use std::{
    fs,
    io::Write,
    path::{Path, PathBuf},
};

use git2::{PushOptions, Repository, build::CheckoutBuilder};
use services::services::git::{GitCli, GitCliError, GitService};
use tempfile::TempDir;
// Avoid direct git CLI usage in tests; exercise GitService instead.

fn write_file<P: AsRef<Path>>(base: P, rel: &str, content: &str) {
    let path = base.as_ref().join(rel);
    if let Some(parent) = path.parent() {
        fs::create_dir_all(parent).unwrap();
    }
    let mut f = fs::File::create(&path).unwrap();
    f.write_all(content.as_bytes()).unwrap();
}

fn commit_all(repo: &Repository, message: &str) {
    let mut index = repo.index().unwrap();
    index
        .add_all(["*"].iter(), git2::IndexAddOption::DEFAULT, None)
        .unwrap();
    index.write().unwrap();
    let tree_id = index.write_tree().unwrap();
    let tree = repo.find_tree(tree_id).unwrap();
    let sig = repo.signature().unwrap();
    let parents: Vec<git2::Commit> = match repo.head() {
        Ok(h) => vec![h.peel_to_commit().unwrap()],
        Err(e) if e.code() == git2::ErrorCode::UnbornBranch => vec![],
        Err(e) => panic!("failed to read HEAD: {e}"),
    };
    let parent_refs: Vec<&git2::Commit> = parents.iter().collect();
    let update_ref = if repo.head().is_ok() {
        Some("HEAD")
    } else {
        None
    };
    repo.commit(update_ref, &sig, &sig, message, &tree, &parent_refs)
        .unwrap();
}

fn checkout_branch(repo: &Repository, name: &str) {
    repo.set_head(&format!("refs/heads/{name}")).unwrap();
    let mut co = CheckoutBuilder::new();
    co.force();
    repo.checkout_head(Some(&mut co)).unwrap();
}

fn create_branch_from_head(repo: &Repository, name: &str) {
    let head = repo.head().unwrap().peel_to_commit().unwrap();
    let _ = repo.branch(name, &head, true).unwrap();
}

fn configure_user(repo: &Repository) {
    let mut cfg = repo.config().unwrap();
    cfg.set_str("user.name", "Test User").unwrap();
    cfg.set_str("user.email", "test@example.com").unwrap();
}

fn push_ref(repo: &Repository, local: &str, remote: &str) {
    let mut remote_handle = repo.find_remote("origin").unwrap();
    let mut opts = PushOptions::new();
    let spec = format!("+{local}:{remote}");
    remote_handle
        .push(&[spec.as_str()], Some(&mut opts))
        .unwrap();
}

fn add_path(repo_path: &Path, path: &str) {
    let git = GitCli::new();
    git.git(repo_path, ["add", path]).unwrap();
}

use services::services::git::DiffTarget;

// Non-conflicting setup used by several tests
fn setup_repo_with_worktree(root: &TempDir) -> (PathBuf, PathBuf) {
    let repo_path = root.path().join("repo");
    let worktree_path = root.path().join("wt-feature");

    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");

    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");

    write_file(&repo_path, "common.txt", "base\n");
    commit_all(&repo, "initial main commit");

    create_branch_from_head(&repo, "old-base");
    checkout_branch(&repo, "old-base");
    write_file(&repo_path, "base.txt", "from old-base\n");
    commit_all(&repo, "old-base commit");

    checkout_branch(&repo, "main");
    create_branch_from_head(&repo, "new-base");
    checkout_branch(&repo, "new-base");
    write_file(&repo_path, "base.txt", "from new-base\n");
    commit_all(&repo, "new-base commit");

    checkout_branch(&repo, "old-base");
    create_branch_from_head(&repo, "feature");

    let svc = GitService::new();
    svc.add_worktree(&repo_path, &worktree_path, "feature", false)
        .expect("create worktree");

    write_file(&worktree_path, "feat.txt", "feat change\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature commit");

    (repo_path, worktree_path)
}

// Conflicting setup to simulate interactive rebase interruption
fn setup_conflict_repo_with_worktree(root: &TempDir) -> (PathBuf, PathBuf) {
    let repo_path = root.path().join("repo");
    let worktree_path = root.path().join("wt-feature");

    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");

    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");

    write_file(&repo_path, "conflict.txt", "base\n");
    commit_all(&repo, "initial main commit");

    // old-base modifies conflict.txt one way
    create_branch_from_head(&repo, "old-base");
    checkout_branch(&repo, "old-base");
    write_file(&repo_path, "conflict.txt", "old-base version\n");
    commit_all(&repo, "old-base change");

    // feature builds on old-base and modifies same lines differently
    create_branch_from_head(&repo, "feature");

    // new-base modifies in a conflicting way
    checkout_branch(&repo, "main");
    create_branch_from_head(&repo, "new-base");
    checkout_branch(&repo, "new-base");
    write_file(&repo_path, "conflict.txt", "new-base version\n");
    commit_all(&repo, "new-base change");

    // add a worktree for feature and create the conflicting commit
    let svc = GitService::new();
    svc.add_worktree(&repo_path, &worktree_path, "feature", false)
        .expect("create worktree");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    write_file(&worktree_path, "conflict.txt", "feature version\n");
    commit_all(&wt_repo, "feature conflicting change");

    (repo_path, worktree_path)
}

// Setup where feature has no unique commits (feature == old-base)
fn setup_no_unique_feature_repo(root: &TempDir) -> (PathBuf, PathBuf) {
    let repo_path = root.path().join("repo");
    let worktree_path = root.path().join("wt-feature");

    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");

    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");

    write_file(&repo_path, "base.txt", "main base\n");
    commit_all(&repo, "initial main commit");

