mahbot 0.6.4

//! Git subprocess wrappers — run git commands and parse porcelain/numstat output.
//!
//! Provides `run_git_*` async functions that operate on a repository path
//! and return results. For diff output parsing, see [`crate::git::diff_parse`].

use anyhow::Context;
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::process::Stdio;
use std::sync::OnceLock;
use std::sync::atomic::{AtomicBool, Ordering};
use std::time::Duration;
use tokio::io::AsyncReadExt;
use tracing::warn;

use crate::tools::shell::apply_safe_env;
use crate::util::unquote_c_style;

/// Result of a successful `git commit` — the full hash and line stats.
#[derive(Debug, Clone)]
pub struct CommitInfo {
    /// Full 40-character commit SHA from `git rev-parse HEAD`.
    pub hash: String,
    /// Total lines added across all changed files.
    pub lines_added: i64,
    /// Total lines removed across all changed files.
    pub lines_removed: i64,
}

impl CommitInfo {
    /// Return the first 7 characters of the commit hash, or the full hash
    /// if it's shorter than 7 characters.
    #[must_use]
    pub fn short_hash(&self) -> &str {
        self.hash.get(..7).unwrap_or(&self.hash)
    }
}

/// Maximum size (1 MiB) for reading untracked files in [`run_git_worktree_snapshot`]
/// and the diff page's untracked-file display.
///
/// Larger untracked files are surfaced via [`DiffStats::huge_binary_file_count`]
/// in the footer rather than line-counted; the diff page still shows a
/// placeholder instead of reading them.
pub(crate) const MAX_UNTRACKED_SIZE: u64 = 1024 * 1024;

/// Cap on the number of collapsed untracked directories enumerated per
/// [`run_git_worktree_snapshot`] refresh.
const MAX_UNTRACKED_DIRS_ENUMERATED: usize = 10;
/// Cap on the total number of untracked files classified (line-counted or
/// oversized/binary-detected) per [`run_git_worktree_snapshot`] refresh.
const MAX_UNTRACKED_FILES_COUNTED: usize = 500;
/// Cap on the total bytes read from untracked files per
/// [`run_git_worktree_snapshot`] refresh.
const MAX_UNTRACKED_BYTES_READ: u64 = 10 * 1024 * 1024;

/// Classification of an untracked file read for diff display / line counting.
///
/// Ordering is load-bearing: size is checked from metadata before reading,
/// then null-byte detection, then UTF-8 validity. Unreadable paths are skipped
/// entirely — only `TooLarge` and `Binary` produce GUI placeholders.
pub(crate) enum UntrackedFileRead {
    Text(String),
    TooLarge(u64),
    Binary,
    Skip,
}

/// Classify an in-memory untracked-file buffer (size already confirmed ≤ the
/// caller's limit). Returns `None` for binary (a null byte, or invalid UTF-8
/// without a null byte), or the UTF-8 text otherwise. Shared by
/// [`read_untracked_file`] and [`count_untracked_file`] so the
/// null-byte/UTF-8 binary rule lives in one place.
fn classify_untracked_content(content: Vec<u8>) -> Option<String> {
    if content.contains(&0) {
        return None;
    }
    String::from_utf8(content).ok()
}

pub(crate) async fn read_untracked_file(path: &Path, max_size: u64) -> UntrackedFileRead {
    if !path.is_file() {
        return UntrackedFileRead::Skip;
    }
    let Ok(meta) = tokio::fs::metadata(path).await else {
        return UntrackedFileRead::Skip;
    };
    if meta.len() > max_size {
        return UntrackedFileRead::TooLarge(meta.len());
    }
    let Ok(content) = tokio::fs::read(path).await else {
        return UntrackedFileRead::Skip;
    };
    // Invalid UTF-8 without a null byte is still binary — never Skip, or the
    // GUI would silently drop the file instead of showing a placeholder.
    classify_untracked_content(content).map_or(UntrackedFileRead::Binary, UntrackedFileRead::Text)
}

/// Whether to discard changes in a single file or an entire directory tree.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DiscardTarget {
    File,
    /// Recursively discard all changes within a directory (and its subdirectories).
    Directory,
}

/// Check if a directory contains a `.git` entry (file for worktrees, directory otherwise).
#[must_use]
pub fn is_git_repo(path: &Path) -> bool {
    path.join(".git").exists()
}

/// Run `git diff HEAD --no-color --find-renames` (when `commit_ref` is `None`)
/// or `git show -m <commit_ref> --no-color --find-renames --format=""` (when `Some`).
///
/// `-m` splits merge commits into per-parent diffs, producing standard unified diff
/// blocks that `parse_git_diff` can handle. This may produce duplicate file paths in the
/// tree sidebar (one `diff --git` block per parent), which is expected — each parent
/// comparison is a different diff.
/// `--format=""` suppresses the commit log header.
pub async fn run_git_diff(repo_path: &Path, commit_ref: Option<&str>) -> anyhow::Result<String> {
    if let Some(hash) = commit_ref {
        run_git_command(
            repo_path,
            &[
                "show",
                "-m",
                hash,
                "--no-color",
                "--find-renames",
                "--format=",
            ],
        )
        .await
    } else {
        run_git_command(repo_path, &["diff", "HEAD", "--no-color", "--find-renames"]).await
    }
}

/// Run `git status --porcelain` and return the output.
pub async fn run_git_status(repo_path: &Path) -> anyhow::Result<String> {
    run_git_command(repo_path, &["status", "--porcelain"]).await
}

/// Run `git show HEAD:<path>` (when `commit_ref` is `None`)
/// or `git show <commit_ref>:<path>` (when `Some`) and return the file content.
///
/// Returns `None` if the file does not exist at that ref (new/untracked files,
/// or root-commit `~1` which has no parent), or if any git error occurs.
///
/// **`~1` parent refs**: The caller constructs the parent hash. To get the parent
/// version, pass `commit_ref = Some(&format!("{hash}~1"))`.
pub async fn run_git_show(
    repo_path: &Path,
    file_path: &str,
    commit_ref: Option<&str>,
) -> Option<String> {
    let show_arg = if let Some(hash) = commit_ref {
        format!("{hash}:{file_path}")
    } else {
        format!("HEAD:{file_path}")
    };
    run_git_command(repo_path, &["show", &show_arg]).await.ok()
}

/// Resolve the repository top-level directory (the `.git`-containing ancestor).
///
/// `repo_path` may be the repo root or a subdirectory of it. Walks upward to
/// the first ancestor that contains a `.git` entry — a directory for normal
/// repos, or a *file* for linked worktrees/submodules, hence [`is_git_repo`]
/// (which uses `exists()`, not `is_dir()`).
///
/// Deliberately does NOT use `git rev-parse --show-toplevel`: repo discovery
/// itself runs the dubious-ownership check this exists to satisfy, so it would
/// recurse into the same failure (circular). Canonicalizes the resolved path
/// where possible so the value matches git's own realpath-normalized discovery.
pub(crate) fn resolve_git_top_level(repo_path: &Path) -> Option<PathBuf> {
    let dir = repo_path.ancestors().find(|dir| is_git_repo(dir))?;
    Some(std::fs::canonicalize(dir).unwrap_or_else(|_| dir.to_path_buf()))
}

/// Inject the repo top-level into git's per-process config as `safe.directory`.
///
/// Uses the process-scoped `GIT_CONFIG_COUNT`/`GIT_CONFIG_KEY_0`/
/// `GIT_CONFIG_VALUE_0` env form — never writes the user's global gitconfig and
/// never uses `*` (which would fully opt out of the CVE ownership guard). The
/// value is scoped to the single resolved repo top-level. On git < 2.38 the env
/// form is silently ignored by git, which is acceptable for the supported
/// target as long as the repo is owned by the running user.
fn inject_safe_directory(cmd: &mut tokio::process::Command, repo_path: &Path) {
    let Some(top_level) = resolve_git_top_level(repo_path) else {
        return;
    };
    cmd.env("GIT_CONFIG_COUNT", "1");
    cmd.env("GIT_CONFIG_KEY_0", "safe.directory");
    cmd.env("GIT_CONFIG_VALUE_0", top_level.as_path());
}

