = body.unwrap()
-                            .body_mut().read_to_string().unwrap();
+                let body = ureq::get(url)
+                    .config().http_status_as_error(false).build()
+                    .header("Authorization", basic_auth)
+                    .call();
 
-                        dbg!(&body);
+                let body = body.map_err(|x| format!("Server {} authentication request failed: {}", self.info.host, x.to_string()))?
+                    .body_mut().read_to_string().expect(format!("Server {} responded with something non-string like", self.info.host).as_str());
 
-                        let body: tinyjson::JsonValue = body
-                            .parse().unwrap();
+                let body = body.parse::<tinyjson::JsonValue>()
+                    .unwrap();
 
-                        let token: &String = body["token"].get().unwrap();
+                let token = body["token"].get::<String>().unwrap();
+                self.stage = AuthStage::Authorized(format!("Bearer {}", token));
+                return Ok(());
 
-                        self.stage = AuthStage::Authorized(format!("Bearer {}", token));
-                        return Ok(());
-                    },
-                    None => todo!("Failed parsing the challenge header"),
-                }
-            } else {
-                todo!("Server didn't ask us to authenticate");
-            }
-        } else {
-            todo!("Authorized request somehow failed (expired token?)");
+            },
+            None => Err(format!("Server {} provided us with a challenge, but we didn't understand it", self.info.host)),
         }
     }
 }
 
-fn perform_registry_request(registry: &str, url: &str, auth: &mut Auth) -> Result<ureq::http::Response<ureq::Body>, ()> {
+fn perform_registry_request(registry: &str, url: &str, accept: &'static str, auth: &mut Auth) -> Result<ureq::http::Response<ureq::Body>, String> {
     let mut state = auth.states.get_mut(registry);
 
     let url = format!("https://{}{}", registry, &url);
 
     for _ in 0..2 {
         let mut request = ureq::get(&url)
+            .header("Accept", accept)
             .config().http_status_as_error(false).build();
 
         if let Some(ref state) = state {
@@ -168,17 +155,19 @@ fn perform_registry_request(registry: &str, url: &str, auth: &mut Auth) -> Resul
 
         if response.status() == 401 {
             if let Some(ref mut state) = state {
-                state.attempt_authorization(&response)?;
+                state.authenticate(&response)?;
                 continue;
             } else {
-                todo!("Server returned 401 but we have no credentials");
+                return Err(format!("Server {} returned 401 but we have no credentials", registry));
             }
+        } else if response.status() != 200 {
+            return Err(format!("Unexpected status code: {}", response.status()))
         }
 
         return Ok(response);
     }
 
-    return Err(());
+    return Err("Authorization failed".to_string());
 }
 
 enum YContext {
@@ -189,94 +178,70 @@ enum YContext {
 }
 
 #[derive(Debug)]
-struct Chunk {
-    position: Range<usize>,
-}
-
-fn scan_yaml_for_images<T: Iterator<Item = char>>(mut yaml: Parser<T>) -> Vec<Chunk> {
-    let mut images = vec!();
-
-    let mut scope = vec!();
-
-    loop {
-        let (ev, mark) = yaml.next_token().unwrap();
-        match ev {
-            Event::StreamStart => {}
-            Event::StreamEnd => { break; }
-            Event::DocumentStart => { scope.push(YContext::InDocument); }
-            Event::DocumentEnd => {
-                assert!(matches!(scope.pop().unwrap(), YContext::InDocument));
-                scope.pop_if(|x| matches!(x, YContext::InValue(_)));
-            },
-            Event::MappingStart(_, _) => { scope.push(YContext::InObject); },
-            Event::MappingEnd => {
-                assert!(matches!(scope.pop().unwrap(), YContext::InObject));
-                scope.pop_if(|x| matches!(x, YContext::InValue(_)));
-            },
-            Event::SequenceStart(_, _) => { scope.push(YContext::InSequence); },
-            Event::SequenceEnd => { 
-                assert!(matches!(scope.pop().unwrap(), YContext::InSequence));
-                scope.pop_if(|x| matches!(x, YContext::InValue(_)));
-            },
-
-            Event::Scalar(ref txt, _, _, _) => {
-                let parent = scope.last().unwrap();
-                match parent {
-                    YContext::InObject => {
-                        // We are the key of a mapping, which means the next even is the value
-                        scope.push(YContext::InValue(txt == "image"));
-                    },
-                    YContext::InSequence => {},
-                    YContext::InValue(img) => {
-                        if *img {
-                            let next_idx = images.len();
-                            images.push(Chunk{
-                                position: mark.index()..mark.index() + txt.len(),
-                            });
-                        }
-                        scope.pop();
-                    },
-
-                    _ => panic!(),
-                }
-            },
-            x => todo!("{:?}", x),
-        }
-    }
-
-    return images;
-}
-
-pub trait SubsliceOffset<T> {
-    fn subslice_range(&self, inner: &Self) -> Option<std::ops::Range<usize>>;
+struct ManifestFile {
+    image_tags: Vec<Range<usize>>,
 }
 
-impl<T> SubsliceOffset<T> for [T] {
-    fn subslice_range(&self, subslice: &[T]) -> Option<std::ops::Range<usize>> {
-        if size_of::<T>() == 0 {
-            panic!("elements are zero-sized");
-        }
-
-        let self_start = self.as_ptr().addr();
-        let subslice_start = subslice.as_ptr().addr();
+impl ManifestFile {
+    fn parse(content: &str) -> Self {
+        let mut yaml = Parser::new_from_str(content);
 
-        let byte_start = subslice_start.wrapping_sub(self_start);
+        let mut images = vec!();
+        let mut scope = vec!();
 
-        if !byte_start.is_multiple_of(size_of::<T>()) {
-            return None;
+        loop {
+            let (ev, mark) = yaml.next_token().unwrap();
+            match ev {
+                Event::StreamStart => {}
+                Event::StreamEnd => { break; }
+                Event::DocumentStart => { scope.push(YContext::InDocument); }
+                Event::DocumentEnd => {
+                    assert!(matches!(scope.pop().unwrap(), YContext::InDocument));
+                    scope.pop_if(|x| matches!(x, YContext::InValue(_)));
+                },
+                Event::MappingStart(_, _) => { scope.push(YContext::InObject); },
+                Event::MappingEnd => {
+                    assert!(matches!(scope.pop().unwrap(), YContext::InObject));
+                    scope.pop_if(|x| matches!(x, YContext::InValue(_)));
+                },
+                Event::SequenceStart(_, _) => { scope.push(YContext::InSequence); },
+                Event::SequenceEnd => { 
+                    assert!(matches!(scope.pop().unwrap(), YContext::InSequence));
+                    scope.pop_if(|x| matches!(x, YContext::InValue(_)));
+                },
+
+                Event::Scalar(ref txt, _, _, _) => {
+                    let parent = scope.last().unwrap();
+                    match parent {
+                        YContext::InObject => {
+                            // We are the key of a mapping, which means the next even is the value
+                            scope.push(YContext::InValue(txt == "image"));
+                        },
+                        YContext::InSequence => {},
+                        YContext::InValue(img) => {
+                            if *img {
+                                images.push(mark.index()..mark.index() + txt.len());
+                            }
+                            scope.pop();
+                        },
+                        // This should only happen for entirely empty documents
+                        YContext::InDocument => assert!(txt == ""),
+
+                        _ => panic!(),
+                    }
+                },
+                x => todo!("{:?}", x),
+            }
         }
 
-        let start = byte_start / size_of::<T>();
-        let end = start.wrapping_add(subslice.len());
-
-        if start <= self.len() && end <= self.len() { Some(start..end) } else { None }
+        return Self{
+            image_tags: images,
+        };
     }
 }
 
 #[derive(Debug, Clone)]
 struct DockerRef {
-    full_range: Range<usize>,
-
     registry: Option<Range<usize>>,
     image: Range<usize>,
     tag: Option<Range<usize>>,
@@ -284,25 +249,25 @@ struct DockerRef {
 }
 
 impl DockerRef{
-    fn parse(file: &str, chunk: &Chunk) -> DockerRef {
-        let mut string_range = chunk.position.clone();
+    fn parse(content: &str, chunk: &Range<usize>) -> DockerRef {
+        let mut string_range = chunk.clone();
 
         let mut digest = None;
-        if let Some(idx) = file[string_range.clone()].rfind("@") {
+        if let Some(idx) = content[string_range.clone()].rfind("@") {
             digest = Some(string_range.start+idx+1..string_range.end);
             string_range.end = string_range.start+idx;
         }
 
         let mut tag = None;
-        if let Some(idx) = file[string_range.clone()].rfind(":") {
+        if let Some(idx) = content[string_range.clone()].rfind(":") {
             tag = Some(string_range.start+idx+1..string_range.end);
             string_range.end = string_range.start+idx;
         }
 
         let mut registry = None;
         let image;
-        if let Some(idx) = file[string_range.clone()].find("/") {
-            let head = &file[string_range.clone()][..idx];
+        if let Some(idx) = content[string_range.clone()].find("/") {
+            let head = &content[string_range.clone()][..idx];
             if head.contains(":") || head.contains(".") {
                 registry = Some(string_range.start..string_range.start+idx);
                 image = string_range.start+idx+1..string_range.end;
@@ -315,8 +280,6 @@ impl DockerRef{
         }
 
         return DockerRef {
-            full_range: chunk.position.clone(),
-
             registry,
             image,
             tag,
@@ -326,16 +289,21 @@ impl DockerRef{
 }
 
 #[derive(Debug)]
-struct Update {
+struct FilePatch {
     position: Range<usize>,
     content: String,
 }
 