    // Create old-base at this point
    create_branch_from_head(&repo, "old-base");
    // Create new-base diverging
    checkout_branch(&repo, "main");
    create_branch_from_head(&repo, "new-base");
    checkout_branch(&repo, "new-base");
    write_file(&repo_path, "advance.txt", "new base\n");
    commit_all(&repo, "advance new-base");

    // Create feature equal to old-base (no unique commits)
    checkout_branch(&repo, "old-base");
    create_branch_from_head(&repo, "feature");
    let svc = GitService::new();
    svc.add_worktree(&repo_path, &worktree_path, "feature", false)
        .expect("create worktree");

    (repo_path, worktree_path)
}

// Simple two-way conflict between main and feature on the same file
fn setup_direct_conflict_repo(root: &TempDir) -> (PathBuf, PathBuf) {
    let repo_path = root.path().join("repo");
    let worktree_path = root.path().join("wt-feature");

    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");

    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");

    write_file(&repo_path, "conflict.txt", "base\n");
    commit_all(&repo, "initial main commit");

    // Create feature and commit conflicting change
    create_branch_from_head(&repo, "feature");
    let svc = GitService::new();
    svc.add_worktree(&repo_path, &worktree_path, "feature", false)
        .expect("create worktree");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    write_file(&worktree_path, "conflict.txt", "feature change\n");
    commit_all(&wt_repo, "feature change");

    // Change main in a conflicting way
    checkout_branch(&repo, "main");
    write_file(&repo_path, "conflict.txt", "main change\n");
    commit_all(&repo, "main change");

    (repo_path, worktree_path)
}

#[test]
fn push_reports_non_fast_forward() {
    let temp_dir = TempDir::new().unwrap();
    let remote_path = temp_dir.path().join("remote.git");
    Repository::init_bare(&remote_path).expect("init bare remote");
    let remote_url = remote_path.to_str().expect("remote path str");

    // Seed the bare repo with an initial main branch commit
    let seed_path = temp_dir.path().join("seed");
    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&seed_path)
        .expect("init seed repo");
    let seed_repo = Repository::open(&seed_path).expect("open seed repo");
    configure_user(&seed_repo);
    seed_repo.remote("origin", remote_url).expect("add remote");
    push_ref(&seed_repo, "refs/heads/main", "refs/heads/main");
    Repository::open_bare(&remote_path)
        .expect("open bare remote")
        .set_head("refs/heads/main")
        .expect("set remote HEAD");

    // Local clone that will attempt the push later
    let local_path = temp_dir.path().join("local");
    let local_repo = Repository::clone(remote_url, &local_path).expect("clone local");
    configure_user(&local_repo);
    checkout_branch(&local_repo, "main");
    write_file(&local_path, "file.txt", "initial local\n");
    commit_all(&local_repo, "initial local commit");
    push_ref(&local_repo, "refs/heads/main", "refs/heads/main");

    // Separate clone simulates someone else pushing first
    let updater_path = temp_dir.path().join("updater");
    let updater_repo = Repository::clone(remote_url, &updater_path).expect("clone updater");
    configure_user(&updater_repo);
    checkout_branch(&updater_repo, "main");
    write_file(&updater_path, "file.txt", "upstream change\n");
    commit_all(&updater_repo, "upstream commit");
    push_ref(&updater_repo, "refs/heads/main", "refs/heads/main");

    // Local branch diverges but has not fetched the updater's commit
    write_file(&local_path, "file.txt", "local change\n");
    commit_all(&local_repo, "local commit");
    let remote = local_repo.find_remote("origin").expect("origin remote");
    let remote_url_string = remote.url().expect("origin url").to_string();

    let git_cli = GitCli::new();
    let result = git_cli.push(&local_path, &remote_url_string, "main", false);
    match result {
        Err(GitCliError::PushRejected(msg)) => {
            let lower = msg.to_ascii_lowercase();
            assert!(
                lower.contains("failed to push some refs") || lower.contains("fetch first"),
                "unexpected stderr: {msg}"
            );
        }
        Err(other) => panic!("expected push rejected, got {other:?}"),
        Ok(_) => panic!("push unexpectedly succeeded"),
    }
}

#[test]
fn fetch_with_missing_ref_returns_error() {
    let temp_dir = TempDir::new().unwrap();
    let remote_path = temp_dir.path().join("remote.git");
    Repository::init_bare(&remote_path).expect("init bare remote");
    let remote_url = remote_path.to_str().expect("remote path str");

    let seed_path = temp_dir.path().join("seed");
    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&seed_path)
        .expect("init seed repo");
    let seed_repo = Repository::open(&seed_path).expect("open seed repo");
    configure_user(&seed_repo);
    seed_repo.remote("origin", remote_url).expect("add remote");
    push_ref(&seed_repo, "refs/heads/main", "refs/heads/main");
    Repository::open_bare(&remote_path)
        .expect("open bare remote")
        .set_head("refs/heads/main")
        .expect("set remote HEAD");

    let local_path = temp_dir.path().join("local");
    Repository::clone(remote_url, &local_path).expect("clone local");

    let git_cli = GitCli::new();
    let refspec = "+refs/heads/missing:refs/remotes/origin/missing";
    let result = git_cli.fetch_with_refspec(&local_path, remote_url, refspec);
    match result {
        Err(GitCliError::CommandFailed(msg)) => {
            assert!(
                msg.to_ascii_lowercase()
                    .contains("couldn't find remote ref"),
                "unexpected stderr: {msg}"
            );
        }
        Err(other) => panic!("expected command failed, got {other:?}"),
        Ok(_) => panic!("fetch unexpectedly succeeded"),
    }
}

