write_since(): Output file paths relative to the current directory

Previously, the file paths of TODO lines in the output were relative to
the repository root. When you're in a subdirectory, though, this makes
them harder to work with, as they're relative paths, but aren't relative
to the current working directory.

Change the file path output so that paths are relative to the current
directory instead of the repo root.

1 files changed, 28 insertions, 1 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 910b488..7adfb2f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -17,6 +17,7 @@
 #![warn(rust_2018_idioms)]
 
 use std::io::Write;
+use std::path::{Path, PathBuf};
 
 use git2::{DiffOptions, Repository, Tree};
 use thiserror::Error;
@@ -71,7 +72,7 @@ impl Todos<'_> {
                                     write!(
                                         write_to,
                                         "{}:{}:{}",
-                                        path.display(),
+                                        relative_path(self.repo, path).display(),
                                         line_number,
                                         l,
                                     ).expect("write error");
@@ -95,3 +96,29 @@ impl Todos<'_> {
         Ok(master.get().peel_to_tree()?)
     }
 }
+
+/// Get `path` relative to the current directory.
+///
+/// Attempt to remove the current directory prefix from `path` to turn it into a
+/// relative path from the current directory.
+fn relative_path(repo: &Repository, path: &Path) -> PathBuf {
+    let workdir = match repo.workdir() {
+        Some(d) => d,
+        None => return path.to_path_buf(),
+    };
+
+    let current_dir = match std::env::current_dir() {
+        Ok(d) => d,
+        Err(_) => return path.to_path_buf(),
+    };
+
+    let current_dir_relative = match current_dir.strip_prefix(workdir) {
+        Ok(d) => d,
+        Err(_) => return path.to_path_buf(),
+    };
+
+    match path.strip_prefix(current_dir_relative) {
+        Ok(d) => d.to_path_buf(),
+        Err(_) => path.to_path_buf(),
+    }
+}