/// Create a [`tokio::process::Command`] for `git` with a sanitized environment.
///
/// The subprocess environment is cleared and re-populated with only safe
/// environment variables (see [`apply_safe_env`]) to prevent credential
/// leakage (CWE-200). `LC_ALL=C` is set for consistent locale behavior
/// across all git invocations. This is the only entry point for production git
/// subprocess creation in this module — all callers must use this helper.
///
/// `repo_root` is the workspace/`current_dir` path for repo-bound invocations;
/// when present, the resolved repo top-level is injected as `safe.directory`
/// (see [`inject_safe_directory`]) so git works on repos owned by a different
/// UID. Pass `None` for repo-agnostic invocations (e.g. [`git_is_installed`]),
/// which must not receive a repo-path value.
///
/// Callers should add further configuration (args, current_dir, stdio, etc.)
/// and then spawn or execute the command.
fn git_command(repo_root: Option<&Path>) -> tokio::process::Command {
    let mut cmd = tokio::process::Command::new("git");
    apply_safe_env(&mut cmd);
    cmd.env("LC_ALL", "C");
    if let Some(path) = repo_root {
        inject_safe_directory(&mut cmd, path);
    }
    cmd
}

/// Run a git command without any interpretation of the exit code.
///
/// Shared by [`run_git_command`] and other raw-output callers to avoid
/// duplicating the spawn + collect + wait pattern. Returns the raw
/// [`std::process::Output`] so each caller can interpret the exit
/// status as appropriate.
///
/// **Environment sanitization**: The subprocess environment is cleared
/// and re-populated with only a safe set of environment variables
/// (see [`apply_safe_env`] for details). This prevents leaking API keys
/// and other secrets into child processes (CWE-200), but it also means
/// variables like `SSH_AUTH_SOCK` and `GIT_SSH_COMMAND` are **not**
/// inherited. This is consistent with the shell tool's behavior — use
/// SSH config (`~/.ssh/config`) for SSH-based git remotes rather than
/// environment variables. ([`run_git_fetch`] is the one exception: it
/// restores `SSH_AUTH_SOCK` so SSH-agent remotes still work.)
pub(crate) async fn run_git_output(
    repo_path: &Path,
    args: &[&str],
) -> anyhow::Result<std::process::Output> {
    let mut cmd = git_command(Some(repo_path));
    cmd.args(args).current_dir(repo_path);
    cmd.output()
        .await
        .with_context(|| format!("Failed to run git {}", args.join(" ")))
}

/// Run a git command and return stdout as string on success.
///
/// Returns an error if git exits with a non-zero status.
pub async fn run_git_command(repo_path: &Path, args: &[&str]) -> anyhow::Result<String> {
    let output = run_git_output(repo_path, args).await?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        anyhow::bail!("git {} failed: {stderr}", args.join(" "));
    }

    Ok(String::from_utf8_lossy(&output.stdout).to_string())
}

/// Run a git command and return its trimmed stdout.
///
/// Shared by the helpers that return a single scalar (hash, branch, message).
async fn run_git_trimmed(repo_path: &Path, args: &[&str]) -> anyhow::Result<String> {
    Ok(run_git_command(repo_path, args).await?.trim().to_string())
}

/// Check if `git status --porcelain` output contains any unstaged changes.
///
/// Looks for any line where the worktree status column (second character) is
/// non-space — this indicates an unstaged modification, deletion, or untracked
/// file (`??` has `?` in the worktree column, `!!` ignored lines also have `!`
/// but are excluded here since default `--porcelain` doesn't show ignored files).
/// Fully-staged-only entries (`M `, `A `) are ignored.
///
/// This is a pure parsing function with no I/O — callers run `git status`
/// themselves and pass the captured stdout here.
///
#[must_use]
pub fn has_unstaged_changes(porcelain: &str) -> bool {
    porcelain.lines().any(|line| {
        let line = line.trim_end();
        if line.is_empty() {
            return false;
        }
        // Check the worktree status column (byte index 1).
        // For `??` (untracked) lines, both columns are `?` — the second is non-space.
        // For ` M`, `MM`, ` D`, etc., the second column is non-space.
        // For `M `, `A `, etc., the second column is space (fully staged).
        line.as_bytes().get(1).is_some_and(|&b| b != b' ')
    })
}

/// Stage all changes in the working tree via `git add -A`.
///
/// This stages tracked modifications, untracked files, and file deletions.
/// Unlike [`run_git_commit`], this does NOT commit — it only stages changes
/// into the index.
///
/// Returns the stdout of the git command on success.
pub async fn run_git_add_all(repo_path: &Path) -> anyhow::Result<String> {
    run_git_command(repo_path, &["add", "-A"]).await
}

/// Run `git rev-parse HEAD` and return the trimmed commit hash.
///
/// Errors when HEAD cannot be resolved (e.g. a repository with no commits
/// yet). Callers that need unknown-as-`None` semantics should use `.ok()`.
pub async fn run_git_head(repo_path: &Path) -> anyhow::Result<String> {
    run_git_trimmed(repo_path, &["rev-parse", "HEAD"]).await
}

/// Run `git write-tree` and return the trimmed index tree hash.
///
/// The tree hash identifies the exact staged content (index). Errors when the
/// index cannot be written (e.g. unmerged entries). Callers that need
/// unknown-as-`None` semantics should use `.ok()`.
pub async fn run_git_write_tree(repo_path: &Path) -> anyhow::Result<String> {
    run_git_trimmed(repo_path, &["write-tree"]).await
}

/// Stage all changes and commit with the given message.
/// Runs `git add -A` followed by `git commit -m "<msg>"`,
/// then captures the full SHA via `git rev-parse HEAD` and
/// line stats via `git diff --numstat`.
pub async fn run_git_commit(repo_path: &Path, message: &str) -> anyhow::Result<CommitInfo> {
    // Stage all changes (tracked, untracked, removed) in the worktree.
    run_git_add_all(repo_path).await?;

    run_git_command(repo_path, &["commit", "-m", message])
        .await
        .context("Failed to commit changes")?;

    // Capture the full 40-char SHA — reliable source, not abbreviated.
    let hash = match run_git_head(repo_path).await {
        Ok(hash) => hash,
        Err(e) => {
            warn!(
                error = %e,
                "git rev-parse HEAD failed after successful commit — commit exists, returning unknown hash"
            );
            return Ok(CommitInfo {
                hash: "unknown".into(),
                lines_added: 0,
                lines_removed: 0,
            });
        }
    };

    // Capture line stats via --numstat. Try HEAD~1..HEAD first.
    let (lines_added, lines_removed) =
        if let Ok(stats) = parse_numstat(repo_path, &["HEAD~1..HEAD"]).await {
            stats
        } else {
            // HEAD~1 doesn't exist (first commit) — fall back to the empty tree hash.
            parse_numstat(
                repo_path,
                &["4b825dc642cb6eb9a060e54bf8d69288fbee4904", "HEAD"],
            )
            .await
            .unwrap_or((0, 0))
        };
    Ok(CommitInfo {
        hash,
        lines_added,
        lines_removed,
    })
}

/// Broadcast for pipeline auto-commit notifications. The pipeline sends the
/// repo path after a successful auto-commit (sanitation → Done); the GUI
/// subscription consumes it and refreshes the footer promptly, since a commit
/// is a ref-only change the file watcher never reports. Lives here (not in the
/// GUI) so the pipeline can signal without depending on the GUI layer.
pub(crate) static GIT_COMMIT_TX: OnceLock<tokio::sync::broadcast::Sender<PathBuf>> =
    OnceLock::new();

