1 files changed, 151 insertions, 0 deletions
diff --git a/src/manifest.rs b/src/manifest.rs
new file mode 100644
index 0000000..908dcbf
--- /dev/null
+++ b/src/manifest.rs
@@ -0,0 +1,151 @@
+use yaml_rust2::parser::Parser;
+use yaml_rust2::Event;
+use std::ops::Range;
+
+enum YContext {
+    InDocument,
+    InObject,
+    InSequence,
+    InValue(bool),
+}
+
+#[derive(Debug, PartialEq)]
+pub struct ManifestFile {
+    pub image_tags: Vec<Range<usize>>,
+}
+
+impl ManifestFile {
+    pub fn parse(content: &str) -> Self {
+        let mut yaml = Parser::new_from_str(content);
+
+        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 {
+                                images.push(mark.index()..mark.index() + txt.len());
+                            }
+                            scope.pop();
+                        },
+                        // This should only happen for entirely empty documents
+                        YContext::InDocument => assert!(txt == ""),
+                    }
+                },
+                x => todo!("{:?}", x),
+            }
+        }
+
+        return Self{
+            image_tags: images,
+        };
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_single_image() {
+        let yaml = "image: nginx:1.21";
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 1);
+        assert_eq!(manifest.image_tags[0], 7..17);
+    }
+
+    #[test]
+    fn parse_multiple_images() {
+        let yaml = r#"
+containers:
+- image: app:v1
+- image: sidecar:v2
+"#;
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 2);
+        assert_eq!(manifest.image_tags[0], 22..28);
+        assert_eq!(manifest.image_tags[1], 38..48);
+    }
+
+    #[test]
+    fn parse_no_images() {
+        let yaml = "key: value";
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 0);
+    }
+
+    #[test]
+    fn parse_empty_document() {
+        let yaml = "";
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 0);
+    }
+
+    #[test]
+    fn parse_nested_object() {
+        let yaml = r#"
+spec:
+  container:
+    image: nginx:1.21
+"#;
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 1);
+        assert_eq!(manifest.image_tags[0], 31..41);
+    }
+
+    #[test]
+    fn parse_multiple_documents() {
+        let yaml = r#"
+kind: Service
+---
+image: nginx:1.21
+"#;
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 1);
+        assert_eq!(manifest.image_tags[0], 26..36);
+    }
+
+    #[test]
+    fn parse_image_with_digest() {
+        let yaml = "image: nginx@sha256:abc123";
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 1);
+        assert_eq!(manifest.image_tags[0], 7..26);
+    }
+
+    #[test]
+    fn parse_image_without_tag() {
+        let yaml = "image: nginx";
+        let manifest = ManifestFile::parse(yaml);
+        assert_eq!(manifest.image_tags.len(), 1);
+        assert_eq!(manifest.image_tags[0], 7..12);
+    }
+}