 #[derive(Debug)]
-struct Version {
-    // It always starts with a string part, so the first string can be empty
-    string_parts: Vec<String>,
-    number_parts: Vec<u64>,
+enum VersionPart {
+    String(String),
+    Number(u64),
+    Hash,
+}
+
+#[derive(Debug)]
+struct VersionPattern {
+    parts: Vec<VersionPart>,
 }
 
 #[derive(Debug)]
@@ -347,41 +315,44 @@ enum CompareOutcome {
     Identical,
 }
 
-impl Version {
+impl VersionPattern {
     fn parse(tag: &str) -> Self {
-        static RE: sync::LazyLock<regex::Regex> = sync::LazyLock::new(|| regex::Regex::new(r"(?<str>[^0-9]*)(?<num>[0-9]+)").unwrap());
-        let mut string_parts = vec!();
-        let mut number_parts = vec!();
+        static RE: sync::LazyLock<regex::Regex> = sync::LazyLock::new(|| regex::Regex::new(r"(?<hash>[a-f0-9]{32})|(?<str>[^0-9]+)|(?<num>[0-9]+)").unwrap());
+        let mut parts = vec![];
         for it in RE.captures_iter(tag) {
-            string_parts.push(it.name("str").unwrap().as_str().to_string());
-            number_parts.push(it.name("num").unwrap().as_str().to_string().parse().unwrap());
+            if let Some(x) = it.name("str") {
+                parts.push(VersionPart::String(x.as_str().to_string()));
+            } else if let Some(x) = it.name("num") {
+                parts.push(VersionPart::Number(x.as_str().parse().unwrap()));
+            } else if let Some(_) = it.name("hash") {
+                parts.push(VersionPart::Hash);
+            }
         }
 
-        return Version {
-            string_parts,
-            number_parts,
+        return VersionPattern {
+            parts,
         }
     }
 
     fn compare(&self, other: &Self) -> CompareOutcome {
-        assert!(self.number_parts.len() == self.string_parts.len());
-        assert!(other.number_parts.len() == other.string_parts.len());
-
-        if self.number_parts.len() != other.number_parts.len() {
+        if self.parts.len() != other.parts.len() {
             return CompareOutcome::Incompatible;
         }
 
-        for (self_string, other_string) in self.string_parts.iter().zip(other.string_parts.iter()) {
-            if self_string != other_string {
-                return CompareOutcome::Incompatible;
-            }
-        }
-
-        for (self_number, other_number) in self.number_parts.iter().zip(other.number_parts.iter()) {
-            if self_number > other_number {
-                return CompareOutcome::Lower;
-            } else if self_number < other_number {
-                return CompareOutcome::Higher;
+        for (self_part, other_part) in self.parts.iter().zip(other.parts.iter()) {
+            match (self_part, other_part) {
+                (VersionPart::String(x1), VersionPart::String(x2)) => if x1 != x2 { return CompareOutcome::Incompatible },
+                (VersionPart::String(_), _) => return CompareOutcome::Incompatible,
+                (VersionPart::Number(x1), VersionPart::Number(x2)) => {
+                    if x1 > x2 {
+                        return CompareOutcome::Lower
+                    } else if x1 > x2 {
+                        return CompareOutcome::Higher
+                    }
+                },
+                (VersionPart::Number(_), _) => return CompareOutcome::Incompatible,
+                (VersionPart::Hash, VersionPart::Hash) => {},
+                (VersionPart::Hash, _) => return CompareOutcome::Incompatible,
             }
         }
 
@@ -389,31 +360,33 @@ impl Version {
     }
 }
 
-fn fetch_new_image(file: &str, auth: &mut Auth, img: DockerRef, edits: &mut Vec<Update>) {
-    let registry = img.registry.map(|x| &file[x]).unwrap_or("registry.jnsn.dev/");
-    let mut tag = img.tag.map(|x| file[x].to_string());
-
-    let mut digest = None;
-
+fn update_images(file: &str, auth: &mut Auth, img: DockerRef, edits: &mut Vec<FilePatch>) -> Result<(), String> {
+    let registry = img.registry.map(|x| &file[x]).unwrap_or("registry.hub.docker.com");
+    let mut tag = img.tag.as_ref().map(|x| file[x.clone()].to_string());
 
     if let Some(ref tag_str) = tag {
-        let mut current = Version::parse(&tag_str);
+        let mut current = VersionPattern::parse(&tag_str);
+
+        let mut new_tag = None;
 
         let mut url = format!("/v2/{}/tags/list", &file[img.image.clone()]);
         loop {
-            let mut response = perform_registry_request(registry, &url, auth).unwrap();
+            let mut response = perform_registry_request(registry, &url, "application/vnd.oci.image.index.v1+json", auth).unwrap();
 
-            let link_str = response.headers()["link"].to_str().unwrap();
-            let (link, _) = parse_link(&link_str.chars().collect(), 0).unwrap();
-            dbg!(&link_str[link.get(0).unwrap().params.get(0).unwrap().value().clone()]);
+            let content_type = response.headers()["Content-Type"].to_str().unwrap();
+            if !content_type.starts_with("application/json") {
+                return Err(format!("Unexpected Content-Type: {}", content_type));
+            }
+
+            let body = response.body_mut().read_to_string().unwrap();
+            let body = body.parse::<tinyjson::JsonValue>().unwrap();
 
-            let body: tinyjson::JsonValue = response.body_mut().read_to_string().unwrap().parse().unwrap();
             for it in body["tags"].get::<Vec<tinyjson::JsonValue>>().unwrap().iter() {
                 let candidate_str = it.get::<String>().unwrap();
-                let candidate = Version::parse(candidate_str);
+                let candidate = VersionPattern::parse(candidate_str);
                 match current.compare(&candidate) {
                     CompareOutcome::Higher => {
-                        tag = Some(candidate_str.clone());
+                        new_tag = Some(candidate_str.clone());
                         current = candidate;
                     },
                     CompareOutcome::Lower => {},
@@ -421,33 +394,113 @@ fn fetch_new_image(file: &str, auth: &mut Auth, img: DockerRef, edits: &mut Vec<
                     CompareOutcome::Identical => {},
                 }
             }
-            dbg!(&tag);
+
+            if let Some(link_header) = response.headers().get("link") {
+                let link_str = link_header.to_str().unwrap();
+                let link = extract_next_page(&link_str).unwrap();
+                url = link_str[link.next_uri.unwrap().clone()].to_string();
+            } else {
+                break;
+            }
+        }
+
+        if let Some(new_tag) = new_tag {
+            tag = Some(new_tag.clone());
+            edits.push(FilePatch {
+                position: img.tag.unwrap(),
+                content: new_tag,
+            });
         }
     }
 
-    if img.digest.is_some() {
+    if let Some(ref digest) = img.digest {
         // Find the digest for the selected tag
-        let url = format!("/v2/{}/manifests/{}", &file[img.image], tag.unwrap_or("latest".to_string()));
-        let mut response = perform_registry_request(registry, &url, auth).unwrap();
+        let url = format!("/v2/{}/manifests/{}", &file[img.image.clone()], tag.as_deref().unwrap_or("latest"));
+        let response = perform_registry_request(registry, &url, "application/vnd.oci.image.manifest.v1+json,application/vnd.oci.image.index.v1+json", auth).unwrap();
 
-        let body: tinyjson::JsonValue = response.body_mut().read_to_string().unwrap().parse().unwrap();
-        dbg!(&body);
+        let digest_string = response.headers()["docker-content-digest"].to_str().unwrap().to_string();
 
-        // let media_type : &String = body["mediaType"].get().unwrap();
-        // assert!(media_type == "application/vnd.docker.distribution.manifest.v2+json");
+        if file[digest.clone()] != digest_string {
+            edits.push(FilePatch{
+                position: img.digest.unwrap(),
+                content: digest_string,
+            });
+        }
+    }
+
+    return Ok(());
+}
+
+enum Output {
+    Overlay(std::fs::File, std::path::PathBuf, std::path::PathBuf),
+    Stdout(std::io::Stdout),
+}
 
-        digest = Some(response.headers()["docker-content-digest"].to_str().unwrap().to_string());
+impl Output {
+    fn overlay_file(infile_path: &std::path::Path) -> Self {
+        loop {
+            let mut filename = std::ffi::OsString::new();
+            filename.push(infile_path.file_name().unwrap());
+            filename.push(std::ffi::OsStr::new(".edit"));
+            filename.push(Alphanumeric.sample_string(&mut rand::rng(), 16));
+            let outfile_path = Some(infile_path.parent().unwrap().join(filename));
+            if let Ok(output_file) = std::fs::File::create_new(outfile_path.as_ref().unwrap()) {
+                return Output::Overlay(output_file, outfile_path.unwrap().into(), infile_path.into());
+            }
+        }
     }
 
-    let image_ref = {
-        let prefix = &file[img.full_range.start..img.digest.unwrap().start];
-        format!("{}{}", prefix, digest.unwrap_or("".to_string()))
-    };
+    fn commit(&mut self) {
+        match self {
+            Output::Overlay(_, outfile_path, infile_path) => {
+                std::fs::remove_file(&infile_path).unwrap();
+                std::fs::rename(&outfile_path, &infile_path).unwrap();
+            }
+            Output::Stdout(_) => {}
+        }
+    }
+}
 