/// Initialise the git-commit broadcast. Called from [`crate::gui::init_git_commit_tx`]
/// in `main` before the iced application runs.
pub(crate) fn init_git_commit_tx() {
    let _ = GIT_COMMIT_TX.set(tokio::sync::broadcast::channel(64).0);
}

/// Notify the GUI that a pipeline auto-commit completed on `repo_path`, so the
/// git footer refreshes promptly instead of waiting for the periodic timer.
pub(crate) fn notify_git_commit(repo_path: &Path) {
    if let Some(tx) = GIT_COMMIT_TX.get() {
        let _ = tx.send(repo_path.to_path_buf());
    }
}

/// A single entry from `git diff --numstat` or `git show --numstat` output.
///
/// `additions` and `deletions` are `None` for binary files (where git outputs `-`
/// instead of a line count). Regular files always have `Some` values.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct NumstatEntry {
    /// Lines added, or `None` if the file is binary.
    pub additions: Option<i64>,
    /// Lines deleted, or `None` if the file is binary.
    pub deletions: Option<i64>,
    /// File path as printed by git.
    pub path: String,
}

/// Parse the output of `git diff --numstat` or `git show --numstat`.
///
/// Returns a vector of [`NumstatEntry`] values for each file.
/// Binary files (displayed as `-\t-\t<path>`) have `additions` and `deletions`
/// set to `None` so callers can distinguish them from regular entries with zero
/// changes. Lines that don't match the expected 3-field format are silently skipped.
///
/// This is a pure parsing function with no I/O — callers run git themselves
/// and pass the captured stdout here.
#[must_use]
pub fn parse_numstat_lines(stdout: &str) -> Vec<NumstatEntry> {
    let mut result = Vec::new();
    for line in stdout.lines() {
        let line = line.trim();
        if line.is_empty() {
            continue;
        }
        // Format: <additions>\t<deletions>\t<path>
        let parts: Vec<&str> = line.splitn(3, '\t').collect();
        if parts.len() != 3 {
            continue;
        }

        let additions_str = parts[0];
        let deletions_str = parts[1];
        let path = parts[2].to_string();

        // Binary files are displayed as "-\t-\t<path>"
        // If either field is "-", treat the file as binary (both fields None).
        // This is defensive: git always outputs "-\t-" for both fields on binary
        // files, but we handle the mixed case conservatively.
        if additions_str == "-" || deletions_str == "-" {
            result.push(NumstatEntry {
                additions: None,
                deletions: None,
                path,
            });
            continue;
        }

        let additions: i64 = additions_str.parse().unwrap_or(0);
        let deletions: i64 = deletions_str.parse().unwrap_or(0);
        result.push(NumstatEntry {
            additions: Some(additions),
            deletions: Some(deletions),
            path,
        });
    }
    result
}

/// Run `git diff --numstat <range...>` and return the per-file entries.
/// Callers pass only the range (e.g. `&["HEAD"]` or `&["4b825d…", "HEAD"]`).
async fn run_git_diff_numstat(
    repo_path: &Path,
    range: &[&str],
) -> anyhow::Result<Vec<NumstatEntry>> {
    let mut args = vec!["diff", "--numstat"];
    args.extend_from_slice(range);
    let stdout = run_git_command(repo_path, &args).await?;
    Ok(parse_numstat_lines(&stdout))
}

/// Run `git diff --numstat <range...>` and sum the line stats across all files.
///
/// Returns `Ok((lines_added, lines_removed))` on success (even if the diff
/// is empty). Returns the git error message on failure.
async fn parse_numstat(repo_path: &Path, range: &[&str]) -> anyhow::Result<(i64, i64)> {
    let entries = run_git_diff_numstat(repo_path, range).await?;

    let mut lines_added: i64 = 0;
    let mut lines_removed: i64 = 0;

    for entry in entries {
        // Binary files have None values — they contribute 0 lines.
        if let Some(added) = entry.additions {
            lines_added += added;
        }
        if let Some(removed) = entry.deletions {
            lines_removed += removed;
        }
    }

    Ok((lines_added, lines_removed))
}

/// Check if git is installed.
pub async fn git_is_installed() -> bool {
    let mut cmd = git_command(None);
    cmd.arg("--version");
    cmd.output().await.is_ok_and(|o| o.status.success())
}

/// Check if a git repo has any commits (spawn/git failures count as `false`).
pub async fn git_has_commits(repo_path: &Path) -> bool {
    run_git_head(repo_path).await.is_ok()
}

/// Get the current branch name (e.g. `main`, `feature/xyz`).
pub async fn run_git_current_branch(repo_path: &Path) -> anyhow::Result<String> {
    run_git_trimmed(repo_path, &["rev-parse", "--abbrev-ref", "HEAD"]).await
}

/// Get behind/ahead counts against the upstream branch.
///
/// Returns `(behind, ahead)`. If there is no upstream configured, returns
/// `(0, 0)` without error.
pub async fn run_git_behind_ahead(repo_path: &Path) -> anyhow::Result<(usize, usize)> {
    match run_git_command(
        repo_path,
        &["rev-list", "--count", "--left-right", "HEAD...@{upstream}"],
    )
    .await
    {
        Ok(out) => {
            let parts: Vec<&str> = out.trim().split('\t').collect();
            if parts.len() == 2 {
                let ahead = parts[0].parse::<usize>().unwrap_or(0);
                let behind = parts[1].parse::<usize>().unwrap_or(0);
                Ok((behind, ahead))
            } else {
                Ok((0, 0))
            }
        }
        Err(e) => {
            // Only git's own "no upstream" verdicts are genuine empty results.
            // The error string embeds the command args (`@{upstream}`), so a
            // naive "contains upstream" match also swallows spawn/runtime
            // failures — anchor on git's stderr wording instead.
            let msg = e.to_string();
            if msg.contains("fatal: no upstream") || msg.contains("HEAD does not point to a branch")
            {
                Ok((0, 0))
            } else {
                Err(e)
            }
        }
    }
}

/// Hard timeout for a single `git fetch` — an unreachable/slow remote must not
/// hang the periodic remote sync indefinitely.
const FETCH_TIMEOUT: Duration = Duration::from_secs(15);

/// Single-flight guard for [`run_git_fetch`]: at most one fetch runs at a time
/// so concurrent fetches cannot overlap/contend on the same ref locks.
static FETCH_IN_FLIGHT: AtomicBool = AtomicBool::new(false);

/// RAII guard that clears [`FETCH_IN_FLIGHT`] when the fetch task finishes
/// (including on error/timeout/cancellation).
struct FetchInFlightGuard;
impl Drop for FetchInFlightGuard {
    fn drop(&mut self) {
        FETCH_IN_FLIGHT.store(false, Ordering::Release);
    }
}

