sem_core/git/

bridge.rs

use std::env;
use std::fs;
use std::path::{Path, PathBuf};
use std::sync::{Mutex, OnceLock};

use git2::{Blame, Delta, Diff, DiffOptions, ErrorCode, Oid, Repository};
use thiserror::Error;

use super::types::{CommitInfo, DiffScope, FileChange, FileStatus};

#[derive(Error, Debug)]
pub enum GitError {
    #[error("not a git repository")]
    NotARepo,
    #[error("git error: {0}")]
    Git2(#[from] git2::Error),
    #[error("io error: {0}")]
    Io(#[from] std::io::Error),
}

pub struct GitBridge {
    repo: Repository,
    repo_root: PathBuf,
}

impl GitBridge {
    pub fn open(path: &Path) -> Result<Self, GitError> {
        let repo = match Repository::discover(path) {
            Ok(repo) => repo,
            Err(error) if should_retry_with_command_line_safe_directory(&error, path) => {
                let _guard = owner_validation_lock()
                    .lock()
                    .unwrap_or_else(|poisoned| poisoned.into_inner());
                let _owner_validation = OwnerValidationDisabled::new()?;
                let repo = Repository::discover(path);
                repo.map_err(map_git_error)?
            }
            Err(error) => return Err(map_git_error(error)),
        };
        let repo_root = repo
            .workdir()
            .ok_or(GitError::NotARepo)?
            .to_path_buf();
        Ok(Self { repo, repo_root })
    }

    pub fn repo_root(&self) -> &Path {
        &self.repo_root
    }

    pub fn blame_file(&self, file_path: &Path) -> Result<Blame<'_>, GitError> {
        Ok(self.repo.blame_file(file_path, None)?)
    }

    pub fn commit_summary(&self, oid: Oid) -> Option<String> {
        self.repo
            .find_commit(oid)
            .ok()
            .and_then(|commit| commit.summary().map(String::from))
    }

    pub fn get_head_sha(&self) -> Result<String, GitError> {
        let head = self.repo.head()?;
        let oid = head.target().ok_or_else(|| {
            git2::Error::from_str("HEAD has no target")
        })?;
        Ok(oid.to_string())
    }

    /// Combined detect scope + get files in one call (fast path).
    /// Matches `git diff` behavior: shows working tree changes by default.
    /// Use `--staged` for staged changes only.
    pub fn detect_and_get_files(&self, pathspecs: &[String]) -> Result<(DiffScope, Vec<FileChange>), GitError> {
        // Show working tree changes (unstaged), matching git diff behavior
        let mut working_files = self.get_working_diff_files(pathspecs)?;
        if !working_files.is_empty() {
            self.populate_contents(&mut working_files, &DiffScope::Working)?;
            return Ok((DiffScope::Working, working_files));
        }

        // Clean worktree = no changes
        Ok((DiffScope::Working, Vec::new()))
    }

    /// Get changed files for a specific scope
    pub fn get_changed_files(&self, scope: &DiffScope, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let mut files = match scope {
            DiffScope::Working => {
                self.get_working_diff_files(pathspecs)?
            }
            DiffScope::Staged => self.get_staged_diff_files(pathspecs)?,
            DiffScope::Commit { sha } => self.get_commit_diff_files(sha, pathspecs)?,
            DiffScope::Range { from, to } => self.get_range_diff_files(from, to, pathspecs)?,
            DiffScope::RefToWorking { refspec } => self.get_ref_to_working_diff_files(refspec, pathspecs)?,
        };

        // Filter .sem/ files
        files.retain(|f| !f.file_path.starts_with(".sem/"));

        self.populate_contents(&mut files, scope)?;
        Ok(files)
    }

    /// Resolve the merge base between two refs
    pub fn resolve_merge_base(&self, ref1: &str, ref2: &str) -> Result<String, GitError> {
        let obj1 = self.repo.revparse_single(ref1)?;
        let obj2 = self.repo.revparse_single(ref2)?;
        let oid = self.repo.merge_base(obj1.id(), obj2.id())?;
        Ok(oid.to_string())
    }