#[test]
fn push_and_fetch_roundtrip_updates_tracking_branch() {
    let temp_dir = TempDir::new().unwrap();
    let remote_path = temp_dir.path().join("remote.git");
    Repository::init_bare(&remote_path).expect("init bare remote");
    let remote_url = remote_path.to_str().expect("remote path str");

    let seed_path = temp_dir.path().join("seed");
    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&seed_path)
        .expect("init seed repo");
    let seed_repo = Repository::open(&seed_path).expect("open seed repo");
    configure_user(&seed_repo);
    seed_repo.remote("origin", remote_url).expect("add remote");
    push_ref(&seed_repo, "refs/heads/main", "refs/heads/main");
    Repository::open_bare(&remote_path)
        .expect("open bare remote")
        .set_head("refs/heads/main")
        .expect("set remote HEAD");

    let producer_path = temp_dir.path().join("producer");
    let producer_repo = Repository::clone(remote_url, &producer_path).expect("clone producer");
    configure_user(&producer_repo);
    checkout_branch(&producer_repo, "main");

    let consumer_path = temp_dir.path().join("consumer");
    let consumer_repo = Repository::clone(remote_url, &consumer_path).expect("clone consumer");
    configure_user(&consumer_repo);
    checkout_branch(&consumer_repo, "main");
    let old_oid = consumer_repo
        .find_reference("refs/remotes/origin/main")
        .expect("consumer tracking ref")
        .target()
        .expect("consumer tracking ref");

    write_file(&producer_path, "file.txt", "new work\n");
    commit_all(&producer_repo, "producer commit");

    let remote = producer_repo.find_remote("origin").expect("origin remote");
    let remote_url_string = remote.url().expect("origin url").to_string();

    let git_cli = GitCli::new();
    git_cli
        .push(&producer_path, &remote_url_string, "main", false)
        .expect("push succeeded");

    let new_oid = producer_repo
        .head()
        .expect("producer head")
        .target()
        .expect("producer head oid");
    assert_ne!(old_oid, new_oid, "producer created new commit");

    git_cli
        .fetch_with_refspec(
            &consumer_path,
            &remote_url_string,
            "+refs/heads/main:refs/remotes/origin/main",
        )
        .expect("fetch succeeded");

    let updated_oid = consumer_repo
        .find_reference("refs/remotes/origin/main")
        .expect("updated tracking ref")
        .target()
        .expect("updated tracking ref");
    assert_eq!(
        updated_oid, new_oid,
        "tracking branch advanced to remote head"
    );
}

#[test]
fn rebase_preserves_untracked_files() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    write_file(&worktree_path, "scratch/untracked.txt", "temporary note\n");

    let service = GitService::new();
    let res = service.rebase_branch(
        &repo_path,
        &worktree_path,
        "new-base",
        "old-base",
        "feature",
    );
    assert!(res.is_ok(), "rebase should succeed: {res:?}");

    let scratch = worktree_path.join("scratch/untracked.txt");
    let content = fs::read_to_string(&scratch).expect("untracked file exists");
    assert_eq!(content, "temporary note\n");
}

#[test]
fn rebase_aborts_on_uncommitted_tracked_changes() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    write_file(&worktree_path, "feat.txt", "feat change (edited)\n");

    let service = GitService::new();
    let res = service.rebase_branch(
        &repo_path,
        &worktree_path,
        "new-base",
        "old-base",
        "feature",
    );
    assert!(res.is_err(), "rebase should fail on dirty worktree");

    let edited = fs::read_to_string(worktree_path.join("feat.txt")).unwrap();
    assert_eq!(edited, "feat change (edited)\n");
}

#[test]
fn rebase_aborts_if_untracked_would_be_overwritten_by_base() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    write_file(&worktree_path, "base.txt", "my scratch note\n");

    let service = GitService::new();
    let res = service.rebase_branch(
        &repo_path,
        &worktree_path,
        "new-base",
        "old-base",
        "feature",
    );
    assert!(
        res.is_err(),
        "rebase should fail due to untracked overwrite risk"
    );

    let content = std::fs::read_to_string(worktree_path.join("base.txt")).unwrap();
    assert_eq!(content, "my scratch note\n");
}

#[test]
fn merge_does_not_overwrite_main_repo_untracked_files() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    write_file(&worktree_path, "danger.txt", "tracked from feature\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "add danger.txt in feature");

    write_file(&repo_path, "danger.txt", "my untracked data\n");
    let main_repo = Repository::open(&repo_path).unwrap();
    checkout_branch(&main_repo, "main");

    let service = GitService::new();
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "squash merge",
    );
    assert!(
        res.is_err(),
        "merge should refuse due to untracked conflict"
    );

    // Untracked file remains untouched
    let content = std::fs::read_to_string(repo_path.join("danger.txt")).unwrap();
    assert_eq!(content, "my untracked data\n");
}

#[test]
fn merge_does_not_touch_tracked_uncommitted_changes_in_base_worktree() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    // Prepare: modify a tracked file in the base worktree (main) without committing
    let _main_repo = Repository::open(&repo_path).unwrap();
    // Base branch commits will be advanced by the merge operation; record before via service
    let g = GitService::new();
    let before_oid = g.get_branch_oid(&repo_path, "main").unwrap();

    // Create a tracked file that will also be added by feature branch to simulate overlap
    write_file(&repo_path, "danger2.txt", "my staged change\n");
    {
        // stage and then unstage to leave WT_MODIFIED? Simpler: just modify an existing tracked file
        // Use common.txt which is tracked
        write_file(&repo_path, "common.txt", "edited locally\n");
    }