-    edits.push(Update{
-        position: img.full_range,
-        content: image_ref,
-    });
+impl std::ops::Deref for Output {
+    type Target = dyn Write;
+
+    fn deref(&self) -> &Self::Target {
+        match self {
+            Output::Overlay(file, _, _) => file,
+            Output::Stdout(stdout) => stdout,
+        }
+    }
+}
+
+impl std::ops::DerefMut for Output {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        match self {
+            Output::Overlay(file, _, _) => file,
+            Output::Stdout(stdout) => stdout,
+        }
+    }
+}
+
+impl std::io::Write for Output {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        return (**self).write(buf);
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        return (**self).flush();
+    }
+
+    fn write_vectored(&mut self, bufs: &[std::io::IoSlice<'_>]) -> std::io::Result<usize> {
+        return (**self).write_vectored(bufs);
+    }
+
+    fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {
+        return (**self).write_all(buf);
+    }
+
+    fn write_fmt(&mut self, args: std::fmt::Arguments<'_>) -> std::io::Result<()> {
+        return (**self).write_fmt(args);
+    }
 }
 
 fn main() {
@@ -457,6 +510,7 @@ fn main() {
 
     let mut auths = vec![];
     let mut positional: Vec<&str> = vec!();
+    let mut overwrite = false;
 
     loop {
         match it.next().map(|x| x.as_str()) {
@@ -474,6 +528,9 @@ fn main() {
                     std::process::exit(1);
                 }
             },
+            Some("-i") | Some("--inplace") => {
+                overwrite = true;
+            },
             Some("-h") | Some("--help") => {
                 help(cmd);
                 std::process::exit(0);
@@ -486,28 +543,89 @@ fn main() {
     if positional.len() != 1 {
         panic!("Bad arguments");
     }
-    let file = positional[0];
-
+    let infile_path = std::path::PathBuf::from(positional[0]);
     let mut auth = Auth::new(auths);
 
-    let file_content = &std::fs::read_to_string(file).unwrap();
-    let yaml = Parser::new_from_str(&file_content);
-    let images : Vec<_> = scan_yaml_for_images(yaml);
+    let inpaths = if infile_path.is_dir() {
+        let mut unsearched = vec![infile_path.clone()];
+        let mut paths = vec![];
 
-    let mut edits = vec![];
+        while let Some(next) = unsearched.pop() {
+            for child in next.read_dir().unwrap() {
+                let child = child.unwrap();
+                let path = child.path();
 
-    let images : Vec<_> = images.iter()
-        .map(|x| DockerRef::parse(&file_content, x))
-        .map(|x| fetch_new_image(&file_content, &mut auth, x, &mut edits))
-        .collect();
+                let ft = child.file_type().unwrap();
+                if ft.is_dir() {
+                    unsearched.push(path);
+                    continue;
+                }
 
-    dbg!(&images);
-    dbg!(&edits);
-    // dbg!(&file_content[images[0].digest.as_ref().unwrap().clone()]);
+                if let Some(ext) = path.extension() {
+                    if ext == "yaml" {
+                        paths.push(path);
+                    }
+                }
+            }
+        }
+
+        paths
+    } else {
+        vec![infile_path]
+    };
+
+    for infile_path in inpaths {
+        let mut file = std::fs::File::open(&infile_path).unwrap();
+        let mut file_content = String::new();
+        file.read_to_string(&mut file_content).unwrap();
 
-    // let body: String = auth.apply(ureq::get("https://registry.jnsn.dev/v2/autobrr/tags/list"))
-    //     .call().unwrap()
-    //     .body_mut()
-    //     .read_to_string().unwrap();
-    // dbg!(body);
+        let images = ManifestFile::parse(&file_content);
+
+        let mut failed = None;
+
+        let mut edits = vec![];
+        for ref image in images.image_tags {
+            let image_ref = DockerRef::parse(&file_content, image);
+            if let Err(msg) = update_images(&file_content, &mut auth, image_ref, &mut edits) {
+                failed = Some(msg);
+                break;
+            }
+        }
+
+        if let Some(msg) = failed {
+            println!("{}: {} ", infile_path.display(), msg);
+            continue;
+        }
+
+        let mut out = if overwrite {
+            Output::overlay_file(&infile_path)
+        } else {
+            Output::Stdout(std::io::stdout())
+        };
+
+        let mut current_position = 0;
+        file.seek(std::io::SeekFrom::Start(0)).unwrap();
+        let mut file_block = file.take(0);
+        for edit in edits {
+            if edit.position.start > current_position {
+                file_block.set_limit((edit.position.start - current_position) as u64);
+                std::io::copy(&mut file_block, &mut out).unwrap();
+            }
+
+            out.write_all(edit.content.as_bytes()).unwrap();
+
+            // We should have been able to just seek to the position.end here, but that doesn't work
+            // for whatever reason. What we can do is calculate the amount to skip ahead, and then do
+            // that.
+            let skip = (edit.position.end - edit.position.start) as i64;
+            file_block.set_limit(skip as u64);
+            file_block.seek(std::io::SeekFrom::Current(skip)).unwrap();
+            current_position = edit.position.end;
+        }
+
+        file_block.set_limit(u64::MAX);
+        std::io::copy(&mut file_block, &mut out).unwrap();
+
+        out.commit();
+    }
 }
diff --git a/src/parser.rs b/src/parser.rs
index 1f028a0..38fa3fe 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -3,11 +3,32 @@ use std::ops::Range;
 #[derive(Debug)]
 pub struct Challenge {
     pub scheme: Range<usize>,
-    pub params: Vec<AuthParam>,
+    pub realm: Option<Range<usize>>,
+    pub scope: Option<Range<usize>>,
+    pub service: Option<Range<usize>>,
+}
+
+#[derive(Default)]
+pub struct PartialChallenge {
+    pub scheme: Option<Range<usize>>,
+    pub realm: Option<Range<usize>>,
+    pub scope: Option<Range<usize>>,
+    pub service: Option<Range<usize>>,
+}
+
+impl Into<Challenge> for PartialChallenge {
+    fn into(self) -> Challenge {
+        return Challenge {
+            scheme: self.scheme.unwrap(),
+            realm: self.realm,
+            scope: self.scope,
+            service: self.service,
+        }
+    }
 }
 
 // RFC 7230
-fn parse_token(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_token(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
     while str.len() > pos {
         match str[pos] {
@@ -26,40 +47,7 @@ fn parse_token(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
         return None;
     }
 
-    return Some((start..pos, pos));
-}
-
-#[cfg(test)]
-mod test_token {
-    use super::*;
-
-    #[test]
-    fn rejects_nontchar() {
-        let data = vec!['>'];
-
-        let res = parse_token(&data, 0);
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn matches_letter() {
-        let data = vec!['a'];
-
-        let (range, pos) = parse_token(&data, 0).unwrap();
-        assert_eq!(pos, 1);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 1);
-    }
-
-    #[test]
-    fn matches_multiple_letters() {
-        let data = vec!['a', '1', '|'];
-
-        let (range, pos) = parse_token(&data, 0).unwrap();
-        assert_eq!(pos, 3);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 3);
-    }
+    return Some(pos);
 }
 
 fn parse_qdtext(str: &Vec<char>, start: usize) -> Option<usize> {
@@ -77,13 +65,14 @@ fn parse_quotedpair(str: &Vec<char>, start: usize) -> Option<usize> {
     return Some(start + 2);
 }
 
-fn parse_quotedstring(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_quotedstring(str: &Vec<char>, start: usize, range: &mut Option<&mut Range<usize>>) -> Option<usize> {
     let mut pos = start;
     if str[pos] != '"' {
         return None;
     }
     pos += 1;
 
+    range.as_mut().map(|x| x.start = pos);
     loop {
         if let Some(npos) = parse_qdtext(str, pos) {
             pos = npos;
@@ -93,16 +82,17 @@ fn parse_quotedstring(str: &Vec<char>, start: usize) -> Option<(Range<usize>, us
             break;
         }
     }
+    range.as_mut().map(|x| x.end = pos);
 
     if str[pos] != '"' {
         return None;
     }
     pos += 1;
 
-    return Some((start+1..pos-1, pos));
+    return Some(pos);
 }
 
-fn parse_sp(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_sp(str: &Vec<char>, start: usize) -> Option<usize> {
     if str.len() <= start {
         return None;
     }
@@ -117,7 +107,20 @@ fn parse_sp(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
         return None;
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
+}
+
+fn parse_ows(str: &Vec<char>, start: usize) -> Option<usize> {
+    // @COMPL: This is not right
+    let mut pos = start;
+    loop {
+        match parse_sp(str, pos) {
+            Some(npos) => pos = npos,
+            None => break,
+        }
+    }
+
+    return Some(pos);
 }
 
 fn parse_crlf(str: &Vec<char>, start: usize) -> Option<usize> {
@@ -132,7 +135,7 @@ fn parse_crlf(str: &Vec<char>, start: usize) -> Option<usize> {
     return None;
 }
 
-fn parse_lws(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_lws(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     match parse_crlf(str, pos) {
@@ -141,28 +144,47 @@ fn parse_lws(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
     }
 
     match parse_sp(str, pos) {
-        Some((_, npos)) => pos = npos,
+        Some(npos) => pos = npos,
         None => return None,
     }
     loop {
         match parse_sp(str, pos) {
-            Some((_, npos)) => pos = npos,
+            Some(npos) => pos = npos,
             None => break,
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-#[derive(Debug)]
-pub struct AuthParam {
-    pub key: Range<usize>,
-    pub value: Range<usize>,
-}
+fn parse_param(str: &Vec<char>, start: usize, partial: &mut PartialChallenge) -> Option<usize> {
+    let mut pos = start;
 
