Support prepare commit hook (#1978)

8 files changed, 171 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61e2589b..af52455f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 * `theme.ron` now supports customizing line break symbol ([#1894](https://github.com/extrawurst/gitui/issues/1894))
 * add confirmation for dialog for undo commit [[@TeFiLeDo](https://github.com/TeFiLeDo)] ([#1912](https://github.com/extrawurst/gitui/issues/1912))
+* support `prepare-commit-msg` hook ([#1873](https://github.com/extrawurst/gitui/issues/1873))
 
 ### Changed
 * do not allow tag when `tag.gpgsign` enabled [[@TeFiLeDo](https://github.com/TeFiLeDo)] ([#1915](https://github.com/extrawurst/gitui/pull/1915))
diff --git a/Cargo.lock b/Cargo.lock
index 1792def0..30cdfc0f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -714,7 +714,7 @@ dependencies = [
 
 [[package]]
 name = "git2-hooks"
-version = "0.3.0"
+version = "0.3.1"
 dependencies = [
  "git2",
  "git2-testing",
diff --git a/README.md b/README.md
index 0ae563ed..3b4b9c9e 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,7 @@
 
 - Fast and intuitive **keyboard only** control
 - Context based help (**no need to memorize** tons of hot-keys)
-- Inspect, commit, and amend changes (incl. hooks: *pre-commit*,*commit-msg*,*post-commit*)
+- Inspect, commit, and amend changes (incl. hooks: *pre-commit*,*commit-msg*,*post-commit*,*prepare-commit-msg*)
 - Stage, unstage, revert and reset files, hunks and lines
 - Stashing (save, pop, apply, drop, and inspect)
 - Push / Fetch to / from remote
diff --git a/asyncgit/src/sync/hooks.rs b/asyncgit/src/sync/hooks.rs
index f480da07..b6928918 100644
--- a/asyncgit/src/sync/hooks.rs
+++ b/asyncgit/src/sync/hooks.rs
@@ -1,5 +1,6 @@
 use super::{repository::repo, RepoPath};
 use crate::error::Result;
+pub use git2_hooks::PrepareCommitMsgSource;
 use scopetime::scope_time;
 
 ///
@@ -59,6 +60,22 @@ pub fn hooks_post_commit(repo_path: &RepoPath) -> Result<HookResult> {
 	Ok(git2_hooks::hooks_post_commit(&repo, None)?.into())
 }
 
+///
+pub fn hooks_prepare_commit_msg(
+	repo_path: &RepoPath,
+	source: PrepareCommitMsgSource,
+	msg: &mut String,
+) -> Result<HookResult> {
+	scope_time!("hooks_prepare_commit_msg");
+
+	let repo = repo(repo_path)?;
+
+	Ok(git2_hooks::hooks_prepare_commit_msg(
+		&repo, None, source, msg,
+	)?
+	.into())
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
diff --git a/asyncgit/src/sync/mod.rs b/asyncgit/src/sync/mod.rs
index 909bea6f..83683a9e 100644
--- a/asyncgit/src/sync/mod.rs
+++ b/asyncgit/src/sync/mod.rs
@@ -65,7 +65,8 @@ pub use config::{
 pub use diff::get_diff_commit;
 pub use git2::BranchType;
 pub use hooks::{
-	hooks_commit_msg, hooks_post_commit, hooks_pre_commit, HookResult,
+	hooks_commit_msg, hooks_post_commit, hooks_pre_commit,
+	hooks_prepare_commit_msg, HookResult, PrepareCommitMsgSource,
 };
 pub use hunks::{reset_hunk, stage_hunk, unstage_hunk};
 pub use ignore::add_to_ignore;
diff --git a/git2-hooks/Cargo.toml b/git2-hooks/Cargo.toml
index c85f4cc9..1c6c63e5 100644
--- a/git2-hooks/Cargo.toml
+++ b/git2-hooks/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "git2-hooks"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["extrawurst <mail@rusticorn.com>"]
 edition = "2021"
 description = "adds git hooks support based on git2-rs"
diff --git a/git2-hooks/src/lib.rs b/git2-hooks/src/lib.rs
index 0cf5ac8d..ea7842cc 100644
--- a/git2-hooks/src/lib.rs
+++ b/git2-hooks/src/lib.rs
@@ -27,6 +27,7 @@ use git2::Repository;
 pub const HOOK_POST_COMMIT: &str = "post-commit";
 pub const HOOK_PRE_COMMIT: &str = "pre-commit";
 pub const HOOK_COMMIT_MSG: &str = "commit-msg";
+pub const HOOK_PREPARE_COMMIT_MSG: &str = "prepare-commit-msg";
 