    /// Check if a string resolves to a valid git revision
    pub fn is_valid_rev(&self, refspec: &str) -> bool {
        self.repo.revparse_single(refspec).is_ok()
    }

    fn make_diff_opts(pathspecs: &[String]) -> DiffOptions {
        let mut opts = DiffOptions::new();
        for spec in pathspecs {
            opts.pathspec(spec.as_str());
        }
        opts
    }

    fn get_staged_diff_files(&self, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let head_tree = match self.repo.head() {
            Ok(head) => {
                let commit = head.peel_to_commit()?;
                Some(commit.tree()?)
            }
            Err(_) => None, // No commits yet
        };

        let mut opts = Self::make_diff_opts(pathspecs);
        let diff = self.repo.diff_tree_to_index(
            head_tree.as_ref(),
            Some(&self.repo.index()?),
            Some(&mut opts),
        )?;

        Ok(self.diff_to_file_changes(&diff))
    }

    fn get_working_diff_files(&self, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let mut opts = Self::make_diff_opts(pathspecs);
        opts.include_untracked(false);

        let diff = self.repo.diff_index_to_workdir(None, Some(&mut opts))?;
        Ok(self.diff_to_file_changes(&diff))
    }

    fn get_commit_diff_files(&self, sha: &str, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let obj = self.repo.revparse_single(sha)?;
        let commit = obj.peel_to_commit()?;
        let tree = commit.tree()?;

        let parent_tree = if commit.parent_count() > 0 {
            Some(commit.parent(0)?.tree()?)
        } else {
            None
        };

        let mut opts = Self::make_diff_opts(pathspecs);
        let diff = self.repo.diff_tree_to_tree(
            parent_tree.as_ref(),
            Some(&tree),
            Some(&mut opts),
        )?;

        Ok(self.diff_to_file_changes(&diff))
    }

    fn get_range_diff_files(&self, from: &str, to: &str, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let from_obj = self.repo.revparse_single(from)?;
        let to_obj = self.repo.revparse_single(to)?;

        let from_tree = from_obj.peel_to_commit()?.tree()?;
        let to_tree = to_obj.peel_to_commit()?.tree()?;

        let mut opts = Self::make_diff_opts(pathspecs);
        let diff = self.repo.diff_tree_to_tree(
            Some(&from_tree),
            Some(&to_tree),
            Some(&mut opts),
        )?;

        Ok(self.diff_to_file_changes(&diff))
    }

    fn get_ref_to_working_diff_files(&self, refspec: &str, pathspecs: &[String]) -> Result<Vec<FileChange>, GitError> {
        let tree = self.resolve_tree(refspec)?;
        let mut opts = Self::make_diff_opts(pathspecs);
        let diff = self.repo.diff_tree_to_workdir_with_index(
            Some(&tree),
            Some(&mut opts),
        )?;
        Ok(self.diff_to_file_changes(&diff))
    }

    fn diff_to_file_changes(&self, diff: &Diff) -> Vec<FileChange> {
        let mut files = Vec::new();

        for delta in diff.deltas() {
            let (status, file_path, old_file_path) = match delta.status() {
                Delta::Added => {
                    let path = delta
                        .new_file()
                        .path()
                        .and_then(|p| p.to_str())
                        .unwrap_or("")
                        .to_string();
                    (FileStatus::Added, path, None)
                }
                Delta::Deleted => {
                    let path = delta
                        .old_file()
                        .path()
                        .and_then(|p| p.to_str())
                        .unwrap_or("")
                        .to_string();
                    (FileStatus::Deleted, path, None)
                }
                Delta::Modified => {
                    let path = delta
                        .new_file()
                        .path()
                        .and_then(|p| p.to_str())
                        .unwrap_or("")
                        .to_string();
                    (FileStatus::Modified, path, None)
                }
                Delta::Renamed => {
                    let new_path = delta
                        .new_file()
                        .path()
                        .and_then(|p| p.to_str())
                        .unwrap_or("")
                        .to_string();
                    let old_path = delta
                        .old_file()
                        .path()
                        .and_then(|p| p.to_str())
                        .unwrap_or("")
                        .to_string();
                    (FileStatus::Renamed, new_path, Some(old_path))
                }
                _ => continue,
            };