-fn parse_param(str: &Vec<char>, start: usize) -> Option<(AuthParam, usize)> {
-    let pos = start;
-    let (param_range, pos) = parse_token(str, pos)?;
+    let mut value_range_slot = None;
+
+    if let Some(npos) = parse_exact_string(str, pos, "realm") {
+        partial.realm = Some(Range {
+            ..Default::default()
+        });
+        value_range_slot = partial.realm.as_mut();
+        pos = npos;
+    } else if let Some(npos) = parse_exact_string(str, pos, "scope") {
+        partial.scope = Some(Range {
+            ..Default::default()
+        });
+        value_range_slot = partial.scope.as_mut();
+        pos = npos;
+    } else if let Some(npos) = parse_exact_string(str, pos, "service") {
+        partial.service = Some(Range {
+            ..Default::default()
+        });
+        value_range_slot = partial.service.as_mut();
+        pos = npos;
+    } else if let Some(npos) = parse_token(str, pos) {
+        pos = npos;
+    } else {
+        return None;
+    }
 
     let mut pos = pos;
     if str[pos] == '=' {
@@ -171,49 +193,65 @@ fn parse_param(str: &Vec<char>, start: usize) -> Option<(AuthParam, usize)> {
         todo!();
     }
 
-    let value_range;
-    if let Some((range, npos)) = parse_token(str, pos) {
-        value_range = range;
+    value_range_slot.as_mut().map(|x| x.start = pos);
+    if let Some(npos) = parse_token(str, pos) {
+        value_range_slot.map(|x| x.end = npos);
         pos = npos;
-    } else if let Some((range, npos)) = parse_quotedstring(str, pos) {
-        value_range = range;
+    } else if let Some(npos) = parse_quotedstring(str, pos, &mut value_range_slot) {
         pos = npos;
     } else {
         todo!("{:?}", &str[pos..]);
     }
 
-    return Some((AuthParam{key: param_range, value: value_range}, pos));
+    return Some(pos);
 }
 
-pub fn parse_challenge(str: &Vec<char>, start: usize) -> Option<(Challenge, usize)> {
-    let pos = start;
-    let (scheme_range, pos) = parse_token(str, pos).unwrap();
+pub fn parse_authenticate_header(header: &str) -> Option<Challenge> {
+    let mut partial: PartialChallenge = Default::default();
+    let data = header.chars().collect();
+
+    parse_challenge(&data, 0, &mut partial)?;
 
-    let (_, pos) = parse_sp(str, pos).unwrap();
+    return Some(partial.into());
+}
+
+fn parse_challenge(str: &Vec<char>, start: usize, partial: &mut PartialChallenge) -> Option<usize> {
+    let mut pos = start;
+
+    {
+        let mut scheme_range = Range {
+            start: pos,
+            ..Default::default()
+        };
+
+        pos = parse_token(str, pos).unwrap();
+
+        scheme_range.end = pos;
+        partial.scheme = Some(scheme_range);
+    }
+
+    let pos = parse_sp(str, pos).unwrap();
     let mut pos = pos;
     loop {
         match parse_sp(str, pos) {
-            Some((_, npos)) => pos = npos,
+            Some(npos) => pos = npos,
             None => break,
         }
     }
 
-    let mut params = vec!();
-
     let mut pos = pos;
     loop {
         match parse_lws(str, pos) {
-            Some((_, npos)) => pos = npos,
+            Some(npos) => pos = npos,
             None => break,
         }
     }
-    let (param, pos) = parse_param(str, pos).unwrap();
-    params.push(param);
+    let pos = parse_param(str, pos, partial).unwrap();
     let mut pos = pos;
     loop {
         loop {
             match parse_lws(str, pos) {
-                Some((_, npos)) => pos = npos,
+                Some(npos) => pos = npos,
                 None => break,
             }
         }
@@ -225,15 +263,14 @@ pub fn parse_challenge(str: &Vec<char>, start: usize) -> Option<(Challenge, usiz
 
         loop {
             match parse_lws(str, pos) {
-                Some((_, npos)) => pos = npos,
+                Some(npos) => pos = npos,
                 None => break,
             }
         }
 
-        match parse_param(str, pos) {
-            Some((param, npos)) => {
+        match parse_param(str, pos, partial) {
+            Some(npos) => {
                 pos = npos;
-                params.push(param);
             },
             None => return None,
         }
@@ -242,58 +279,39 @@ pub fn parse_challenge(str: &Vec<char>, start: usize) -> Option<(Challenge, usiz
     if pos < str.len() {
         return None;
     }
-    return Some((Challenge {scheme: scheme_range, params}, pos));
-}
-
-#[derive(Debug)]
-pub enum LinkParam {
-    Rel{relation: Range<usize>},
-}
-
-impl LinkParam {
-    pub fn value(&self) -> &Range<usize> {
-        match self {
-            LinkParam::Rel{relation} => &relation,
-        }
-    }
+    return Some(pos);
 }
 
-#[derive(Debug)]
-pub struct LinkValue {
-    uri: Range<usize>,
-    pub params: Vec<LinkParam>,
-}
-
-fn parse_alpha(str: &Vec<char>, pos: usize) -> Option<(Range<usize>, usize)> {
+fn parse_alpha(str: &Vec<char>, pos: usize) -> Option<usize> {
     if pos >= str.len() {
         return None;
     }
 
     return match str[pos] {
-        'a'..='z' | 'A'..='Z' => Some((pos..pos+1, pos+1)),
+        'a'..='z' | 'A'..='Z' => Some(pos+1),
         _ => None,
     }
 }
 
-fn parse_digit(str: &Vec<char>, pos: usize) -> Option<(Range<usize>, usize)> {
+fn parse_digit(str: &Vec<char>, pos: usize) -> Option<usize> {
     if pos >= str.len() {
         return None;
     }
 
     return match str[pos] {
-        '0'..='9' => Some((pos..pos+1, pos+1)),
+        '0'..='9' => Some(pos+1),
         _ => None,
     }
 }
 
-fn parse_dec_octet(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_dec_octet(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     let mut len = 0;
     let mut value: u16 = 0;
 
     while len < 3 {
-        if let Some((_, npos)) = parse_digit(str, pos) {
+        if let Some(npos) = parse_digit(str, pos) {
             value = value * 10 + (str[pos] as u16 - '0' as u16);
             pos = npos;
             len += 1;
@@ -314,13 +332,13 @@ fn parse_dec_octet(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize
         return None;
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_ipv4address(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_ipv4address(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_dec_octet(str, pos)?;
+    let npos = parse_dec_octet(str, pos)?;
     pos = npos;
 
     if let Some(ch) = str.get(pos) && *ch == '.' {
@@ -329,7 +347,7 @@ fn parse_ipv4address(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usi
         return None;
     }
 
-    let (_, npos) = parse_dec_octet(str, pos)?;
+    let npos = parse_dec_octet(str, pos)?;
     pos = npos;
 
     if let Some(ch) = str.get(pos) && *ch == '.' {
@@ -338,7 +356,7 @@ fn parse_ipv4address(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usi
         return None;
     }
 
-    let (_, npos) = parse_dec_octet(str, pos)?;
+    let npos = parse_dec_octet(str, pos)?;
     pos = npos;
 
     if let Some(ch) = str.get(pos) && *ch == '.' {
@@ -347,31 +365,31 @@ fn parse_ipv4address(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usi
         return None;
     }
 
-    let (_, npos) = parse_dec_octet(str, pos)?;
+    let npos = parse_dec_octet(str, pos)?;
     pos = npos;
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_hexdig(str: &Vec<char>, pos: usize) -> Option<(Range<usize>, usize)> {
+fn parse_hexdig(str: &Vec<char>, pos: usize) -> Option<usize> {
     if pos >= str.len() {
         return None;
     }
 
     return match str[pos] {
-        '0'..='9' | 'A'..='F' | 'a'..='f' => Some((pos..pos+1, pos+1)),
+        '0'..='9' | 'A'..='F' | 'a'..='f' => Some(pos+1),
         _ => None,
     }
 }
 
-fn parse_scheme(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_scheme(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_alpha(str, pos)?;
+    let npos = parse_alpha(str, pos)?;
     pos = npos;
 
     loop {
-        if let Some((_, npos)) = parse_alpha(str, pos) {
+        if let Some(npos) = parse_alpha(str, pos) {
             pos = npos;
         } else {
             break;
@@ -381,685 +399,404 @@ fn parse_scheme(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)>
     return None;
 }
 
-fn parse_reg_name(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_reg_name(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     loop {
-        if let Some((_, npos)) = parse_unreserved(str, pos) {
+        if let Some(npos) = parse_unreserved(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_pct_encoded(str, pos) {
+        } else if let Some(npos) = parse_pct_encoded(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+        } else if let Some(npos) = parse_sub_delims(str, pos) {
             pos = npos;
         } else {
             break;
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_h16(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_h16(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_hexdig(str, pos)?;
+    let npos = parse_hexdig(str, pos)?;
     pos = npos;
 
     for _ in 0..3 {
-        if let Some((_, npos)) = parse_hexdig(str, pos) {
+        if let Some(npos) = parse_hexdig(str, pos) {
             pos = npos;
         } else {
             break;
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_ls32(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_ls32(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    if let Some((_, npos)) = parse_h16(str, pos) {
-        if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-            if let Some((_, npos)) = parse_h16(str, npos) {
-                return Some((start..npos, npos));
+    if let Some(npos) = parse_h16(str, pos) {
+        if let Some(npos) = parse_exact_string(str, npos, ":") {
+            if let Some(npos) = parse_h16(str, npos) {
+                return Some(npos);
             }
         }
     }
 