 const HOOK_COMMIT_MSG_TEMP_FILE: &str = "COMMIT_EDITMSG";
 
@@ -152,6 +153,65 @@ pub fn hooks_post_commit(
 	hook.run_hook(&[])
 }
 
+///
+pub enum PrepareCommitMsgSource {
+	Message,
+	Template,
+	Merge,
+	Squash,
+	Commit(git2::Oid),
+}
+
+/// this hook is documented here <https://git-scm.com/docs/githooks#_prepare_commit_msg>
+pub fn hooks_prepare_commit_msg(
+	repo: &Repository,
+	other_paths: Option<&[&str]>,
+	source: PrepareCommitMsgSource,
+	msg: &mut String,
+) -> Result<HookResult> {
+	let hook =
+		HookPaths::new(repo, other_paths, HOOK_PREPARE_COMMIT_MSG)?;
+
+	if !hook.found() {
+		return Ok(HookResult::NoHookFound);
+	}
+
+	let temp_file = hook.git.join(HOOK_COMMIT_MSG_TEMP_FILE);
+	File::create(&temp_file)?.write_all(msg.as_bytes())?;
+
+	let temp_file_path = temp_file.as_os_str().to_string_lossy();
+
+	let vec = vec![
+		temp_file_path.as_ref(),
+		match source {
+			PrepareCommitMsgSource::Message => "message",
+			PrepareCommitMsgSource::Template => "template",
+			PrepareCommitMsgSource::Merge => "merge",
+			PrepareCommitMsgSource::Squash => "squash",
+			PrepareCommitMsgSource::Commit(_) => "commit",
+		},
+	];
+	let mut args = vec;
+
+	let id = if let PrepareCommitMsgSource::Commit(id) = &source {
+		Some(id.to_string())
+	} else {
+		None
+	};
+
+	if let Some(id) = &id {
+		args.push(id);
+	}
+
+	let res = hook.run_hook(args.as_slice())?;
+
+	// load possibly altered msg
+	msg.clear();
+	File::open(temp_file)?.read_to_string(msg)?;
+
+	Ok(res)
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -480,4 +540,65 @@ exit 0
 