    // Feature adds a change and is committed in worktree
    write_file(&worktree_path, "danger2.txt", "feature tracked\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature adds danger2.txt");

    // Merge via service (squash into main) should not modify files in the main worktree
    let service = GitService::new();
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "squash merge",
    );
    assert!(
        res.is_ok(),
        "merge should succeed without touching worktree"
    );

    // Confirm the local edit to tracked file remains
    let content = std::fs::read_to_string(repo_path.join("common.txt")).unwrap();
    assert_eq!(content, "edited locally\n");

    // Confirm the main branch ref advanced
    let after_oid = g.get_branch_oid(&repo_path, "main").unwrap();
    assert_ne!(before_oid, after_oid, "main ref should be updated by merge");
}

#[test]
fn merge_refuses_with_staged_changes_on_base() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let s = GitService::new();
    // ensure main is checked out
    let repo = Repository::open(&repo_path).unwrap();
    checkout_branch(&repo, "main");
    // feature adds change and commits
    write_file(&worktree_path, "m.txt", "feature\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feat change");
    // main has staged change
    write_file(&repo_path, "staged.txt", "staged\n");
    add_path(&repo_path, "staged.txt");
    let res = s.merge_changes(&repo_path, &worktree_path, "feature", "main", "squash");
    assert!(res.is_err(), "should refuse merge due to staged changes");
    // staged file remains
    let content = std::fs::read_to_string(repo_path.join("staged.txt")).unwrap();
    assert_eq!(content, "staged\n");
}

#[test]
fn merge_preserves_unstaged_changes_on_base() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let s = GitService::new();
    let repo = Repository::open(&repo_path).unwrap();
    checkout_branch(&repo, "main");
    // modify unstaged
    write_file(&repo_path, "common.txt", "local edited\n");
    // feature modifies a different file
    write_file(&worktree_path, "merged.txt", "merged content\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature merged");

    let _sha = s
        .merge_changes(&repo_path, &worktree_path, "feature", "main", "squash")
        .unwrap();
    // local edit preserved
    let loc = std::fs::read_to_string(repo_path.join("common.txt")).unwrap();
    assert_eq!(loc, "local edited\n");
    // merged file updated
    let m = std::fs::read_to_string(repo_path.join("merged.txt")).unwrap();
    assert_eq!(m, "merged content\n");
}

#[test]
fn update_ref_does_not_destroy_feature_worktree_dirty_state() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let s = GitService::new();
    let repo = Repository::open(&repo_path).unwrap();
    // ensure main is checked out
    checkout_branch(&repo, "main");
    // feature makes an initial change and commits
    write_file(&worktree_path, "f.txt", "feat\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feat commit");
    // dirty change in feature worktree (uncommitted)
    write_file(&worktree_path, "dirty.txt", "unstaged\n");
    // merge from feature into main (CLI path updates task ref via update-ref)
    let sha = s
        .merge_changes(&repo_path, &worktree_path, "feature", "main", "squash")
        .unwrap();
    // uncommitted change in feature worktree preserved
    let dirty = std::fs::read_to_string(worktree_path.join("dirty.txt")).unwrap();
    assert_eq!(dirty, "unstaged\n");
    // feature branch ref updated to the squash commit in main repo
    let feature_oid = s.get_branch_oid(&repo_path, "feature").unwrap();
    assert_eq!(feature_oid, sha);
    // and the feature worktree HEAD now points to that commit
    let head = s.get_head_info(&worktree_path).unwrap();
    assert_eq!(head.branch, "feature");
    assert_eq!(head.oid, sha);
}

#[test]
fn libgit2_merge_updates_base_ref_in_both_repos() {
    // Ensure we hit the libgit2 path by NOT checking out the base branch in main repo
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let s = GitService::new();

    // Record current main OID from both main repo and worktree repo; they should match pre-merge
    let before_main_repo = s.get_branch_oid(&repo_path, "main").unwrap();
    let before_main_wt = s.get_branch_oid(&worktree_path, "main").unwrap();
    assert_eq!(before_main_repo, before_main_wt);

    // Perform merge (squash) while main repo is NOT on base branch (libgit2 path)
    let sha = s
        .merge_changes(&repo_path, &worktree_path, "feature", "main", "squash")
        .expect("merge should succeed via libgit2 path");

    // Base branch ref advanced in both main and worktree repositories
    let after_main_repo = s.get_branch_oid(&repo_path, "main").unwrap();
    let after_main_wt = s.get_branch_oid(&worktree_path, "main").unwrap();
    assert_eq!(after_main_repo, sha);
    assert_eq!(after_main_wt, sha);
}

#[test]
fn libgit2_merge_updates_task_ref_and_feature_head_preserves_dirty() {
    // Hit libgit2 path (main repo not on base) and verify task ref + HEAD update safely
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let s = GitService::new();

    // Make an uncommitted change in the feature worktree to ensure it's preserved
    write_file(&worktree_path, "dirty2.txt", "keep me\n");

    // Perform merge (squash) from feature into main; this path uses libgit2
    let sha = s
        .merge_changes(&repo_path, &worktree_path, "feature", "main", "squash")
        .expect("merge should succeed via libgit2 path");

    // Dirty file preserved in worktree
    let dirty = std::fs::read_to_string(worktree_path.join("dirty2.txt")).unwrap();
    assert_eq!(dirty, "keep me\n");

    // Task branch (feature) updated to squash commit in both repos
    let feat_main_repo = s.get_branch_oid(&repo_path, "feature").unwrap();
    let feat_worktree = s.get_branch_oid(&worktree_path, "feature").unwrap();
    assert_eq!(feat_main_repo, sha);
    assert_eq!(feat_worktree, sha);