-    if let Some((_, npos)) = parse_ipv4address(str, pos) {
-        return Some((start..npos, npos));
+    if let Some(npos) = parse_ipv4address(str, pos) {
+        return Some(npos);
     }
 
     return None;
 }
 
-fn parse_ipv6address(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_first_part_ipv6(str: &Vec<char>, start: usize, max_reps: usize) -> Option<usize> {
+    let mut pos;
+
+    if let Some(npos) = parse_h16(str, start) {
+        pos = Some(npos);
+    } else {
+        pos = Some(start);
+    }
+
+    for _ in 0..max_reps {
+        if let Some(npos) = parse_exact_string(str, pos.unwrap(), ":") {
+            if let Some(npos) = parse_h16(str, npos) {
+                pos = Some(npos);
+                continue;
+            }
+        }
+
+        break;
+    }
+
+    if let Some(npos) = parse_exact_string(str, pos.unwrap(), "::") {
+        pos = Some(npos);
+    } else {
+        pos = None;
+    }
+
+    return pos;
+}
+
+fn parse_ipv6address(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    {
-        let mut tpos = pos;
+    // 6( h16 ":" ) ls32
+    if pos == start { // Just for symmetry, this is always true
+        let mut tpos = Some(pos);
+
         for _ in 0..6 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
+            if let Some(npos) = parse_h16(str, tpos.unwrap()) {
+                if let Some(npos) = parse_exact_string(str, npos, ":") {
+                    tpos = Some(npos);
                     continue;
                 }
             }
 
             // We fail the match, Rollback and stop
-            tpos = pos;
+            tpos = None;
             break;
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None;
             }
         }
+
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
+        }
     }
 
+    // "::" 5( h16 ":" ) ls32
     if pos == start {
-        let mut tpos = pos;
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
+        let mut tpos;
+
+        if let Some(npos) = parse_exact_string(str, pos, "::") {
+            tpos = Some(npos);
         } else {
-            tpos = pos;
+            tpos = None;
         }
 
-        if tpos != pos {
+        if let Some(ref mut tpos_val) = tpos {
             for _ in 0..5 {
-                if let Some((_, npos)) = parse_h16(str, tpos) {
-                    if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                        tpos = npos;
+                if let Some(npos) = parse_h16(str, *tpos_val) {
+                    if let Some(npos) = parse_exact_string(str, npos, ":") {
+                        *tpos_val = npos;
                         continue;
                     }
                 }
 
                 // We fail the match, Rollback and stop
-                tpos = pos;
+                tpos = None;
                 break;
             }
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None;
             }
         }
+
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
+        }
     }
 
+    // [               h16 ] "::" 4( h16 ":" ) ls32
     if pos == start {
-        let mut tpos = pos;
+        let mut tpos;
 
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
+        if let Some(npos) = parse_h16(str, pos) {
+            tpos = Some(npos);
+        } else {
+            tpos = Some(pos);
         }
 
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
+        if let Some(npos) = parse_exact_string(str, tpos.unwrap(), "::") {
+            tpos = Some(npos);
         } else {
-            tpos = pos;
+            tpos = None;
         }
 
-        if tpos != pos {
+        if let Some(ref mut tpos_val) = tpos {
             for _ in 0..4 {
-                if let Some((_, npos)) = parse_h16(str, tpos) {
-                    if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                        tpos = npos;
+                if let Some(npos) = parse_h16(str, *tpos_val) {
+                    if let Some(npos) = parse_exact_string(str, npos, ":") {
+                        *tpos_val = npos;
                         continue;
                     }
                 }
 
                 // We fail the match, Rollback and stop
-                tpos = pos;
+                tpos = None;
                 break;
             }
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
-            }
-        }
-    }
-
-    if pos == start {
-        let mut tpos = pos;
-
-        for _ in 0..1 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None;
             }
-
-            // Match failed
-            break;
         }
 
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
+    }
 
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
-        }
+    // [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
+    // Implementing this parsing rule sucks. When reading the first repeating block ( h16 ":" ) we
+    // have to speculatively read those two tokens, but we can't commit them since we don't know if
+    // they're valid until we then read ANOTHER h16 followed by another colon, which can then of
+    // course ALSO be part of the repetition if not followed by a second colon. I don't want to
+    // write that lookahead/rollback code. Instead we can reformulate that production into:
+    // [ h16 *1( ":" h16 ) ] "::" 3( h16 ":" ) ls32
+    // This is much easier to implement, since we now just have to try and read a colon followed by
+    // an h16, and if we don't find that fall through to the double colon or fail.
+    // @COMPL We have to be a little careful, since this may interact differently with whitespace
+    // and such, but that's for later.
+    if pos == start {
+        let mut tpos = parse_first_part_ipv6(str, pos, 1);
 
-        if tpos != pos {
+        if let Some(ref mut tpos_val) = tpos {
             for _ in 0..3 {
-                if let Some((_, npos)) = parse_h16(str, tpos) {
-                    if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                        tpos = npos;
+                if let Some(npos) = parse_h16(str, *tpos_val) {
+                    if let Some(npos) = parse_exact_string(str, npos, ":") {
+                        *tpos_val = npos;
                         continue;
                     }
                 }
 
                 // We fail the match, Rollback and stop
-                tpos = pos;
+                tpos = None;
                 break;
             }
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
-            }
-        }
-    }
-
-    if pos == start {
-        let mut tpos = pos;
-
-        for _ in 0..2 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None
             }
-
-            // Match failed
-            break;
         }
 
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
+    }
 
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
-        }
+    // [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
+    if pos == start {
+        let mut tpos = parse_first_part_ipv6(str, pos, 2);
 
-        if tpos != pos {
+        if let Some(ref mut tpos_val) = tpos {
             for _ in 0..2 {
-                if let Some((_, npos)) = parse_h16(str, tpos) {
-                    if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                        tpos = npos;
+                if let Some(npos) = parse_h16(str, *tpos_val) {
+                    if let Some(npos) = parse_exact_string(str, npos, ":") {
+                        *tpos_val = npos;
                         continue;
                     }
                 }
 
                 // We fail the match, Rollback and stop
-                tpos = pos;
+                tpos = None;
                 break;
             }
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None
             }
         }
-    }
-
-    if pos == start {
-        let mut tpos = pos;
 
-        for _ in 0..3 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
-            }
-
-            // Match failed
-            break;
-        }
-
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
+    }
 
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
-        }
+    // [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
+    if pos == start {
+        let mut tpos = parse_first_part_ipv6(str, pos, 3);
 
-        if tpos != pos {
+        if let Some(ref mut tpos_val) = tpos {
             for _ in 0..1 {
-                if let Some((_, npos)) = parse_h16(str, tpos) {
-                    if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                        tpos = npos;
+                if let Some(npos) = parse_h16(str, *tpos_val) {
+                    if let Some(npos) = parse_exact_string(str, npos, ":") {
+                        *tpos_val = npos;
                         continue;
                     }
                 }
 
                 // We fail the match, Rollback and stop
-                tpos = pos;
+                tpos = None;
                 break;
             }
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None
             }
         }
+
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
+        }
     }
 
+    // [ *4( h16 ":" ) h16 ] "::"              ls32
     if pos == start {
-        let mut tpos = pos;
+        let mut tpos = parse_first_part_ipv6(str, pos, 4);
 
-        for _ in 0..4 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_ls32(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None
             }
-
-            // Match failed
-            break;
-        }
-
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
-        }
-
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
         }
 
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_ls32(str, tpos) {
-                pos = npos;
-            }
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
     }
 
+    // [ *5( h16 ":" ) h16 ] "::"              h16
     if pos == start {
-        let mut tpos = pos;
+        let mut tpos = parse_first_part_ipv6(str, pos, 5);
 
-        for _ in 0..5 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
+        if let Some(ref mut tpos_val) = tpos {
+            if let Some(npos) = parse_h16(str, *tpos_val) {
+                *tpos_val = npos;
+            } else {
+                tpos = None
             }
-
-            // Match failed
-            break;
-        }
-
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
         }
 
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
-        }
-
-        if tpos != pos {
-            // We successfully matched the last part
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                pos = npos;
-            }
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
     }
 
     if pos == start {
-        let mut tpos = pos;
-
-        for _ in 0..6 {
-            if let Some((_, npos)) = parse_h16(str, tpos) {
-                if let Some((_, npos)) = parse_exact_string(str, npos, ":") {
-                    tpos = npos;
-                    continue;
-                }
-            }
+        let tpos = parse_first_part_ipv6(str, pos, 6);
 
-            // Match failed
-            break;
-        }
-
-        if let Some((_, npos)) = parse_h16(str, tpos) {
-            tpos = npos;
+        if let Some(tpos_val) = tpos {
+            pos = tpos_val;
         }
-
-        if let Some((_, npos)) = parse_exact_string(str, tpos, "::") {
-            tpos = npos;
-        } else {
-            tpos = pos;
-        }
-
-        pos = tpos;
     }
 
