feat(jujutsu): add jujustu support (#930)

* feat: jujustu support

If the .git directory can't be opened (usually because the `.git` directory is missing) it attempts to find the git repository in the location used by Jujutsu (i.e. `.jj/repo/store/git`). If the Jujutsu git directory doesn't exist, then the origin error is propogated.
CODE

test: add unit tests for opening jujutsu repo
Update git-cliff-core/src/repo.rs

Co-authored-by: Orhun Parmaksız <[email protected]>
Update git-cliff-core/src/repo.rs

Co-authored-by: Orhun Parmaksız <[email protected]>
Update git-cliff-core/src/repo.rs

Co-authored-by: Orhun Parmaksız <[email protected]>
Update git-cliff-core/src/repo.rs

Co-authored-by: Orhun Parmaksız <[email protected]>

* docs: Add page to website for jujutsu

---------

Co-authored-by: Orhun Parmaksız <[email protected]>

git-cliff-core/src/repo.rs

@@ -48,7 +48,15 @@ impl Repository {
 	/// Initializes (opens) the repository.
 	pub fn init(path: PathBuf) -> Result<Self> {
 		if path.exists() {
-			let inner = GitRepository::open(&path)?;
+			let inner = GitRepository::open(&path).or_else(|err| {
+				let jujutsu_path =
+					path.join(".jj").join("repo").join("store").join("git");
+				if jujutsu_path.exists() {
+					GitRepository::open_bare(&jujutsu_path)
+				} else {
+					Err(err)
+				}
+			})?;
 			let changed_files_cache_path = inner
 				.path()
 				.join(env!("CARGO_PKG_NAME"))
@@ -503,9 +511,12 @@ fn ssh_path_segments(url: &str) -> Result<Remote> {
 mod test {
 	use super::*;
 	use crate::commit::Commit as AppCommit;
-	use std::env;
 	use std::process::Command;
 	use std::str;
+	use std::{
+		env,
+		fs,
+	};
 	use temp_dir::TempDir;
 
 	fn get_last_commit_hash() -> Result<String> {
@@ -735,6 +746,62 @@ mod test {
 		(repo, temp_dir)
 	}
 
+	#[test]
+	fn open_jujutsu_repo() {
+		let (repo, _temp_dir) = create_temp_repo();
+		// working copy is the directory that contains the .git directory:
+		let working_copy = repo.path;
+
+		// Make the Git repository bare and set HEAD
+		std::process::Command::new("git")
+			.args(["config", "core.bare", "true"])
+			.current_dir(&working_copy)
+			.status()
+			.expect("failed to make git repo non-bare");
+		// Move the Git repo into jj
+		let store = working_copy.join(".jj").join("repo").join("store");
+		fs::create_dir_all(&store).expect("failed to create dir");
+		fs::rename(working_copy.join(".git"), store.join("git"))
+			.expect("failed to move git repo");
+
+		// Open repo from working copy, that contains the .jj directory
+		let repo = Repository::init(working_copy).expect("failed to init repo");
+
+		// macOS canonical path for temp directories is in /private
+		// libgit2 forces the path to be canonical regardless of what we pass in
+		if repo.inner.path().starts_with("/private") {
+			assert_eq!(
+				repo.inner.path().strip_prefix("/private"),
+				store.join("git").strip_prefix("/"),
+				"open git repo in .jj/repo/store/"
+			);
+		} else {
+			assert_eq!(
+				repo.inner.path(),
+				store.join("git"),
+				"open git repo in .jj/repo/store/"
+			);
+		}
+	}
+
+	#[test]
+	fn propagate_error_if_no_repo_found() {
+		let temp_dir =
+			TempDir::with_prefix("git-cliff-").expect("failed to create temp dir");
+
+		let path = temp_dir.path().to_path_buf();
+
+		let result = Repository::init(path.clone());
+
+		assert!(result.is_err());
+		if let Err(error) = result {
+			assert!(format!("{error:?}").contains(
+				format!("could not find repository at '{}'", path.display())
+					.as_str()
+			))
+		}
+	}
+
 	fn create_commit_with_files<'a>(
 		repo: &'a Repository,
 		files: Vec<(&'a str, &'a str)>,

website/docs/usage/jujutsu.md

@@ -0,0 +1,33 @@
+---
+sidebar_position: 12
+---
+
+# Jujutsu
+
+You can use with a repository that has been cloned using [jujutsu](https://martinvonz.github.io/jj/latest/).
+
+## Colocated
+
+If the repository was cloned by `jujutsu` using the `--colocate` option, then all you need to do is make sure that
+you have checked out your mainline branch using git.
+If you don't, then you will likely see an error about an unborn branch.
+
+## Non-colocated
+
+If the repository was cloned by `jujutsu` but *not* using the `--colocate` option,
+then the Git repository, normally the `.git` directory, is located in `.jj/repo/store/git`
+
+Create a file in the root of your repository that tells Git, and `git-cliff` where the Git repository is
+and update the `HEAD` to point to your main remote branch:
+
+e.g.:
+
+```bash
+jj git clone https://github.com/orhun/menyoki
+cd menyoki
+echo "gitdir: .jj/repo/store/git" > .git
+echo "ref: refs/remotes/origin/master" > .jj/repo/store/git/HEAD
+```
+
+N.B.: Replace `master` in the last command with the name of your main remote branch. e.g. `main`, `trunk`, etc.
+