            if !file_path.starts_with(".sem/") {
                files.push(FileChange {
                    file_path,
                    status,
                    old_file_path,
                    before_content: None,
                    after_content: None,
                });
            }
        }

        files
    }

    fn populate_contents(
        &self,
        files: &mut [FileChange],
        scope: &DiffScope,
    ) -> Result<(), GitError> {
        match scope {
            DiffScope::Working => {
                // Resolve HEAD tree once for all before_content reads
                let head_tree = self.resolve_tree("HEAD").ok();
                for file in files.iter_mut() {
                    if file.status != FileStatus::Deleted {
                        file.after_content = self.read_working_file(&file.file_path);
                    }
                    if file.status != FileStatus::Added {
                        file.before_content = head_tree
                            .as_ref()
                            .and_then(|t| self.read_blob_from_tree(t, &file.file_path));
                    }
                }
            }
            DiffScope::Staged => {
                let head_tree = self.resolve_tree("HEAD").ok();
                for file in files.iter_mut() {
                    if file.status != FileStatus::Deleted {
                        file.after_content = self
                            .read_index_file(&file.file_path)
                            .or_else(|| self.read_working_file(&file.file_path));
                    }
                    if file.status != FileStatus::Added {
                        file.before_content = head_tree
                            .as_ref()
                            .and_then(|t| self.read_blob_from_tree(t, &file.file_path));
                    }
                }
            }
            DiffScope::Commit { sha } => {
                // Resolve both trees once instead of per-file
                let after_tree = self.resolve_tree(sha)?;
                let before_tree = self.resolve_tree(&format!("{sha}~1")).ok();
                for file in files.iter_mut() {
                    if file.status != FileStatus::Deleted {
                        file.after_content =
                            self.read_blob_from_tree(&after_tree, &file.file_path);
                    }
                    if file.status != FileStatus::Added {
                        file.before_content = before_tree
                            .as_ref()
                            .and_then(|t| self.read_blob_from_tree(t, &file.file_path));
                    }
                }
            }
            DiffScope::Range { from, to } => {
                let after_tree = self.resolve_tree(to)?;
                let before_tree = self.resolve_tree(from)?;
                for file in files.iter_mut() {
                    if file.status != FileStatus::Deleted {
                        file.after_content =
                            self.read_blob_from_tree(&after_tree, &file.file_path);
                    }
                    if file.status != FileStatus::Added {
                        let path = file
                            .old_file_path
                            .as_deref()
                            .unwrap_or(&file.file_path);
                        file.before_content =
                            self.read_blob_from_tree(&before_tree, path);
                    }
                }
            }
            DiffScope::RefToWorking { refspec } => {
                let before_tree = self.resolve_tree(refspec)?;
                for file in files.iter_mut() {
                    if file.status != FileStatus::Deleted {
                        file.after_content = self.read_working_file(&file.file_path);
                    }
                    if file.status != FileStatus::Added {
                        file.before_content =
                            self.read_blob_from_tree(&before_tree, &file.file_path);
                    }
                }
            }
        }
        Ok(())
    }

    fn resolve_tree(&self, refspec: &str) -> Result<git2::Tree<'_>, GitError> {
        let obj = self.repo.revparse_single(refspec)?;
        let commit = obj.peel_to_commit()?;
        Ok(commit.tree()?)
    }

    fn normalize_line_endings(s: String) -> String {
        if s.contains('\r') {
            s.replace("\r\n", "\n").replace('\r', "\n")
        } else {
            s
        }
    }

    fn read_blob_from_tree(&self, tree: &git2::Tree, file_path: &str) -> Option<String> {
        let entry = tree.get_path(Path::new(file_path)).ok()?;
        let blob = self.repo.find_blob(entry.id()).ok()?;
        std::str::from_utf8(blob.content())
            .ok()
            .map(|s| Self::normalize_line_endings(s.to_string()))
    }

    fn read_working_file(&self, file_path: &str) -> Option<String> {
        let full_path = self.repo_root.join(file_path);
        fs::read_to_string(full_path)
            .ok()
            .map(Self::normalize_line_endings)
    }

    fn read_index_file(&self, file_path: &str) -> Option<String> {
        let index = self.repo.index().ok()?;
        let entry = index.get_path(Path::new(file_path), 0)?;
        let blob = self.repo.find_blob(entry.id).ok()?;
        std::str::from_utf8(blob.content())
            .ok()
            .map(|s| Self::normalize_line_endings(s.to_string()))
    }