     if pos == start {
         return None;
     }
 
-    return Some((start..pos, pos));
-}
-
-#[cfg(test)]
-mod test_ipv6address {
-    use super::*;
-
-    #[test]
-    fn parses_full_ipv6address() {
-        let data = "2001:0db8:85a3:0000:0000:8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 39);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 39);
-    }
-
-    #[test]
-    fn parses_7part_ipv6address() {
-        let data = "::0db8:85a3:0000:0000:8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 36);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 36);
-    }
-
-    #[test]
-    fn parses_6part_ipv6address() {
-        let data = "::85a3:0000:0000:8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 31);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 31);
-    }
-
-    #[test]
-    fn parses_5part_ipv6address() {
-        let data = "::0000:0000:8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 26);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 26);
-    }
-
-    #[test]
-    fn parses_4part_ipv6address() {
-        let data = "::0000:8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 21);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 21);
-    }
-
-    #[test]
-    fn parses_3part_ipv6address() {
-        let data = "::8a2e:0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 16);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 16);
-    }
-
-    #[test]
-    fn parses_2part_ipv6address() {
-        let data = "::0370:7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 11);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 11);
-    }
-
-    #[test]
-    fn parses_1part_ipv6address() {
-        let data = "::7334".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 6);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 6);
-    }
-
-    #[test]
-    fn parses_0part_ipv6address() {
-        let data = "::".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 2);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 2);
-    }
-
-    #[test]
-    fn parses_full_ipv6address_trailing_ipv4() {
-        let data = "2001:0db8:85a3:0000:0000:8a2e:127.0.0.1".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 39);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 39);
-    }
-
-    #[test]
-    fn parses_compressed_ipv6_loopback() {
-        let data = "::1".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 3);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 3);
-    }
-
-    #[test]
-    fn parses_ipv6_with_embedded_ipv4() {
-        let data = "::ffff:192.0.2.128".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 18);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 18);
-    }
-
-    #[test]
-    fn rejects_invalid_ipv6_hex() {
-        let data = "2001:db8::g1".chars().collect();
-
-        let res = parse_ipv6address(&data, 0);
-
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn rejects_multiple_compressions() {
-        let data = "2001::85a3::7334".chars().collect();
-
-        let res = parse_ipv6address(&data, 0);
-
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn rejects_too_many_segments() {
-        let data = "1:2:3:4:5:6:7:8:9".chars().collect();
-
-        let res = parse_ipv6address(&data, 0);
-
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn rejects_missing_segments_without_compression() {
-        let data = "2001:db8:85a3:0:0:8a2e:370".chars().collect();
-
-        let res = parse_ipv6address(&data, 0);
-
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn parses_trailing_compression() {
-        let data = "2001:db8:85a3::".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 15);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 15);
-    }
-
-    #[test]
-    fn parses_compressed_ipv6_with_ipv4_tail() {
-        let data = "2001:db8::192.0.2.33".chars().collect();
-
-        let (range, pos) = parse_ipv6address(&data, 0).unwrap();
-
-        assert_eq!(pos, 21);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 21);
-    }
-
-    #[test]
-    fn rejects_ipv4_tail_out_of_range() {
-        let data = "2001::256.0.0.1".chars().collect();
-
-        let res = parse_ipv6address(&data, 0);
-
-        assert!(res.is_none());
-    }
+    return Some(pos);
 }
 
-
-fn parse_ipvfuture(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_ipvfuture(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_exact_string(str, pos, "v")?;
+    let npos = parse_exact_string(str, pos, "v")?;
     pos = npos;
 
-    let (_, npos) = parse_hexdig(str, pos)?;
+    let npos = parse_hexdig(str, pos)?;
     pos = npos;
 
     loop {
-        if let Some((_, npos)) = parse_hexdig(str, pos) {
+        if let Some(npos) = parse_hexdig(str, pos) {
             pos = npos;
         } else {
             break;
         }
     }
 
-    let (_, npos) = parse_exact_string(str, pos, ".")?;
+    let npos = parse_exact_string(str, pos, ".")?;
     pos = npos;
 
-    if let Some((_, npos)) = parse_unreserved(str, pos) {
+    if let Some(npos) = parse_unreserved(str, pos) {
         pos = npos;
-    } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+    } else if let Some(npos) = parse_sub_delims(str, pos) {
         pos = npos;
-    } else if let Some((_, npos)) = parse_exact_string(str, pos, ":") {
+    } else if let Some(npos) = parse_exact_string(str, pos, ":") {
         pos = npos;
     } else {
         return None;
     }
 
     loop {
-        if let Some((_, npos)) = parse_unreserved(str, pos) {
+        if let Some(npos) = parse_unreserved(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+        } else if let Some(npos) = parse_sub_delims(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_exact_string(str, pos, ":") {
+        } else if let Some(npos) = parse_exact_string(str, pos, ":") {
             pos = npos;
         } else {
             break;
         }
     }
 
-    return Some((start..pos, pos));
-}
-
-#[cfg(test)]
-mod test_ipvfuture {
-    use super::*;
-
-    #[test]
-    fn parses_ipvfuture_with_colons_and_subdelims() {
-        let data = "vF.fe80::1-._~+!".chars().collect();
-
-        let (range, pos) = parse_ipvfuture(&data, 0).unwrap();
-
-        assert_eq!(pos, 16);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 16);
-    }
-
-    #[test]
-    fn rejects_ipvfuture_missing_dot() {
-        let data = "v1fe80::1".chars().collect();
-
-        let res = parse_ipvfuture(&data, 0);
-
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn rejects_ipvfuture_with_percent_encoded() {
-        let data = "v1.fe80::1%25".chars().collect();
-
-        let (range, pos) = parse_ipvfuture(&data, 0).unwrap();
-
-        assert_eq!(pos, 10);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 10);
-    }
+    return Some(pos);
 }
 
-
-fn parse_ip_literal(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_ip_literal(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     if let Some(ch) = str.get(pos) && *ch == '[' {
@@ -1068,9 +805,9 @@ fn parse_ip_literal(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usiz
         return None;
     }
 
-    if let Some((_, npos)) = parse_ipv6address(str, pos) {
+    if let Some(npos) = parse_ipv6address(str, pos) {
         pos = npos;
-    } else if let Some((_, npos)) = parse_ipvfuture(str, pos) {
+    } else if let Some(npos) = parse_ipvfuture(str, pos) {
         pos = npos;
     } else {
         return None;
@@ -1078,13 +815,13 @@ fn parse_ip_literal(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usiz
 
     if let Some(ch) = str.get(pos) && *ch == ']' {
         pos += 1;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
     return None;
 }
 
-fn parse_port(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_port(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     while let Some(ch) = str.get(pos) {
@@ -1094,39 +831,39 @@ fn parse_port(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_host(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_host(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    if let Some((_, npos)) = parse_ip_literal(str, pos) {
+    if let Some(npos) = parse_ip_literal(str, pos) {
         pos = npos;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
-    if let Some((_, npos)) = parse_ipv4address(str, pos) {
+    if let Some(npos) = parse_ipv4address(str, pos) {
         pos = npos;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
-    if let Some((_, npos)) = parse_reg_name(str, pos) {
+    if let Some(npos) = parse_reg_name(str, pos) {
         pos = npos;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
     return None;
 }
 
-fn parse_userinfo(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_userinfo(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     loop {
-        if let Some((_, npos)) = parse_unreserved(str, pos) {
+        if let Some(npos) = parse_unreserved(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_pct_encoded(str, pos) {
+        } else if let Some(npos) = parse_pct_encoded(str, pos) {
             pos = npos;
-        } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+        } else if let Some(npos) = parse_sub_delims(str, pos) {
             pos = npos;
         } else if let Some(ch) = str.get(pos) && *ch == ':' {
             pos += 1;
@@ -1135,37 +872,37 @@ fn parse_userinfo(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_authority(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_authority(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    if let Some((_, npos)) = parse_userinfo(str, pos) {
+    if let Some(npos) = parse_userinfo(str, pos) {
         if let Some(ch) = str.get(npos) && *ch == '@' {
             pos = npos;
         }
     }
     // If the character after the userinfo isn't a @ we roll back that parse and try it as a host.
 
-    if let Some((_, npos)) = parse_host(str, pos) {
+    if let Some(npos) = parse_host(str, pos) {
         pos = npos;
     } else {
         return None;
     }
 
     if let Some(ch) = str.get(pos) && *ch == ':' {
-        if let Some((_, npos)) = parse_port(str, pos+1) {
+        if let Some(npos) = parse_port(str, pos+1) {
             pos = npos;
         } else {
             return None;
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_relative_part_1(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_relative_part_1(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     if str[pos] != '/' || str[pos+1] != '/' {
@@ -1173,16 +910,16 @@ fn parse_relative_part_1(str: &Vec<char>, start: usize) -> Option<(Range<usize>,
     }
     pos += 2;
 
-    let (_, npos) = parse_authority(str, pos)?;
+    let npos = parse_authority(str, pos)?;
     pos = npos;
 
-    let (_, npos) = parse_path_abempty(str, pos)?;
+    let npos = parse_path_abempty(str, pos)?;
     pos = npos;
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_unreserved(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_unreserved(str: &Vec<char>, start: usize) -> Option<usize> {
     if let Some(x) = parse_alpha(str, start) {
         return Some(x);
     }
@@ -1195,12 +932,12 @@ fn parse_unreserved(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usiz
         return None;
     }
     match str[start] {
-        '-' | '.' | '_' | '~' => Some((start..start+1, start+1)),
+        '-' | '.' | '_' | '~' => Some(start+1),
         _ => None
     }
 }
 
-fn parse_pct_encoded(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_pct_encoded(str: &Vec<char>, start: usize) -> Option<usize> {
     if start + 2 >= str.len() {
         return None;
     }
@@ -1212,25 +949,25 @@ fn parse_pct_encoded(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usi
     let is_hexdig = |ch: char| matches!(ch, '0'..='9' | 'A'..='F' | 'a'..='f');
 
     if is_hexdig(str[start + 1]) && is_hexdig(str[start + 2]) {
-        return Some((start..start + 3, start + 3));
+        return Some(start + 3);
     }
 
     return None;
 }
 
-fn parse_sub_delims(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_sub_delims(str: &Vec<char>, start: usize) -> Option<usize> {
     if start >= str.len() {
         return None;
     }
 
     match str[start] {
-        '!' | '$' | '&' | '\'' | '(' | ')' | '*' | '+' | ',' | ';' | '=' => Some((start..start+1, start+1)),
+        '!' | '$' | '&' | '\'' | '(' | ')' | '*' | '+' | ',' | ';' | '=' => Some(start+1),
         _ => None
     }
 