/// Run `git fetch` so upstream refs are refreshed before behind/ahead is
/// computed (a fetch-free comparison only sees the last-fetched remote state).
///
/// The subprocess environment is sanitized (see [`git_command`]), then
/// `GIT_TERMINAL_PROMPT=0` prevents git/credential helpers from popping an
/// interactive (osxkeychain) prompt for a credential-less remote, and
/// `SSH_AUTH_SOCK` is restored (if present) so SSH-agent remotes still work —
/// the sanitized base drops it, and with it dropped behind/ahead would be
/// limited to the locally-available remote ref. The fetch is time-boxed by
/// [`FETCH_TIMEOUT`] and single-flight guarded.
///
/// On timeout the direct `git` child is killed and reaped; a remote helper it
/// spawned (e.g. `git-remote-https`) is not signalled directly but terminates
/// when its communication pipe closes, so it cannot hold the fetch open past
/// the timeout.
///
/// Returns the fetch stdout; callers most often discard it and only log a
/// failure (the subsequent behind/ahead read still works against local refs).
pub async fn run_git_fetch(repo_path: &Path) -> anyhow::Result<String> {
    // Single-flight: if a fetch is already running, skip this one rather than
    // queueing it (it would only contend on the same ref locks).
    if FETCH_IN_FLIGHT.swap(true, Ordering::AcqRel) {
        return Ok(String::new());
    }
    let _guard = FetchInFlightGuard;

    let mut cmd = git_command(Some(repo_path));
    cmd.arg("fetch").arg("--quiet").current_dir(repo_path);
    cmd.env("GIT_TERMINAL_PROMPT", "0");
    // Restore the SSH agent socket for SSH remotes (dropped by apply_safe_env).
    if let Some(sock) = std::env::var_os("SSH_AUTH_SOCK") {
        cmd.env("SSH_AUTH_SOCK", sock);
    }
    cmd.stdin(Stdio::null());
    cmd.stdout(Stdio::piped());
    cmd.stderr(Stdio::piped());
    // Kill the child if this task is cancelled (e.g. on shutdown) so a running
    // fetch cannot outlive the runtime and orphan.
    cmd.kill_on_drop(true);

    let mut child = cmd.spawn().context("Failed to spawn git fetch")?;
    let mut stdout = child.stdout.take();
    let mut stderr = child.stderr.take();
    let mut stdout_buf = Vec::new();
    let mut stderr_buf = Vec::new();

    // Wait for the child while draining its pipes concurrently, all inside the
    // timeout — a slow/unreachable remote (or a subprocess that outlives git
    // holding the pipes) cannot hang the periodic sync. On timeout, kill and
    // reap so the process does not linger as a zombie.
    let wait = child.wait();
    let read_stdout = async {
        if let Some(out) = &mut stdout {
            let _ = out.read_to_end(&mut stdout_buf).await;
        }
    };
    let read_stderr = async {
        if let Some(err) = &mut stderr {
            let _ = err.read_to_end(&mut stderr_buf).await;
        }
    };

    let status = if let Ok(res) = tokio::time::timeout(FETCH_TIMEOUT, async {
        tokio::join!(wait, read_stdout, read_stderr).0
    })
    .await
    {
        res.context("git fetch wait failed")?
    } else {
        let _ = child.kill().await;
        let _ = child.wait().await;
        anyhow::bail!("git fetch timed out after {}s", FETCH_TIMEOUT.as_secs());
    };

    if !status.success() {
        anyhow::bail!("git fetch failed: {}", String::from_utf8_lossy(&stderr_buf));
    }

    Ok(String::from_utf8_lossy(&stdout_buf).to_string())
}

/// Aggregate working-tree diff statistics for the GUI footer.
///
/// `added`/`removed` are the exact line counts used by the footer (+X / -Y)
/// and by reviewer churn calibration. `huge_binary_file_count` counts
/// oversized (> [`MAX_UNTRACKED_SIZE`]) and binary *untracked* files
/// (top-level or inside a collapsed untracked directory). It is a separate
/// indicator and is deliberately NOT folded into `added`/`removed`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct DiffStats {
    /// Total lines added (tracked diff + line-counted untracked text files).
    pub added: i64,
    /// Total lines removed (tracked diff only).
    pub removed: i64,
    /// Count of oversized/binary untracked files surfaced as a separate
    /// "N files" indicator, not line counts.
    pub huge_binary_file_count: usize,
}

/// Git file status for coloring the file tree.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum GitFileStatus {
    /// File has uncommitted modifications (M in porcelain output).
    Modified,
    /// File is untracked (?? in porcelain output) or newly added (A).
    Added,
}

/// Accumulator for untracked-file classification during a single
/// [`run_git_worktree_snapshot`] refresh. Enforces the per-refresh work caps.
#[derive(Default)]
struct UntrackedAccumulator {
    added: i64,
    huge_binary_file_count: usize,
    files_processed: usize,
    bytes_read: u64,
}

impl UntrackedAccumulator {
    /// Whether another untracked file may still be inspected this refresh.
    fn can_process(&self) -> bool {
        self.files_processed < MAX_UNTRACKED_FILES_COUNTED
            && self.bytes_read < MAX_UNTRACKED_BYTES_READ
    }
}

/// Count a single untracked file (or file enumerated inside a collapsed
/// directory) toward the diff-stats accumulation.
///
/// Oversized files are surfaced via `huge_binary_file_count` (metadata-only
/// check, no bytes read). Normal-size files are read (bounded by
/// [`MAX_UNTRACKED_BYTES_READ`]) and their line count added; binary /
/// invalid-UTF-8 files increment `huge_binary_file_count` instead.
/// Files beyond the per-refresh caps are skipped entirely (not line-counted
/// and NOT added to the file-count) — a bounded limitation for a pathological
/// very-large untracked tree.
async fn count_untracked_file(repo_path: &Path, path: &str, accum: &mut UntrackedAccumulator) {
    if !accum.can_process() {
        return;
    }
    let full_path = repo_path.join(path);
    if !full_path.is_file() {
        return;
    }
    let Ok(meta) = tokio::fs::metadata(&full_path).await else {
        return;
    };
    accum.files_processed += 1;
    if meta.len() > MAX_UNTRACKED_SIZE {
        accum.huge_binary_file_count += 1;
        return;
    }
    if accum.bytes_read + meta.len() > MAX_UNTRACKED_BYTES_READ {
        return;
    }
    let Ok(content) = tokio::fs::read(&full_path).await else {
        return;
    };
    accum.bytes_read += content.len() as u64;
    match classify_untracked_content(content) {
        Some(text) => {
            #[expect(clippy::cast_possible_wrap)]
            let line_count = text.lines().count() as i64;
            accum.added += line_count;
        }
        None => accum.huge_binary_file_count += 1,
    }
}

/// Enumerate the (untracked) files inside a collapsed `?? dir/` porcelain
/// entry with a git-scoped, gitignore-respecting listing.
///
/// Uses `git status --porcelain --untracked-files=all` scoped by a
/// `:(literal)` pathspec so the directory path is never interpreted as a glob
/// (names containing `*`/`?`/`:` match literally). `git` handles nesting,
/// ignores, and symlinks — no manual filesystem walk.
async fn enumerate_untracked_dir(repo_path: &Path, dir: &str) -> anyhow::Result<Vec<String>> {
    let pathspec = format!(":(literal){dir}");
    let out = run_git_command(
        repo_path,
        &[
            "status",
            "--porcelain",
            "--untracked-files=all",
            "--",
            &pathspec,
        ],
    )
    .await?;
    Ok(parse_untracked_from_porcelain(&out))
}

/// Working-tree snapshot: aggregate diff stats plus per-file porcelain
/// statuses, from a single `git status --porcelain` + one numstat pass.
///
/// The statuses are the same map the editor's file-tree coloring uses (once
/// forwarded by `GitState`), and the stats drive the footer (+N / -M) and
/// reviewer churn calibration.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GitWorktreeSnapshot {
    /// Aggregate line stats (tracked diff + line-counted untracked text).
    pub stats: DiffStats,
    /// Per-file porcelain status, keyed by workspace-relative path.
    pub file_statuses: HashMap<String, GitFileStatus>,
    /// The repo has no commits (unborn HEAD): tracked stats are `(0, 0)` but
    /// per-file statuses still flow. Consumers that predate the unborn-HEAD
    /// tolerance and must keep their old error semantics (reviewer churn)
    /// check this instead of treating the snapshot as a valid diff baseline.
    pub unborn_head: bool,
}