    // Feature worktree HEAD points to the new squash commit
    let head = s.get_head_info(&worktree_path).unwrap();
    assert_eq!(head.branch, "feature");
    assert_eq!(head.oid, sha);
}

#[test]
fn rebase_refuses_to_abort_existing_rebase() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_conflict_repo_with_worktree(&td);

    // Start a rebase via GitService that will pause/conflict
    let svc = GitService::new();
    let _ = svc
        .rebase_branch(
            &repo_path,
            &worktree_path,
            "new-base",
            "old-base",
            "feature",
        )
        .expect_err("first rebase should error and leave in-progress state");

    // Our service should refuse to proceed and not abort the user's rebase
    let service = GitService::new();
    let res = service.rebase_branch(
        &repo_path,
        &worktree_path,
        "new-base",
        "old-base",
        "feature",
    );
    assert!(res.is_err(), "should error because rebase is in progress");
    // Note: We do not auto-abort; user should resolve or abort explicitly
}

#[test]
fn rebase_fast_forwards_when_no_unique_commits() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_no_unique_feature_repo(&td);
    let g = GitService::new();
    let before = g.get_head_info(&worktree_path).unwrap().oid;
    let new_base_oid = g.get_branch_oid(&repo_path, "new-base").unwrap();

    let _res = g
        .rebase_branch(
            &repo_path,
            &worktree_path,
            "new-base",
            "old-base",
            "feature",
        )
        .expect("rebase should succeed");
    let after_oid = g.get_head_info(&worktree_path).unwrap().oid;
    assert_ne!(before, after_oid, "HEAD should move after rebase");
    assert_eq!(after_oid, new_base_oid, "fast-forward onto new-base");
}

#[test]
fn rebase_applies_multiple_commits_onto_ahead_base() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let repo = Repository::open(&repo_path).unwrap();
    // Advance new-base further
    checkout_branch(&repo, "new-base");
    write_file(&repo_path, "base_more.txt", "nb more\n");
    commit_all(&repo, "advance new-base more");

    // Add another commit to feature
    write_file(&worktree_path, "feat2.txt", "second change\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature second commit");

    // Rebase feature onto new-base
    let service = GitService::new();
    let _ = service
        .rebase_branch(
            &repo_path,
            &worktree_path,
            "new-base",
            "old-base",
            "feature",
        )
        .expect("rebase should succeed");

    // Verify both files exist with expected content in the rebased worktree
    let feat = std::fs::read_to_string(worktree_path.join("feat.txt")).unwrap();
    let feat2 = std::fs::read_to_string(worktree_path.join("feat2.txt")).unwrap();
    assert_eq!(feat, "feat change\n");
    assert_eq!(feat2, "second change\n");
}

#[test]
fn merge_when_base_ahead_and_feature_ahead_fails() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let repo = Repository::open(&repo_path).unwrap();
    // Advance base (main) after feature was created
    checkout_branch(&repo, "main");
    write_file(&repo_path, "base_ahead.txt", "base ahead\n");
    commit_all(&repo, "base ahead commit");

    // Feature adds its own file (already has feat.txt from setup) and commit another
    write_file(&worktree_path, "another.txt", "feature ahead\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature ahead extra");

    let g = GitService::new();
    let before_main = g.get_branch_oid(&repo_path, "main").unwrap();

    // Attempt to merge (squash) into main - should fail because base is ahead
    let service = GitService::new();
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "squash merge",
    );

    assert!(
        res.is_err(),
        "merge should fail when base branch is ahead of task branch"
    );

    // Verify main branch was not modified
    let after_main = g.get_branch_oid(&repo_path, "main").unwrap();
    assert_eq!(
        before_main, after_main,
        "main ref should remain unchanged when merge fails"
    );
}

#[test]
fn merge_conflict_does_not_move_base_ref() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_direct_conflict_repo(&td);

    // Record main ref before
    let _repo = Repository::open(&repo_path).unwrap();
    let g = GitService::new();
    let before = g.get_branch_oid(&repo_path, "main").unwrap();

    let service = GitService::new();
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "squash merge",
    );

    assert!(res.is_err(), "conflicting merge should fail");

    let after = g.get_branch_oid(&repo_path, "main").unwrap();
    assert_eq!(before, after, "main ref must remain unchanged on conflict");
}

#[test]
fn merge_delete_vs_modify_conflict_behaves_safely() {
    // main modifies file, feature deletes it -> but now blocked by branch ahead check
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);
    let repo = Repository::open(&repo_path).unwrap();

    // start from main with a file
    checkout_branch(&repo, "main");
    write_file(&repo_path, "conflict_dm.txt", "base\n");
    commit_all(&repo, "add conflict file");

    // feature deletes it and commits
    let wt_repo = Repository::open(&worktree_path).unwrap();
    let path = worktree_path.join("conflict_dm.txt");
    if path.exists() {
        std::fs::remove_file(&path).unwrap();
    }
    commit_all(&wt_repo, "delete in feature");

    // main modifies same file (this puts main ahead of feature)
    write_file(&repo_path, "conflict_dm.txt", "main modify\n");
    commit_all(&repo, "modify in main");

    // Capture main state AFTER all setup commits
    let g = GitService::new();
    let before = g.get_branch_oid(&repo_path, "main").unwrap();

    let service = GitService::new();
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "squash merge",
    );

    // Should now fail due to base branch being ahead, not due to merge conflicts
    assert!(res.is_err(), "merge should fail when base branch is ahead");

    // Ensure base ref unchanged on failure
    let after = g.get_branch_oid(&repo_path, "main").unwrap();
    assert_eq!(before, after, "main ref must remain unchanged on failure");
}

