1 files changed, 38 insertions, 11 deletions

diff --git a/src/lib.rs b/src/lib.rs
index fa6b1a9..9e9afcf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,15 +1,11 @@
-use std::path::{Path, PathBuf, Component};
+use std::path::{Component, Path, PathBuf};
 
 #[derive(Debug)]
 pub enum NormalizeError {
     EmptyInput,
 }
 
-pub fn normalize_path(
-    _root: &Path,
-    origin: &Path,
-    input: &Path,
-) -> Result<PathBuf, NormalizeError> {
+pub fn normalize_path(root: &Path, origin: &Path, input: &Path) -> Result<PathBuf, NormalizeError> {
     if input.as_os_str().is_empty() {
         return Err(NormalizeError::EmptyInput);
     }
@@ -18,13 +14,26 @@ pub fn normalize_path(
     for component in origin_joint_input.components() {
         match component {
             Component::CurDir => (),
-            Component::ParentDir => { stack.pop(); },
-            Component::Prefix(_) => { stack.push(component); },
-            Component::Normal(_) => { stack.push(component); },
-            Component::RootDir => { stack.push(component) },
+            Component::ParentDir => {
+                stack.pop();
+            }
+            Component::Prefix(_) => stack.push(component),
+            Component::Normal(_) => stack.push(component),
+            Component::RootDir => stack.push(component),
         }
     }
-    Ok(PathBuf::from_iter(stack))
+    let normalized_origin_join_input = PathBuf::from_iter(stack);
+    Ok(normalize_to_root(&normalized_origin_join_input, root))
+}
+
+fn normalize_to_root(target_path: &Path, root: &Path,) -> PathBuf {
+    match target_path.strip_prefix(root) {
+        Ok(normalized_path) => normalized_path.to_path_buf(),
+        Err(_) => {
+            let root_parent = root.parent().expect("failed cuz target_path is not absolute");
+            PathBuf::from("..").join(normalize_to_root(target_path, root_parent))
+        },
+    }
 }
 
 #[cfg(test)]
@@ -61,4 +70,22 @@ mod tests {
         assert!(result.is_ok());
         assert_eq!(result.unwrap(), Path::new("main.rs"));
     }
+
+    #[test]
+    fn path_is_made_relative_to_root() {
+        let root = Path::new("/project");
+        let origin_dir = Path::new("/project/src");
+        let input = Path::new("main.rs");
+        let result = normalize_path(root, origin_dir, input);
+        assert_eq!(result.unwrap(), Path::new("src/main.rs"));
+    }
+
+    #[test]
+    fn path_is_made_relative_to_root_from_outside() {
+        let root = Path::new("/project");
+        let origin_dir = Path::new("/outside");
+        let input = Path::new("main.rs");
+        let result = normalize_path(root, origin_dir, input);
+        assert_eq!(result.unwrap(), Path::new("../outside/main.rs"));
+    }
 }