 		assert_eq!(hook.pwd, git_root.parent().unwrap());
 	}
+
+	#[test]
+	fn test_hooks_prep_commit_msg_success() {
+		let (_td, repo) = repo_init();
+
+		let hook = b"#!/bin/sh
+echo msg:$2 > $1
+exit 0
+        ";
+
+		create_hook(&repo, HOOK_PREPARE_COMMIT_MSG, hook);
+
+		let mut msg = String::from("test");
+		let res = hooks_prepare_commit_msg(
+			&repo,
+			None,
+			PrepareCommitMsgSource::Message,
+			&mut msg,
+		)
+		.unwrap();
+
+		assert!(matches!(res, HookResult::Ok { .. }));
+		assert_eq!(msg, String::from("msg:message\n"));
+	}
+
+	#[test]
+	fn test_hooks_prep_commit_msg_reject() {
+		let (_td, repo) = repo_init();
+
+		let hook = b"#!/bin/sh
+echo $2,$3 > $1
+echo 'rejected'
+exit 2
+        ";
+
+		create_hook(&repo, HOOK_PREPARE_COMMIT_MSG, hook);
+
+		let mut msg = String::from("test");
+		let res = hooks_prepare_commit_msg(
+			&repo,
+			None,
+			PrepareCommitMsgSource::Commit(git2::Oid::zero()),
+			&mut msg,
+		)
+		.unwrap();
+
+		let HookResult::RunNotSuccessful { code, stdout, .. } = res
+		else {
+			unreachable!()
+		};
+
+		assert_eq!(code.unwrap(), 2);
+		assert_eq!(&stdout, "rejected\n");
+
+		assert_eq!(
+			msg,
+			String::from(
+				"commit,0000000000000000000000000000000000000000\n"
+			)
+		);
+	}
 }
diff --git a/src/components/commit.rs b/src/components/commit.rs
index ba32394a..bd762878 100644
--- a/src/components/commit.rs
+++ b/src/components/commit.rs
@@ -14,8 +14,8 @@ use anyhow::{bail, Ok, Result};
 use asyncgit::{
 	cached, message_prettify,
 	sync::{
-		self, get_config_string, CommitId, HookResult, RepoPathRef,
-		RepoState,
+		self, get_config_string, CommitId, HookResult,
+		PrepareCommitMsgSource, RepoPathRef, RepoState,
 	},
 	StatusItem, StatusItemType,
 };
@@ -366,7 +366,7 @@ impl CommitComponent {
 
 		let repo_state = sync::repo_state(&self.repo.borrow())?;
 
-		self.mode = if repo_state != RepoState::Clean
+		let (mode, msg_source) = if repo_state != RepoState::Clean
 			&& reword.is_some()
 		{
 			bail!("cannot reword while repo is not in a clean state");
@@ -381,7 +381,7 @@ impl CommitComponent {
 				.combine(),
 			);
 			self.input.set_title(strings::commit_reword_title());
-			Mode::Reword(reword_id)
+			(Mode::Reword(reword_id), PrepareCommitMsgSource::Message)
 		} else {
 			match repo_state {
 				RepoState::Merge => {
@@ -392,7 +392,7 @@ impl CommitComponent {
 					self.input.set_text(sync::merge_msg(
 						&self.repo.borrow(),
 					)?);
-					Mode::Merge(ids)
+					(Mode::Merge(ids), PrepareCommitMsgSource::Merge)
 				}
 				RepoState::Revert => {
 					self.input
@@ -400,7 +400,7 @@ impl CommitComponent {
 					self.input.set_text(sync::merge_msg(
 						&self.repo.borrow(),
 					)?);
-					Mode::Revert
+					(Mode::Revert, PrepareCommitMsgSource::Message)
 				}
 
 				_ => {
@@ -430,17 +430,35 @@ impl CommitComponent {
 							.ok()
 					});
 
-					if self.is_empty() {
+					let msg_source = if self.is_empty() {
 						if let Some(s) = &self.commit_template {
 							self.input.set_text(s.clone());
+							PrepareCommitMsgSource::Template
+						} else {
+							PrepareCommitMsgSource::Message
 						}
-					}
+					} else {
+						PrepareCommitMsgSource::Message
+					};
 					self.input.set_title(strings::commit_title());
-					Mode::Normal
+
+					(Mode::Normal, msg_source)
 				}
 			}
 		};
 
+		self.mode = mode;
+
+		let mut msg = self.input.get_text().to_string();
+		if let HookResult::NotOk(e) = sync::hooks_prepare_commit_msg(
+			&self.repo.borrow(),
+			msg_source,
+			&mut msg,
+		)? {
+			log::error!("prepare-commit-msg hook rejection: {e}",);
+		}
+		self.input.set_text(msg);
+
 		self.commit_msg_history_idx = 0;
 		self.input.show()?;