feat: add gix blame to the CLI

That way it's possible to see the `blame` result of any file in the
repository.

Co-authored-by: Sebastian Thiel <[email protected]>

Author: cruessler

gitoxide-core/src/repository/blame.rs

@@ -0,0 +1,56 @@
+use std::{ffi::OsStr, path::PathBuf, str::Lines};
+
+use gix::bstr::BStr;
+
+pub fn blame_file(mut repo: gix::Repository, file: &OsStr, out: impl std::io::Write) -> anyhow::Result<()> {
+    repo.object_cache_size_if_unset(repo.compute_object_cache_size_for_tree_diffs(&**repo.index_or_empty()?));
+
+    let suspect = repo.head()?.peel_to_commit_in_place()?;
+    let traverse: Vec<_> = gix::traverse::commit::Simple::new(Some(suspect.id), &repo.objects).collect();
+    let mut resource_cache = repo.diff_resource_cache_for_tree_diff()?;
+
+    let work_dir: PathBuf = repo.work_dir().expect("TODO").into();
+    let file_path: &BStr = gix::path::os_str_into_bstr(file)?;
+
+    let blame_entries = gix::blame::blame_file(
+        &repo.objects,
+        traverse,
+        &mut resource_cache,
+        suspect.id,
+        work_dir.clone(),
+        file_path,
+    )
+    .expect("TODO");
+
+    let absolute_path = work_dir.join(file);
+    let file_content = std::fs::read_to_string(absolute_path).expect("TODO");
+    let lines = file_content.lines();
+
+    write_blame_entries(out, lines, blame_entries)?;
+
+    Ok(())
+}
+
+fn write_blame_entries(
+    mut out: impl std::io::Write,
+    mut lines: Lines<'_>,
+    blame_entries: Vec<gix::blame::BlameEntry>,
+) -> Result<(), std::io::Error> {
+    for blame_entry in blame_entries {
+        for line_number in blame_entry.range_in_blamed_file {
+            let line = lines.next().unwrap();
+
+            writeln!(
+                out,
+                "{} {} {}",
+                blame_entry.commit_id.to_hex_with_len(8),
+                // `line_number` is 0-based, but we want to show 1-based line numbers (as `git`
+                // does).
+                line_number + 1,
+                line
+            )?;
+        }
+    }
+
+    Ok(())
+}

gitoxide-core/src/repository/mod.rs

@@ -21,6 +21,7 @@ pub enum PathsOrPatterns {
 pub mod archive;
 pub mod cat;
 pub use cat::function::cat;
+pub mod blame;
 pub mod commit;
 pub mod config;
 mod credential;

src/plumbing/main.rs

@@ -1483,6 +1483,15 @@ pub fn main() -> Result<()> {
                 },
             ),
         },
+        Subcommands::Blame { file } => prepare_and_run(
+            "blame",
+            trace,
+            verbose,
+            progress,
+            progress_keep_open,
+            None,
+            move |_progress, out, _err| core::repository::blame::blame_file(repository(Mode::Lenient)?, &file, out),
+        ),
         Subcommands::Completions { shell, out_dir } => {
             let mut app = Args::command();
 

src/plumbing/options/mod.rs

@@ -150,6 +150,10 @@ pub enum Subcommands {
     /// Subcommands that need no git repository to run.
     #[clap(subcommand)]
     Free(free::Subcommands),
+    /// Blame lines in a file
+    Blame {
+        file: std::ffi::OsString,
+    },
     /// Generate shell completions to stdout or a directory.
     #[clap(visible_alias = "generate-completions", visible_alias = "shell-completions")]
     Completions {