/// Capture the working-tree snapshot for a repository path.
///
/// Runs `git status --porcelain` first — the single source for both the
/// untracked-file list and the per-file status map. A failure here is fatal:
/// broken or missing git never yields a snapshot, so callers keep their
/// last-known-good state (or default churn).
///
/// Untracked files are line-counted (since `git diff HEAD` only considers
/// tracked files). Untracked files larger than [`MAX_UNTRACKED_SIZE`] or
/// detected as binary are surfaced via `huge_binary_file_count`. Collapsed
/// `?? dir/` entries are enumerated with a scoped `git status
/// --untracked-files=all` listing (gitignore-respecting), and each file
/// inside contributes exact line counts (or the file-count if
/// oversized/binary). Per-refresh work is bounded by the `MAX_UNTRACKED_*`
/// caps. A missing HEAD (unborn repo) yields `(0, 0)` stats so per-file
/// statuses still flow; any other numstat failure is fatal.
pub async fn run_git_worktree_snapshot(repo_path: &Path) -> anyhow::Result<GitWorktreeSnapshot> {
    let porcelain = run_git_status(repo_path).await?;
    let file_statuses = parse_git_status_porcelain(&porcelain);
    let untracked = parse_untracked_from_porcelain(&porcelain);

    let (added, removed, unborn_head) = match parse_numstat(repo_path, &["HEAD"]).await {
        Ok(stats) => (stats.0, stats.1, false),
        // `git_has_commits` distinguishes an unborn HEAD (a freshly
        // `git init`ed repo with no commits) from other numstat failures —
        // an unborn repo should still yield a snapshot with empty stats and
        // full per-file statuses.
        Err(_) if !git_has_commits(repo_path).await => (0, 0, true),
        Err(e) => return Err(e.context("Failed to compute working-tree diff stats")),
    };
    let mut accum = UntrackedAccumulator {
        added,
        ..Default::default()
    };

    let mut dirs_enumerated = 0;
    for path in &untracked {
        if path.ends_with('/') {
            if dirs_enumerated >= MAX_UNTRACKED_DIRS_ENUMERATED {
                continue;
            }
            dirs_enumerated += 1;
            match enumerate_untracked_dir(repo_path, path).await {
                Ok(files) => {
                    for file in &files {
                        count_untracked_file(repo_path, file, &mut accum).await;
                    }
                }
                Err(e) => warn!(error = %e, dir = %path, "Failed to enumerate untracked directory"),
            }
        } else {
            count_untracked_file(repo_path, path, &mut accum).await;
        }
    }

    Ok(GitWorktreeSnapshot {
        stats: DiffStats {
            added: accum.added,
            removed,
            huge_binary_file_count: accum.huge_binary_file_count,
        },
        file_statuses,
        unborn_head,
    })
}

/// Sync with remote: `git pull --ff-only` then `git push`.
///
/// Returns the combined output of both commands.
pub async fn run_git_sync(repo_path: &Path) -> anyhow::Result<String> {
    let pull_out = run_git_command(repo_path, &["pull", "--ff-only"]).await?;
    let push_out = run_git_command(repo_path, &["push"]).await?;
    let combined = if pull_out.trim().is_empty() {
        push_out
    } else if push_out.trim().is_empty() {
        pull_out
    } else {
        format!("{pull_out}\n{push_out}")
    };
    Ok(combined)
}

/// Discard all changes to a path — restores tracked files from HEAD, unstages
/// staged new files, and removes untracked files. Uses a 3-step git command
/// sequence to handle ALL file states:
///
/// 1. `git checkout HEAD -- <path>`
///    — restores tracked files from HEAD (handles Modified, Deleted, Renamed).
///    For files staged in the index (Added) that don't exist in HEAD, checkout
///    removes them from both index and working tree. Untracked files fail with
///    "did not match" — absorbed below.
///
/// 2. `git reset HEAD -- <path>`
///    — unstages staged new (Added) files so that `git clean` can remove them.
///    For files already restored by checkout this is a no-op. Errors
///    (e.g. untracked files not in index) are absorbed.
///
/// 3. `git clean -f[d] -- <path>`
///    — removes untracked files. `-f` for files, `-fd` for directories (recurses
///    into subdirectories). Errors (file already tracked, already removed by
///    checkout) are absorbed.
///
/// All errors from all three steps are absorbed. After the sequence, the working
/// tree is verified via `git status --porcelain -- <path>`: if the output is
/// empty the operation succeeded; otherwise the remaining changes are reported.
///
/// Note: `git reset HEAD` also exits with non-zero status when the path is
/// outside the repository — callers should validate paths before calling this.
pub async fn run_git_discard(
    repo_path: &Path,
    path: &str,
    target: DiscardTarget,
) -> anyhow::Result<()> {
    let _ = run_git_command(repo_path, &["checkout", "HEAD", "--", path]).await;

    let _ = run_git_command(repo_path, &["reset", "HEAD", "--", path]).await;

    let clean_args: &[&str] = match target {
        DiscardTarget::Directory => &["clean", "-fd", "--", path],
        DiscardTarget::File => &["clean", "-f", "--", path],
    };
    let _ = run_git_command(repo_path, clean_args).await;

    // Verify: check if any changes remain.
    match run_git_command(repo_path, &["status", "--porcelain", "--", path]).await {
        Ok(status) if status.trim().is_empty() => Ok(()),
        Ok(status) => anyhow::bail!("Changes remain after discard:\n{}", status.trim()),
        Err(e) => anyhow::bail!("Discard ran but verification failed: {e}"),
    }
}

/// Get the last commit's subject via `git log -1 --format=%s`.
///
/// If `commit_hash` is `Some`, get the message for that specific commit
/// instead of HEAD.
pub async fn run_git_commit_message(
    repo_path: &Path,
    commit_hash: Option<&str>,
) -> anyhow::Result<String> {
    let mut args = vec!["log", "-1", "--format=%s"];
    if let Some(hash) = commit_hash {
        args.push(hash);
    }
    run_git_trimmed(repo_path, &args).await
}

/// List new or untracked files in the working tree.
///
/// Delegates to [`run_git_status`] to run `git status --porcelain`, then passes
/// the output to [`parse_new_files_from_porcelain`] for parsing.
///
/// Catches both `??` (untracked) and any entry starting with `A` (staged as new,
/// including `A ` clean staged and `AM` staged+modified).
pub(crate) async fn list_new_or_untracked_files(repo_path: &Path) -> anyhow::Result<Vec<String>> {
    let porcelain = run_git_status(repo_path).await?;
    Ok(parse_new_files_from_porcelain(&porcelain))
}

/// Shared helper for parsing file paths from `git status --porcelain` output.
///
/// Iterates over lines, applies `predicate` to select relevant entries, then
/// extracts the path portion (starting at index 3 after the 2-char status
/// prefix and space). Guarded with `get(3..)` to avoid panics on malformed
/// input (empty lines, truncated porcelain entries).
fn parse_porcelain_paths(porcelain: &str, predicate: impl FnMut(&&str) -> bool) -> Vec<String> {
    porcelain
        .lines()
        .filter(predicate)
        // Note: porcelain lines are at minimum 4 chars (<XY><space><path>), but
        // we guard with `get()` to prevent panics on malformed input.
        .filter_map(|line| {
            let path = line.get(3..)?;
            if path.is_empty() {
                None
            } else {
                Some(unquote_c_style(path).unwrap_or_else(|| path.to_string()))
            }
        })
        .collect()
}

/// Parse new/added file paths from `git status --porcelain` output.
///
/// Returns file paths for entries where the index status indicates a new file:
/// - `??` — untracked file
/// - `A ` at position 0 — staged as new (first char is `A`)
///
/// This correctly catches `A ` (staged, clean) and `AM` (staged as new, then
/// modified in working tree) because both start with `A`. The porcelain format
/// is `<XY><space><path>` where X = index status, Y = working tree status.
/// Path always starts at index 3.
///
/// Excludes ` A` (not tracked, added only to working tree — this is a file
/// that exists but is not tracked by git; it falls under `??` instead).
///
/// To parse only truly untracked files (those prefixed with `?? `), use
/// [`parse_untracked_from_porcelain`] instead.
#[must_use]
fn parse_new_files_from_porcelain(porcelain: &str) -> Vec<String> {
    parse_porcelain_paths(porcelain, |line| {
        line.starts_with("?? ") || line.starts_with('A')
    })
}