#[test]
fn rebase_preserves_rename_changes() {
    // feature renames a file; rebase onto new-base preserves rename
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    // feature: rename feat.txt -> feat_renamed.txt
    std::fs::rename(
        worktree_path.join("feat.txt"),
        worktree_path.join("feat_renamed.txt"),
    )
    .unwrap();
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "rename feat");

    // rebase onto new-base
    let service = GitService::new();
    let _ = service
        .rebase_branch(
            &repo_path,
            &worktree_path,
            "new-base",
            "old-base",
            "feature",
        )
        .expect("rebase should succeed");
    // after rebase, renamed file present; original absent
    assert!(worktree_path.join("feat_renamed.txt").exists());
    assert!(!worktree_path.join("feat.txt").exists());
}

#[test]
fn merge_refreshes_main_worktree_when_on_base() {
    let td = TempDir::new().unwrap();
    // Initialize repo and ensure main is checked out
    let repo_path = td.path().join("repo_refresh");
    let s = GitService::new();
    s.initialize_repo_with_main_branch(&repo_path).unwrap();
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");
    // Baseline file
    write_file(&repo_path, "file.txt", "base\n");
    let _ = s.commit(&repo_path, "add base").unwrap();

    // Create feature branch and worktree
    create_branch_from_head(&repo, "feature");
    let wt = td.path().join("wt_refresh");
    s.add_worktree(&repo_path, &wt, "feature", false).unwrap();
    // Modify file in worktree and commit
    write_file(&wt, "file.txt", "feature change\n");
    let _ = s.commit(&wt, "feature change").unwrap();

    // Merge into main (squash) and ensure main worktree is updated since it is on base
    let merge_sha = s
        .merge_changes(&repo_path, &wt, "feature", "main", "squash")
        .unwrap();
    // Since main is on base branch and we use safe CLI merge, both working tree
    // and ref should reflect the merged content.
    let content = std::fs::read_to_string(repo_path.join("file.txt")).unwrap();
    assert_eq!(content, "feature change\n");
    let oid = s.get_branch_oid(&repo_path, "main").unwrap();
    assert_eq!(oid, merge_sha);
}

#[test]
fn sparse_checkout_respected_in_worktree_diffs_and_commit() {
    let td = TempDir::new().unwrap();
    let repo_path = td.path().join("repo_sparse");
    let s = GitService::new();
    s.initialize_repo_with_main_branch(&repo_path).unwrap();
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");
    // baseline content
    write_file(&repo_path, "included/a.txt", "A\n");
    write_file(&repo_path, "excluded/b.txt", "B\n");
    let _ = s.commit(&repo_path, "baseline").unwrap();

    // enable sparse-checkout for 'included' only
    let cli = GitCli::new();
    cli.git(&repo_path, ["sparse-checkout", "init", "--cone"])
        .unwrap();
    cli.git(&repo_path, ["sparse-checkout", "set", "included"])
        .unwrap();

    // create feature branch and worktree
    create_branch_from_head(&repo, "feature");
    let wt = td.path().join("wt_sparse");
    s.add_worktree(&repo_path, &wt, "feature", false).unwrap();

    // materialization check: included exists, excluded does not
    assert!(wt.join("included/a.txt").exists());
    assert!(!wt.join("excluded/b.txt").exists());

    // modify included file
    write_file(&wt, "included/a.txt", "A-mod\n");
    let base_commit = s.get_base_commit(&repo_path, "feature", "main").unwrap();
    // get worktree diffs vs main, ensure excluded/b.txt is NOT reported deleted
    let diffs = s
        .get_diffs(
            DiffTarget::Worktree {
                worktree_path: Path::new(&wt),
                base_commit: &base_commit,
            },
            None,
        )
        .unwrap();
    assert!(
        diffs
            .iter()
            .any(|d| d.new_path.as_deref() == Some("included/a.txt"))
    );
    assert!(
        !diffs
            .iter()
            .any(|d| d.old_path.as_deref() == Some("excluded/b.txt")
                || d.new_path.as_deref() == Some("excluded/b.txt"))
    );

    // commit and verify commit diffs also only include included/ changes
    let _ = s.commit(&wt, "modify included").unwrap();
    let head_sha = s.get_head_info(&wt).unwrap().oid;
    let commit_diffs = s
        .get_diffs(
            DiffTarget::Commit {
                repo_path: Path::new(&wt),
                commit_sha: &head_sha,
            },
            None,
        )
        .unwrap();
    assert!(
        commit_diffs
            .iter()
            .any(|d| d.new_path.as_deref() == Some("included/a.txt"))
    );
    assert!(
        commit_diffs
            .iter()
            .all(|d| d.new_path.as_deref() != Some("excluded/b.txt")
                && d.old_path.as_deref() != Some("excluded/b.txt"))
    );
}

#[test]
fn worktree_diff_ignores_commits_where_base_branch_is_ahead() {
    let td = TempDir::new().unwrap();
    let repo_path = td.path().join("repo_base_ahead");
    let s = GitService::new();
    s.initialize_repo_with_main_branch(&repo_path).unwrap();
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");

    write_file(&repo_path, "shared.txt", "base\n");
    let _ = s.commit(&repo_path, "add shared").unwrap();

    create_branch_from_head(&repo, "feature");
    let wt = td.path().join("wt_base_ahead");
    s.add_worktree(&repo_path, &wt, "feature", false).unwrap();

    write_file(&repo_path, "base_only.txt", "main ahead\n");
    let _ = s.commit(&repo_path, "main ahead").unwrap();

    write_file(&wt, "feature.txt", "feature change\n");
    let base_commit = s.get_base_commit(&repo_path, "feature", "main").unwrap();

    let diffs = s
        .get_diffs(
            DiffTarget::Worktree {
                worktree_path: Path::new(&wt),
                base_commit: &base_commit,
            },
            None,
        )
        .unwrap();

    assert!(
        diffs
            .iter()
            .any(|d| d.new_path.as_deref() == Some("feature.txt"))
    );
    assert!(diffs.iter().all(|d| {
        d.new_path.as_deref() != Some("base_only.txt")
            && d.old_path.as_deref() != Some("base_only.txt")
    }));
}