    /// Read file content at a specific git ref (commit SHA, branch, tag, etc.)
    pub fn read_file_at_ref(&self, refspec: &str, file_path: &str) -> Result<Option<String>, GitError> {
        let tree = self.resolve_tree(refspec)?;
        Ok(self.read_blob_from_tree(&tree, file_path))
    }

    /// Get commits that modified a specific file, walking history from HEAD.
    /// Returns commits in reverse chronological order (newest first).
    pub fn get_file_commits(&self, file_path: &str, limit: usize) -> Result<Vec<CommitInfo>, GitError> {
        let mut revwalk = self.repo.revwalk()?;
        revwalk.push_head()?;
        revwalk.set_sorting(git2::Sort::TIME)?;

        let mut commits = Vec::new();
        let path = Path::new(file_path);

        for oid_result in revwalk {
            let oid = oid_result?;
            let commit = self.repo.find_commit(oid)?;
            let tree = commit.tree()?;

            // Check if this file exists in this commit's tree
            let file_in_commit = tree.get_path(path).ok().map(|e| e.id());

            // Compare with parent to see if the file changed
            let file_in_parent = if commit.parent_count() > 0 {
                commit.parent(0)
                    .ok()
                    .and_then(|p| p.tree().ok())
                    .and_then(|t| t.get_path(path).ok().map(|e| e.id()))
            } else {
                None // No parent = initial commit, file was added
            };

            // Include if file changed between parent and this commit
            let changed = match (file_in_commit, file_in_parent) {
                (Some(cur), Some(prev)) => cur != prev,  // content changed
                (Some(_), None) => true,                   // file added
                (None, Some(_)) => true,                   // file deleted
                (None, None) => false,                     // file not present in either
            };

            if changed {
                let sha = oid.to_string();
                commits.push(CommitInfo {
                    short_sha: sha[..7.min(sha.len())].to_string(),
                    sha,
                    author: commit.author().name().unwrap_or("unknown").to_string(),
                    date: commit.time().seconds().to_string(),
                    message: commit.message().unwrap_or("").to_string(),
                });

                if commits.len() >= limit {
                    break;
                }
            }
        }

        Ok(commits)
    }

    /// Get all file paths changed in a single commit (vs its parent).
    /// Returns file paths from the new side of each delta.
    pub fn get_commit_changed_files(&self, sha: &str) -> Result<Vec<String>, GitError> {
        let obj = self.repo.revparse_single(sha)?;
        let commit = obj.peel_to_commit()?;
        let tree = commit.tree()?;
        let parent_tree = if commit.parent_count() > 0 {
            Some(commit.parent(0)?.tree()?)
        } else {
            None
        };
        let diff = self.repo.diff_tree_to_tree(parent_tree.as_ref(), Some(&tree), None)?;
        let mut paths = Vec::new();
        for delta in diff.deltas() {
            if let Some(p) = delta.new_file().path().and_then(|p| p.to_str()) {
                paths.push(p.to_string());
            }
            // Also include old path for deletions/renames
            if let Some(p) = delta.old_file().path().and_then(|p| p.to_str()) {
                if !paths.contains(&p.to_string()) {
                    paths.push(p.to_string());
                }
            }
        }
        Ok(paths)
    }

    pub fn get_log(&self, limit: usize) -> Result<Vec<CommitInfo>, GitError> {
        let mut revwalk = self.repo.revwalk()?;
        revwalk.push_head()?;

        let mut commits = Vec::new();
        for (i, oid_result) in revwalk.enumerate() {
            if i >= limit {
                break;
            }
            let oid = oid_result?;
            let commit = self.repo.find_commit(oid)?;
            let sha = oid.to_string();
            commits.push(CommitInfo {
                short_sha: sha[..7.min(sha.len())].to_string(),
                sha,
                author: commit.author().name().unwrap_or("unknown").to_string(),
                date: commit.time().seconds().to_string(),
                message: commit.message().unwrap_or("").to_string(),
            });
        }