 }
 
-fn parse_pchar(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_pchar(str: &Vec<char>, start: usize) -> Option<usize> {
     if let Some(x) = parse_unreserved(str, start) {
         return Some(x);
     }
@@ -1245,7 +982,7 @@ fn parse_pchar(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
 
     if let Some(ch) = str.get(start) {
         match ch {
-            ':' | '@' => return Some((start..start + 1, start + 1)),
+            ':' | '@' => return Some(start + 1),
             _ => {}
         }
     }
@@ -1253,38 +990,38 @@ fn parse_pchar(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
     return None;
 }
 
-fn parse_segment_nz(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_segment_nz(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_pchar(str, pos)?;
+    let npos = parse_pchar(str, pos)?;
     pos = npos;
 
     loop {
-        if let Some((_, npos)) = parse_pchar(str, pos) {
+        if let Some(npos) = parse_pchar(str, pos) {
             pos = npos;
         } else {
             break;
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_segment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_segment(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     loop {
-        if let Some((_, npos)) = parse_pchar(str, pos) {
+        if let Some(npos) = parse_pchar(str, pos) {
             pos = npos;
         } else {
             break;
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     if str[pos] != '/' {
@@ -1292,7 +1029,7 @@ fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<(Range<usize>, u
     }
     pos += 1;
 
-    if let Some((_, npos)) = parse_segment_nz(str, pos) {
+    if let Some(npos) = parse_segment_nz(str, pos) {
         pos = npos;
 
         loop {
@@ -1300,7 +1037,7 @@ fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<(Range<usize>, u
                 break;
             }
 
-            if let Some((_, npos)) = parse_segment(str, pos+1) {
+            if let Some(npos) = parse_segment(str, pos+1) {
                 pos = npos;
             } else {
                 break;
@@ -1308,15 +1045,15 @@ fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<(Range<usize>, u
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_path_abempty(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_path_abempty(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     loop {
         if let Some(ch) = str.get(pos) && *ch == '/' {
-            if let Some((_, npos)) = parse_segment(str, pos+1) {
+            if let Some(npos) = parse_segment(str, pos+1) {
                 pos = npos;
             } else {
                 break;
@@ -1326,41 +1063,26 @@ fn parse_path_abempty(str: &Vec<char>, start: usize) -> Option<(Range<usize>, us
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_relative_part(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_relative_part(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    if let Some((_, npos)) = parse_relative_part_1(str, pos) {
+    if let Some(npos) = parse_relative_part_1(str, pos) {
         pos = npos;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
-    if let Some((_, npos)) = parse_path_absolute(str, pos) {
+    if let Some(npos) = parse_path_absolute(str, pos) {
         pos = npos;
-        return Some((start..pos, pos));
+        return Some(pos);
     }
 
     return None;
 }
 
-#[cfg(test)]
-mod test_relative_part {
-    use super::*;
-
-    #[test]
-    fn absolute_path() {
-        let data = "/foo?".chars().collect();
-
-        let (range, pos) = parse_relative_part(&data, 0).unwrap();
-        assert_eq!(pos, 4);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 4);
-    }
-}
-
-fn parse_query(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_query(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     if start >= str.len() {
@@ -1368,7 +1090,7 @@ fn parse_query(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
     }
 
     loop {
-        if let Some((_, npos)) = parse_pchar(str, pos) {
+        if let Some(npos) = parse_pchar(str, pos) {
             pos = npos;
         } else if let Some(ch) = str.get(pos) && *ch == '/' {
             pos += 1;
@@ -1379,10 +1101,10 @@ fn parse_query(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_fragment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_fragment(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
     if start >= str.len() {
@@ -1390,7 +1112,7 @@ fn parse_fragment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)
     }
 
     loop {
-        if let Some((_, npos)) = parse_pchar(str, pos) {
+        if let Some(npos) = parse_pchar(str, pos) {
             pos = npos;
         } else if let Some(ch) = str.get(pos) && (*ch == '/' || *ch == '?') {
             pos += 1;
@@ -1399,90 +1121,37 @@ fn parse_fragment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)
         }
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
 // RFC 3986
-fn parse_relative_ref(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_relative_ref(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_relative_part(str, pos)?;
+    let npos = parse_relative_part(str, pos)?;
     pos = npos;
 
-    if let Some(ch) = str.get(pos) && *ch == '?' && let Some((_, npos)) = parse_query(str, pos+1) {
+    if let Some(ch) = str.get(pos) && *ch == '?' && let Some(npos) = parse_query(str, pos+1) {
         pos = npos;
     }
 
-    if let Some(ch) = str.get(pos) && *ch == '#' && let Some((_, npos)) = parse_fragment(str, pos+1) {
+    if let Some(ch) = str.get(pos) && *ch == '#' && let Some(npos) = parse_fragment(str, pos+1) {
         pos = npos;
     }
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-#[cfg(test)]
-mod test_relative_ref {
-    use super::*;
-
-    #[test]
-    fn reject_not_starting_slash() {
-        let data = vec!['?'];
-
-        let res = parse_relative_ref(&data, 0);
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn simple() {
-        let data = vec!['/', '/', 'h', 'e', 'l', 'l', 'o', '/'];
-
-        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
-        assert_eq!(pos, 8);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 8);
-    }
-
-    #[test]
-    fn with_query_parameter() {
-        let data = "/foo?bar=baz".chars().collect();
-
-        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
-        assert_eq!(pos, 12);
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, 12);
-    }
-
-    #[test]
-    fn with_fragment() {
-        let data = "/foo#frag".chars().collect();
-
-        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
-        assert_eq!(pos, data.len());
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, data.len());
-    }
-
-    #[test]
-    fn with_percent_encoded_fragment() {
-        let data = "/foo#fr%20ag".chars().collect();
-
-        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
-        assert_eq!(pos, data.len());
-        assert_eq!(range.start, 0);
-        assert_eq!(range.end, data.len());
-    }
-}
-
-fn parse_uri(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_uri(str: &Vec<char>, start: usize) -> Option<usize> {
     let mut pos = start;
 
-    let(_, npos) = parse_scheme(str, pos)?;
+    let npos = parse_scheme(str, pos)?;
     pos = npos;
 
-    return Some((start..pos, pos));
+    return Some(pos);
 }
 
-fn parse_exact_string(str: &Vec<char>, start: usize, to_match: &str) -> Option<(Range<usize>, usize)> {
+fn parse_exact_string(str: &Vec<char>, start: usize, to_match: &str) -> Option<usize> {
     let mut pos = start;
     let end = pos + to_match.len();
 
@@ -1495,171 +1164,117 @@ fn parse_exact_string(str: &Vec<char>, start: usize, to_match: &str) -> Option<(
     }
     pos += to_match.len();
 
-    return Some((start..pos, pos));
-}
-
-fn parse_loalpha(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
-    match str.get(start) {
-        Some('a'..='z') => Some((start..start+1, start+1)),
-        _ => None,
-    }
+    return Some(pos);
 }
 
-fn parse_relation_type(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+fn parse_link_param(str: &Vec<char>, start: usize, res: &mut PartialNextPage) -> Option<usize> {
     let mut pos = start;
 
-    let (_, npos) = parse_loalpha(str, pos)?;
-    pos = npos;
+    let mut is_rel = false;
 
-    loop {
-        if let Some((_, npos)) = parse_loalpha(str, pos) {
-            pos = npos;
-            continue;
-        } else if let Some((_, npos)) = parse_digit(str, pos) {
-            pos = npos;
-            continue;
-        } else if let Some((_, npos)) = parse_exact_string(str, pos, ".") {
-            pos = npos;
-            continue;
-        } else if let Some((_, npos)) = parse_exact_string(str, pos, "-") {
-            pos = npos;
-            continue;
-        } else {
-            break;
-        }
+    if let Some(npos) = parse_exact_string(str, pos, "rel") {
+        is_rel = true;
+        pos = npos;
+    } else if let Some(npos) = parse_token(str, pos) {
+        pos = npos;
+    } else {
+        return None;
     }
 
-    return Some((start..pos, pos));
-}
-
-fn parse_relation_types(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
-    let mut pos = start;
-
-    if let Some((_, npos)) = parse_relation_type(str, pos) {
+    // @CORRECT This part is actually supposed to be optional
+    if let Some(npos) = parse_ows(str, pos) {
         pos = npos;
+    }
 
-        return Some((start..pos, pos));
-    } else if let Some((_, npos)) = parse_exact_string(str, pos, "\"") {
+    if let Some(npos) = parse_exact_string(str, pos, "=") {
         pos = npos;
-
-        if let Some((_, npos)) = parse_relation_type(str, pos) {
-            pos = npos;
-
-            loop {
-                if let Some((_, npos)) = parse_sp(str, pos) {
-
-                    loop {
-                        if let Some((_, npos)) = parse_sp(str, pos) {
-                            pos = npos;
-                        } else {
-                            break;
-                        }
-                    }
-
-                    pos = npos;
-                    if let Some((_, npos)) = parse_relation_type(str, pos) {
-                        pos = npos;
-                        continue;
-                    }
-                }
-                break;
-            }
-
-            if let Some((_, npos)) = parse_exact_string(str, pos, "\"") {
-                pos = npos;
-                return Some((start+1..pos-1, pos));
-            }
-        }
+    } else {
+        return None;
     }
 
-    return None;
-}
-
-fn parse_link_param(str: &Vec<char>, start: usize) -> Option<(LinkParam, usize)> {
-    let mut pos = start;
-
-    // Non-standard but seen in the wild
-    if let Some((_, npos)) = parse_sp(str, pos) {
+    if let Some(npos) = parse_ows(str, pos) {
         pos = npos;
     }
 