/// Parse only truly untracked file paths from `git status --porcelain` output.
///
/// Returns file paths for entries where the porcelain status is `?? ` (untracked
/// file not in the index). Unlike [`parse_new_files_from_porcelain`], this does
/// *not* include staged-as-new (`A `) files — it only catches entries starting
/// with `?? `.
///
/// Use this when you only want files that are truly untracked and do not want
/// overlap with staged-as-new files that might already be present from a
/// `git diff HEAD` parse.
#[must_use]
pub(crate) fn parse_untracked_from_porcelain(porcelain: &str) -> Vec<String> {
    parse_porcelain_paths(porcelain, |line| line.starts_with("?? "))
}

/// Parse `git status --porcelain` output into a map of file path → `GitFileStatus`.
///
/// The porcelain format uses a two-column status (index + worktree).
/// If either column is `M` the file is [`GitFileStatus::Modified`]; otherwise
/// staged-new (`A`) and untracked (`??`) entries both map to
/// [`GitFileStatus::Added`]. If a file appears both modified and added,
/// `Modified` wins. Rename entries (`R`) extract
/// the new path after ` -> `. Deleted files (`D`) are ignored. Handles
/// git's C-style quoting for paths with special characters.
///
/// Keys are the paths as emitted by `git status --porcelain`. When the
/// command runs with cwd = the workspace root, these are workspace-relative
/// paths (the same key space as the editor's file tree).
#[must_use]
pub(crate) fn parse_git_status_porcelain(output: &str) -> HashMap<String, GitFileStatus> {
    let mut map: HashMap<String, GitFileStatus> = HashMap::new();

    for line in output.lines() {
        let trimmed = line.trim_end();
        if trimmed.len() < 2 {
            continue;
        }

        let chars: Vec<char> = trimmed.chars().take(2).collect();
        if chars.len() < 2 {
            continue;
        }

        let ix = chars[0];
        let wt = chars[1];

        // Skip deleted files — they don't appear in the working tree.
        if ix == 'D' || wt == 'D' {
            continue;
        }

        // Rename entries: "R  old_path -> new_path"
        // Both paths may be individually C-quoted by git. The separator
        // ` -> ` appears at the boundary between the two paths.
        if ix == 'R' {
            let rest = &trimmed[2..];
            let rest = rest.trim_start();
            let new_path: String = if rest.starts_with('"') {
                // Both paths are quoted. The boundary is `" -> "`.
                // rsplit_once on `" -> "` strips the opening quote of the
                // new path — add it back so `unquote_c_style` can strip both.
                if let Some((_, tail)) = rest.rsplit_once("\" -> \"") {
                    format!("\"{tail}")
                } else {
                    // Malformed — skip.
                    continue;
                }
            } else {
                // Unquoted paths: split on ` -> `.
                if let Some((_, tail)) = rest.rsplit_once(" -> ") {
                    tail.to_string()
                } else {
                    continue;
                }
            };
            if let Some(unquoted) = unquote_c_style(&new_path) {
                map.insert(unquoted, GitFileStatus::Modified);
            }
            continue;
        }

        // Extract path: strip first 2 chars (status columns) and leading space.
        let path = trimmed[2..].trim_start();
        if path.is_empty() {
            continue;
        }

        let status = if ix == 'M' || wt == 'M' {
            GitFileStatus::Modified
        } else if ix == 'A' || wt == 'A' || (ix == '?' && wt == '?') {
            GitFileStatus::Added
        } else {
            // Clean or ignored — don't store.
            continue;
        };

        let Some(path) = unquote_c_style(path) else {
            continue;
        };
        // Strip trailing slash — git appends '/' for untracked directories
        // (e.g., `?? new_dir/`), but tree node full_path has no trailing slash.
        let path = path.strip_suffix('/').unwrap_or(&path).to_string();

        // For entries with multiple lines referencing the same file (e.g., staged +
        // unstaged), keep the most "interesting" status: Modified > Added.
        let entry = map.entry(path).or_insert(status);
        if status == GitFileStatus::Modified && *entry == GitFileStatus::Added {
            *entry = GitFileStatus::Modified;
        }
    }

    map
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::util::test::init_temp_repo;

    // ── Unit tests for CommitInfo::short_hash ────────────────────

    #[test]
    fn short_hash_cases() {
        let cases = [
            (
                "long hash truncated to 7 chars",
                "abc1234def5678",
                "abc1234",
            ),
            ("short hash returned as-is", "abc12", "abc12"),
            ("exactly 7 chars returned as-is", "abc1234", "abc1234"),
        ];
        for (name, hash, expected) in &cases {
            let info = CommitInfo {
                hash: hash.to_string(),
                lines_added: 0,
                lines_removed: 0,
            };
            assert_eq!(info.short_hash(), *expected, "{name}");
        }
    }

    // ── safe.directory resolver (CVE-2022-24765 ancestor walk) ───

    #[test]
    fn resolve_git_top_level_repo_root() {
        let (_dir, repo_path) = init_temp_repo();
        let expected = std::fs::canonicalize(&repo_path).expect("canonicalize repo");
        assert_eq!(resolve_git_top_level(&repo_path), Some(expected));
    }

    #[test]
    fn resolve_git_top_level_from_subdir() {
        let (_dir, repo_path) = init_temp_repo();
        let subdir = repo_path.join("src");
        std::fs::create_dir(&subdir).expect("create subdir");
        let expected = std::fs::canonicalize(&repo_path).expect("canonicalize repo");
        assert_eq!(resolve_git_top_level(&subdir), Some(expected));
    }

    #[test]
    fn resolve_git_top_level_non_repo_is_none() {
        let dir = tempfile::tempdir().expect("create temp dir");
        assert_eq!(
            resolve_git_top_level(dir.path()),
            None,
            "non-repo dir must resolve to None"
        );
    }

    #[test]
    fn resolve_git_top_level_accepts_git_file() {
        let dir = tempfile::tempdir().expect("create temp dir");
        // A `.git` *file* (linked worktree / submodule marker) is sufficient —
        // the walk uses `exists()`, not `is_dir()`.
        std::fs::write(dir.path().join(".git"), b"gitdir: /elsewhere").expect("write .git file");
        let expected = std::fs::canonicalize(dir.path()).expect("canonicalize dir");
        assert_eq!(resolve_git_top_level(dir.path()), Some(expected));
    }

    // ── Safe.directory injection (dubious-ownership fix) ──────────

    /// Build a git command with a hermetic config environment: `safe.directory`
    /// must come only from the injected `GIT_CONFIG_*` env, never from the
    /// developer's global/system gitconfig (which may already list the repo or
    /// use `*`). `GIT_TEST_ASSUME_DIFFERENT_OWNER=1` simulates a repo owned by a
    /// different UID without requiring `chown`/root.
    fn hermetic_git_command(repo_root: Option<&Path>) -> tokio::process::Command {
        let mut cmd = git_command(repo_root);
        cmd.env("GIT_CONFIG_GLOBAL", "/dev/null");
        cmd.env("GIT_CONFIG_NOSYSTEM", "1");
        cmd.env("GIT_TEST_ASSUME_DIFFERENT_OWNER", "1");
        cmd
    }

    /// Simulates a repo owned by a different UID via git's
    /// `GIT_TEST_ASSUME_DIFFERENT_OWNER` hook: the injected top-level
    /// `safe.directory` must make git operable.
    #[tokio::test]
    async fn test_safe_directory_injection_bypasses_dubious_ownership() {
        let (_dir, repo_path) = init_temp_repo();

        let mut cmd = hermetic_git_command(Some(&repo_path));
        cmd.arg("status").arg("--porcelain").current_dir(&repo_path);
        let out = cmd.output().await.expect("run git status");
        assert!(
            out.status.success(),
            "git status must succeed with safe.directory injected: {}",
            String::from_utf8_lossy(&out.stderr)
        );
    }