        Ok(commits)
    }
}

fn map_git_error(error: git2::Error) -> GitError {
    if error.code() == ErrorCode::NotFound {
        GitError::NotARepo
    } else {
        GitError::Git2(error)
    }
}

fn should_retry_with_command_line_safe_directory(error: &git2::Error, path: &Path) -> bool {
    let safe_directories = command_line_safe_directories();
    should_retry_with_safe_directory(error, path, &safe_directories)
}

fn should_retry_with_safe_directory(error: &git2::Error, path: &Path, safe_directories: &[String]) -> bool {
    error.code() == ErrorCode::Owner
        && nearest_git_root(path).is_some_and(|repo_root| {
            safe_directories.iter().any(|safe_directory| {
                safe_directory == "*"
                    || paths_match(&repo_root, Path::new(safe_directory))
            })
        })
}

fn command_line_safe_directories() -> Vec<String> {
    let count = env::var("GIT_CONFIG_COUNT")
        .ok()
        .and_then(|value| value.parse::<usize>().ok())
        .unwrap_or_default();

    (0..count)
        .filter_map(|index| {
            let key = env::var(format!("GIT_CONFIG_KEY_{index}")).ok()?;
            if key.eq_ignore_ascii_case("safe.directory") {
                env::var(format!("GIT_CONFIG_VALUE_{index}")).ok()
            } else {
                None
            }
        })
        .collect()
}

fn nearest_git_root(path: &Path) -> Option<PathBuf> {
    let mut current = if path.is_file() {
        path.parent()?
    } else {
        path
    };

    loop {
        if current.join(".git").exists() {
            return Some(fs::canonicalize(current).unwrap_or_else(|_| current.to_path_buf()));
        }

        current = current.parent()?;
    }
}

fn paths_match(left: &Path, right: &Path) -> bool {
    let left = fs::canonicalize(left).unwrap_or_else(|_| left.to_path_buf());
    let right = fs::canonicalize(right).unwrap_or_else(|_| right.to_path_buf());

    if cfg!(windows) {
        left.to_string_lossy()
            .eq_ignore_ascii_case(&right.to_string_lossy())
    } else {
        left == right
    }
}

fn owner_validation_lock() -> &'static Mutex<()> {
    static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
    LOCK.get_or_init(|| Mutex::new(()))
}

struct OwnerValidationDisabled;

impl OwnerValidationDisabled {
    fn new() -> Result<Self, GitError> {
        // libgit2 stores this as a process-global option; callers hold owner_validation_lock.
        unsafe { git2::opts::set_verify_owner_validation(false)? };
        Ok(Self)
    }
}

impl Drop for OwnerValidationDisabled {
    fn drop(&mut self) {
        // Restore the default before the owner-validation lock is released.
        unsafe {
            let _ = git2::opts::set_verify_owner_validation(true);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use git2::{ErrorClass, Oid, Repository, Signature};
    use tempfile::TempDir;

    fn commit_file(repo: &Repository, file_path: &str, contents: &str, message: &str) -> Oid {
        fs::write(repo.workdir().unwrap().join(file_path), contents).unwrap();

        let mut index = repo.index().unwrap();
        index.add_path(Path::new(file_path)).unwrap();
        index.write().unwrap();

        let tree_id = index.write_tree().unwrap();
        let tree = repo.find_tree(tree_id).unwrap();
        let sig = Signature::now("Test User", "test@example.com").unwrap();

        match repo.head() {
            Ok(head) => {
                let parent = repo.find_commit(head.target().unwrap()).unwrap();
                repo.commit(Some("HEAD"), &sig, &sig, message, &tree, &[&parent])
                    .unwrap()
            }
            Err(_) => repo
                .commit(Some("HEAD"), &sig, &sig, message, &tree, &[])
                .unwrap(),
        }
    }