// Helper: initialize a repo with main, configure user via service
fn init_repo_only_service(root: &TempDir) -> PathBuf {
    let repo_path = root.path().join("repo_svc");
    let s = GitService::new();
    s.initialize_repo_with_main_branch(&repo_path).unwrap();
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);
    checkout_branch(&repo, "main");
    repo_path
}

#[test]
fn merge_binary_conflict_does_not_move_ref() {
    let td = TempDir::new().unwrap();
    let repo_path = init_repo_only_service(&td);
    let repo = Repository::open(&repo_path).unwrap();
    let s = GitService::new();
    // seed
    let _ = s.commit(&repo_path, "seed").unwrap();
    // create feature branch and worktree
    create_branch_from_head(&repo, "feature");
    let worktree_path = td.path().join("wt_bin");
    s.add_worktree(&repo_path, &worktree_path, "feature", false)
        .unwrap();

    // feature adds/commits binary file
    let mut f = fs::File::create(worktree_path.join("bin.dat")).unwrap();
    f.write_all(&[0, 1, 2, 3]).unwrap();
    let _ = s.commit(&worktree_path, "feature bin").unwrap();

    // main adds conflicting binary content
    let mut f2 = fs::File::create(repo_path.join("bin.dat")).unwrap();
    f2.write_all(&[9, 8, 7, 6]).unwrap();
    let _ = s.commit(&repo_path, "main bin").unwrap();

    let before = s.get_branch_oid(&repo_path, "main").unwrap();
    let res = s.merge_changes(&repo_path, &worktree_path, "feature", "main", "merge bin");
    assert!(res.is_err(), "binary conflict should fail");
    let after = s.get_branch_oid(&repo_path, "main").unwrap();
    assert_eq!(before, after, "main ref unchanged on conflict");
}

#[test]
fn merge_rename_vs_modify_conflict_does_not_move_ref() {
    let td = TempDir::new().unwrap();
    let repo_path = init_repo_only_service(&td);
    let repo = Repository::open(&repo_path).unwrap();
    let s = GitService::new();
    // base file
    fs::write(repo_path.join("conflict.txt"), b"base\n").unwrap();
    let _ = s.commit(&repo_path, "base").unwrap();
    create_branch_from_head(&repo, "feature");
    let worktree_path = td.path().join("wt_ren");
    s.add_worktree(&repo_path, &worktree_path, "feature", false)
        .unwrap();

    // feature renames file
    std::fs::rename(
        worktree_path.join("conflict.txt"),
        worktree_path.join("conflict_renamed.txt"),
    )
    .unwrap();
    let _ = s.commit(&worktree_path, "rename").unwrap();

    // main modifies original path
    fs::write(repo_path.join("conflict.txt"), b"main change\n").unwrap();
    let _ = s.commit(&repo_path, "modify main").unwrap();

    let before = s.get_branch_oid(&repo_path, "main").unwrap();
    let res = s.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "merge rename",
    );
    match res {
        Err(_) => {
            let after = s.get_branch_oid(&repo_path, "main").unwrap();
            assert_eq!(before, after, "main unchanged on conflict");
        }
        Ok(sha) => {
            // ensure main advanced and result contains either renamed or modified content
            let after = s.get_branch_oid(&repo_path, "main").unwrap();
            assert_eq!(after, sha);
            let diffs = s
                .get_diffs(
                    DiffTarget::Commit {
                        repo_path: Path::new(&repo_path),
                        commit_sha: &after,
                    },
                    None,
                )
                .unwrap();
            let has_renamed = diffs
                .iter()
                .any(|d| d.new_path.as_deref() == Some("conflict_renamed.txt"));
            let has_modified = diffs.iter().any(|d| {
                d.new_path.as_deref() == Some("conflict.txt")
                    && d.new_content.as_deref() == Some("main change\n")
            });
            assert!(has_renamed || has_modified);
        }
    }
}

#[test]
fn merge_leaves_no_staged_changes_on_target_branch() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    // Ensure main repo is on the base branch (triggers CLI merge path)
    let s = GitService::new();
    let repo = Repository::open(&repo_path).unwrap();
    checkout_branch(&repo, "main");

    // Feature branch makes some changes
    write_file(&worktree_path, "feature_file.txt", "feature content\n");
    write_file(&worktree_path, "common.txt", "modified by feature\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature changes");

    // Perform the merge
    let _merge_sha = s
        .merge_changes(
            &repo_path,
            &worktree_path,
            "feature",
            "main",
            "merge feature",
        )
        .expect("merge should succeed");

    // THE KEY CHECK: Verify no staged changes remain on target branch
    let git_cli = GitCli::new();
    let has_staged = git_cli
        .has_staged_changes(&repo_path)
        .expect("should be able to check staged changes");

    assert!(
        !has_staged,
        "Target branch should have no staged changes after merge"
    );

    // Debug info if test fails
    if has_staged {
        let status_output = git_cli.git(&repo_path, ["status", "--porcelain"]).unwrap();
        panic!("Found staged changes after merge:\n{status_output}");
    }
}

#[test]
fn worktree_to_worktree_merge_leaves_no_staged_changes() {
    let td = TempDir::new().unwrap();
    let repo_path = td.path().join("repo");
    let worktree_a_path = td.path().join("wt-feature-a");
    let worktree_b_path = td.path().join("wt-feature-b");