    #[tokio::test]
    async fn test_without_safe_directory_fails_dubious_ownership() {
        let (_dir, repo_path) = init_temp_repo();

        let mut cmd = hermetic_git_command(None);
        cmd.arg("status").arg("--porcelain").current_dir(&repo_path);
        let out = cmd.output().await.expect("run git status");
        assert!(
            !out.status.success(),
            "git must refuse dubious ownership without safe.directory injection"
        );
    }

    /// The injected value must be the repo *top-level* even when the invocation
    /// runs from a subdirectory workspace — git's own discovery normalizes to
    /// the top-level, so a subdir value would not match.
    #[tokio::test]
    async fn test_safe_directory_injects_top_level_for_subdir_workspace() {
        let (_dir, repo_path) = init_temp_repo();
        let subdir = repo_path.join("src");
        std::fs::create_dir(&subdir).expect("create subdir");

        let mut cmd = hermetic_git_command(Some(&subdir));
        cmd.arg("status").arg("--porcelain").current_dir(&subdir);
        let out = cmd.output().await.expect("run git status");
        assert!(
            out.status.success(),
            "git from a repo subdir must match the repo top-level safe.directory: {}",
            String::from_utf8_lossy(&out.stderr)
        );
    }

    // ── Integration tests for run_git_* functions ────────────────

    #[tokio::test]
    async fn test_git_has_commits_true() {
        let (_dir, repo_path) = init_temp_repo();
        let has = git_has_commits(&repo_path).await;
        assert!(has, "repo with initial commit should have commits");
    }

    #[tokio::test]
    async fn test_run_git_head_and_write_tree_fingerprint() {
        let (_dir, repo_path) = init_temp_repo();
        let head1 = run_git_head(&repo_path).await.expect("repo has commits");
        let tree1 = run_git_write_tree(&repo_path)
            .await
            .expect("index writable");

        // Staged content change → new index tree, unchanged HEAD.
        std::fs::write(repo_path.join("test.txt"), b"line1\nline2\n").expect("write file");
        run_git_add_all(&repo_path).await.expect("git add");
        let head2 = run_git_head(&repo_path).await.expect("repo has commits");
        let tree2 = run_git_write_tree(&repo_path)
            .await
            .expect("index writable");
        assert_eq!(head1, head2, "staging must not change HEAD");
        assert_ne!(tree1, tree2, "staging must change the index tree");
    }

    #[tokio::test]
    async fn test_run_git_head_none_without_commits() {
        let dir = tempfile::tempdir().expect("create temp dir");
        let repo_path = dir.path().to_path_buf();

        let status = std::process::Command::new("git")
            .args(["init"])
            .current_dir(&repo_path)
            .status()
            .expect("git init");
        assert!(status.success());

        let head = run_git_head(&repo_path).await.ok();
        assert!(head.is_none(), "commit-less repo must not resolve HEAD");
    }

    #[tokio::test]
    async fn test_run_git_current_branch_default() {
        let (_dir, repo_path) = init_temp_repo();
        let branch = run_git_current_branch(&repo_path).await.expect("branch");
        assert!(!branch.is_empty(), "branch name should not be empty");
    }

    #[tokio::test]
    async fn test_run_git_behind_ahead_no_upstream() {
        let (_dir, repo_path) = init_temp_repo();
        let (behind, ahead) = run_git_behind_ahead(&repo_path)
            .await
            .expect("behind/ahead");
        assert_eq!(behind, 0);
        assert_eq!(ahead, 0);
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_clean_tree() {
        let (_dir, repo_path) = init_temp_repo();
        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(snap.stats.added, 0);
        assert_eq!(snap.stats.removed, 0);
        assert_eq!(snap.stats.huge_binary_file_count, 0);
        assert!(snap.file_statuses.is_empty(), "clean tree has no statuses");
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_with_changes() {
        let (_dir, repo_path) = init_temp_repo();
        // Modify: change "line2" to "line2 modified", add "line4"
        std::fs::write(
            repo_path.join("test.txt"),
            b"line1\nline2 modified\nline3\nline4\n",
        )
        .expect("write modified file");
        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(snap.stats.added, 2, "two lines added (modified + new line)");
        assert_eq!(snap.stats.removed, 1, "one line removed (line2)");
        assert_eq!(snap.stats.huge_binary_file_count, 0);
        assert_eq!(
            snap.file_statuses.get("test.txt"),
            Some(&GitFileStatus::Modified)
        );
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_with_untracked() {
        let (_dir, repo_path) = init_temp_repo();

        // Create an untracked file — not staged, not tracked by git.
        std::fs::write(
            repo_path.join("new_file.rs"),
            b"fn foo() {\n    bar();\n}\n",
        )
        .expect("write untracked file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        // The untracked file has 3 lines; unmodified tracked file contributes 0.
        assert_eq!(
            snap.stats.added, 3,
            "should count lines from untracked file"
        );
        assert_eq!(snap.stats.removed, 0, "no removed lines");
        assert_eq!(snap.stats.huge_binary_file_count, 0);
        assert_eq!(
            snap.file_statuses.get("new_file.rs"),
            Some(&GitFileStatus::Added)
        );
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_counts_binary_untracked_as_huge() {
        let (_dir, repo_path) = init_temp_repo();

        // Create an untracked file containing a null byte (binary).
        std::fs::write(repo_path.join("binary.bin"), b"line1\nline2\x00\n")
            .expect("write binary file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 0,
            "binary untracked file should not be counted as added"
        );
        assert_eq!(snap.stats.removed, 0, "no removed lines");
        assert_eq!(
            snap.stats.huge_binary_file_count, 1,
            "binary untracked file should be surfaced as huge/binary"
        );
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_counts_large_untracked_as_huge() {
        let (_dir, repo_path) = init_temp_repo();

        // Create an untracked file larger than MAX_UNTRACKED_SIZE (1 MiB).
        let size = usize::try_from(MAX_UNTRACKED_SIZE).unwrap() + 1;
        let mut content = Vec::with_capacity(size);
        content.resize(size, b'a');
        std::fs::write(repo_path.join("large.bin"), &content).expect("write large file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 0,
            "large untracked file should not be counted as added"
        );
        assert_eq!(snap.stats.removed, 0, "no removed lines");
        assert_eq!(
            snap.stats.huge_binary_file_count, 1,
            "large untracked file should be surfaced as huge/binary"
        );
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_counts_untracked_directory_files() {
        let (_dir, repo_path) = init_temp_repo();

        // Create an untracked directory with a normal file (3 lines) and a
        // binary file. The collapsed `?? new_dir/` entry is enumerated and both
        // files contribute (the binary one via the huge/binary count).
        std::fs::create_dir_all(repo_path.join("new_dir")).expect("create directory");
        std::fs::write(
            repo_path.join("new_dir/a.rs"),
            b"fn foo() {\n    bar();\n}\n",
        )
        .expect("write normal file");
        std::fs::write(repo_path.join("new_dir/binary.bin"), b"line1\x00\n")
            .expect("write binary file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 3,
            "should count lines from directory files"
        );
        assert_eq!(snap.stats.removed, 0, "no removed lines");
        assert_eq!(
            snap.stats.huge_binary_file_count, 1,
            "binary file inside the directory surfaces as huge/binary"
        );
    }

    #[expect(clippy::cast_possible_wrap)] // MAX_UNTRACKED_FILES_COUNTED is a small compile-time cap
    #[tokio::test]
    async fn test_run_git_worktree_snapshot_bounded_file_count_cap() {
        let (_dir, repo_path) = init_temp_repo();