    #[test]
    fn clean_worktree_does_not_fall_back_to_head_commit() {
        let temp = TempDir::new().unwrap();
        let repo = Repository::init(temp.path()).unwrap();

        commit_file(&repo, "sample.ts", "export function a() {\n  return 1;\n}\n", "init");
        commit_file(
            &repo,
            "sample.ts",
            "export function a() {\n  return 2;\n}\n",
            "change a",
        );

        let bridge = GitBridge::open(temp.path()).unwrap();
        let (scope, files) = bridge.detect_and_get_files(&[]).unwrap();

        assert!(matches!(scope, DiffScope::Working));
        assert!(files.is_empty());
    }

    #[test]
    fn owner_error_retries_for_command_line_safe_directory() {
        let temp = TempDir::new().unwrap();
        Repository::init(temp.path()).unwrap();

        let owner_error = git2::Error::new(
            ErrorCode::Owner,
            ErrorClass::Config,
            "owner mismatch",
        );
        let safe_directories = [temp.path().to_string_lossy().to_string()];

        assert!(should_retry_with_safe_directory(
            &owner_error,
            temp.path(),
            &safe_directories,
        ));

        let other_directories = [temp.path().join("other").to_string_lossy().to_string()];
        assert!(!should_retry_with_safe_directory(
            &owner_error,
            temp.path(),
            &other_directories,
        ));

        let not_found_error = git2::Error::new(
            ErrorCode::NotFound,
            ErrorClass::Repository,
            "not found",
        );
        assert!(!should_retry_with_safe_directory(
            &not_found_error,
            temp.path(),
            &["*".to_string()],
        ));
    }

    #[test]
    fn explicit_commit_scope_still_reads_head_commit_diff() {
        let temp = TempDir::new().unwrap();
        let repo = Repository::init(temp.path()).unwrap();

        commit_file(&repo, "sample.ts", "export function a() {\n  return 1;\n}\n", "init");
        let head_oid = commit_file(
            &repo,
            "sample.ts",
            "export function a() {\n  return 2;\n}\n",
            "change a",
        );

        let bridge = GitBridge::open(temp.path()).unwrap();
        let files = bridge
            .get_changed_files(&DiffScope::Commit {
                sha: head_oid.to_string(),
            }, &[])
            .unwrap();

        assert_eq!(files.len(), 1);
        assert_eq!(files[0].file_path, "sample.ts");
        assert_eq!(files[0].status, FileStatus::Modified);
    }

    #[test]
    fn crlf_only_difference_in_working_file_is_invisible() {
        let temp = TempDir::new().unwrap();
        let repo = Repository::init(temp.path()).unwrap();

        commit_file(&repo, "sample.rs", "fn a() {}\n", "init");
        fs::write(temp.path().join("sample.rs"), "fn a() {}\r\n").unwrap();

        let bridge = GitBridge::open(temp.path()).unwrap();
        let files = bridge.get_changed_files(&DiffScope::Working, &[]).unwrap();

        assert_eq!(files.len(), 1, "expected git to detect the CRLF change as modified");

        let before = files[0].before_content.as_deref().unwrap();
        let after = files[0].after_content.as_deref().unwrap();

        assert_eq!(before, after, "CRLF-only difference should be invisible after normalization");
    }

    #[test]
    fn crlf_stored_in_blob_is_normalized_on_read() {
        let temp = TempDir::new().unwrap();
        let repo = Repository::init(temp.path()).unwrap();

        repo.config().unwrap().set_str("core.autocrlf", "false").unwrap();
        commit_file(&repo, "sample.rs", "fn a() {}\r\n", "init");
        fs::write(temp.path().join("sample.rs"), "fn a() {}\r\nfn b() {}\r\n").unwrap();

        let bridge = GitBridge::open(temp.path()).unwrap();
        let files = bridge.get_changed_files(&DiffScope::Working, &[]).unwrap();

        assert_eq!(files.len(), 1, "expected git to detect the modification");

        let before = files[0].before_content.as_deref().unwrap();
        assert!(!before.contains('\r'), "before_content read from CRLF blob should be normalized to LF");
    }
}