    // Setup: Initialize repo with main branch
    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);

    write_file(&repo_path, "base.txt", "base content\n");
    commit_all(&repo, "initial commit");

    // Create two feature branches
    create_branch_from_head(&repo, "feature-a");
    create_branch_from_head(&repo, "feature-b");

    // Create worktrees for both feature branches
    service
        .add_worktree(&repo_path, &worktree_a_path, "feature-a", false)
        .expect("create worktree A");
    service
        .add_worktree(&repo_path, &worktree_b_path, "feature-b", false)
        .expect("create worktree B");

    // Make changes in worktree A
    write_file(
        &worktree_a_path,
        "feature_a.txt",
        "content from feature A\n",
    );
    write_file(&worktree_a_path, "base.txt", "modified by feature A\n");
    let wt_a_repo = Repository::open(&worktree_a_path).unwrap();
    commit_all(&wt_a_repo, "feature A changes");

    // Ensure main repo is on different branch (neither feature-a nor feature-b)
    checkout_branch(&repo, "main");

    let _sha = service.merge_changes(
        &repo_path,
        &worktree_a_path,
        "feature-a",
        "feature-b",
        "merge feature-a into feature-b",
    );

    // Verify no staged changes were introduced
    let git_cli = GitCli::new();
    let has_staged_main = git_cli
        .has_staged_changes(&repo_path)
        .expect("should be able to check staged changes in main repo");
    let has_staged_target = git_cli
        .has_staged_changes(&worktree_b_path)
        .expect("should be able to check staged changes in target worktree");

    assert!(
        !has_staged_main,
        "Main repo should have no staged changes after failed merge"
    );
    assert!(
        !has_staged_target,
        "Target worktree should have no staged changes after failed merge"
    );
}

#[test]
fn merge_into_orphaned_branch_uses_libgit2_fallback() {
    let td = TempDir::new().unwrap();
    let (repo_path, worktree_path) = setup_repo_with_worktree(&td);

    // Create an "orphaned" target branch that exists as ref but isn't checked out anywhere
    let service = GitService::new();
    let repo = Repository::open(&repo_path).unwrap();

    // Create orphaned-feature branch from current main HEAD but don't check it out
    let main_commit = repo.head().unwrap().peel_to_commit().unwrap();
    repo.branch("orphaned-feature", &main_commit, false)
        .unwrap();

    // Ensure main repo is on different branch and no worktree has orphaned-feature
    checkout_branch(&repo, "main");

    // Make changes in source worktree
    write_file(
        &worktree_path,
        "feature_content.txt",
        "content from feature\n",
    );
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature changes");

    // orphaned-feature is not checked out anywhere, so should trigger libgit2 path

    // Perform merge into orphaned branch (should use libgit2 fallback)
    let merge_sha = service
        .merge_changes(
            &repo_path,
            &worktree_path,
            "feature",
            "orphaned-feature",
            "merge into orphaned branch",
        )
        .expect("libgit2 merge into orphaned branch should succeed");

    // Verify merge worked - orphaned-feature branch should now point to merge commit
    let orphaned_branch_oid = service
        .get_branch_oid(&repo_path, "orphaned-feature")
        .unwrap();
    assert_eq!(
        orphaned_branch_oid, merge_sha,
        "orphaned-feature branch should point to merge commit"
    );

    // Verify no working tree was affected (since branch wasn't checked out anywhere)
    let main_git_cli = GitCli::new();
    let main_has_staged = main_git_cli.has_staged_changes(&repo_path).unwrap();
    let worktree_has_staged = main_git_cli.has_staged_changes(&worktree_path).unwrap();

    assert!(
        !main_has_staged,
        "Main repo should remain clean after libgit2 merge"
    );
    assert!(
        !worktree_has_staged,
        "Source worktree should remain clean after libgit2 merge"
    );
}

#[test]
fn merge_base_ahead_of_task_should_error() {
    let td = TempDir::new().unwrap();
    let repo_path = td.path().join("repo");
    let worktree_path = td.path().join("wt-feature");

    // Setup: Initialize repo with main branch
    let service = GitService::new();
    service
        .initialize_repo_with_main_branch(&repo_path)
        .expect("init repo");
    let repo = Repository::open(&repo_path).unwrap();
    configure_user(&repo);

    // Initial commit on main
    write_file(&repo_path, "base.txt", "initial content\n");
    commit_all(&repo, "initial commit");

    // Create feature branch from this point
    create_branch_from_head(&repo, "feature");
    service
        .add_worktree(&repo_path, &worktree_path, "feature", false)
        .expect("create worktree");

    // Feature makes a change and commits
    write_file(&worktree_path, "feature.txt", "feature content\n");
    let wt_repo = Repository::open(&worktree_path).unwrap();
    commit_all(&wt_repo, "feature change");

    // Main branch advances ahead of feature (this is the key scenario)
    checkout_branch(&repo, "main");
    write_file(&repo_path, "main_advance.txt", "main advanced\n");
    commit_all(&repo, "main advances ahead");
    write_file(&repo_path, "main_advance2.txt", "main advanced more\n");
    commit_all(&repo, "main advances further");

    // Attempt to merge feature into main when main is ahead
    // This should error because base branch has moved ahead of task branch
    let res = service.merge_changes(
        &repo_path,
        &worktree_path,
        "feature",
        "main",
        "attempt merge when base ahead",
    );

    // TDD: This test will initially fail because merge currently succeeds
    // Later we'll fix the merge logic to detect this scenario and error
    assert!(
        res.is_err(),
        "Merge should error when base branch is ahead of task branch"
    );
}