-    if let Some((_, npos)) = parse_exact_string(str, pos, "rel=") {
-        if let Some((relation, npos)) = parse_relation_types(str, npos) {
-            pos = npos;
-            return Some((LinkParam::Rel{relation}, pos));
-        }
+    // @INCOMPLETE This is not exhaustive
+    if is_rel && let Some(npos) = parse_exact_string(str, pos, "\"next\"") {
+        res.found_next_uri = Some(res.current_uri.clone());
+        pos = npos;
+    } else if let Some(npos) = parse_token(str, pos) {
+        pos = npos;
+    } else if let Some(npos) = parse_quotedstring(str, pos, &mut None) {
+        pos = npos;
+    } else {
+        return None;
     }
 
-    return None;
+    return Some(pos);
 }
 
-fn parse_link_value(str: &Vec<char>, start: usize) -> Option<(LinkValue, usize)> {
+fn parse_link_value(str: &Vec<char>, start: usize, res: &mut PartialNextPage) -> Option<usize> {
     let mut pos = start;
 
-    if let Some((_, npos)) = parse_exact_string(str, pos, "<") {
+    if let Some(npos) = parse_exact_string(str, pos, "<") {
         pos = npos;
     } else {
         return None;
     }
 
-    let uri_range;
-    let mut params = vec!();
-
-    if let Some((range, npos)) = parse_uri(str, pos) {
-        uri_range = range;
+    res.current_uri.start = pos;
+    if let Some(npos) = parse_uri(str, pos) {
         pos = npos;
-    } else if let Some((range, npos)) = parse_relative_ref(str, pos) {
-        uri_range = range;
+    } else if let Some(npos) = parse_relative_ref(str, pos) {
         pos = npos;
     } else {
         return None;
     }
+    res.current_uri.end = pos;
 
-    if let Some((_, npos)) = parse_exact_string(str, pos, ">") {
+    if let Some(npos) = parse_exact_string(str, pos, ">") {
         pos = npos;
     } else {
         return None;
     }
 
     loop {
-        if let Some((_, npos)) = parse_exact_string(str, pos, ";") {
+        if let Some(npos) = parse_exact_string(str, pos, ";") {
             pos = npos;
         } else {
             break;
         }
 
-        if let Some((param, npos)) = parse_link_param(str, pos) {
+        if let Some(npos) = parse_ows(str, pos) {
+            pos = npos;
+        }
+
+        if let Some(npos) = parse_link_param(str, pos, res) {
             pos = npos;
-            params.push(param);
         } else {
             break;
         }
     }
 
-    return Some((LinkValue{ uri: uri_range, params: params }, pos));
+    return Some(pos);
 }
 
-pub fn parse_link(str: &Vec<char>, start: usize) -> Option<(Vec<LinkValue>, usize)> {
+fn parse_link_into(str: &Vec<char>, start: usize, res: &mut PartialNextPage) -> Option<usize> {
     let mut pos = start;
 
-    let mut values = vec!();
-
     loop {
         match parse_lws(str, pos) {
-            Some((_, npos)) => pos = npos,
+            Some(npos) => pos = npos,
             None => break,
         }
     }
 
-    let (param, npos) = parse_link_value(str, pos)?;
-    values.push(param);
+    let npos = parse_link_value(str, pos, res)?;
     pos = npos;
 
     loop {
         let mut ipos = pos;
         loop {
             match parse_lws(str, ipos) {
-                Some((_, npos)) => ipos = npos,
+                Some(npos) => ipos = npos,
                 None => break,
             }
         }
@@ -1671,15 +1286,14 @@ pub fn parse_link(str: &Vec<char>, start: usize) -> Option<(Vec<LinkValue>, usiz
 
         loop {
             match parse_lws(str, ipos) {
-                Some((_, npos)) => ipos = npos,
+                Some(npos) => ipos = npos,
                 None => break,
             }
         }
 
-        match parse_link_value(str, ipos) {
-            Some((param, npos)) => {
+        match parse_link_value(str, ipos, res) {
+            Some(npos) => {
                 ipos = npos;
-                values.push(param);
             },
             None => {
                 break;
@@ -1690,194 +1304,34 @@ pub fn parse_link(str: &Vec<char>, start: usize) -> Option<(Vec<LinkValue>, usiz
     }
 
 
-    return Some((values, pos));
+    return Some(pos);
 }
 
-#[cfg(test)]
-mod test_link {
-    use super::*;
-
-    #[test]
-    fn parses_relative_authority_only() {
-        let data: Vec<char> = "<//example.com>".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 15);
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].uri, 1..14);
-        assert_eq!(links[0].params.len(), 0);
-    }
-
-    #[test]
-    fn parses_relative_absolute_path() {
-        let data: Vec<char> = "</path/to/resource>".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 19);
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].uri, 1..18);
-    }
-
-    #[test]
-    fn parses_relative_with_query() {
-        let data: Vec<char> = "</foo?bar=baz>".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 14);
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].uri, 1..13);
-    }
-
-    #[test]
-    fn parses_rel_param_unquoted() {
-        let data: Vec<char> = "<//example.com>; rel=preconnect".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 31);
-
-        match &links[0].params[0] {
-            LinkParam::Rel { relation } => {
-                assert_eq!(relation.clone(), 21..31);
-            }
-            _ => assert!(false),
-        }
-    }
-
-    #[test]
-    fn parses_multiple_links_with_lws() {
-        let data: Vec<char> = "<//a>; rel=preconnect, <//b>".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 28);
-        assert_eq!(links.len(), 2);
-
-        match &links[0].params[0] {
-            LinkParam::Rel { relation } => {
-                assert_eq!(relation.clone(), 11..21);
-            }
-        }
-
-        assert_eq!(links[1].params.len(), 0);
-        assert_eq!(links[0].uri, 1..4);
-        assert_eq!(links[1].uri, 24..27);
-    }
-
-    #[test]
-    fn parses_lws_between_link_values() {
-        let data: Vec<char> = "<//a>,\r\n <//b>".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 14);
-        assert_eq!(links.len(), 2);
-        assert_eq!(links[0].uri, 1..4);
-        assert_eq!(links[1].uri, 10..13);
-    }
-
-    #[test]
-    // Is this correct?
-    fn rejects_absolute_uri() {
-        let data: Vec<char> = "<http://example.com>".chars().collect();
-
-        let res = parse_link(&data, 0);
-        assert!(res.is_none());
-    }
-
-    #[test]
-    fn rejects_missing_closing_delimiter() {
-        let data: Vec<char> = "<//example.com".chars().collect();
-
-        let res = parse_link(&data, 0);
-        assert!(res.is_none());
-    }
+#[derive(Default)]
+struct PartialNextPage {
+    current_uri: Range<usize>,
 
-    #[test]
-    fn parses_quoted_rel_multiple_values() {
-        let data: Vec<char> = "<//example.com>; rel=\"preconnect dns-prefetch\"".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, data.len());
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].params.len(), 1);
-
-        match &links[0].params[0] {
-            LinkParam::Rel { relation } => {
-                assert_eq!(relation.clone(), 22..45);
-            }
-        }
-    }
-
-    #[test]
-    #[ignore = "absolute URI targets are not parsed yet"]
-    fn parses_absolute_uri_with_rel() {
-        let data: Vec<char> = "<http://example.com>; rel=preconnect".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
+    found_next_uri: Option<Range<usize>>,
+}
 
-        assert_eq!(pos, 35);
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].uri, 1..19);
-        match &links[0].params[0] {
-            LinkParam::Rel { relation } => assert_eq!(relation.clone(), 22..32),
+impl Into<NextPage> for PartialNextPage {
+    fn into(self) -> NextPage {
+        return NextPage {
+            next_uri: self.found_next_uri,
         }
     }
+}
 
-    #[test]
-    #[ignore = "additional parameters beyond rel= are not parsed"]
-    fn parses_title_parameter() {
-        let data: Vec<char> = "<//example.com>; rel=preconnect; title=\"Example\"".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 57);
-        assert_eq!(links.len(), 1);
-        assert_eq!(links[0].params.len(), 2);
-    }
-
-    #[test]
-    #[ignore = "extended title* parameter not supported"]
-    fn parses_title_star_parameter() {
-        let data: Vec<char> = "<//example.com>; rel=preconnect; title*=UTF-8''Ex%C3%A4mple".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 65);
-        assert_eq!(links.len(), 1);
-    }
-
-    #[test]
-    #[ignore = "anchor parameter not parsed"]
-    fn parses_anchor_parameter() {
-        let data: Vec<char> = "<//example.com>; rel=preconnect; anchor=\"/base\"".chars().collect();
-
-        let (links, pos) = parse_link(&data, 0).unwrap();
-
-        assert_eq!(pos, 56);
-        assert_eq!(links.len(), 1);
-    }
-
-    #[test]
-    #[ignore = "hreflang parameter not parsed"]
-    fn parses_hreflang_parameter() {
-        let data: Vec<char> = "<//example.com>; rel=preconnect; hreflang=en".chars().collect();
+pub struct NextPage {
+    pub next_uri: Option<Range<usize>>
+}
 
-        let (links, pos) = parse_link(&data, 0).unwrap();
+pub fn extract_next_page(header: &str) -> Option<NextPage> {
+    let mut partial = Default::default();
 
-        assert_eq!(pos, 53);
-        assert_eq!(links.len(), 1);
-    }
+    let data = header.chars().collect();
 
-    #[test]
-    fn rejects_percent_encoded_path() {
-        let data: Vec<char> = "</pa%20th>".chars().collect();
+    parse_link_into(&data, 0, &mut partial)?;
 
-        let res = parse_link(&data, 0);
-        assert!(res.is_some());
-    }
+    return Some(partial.into());
 }