        // A collapsed untracked directory with more files than the per-refresh
        // cap — only the first `MAX_UNTRACKED_FILES_COUNTED` files are counted.
        std::fs::create_dir_all(repo_path.join("big_dir")).expect("create directory");
        for i in 0..(MAX_UNTRACKED_FILES_COUNTED + 50) {
            std::fs::write(
                repo_path.join("big_dir").join(format!("f{i}")),
                format!("x{i}\n"),
            )
            .expect("write counted file");
        }

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, MAX_UNTRACKED_FILES_COUNTED as i64,
            "only the first cap files are line-counted"
        );
        assert_eq!(snap.stats.removed, 0);
        assert_eq!(snap.stats.huge_binary_file_count, 0);
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_gitignore_respected_in_directory() {
        let (_dir, repo_path) = init_temp_repo();

        // .gitignore is committed (tracked) so it is not itself counted.
        std::fs::write(repo_path.join(".gitignore"), b"ignored.log\n").expect("write gitignore");
        run_git_command(&repo_path, &["add", ".gitignore"])
            .await
            .expect("git add .gitignore");
        run_git_command(&repo_path, &["commit", "-m", "add .gitignore"])
            .await
            .expect("git commit .gitignore");

        // An untracked directory with a kept file and a gitignored file.
        std::fs::create_dir_all(repo_path.join("new_dir")).expect("create directory");
        std::fs::write(repo_path.join("new_dir/keep.rs"), b"aa\nbb\n").expect("write kept file");
        std::fs::write(repo_path.join("new_dir/ignored.log"), b"ignored\n")
            .expect("write ignored file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 2,
            "gitignored file inside a directory is not counted"
        );
        assert_eq!(snap.stats.removed, 0);
        assert_eq!(snap.stats.huge_binary_file_count, 0);
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_glob_chars_in_directory_path() {
        let (_dir, repo_path) = init_temp_repo();

        // A directory whose name contains glob metacharacters — the
        // `:(literal)` pathspec must match it literally.
        std::fs::create_dir_all(repo_path.join("we*ird?dir")).expect("create directory");
        std::fs::write(repo_path.join("we*ird?dir/x.rs"), b"xx\n").expect("write glob-dir file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 1,
            "glob chars in the directory path are literal"
        );
        assert_eq!(snap.stats.removed, 0);
        assert_eq!(snap.stats.huge_binary_file_count, 0);
    }

    #[tokio::test]
    async fn test_run_git_worktree_snapshot_unborn_head() {
        // A freshly `git init`ed repo with no commits has no HEAD; numstat
        // fails, but the per-file statuses must still flow with (0, 0) stats.
        let dir = tempfile::tempdir().expect("create temp dir");
        let repo_path = dir.path().to_path_buf();
        let status = std::process::Command::new("git")
            .args(["init"])
            .current_dir(&repo_path)
            .status()
            .expect("git init");
        assert!(status.success());

        std::fs::write(repo_path.join("first.rs"), b"fn main() {}\n")
            .expect("write untracked file");

        let snap = run_git_worktree_snapshot(&repo_path)
            .await
            .expect("worktree snapshot");
        assert_eq!(
            snap.stats.added, 1,
            "untracked line counted despite unborn HEAD"
        );
        assert_eq!(snap.stats.removed, 0);
        assert_eq!(snap.stats.huge_binary_file_count, 0);
        assert!(snap.unborn_head, "unborn HEAD must be flagged");
        assert_eq!(
            snap.file_statuses.get("first.rs"),
            Some(&GitFileStatus::Added),
            "untracked file status flows on an unborn repo"
        );
    }

    #[tokio::test]
    async fn test_run_git_list_branches_single() {
        let (_dir, repo_path) = init_temp_repo();
        let out = run_git_command(&repo_path, &["branch", "--format=%(refname:short)"])
            .await
            .expect("list branches");
        let branches: Vec<String> = out.lines().map(ToString::to_string).collect();
        assert_eq!(branches.len(), 1, "single branch in new repo");
    }

    #[tokio::test]
    async fn test_run_git_switch_and_create_branch() {
        let (_dir, repo_path) = init_temp_repo();
        // Note the default branch name before creating a new one
        let default_branch = run_git_current_branch(&repo_path)
            .await
            .expect("current branch");

        // Create and switch to a new branch
        run_git_command(&repo_path, &["switch", "-c", "feature/test"])
            .await
            .expect("create branch");
        // Verify we're on the new branch
        let current = run_git_current_branch(&repo_path)
            .await
            .expect("current branch");
        assert_eq!(current, "feature/test");
        // Verify it appears in the branch list
        let out = run_git_command(&repo_path, &["branch", "--format=%(refname:short)"])
            .await
            .expect("list branches");
        let branches: Vec<String> = out.lines().map(ToString::to_string).collect();
        assert!(branches.contains(&"feature/test".to_string()));
        // Switch back to the default branch
        run_git_command(&repo_path, &["switch", default_branch.as_str()])
            .await
            .expect("switch back");
        let switched = run_git_current_branch(&repo_path)
            .await
            .expect("current branch");
        assert_eq!(switched, default_branch, "should be back on default branch");
    }

    #[tokio::test]
    async fn test_run_git_commit_message() {
        let (_dir, repo_path) = init_temp_repo();

        // Without hash — should return HEAD's message
        let msg = run_git_commit_message(&repo_path, None)
            .await
            .expect("commit message without hash");
        assert_eq!(msg, "Initial commit");

        // Create a second commit
        std::fs::write(repo_path.join("test.txt"), b"line1\nline2\n").expect("write test file");
        let status = std::process::Command::new("git")
            .args(["add", "-A"])
            .current_dir(&repo_path)
            .status()
            .expect("git add");
        assert!(status.success());
        let status = std::process::Command::new("git")
            .args(["commit", "-m", "Second commit"])
            .current_dir(&repo_path)
            .status()
            .expect("git commit");
        assert!(status.success());

        // Get the second commit's hash
        let output = std::process::Command::new("git")
            .args(["rev-parse", "HEAD"])
            .current_dir(&repo_path)
            .output()
            .expect("git rev-parse");
        let second_hash = String::from_utf8_lossy(&output.stdout).trim().to_string();

        // With hash — should return that commit's message
        let msg = run_git_commit_message(&repo_path, Some(&second_hash))
            .await
            .expect("commit message with hash");
        assert_eq!(msg, "Second commit");

        // Without hash should now return HEAD (second commit)
        let msg = run_git_commit_message(&repo_path, None)
            .await
            .expect("commit message without hash");
        assert_eq!(msg, "Second commit");
    }

    #[tokio::test]
    async fn test_run_git_sync_no_remote() {
        let (_dir, repo_path) = init_temp_repo();
        // No remote configured — run_git_sync should return an error
        // from git pull --ff-only (no remote) rather than panicking.
        let result = run_git_sync(&repo_path).await;
        assert!(result.is_err(), "sync without remote should fail");
        let err = result.unwrap_err();
        assert!(
            err.to_string().contains("remote")
                || err.to_string().contains("push")
                || err.to_string().contains("pull"),
            "error should mention remote/push/pull: {err}"
        );
    }

    // ── parse_new_files_from_porcelain — combined untracked + staged-as-new ──

    /// Shared porcelain test input with a mix of untracked (`??`), staged-as-new
    /// (`A `), modified, and C-quoted special-character paths.  Used by both
    /// `parse_new_files_from_porcelain` and `parse_untracked_from_porcelain` tests.
    const PORCELAIN_INPUT: &str = "\
?? new_file.rs
M  modified.rs
?? another_new.py
A  staged_new.js
?? dir/untracked.txt
 M working_tree_only.txt
?? temp.log
AM staged_then_modified.js
 A working_tree_new.txt
?? \"file\\tname.rs\"
A  \"staged\\\"file.js\"
?? \"file\\\\backslash.rs\"
";

    /// Verify that `parse_new_files_from_porcelain` correctly extracts untracked
    /// and staged-as-new file paths from git porcelain output, including C-quoted
    /// paths with special characters (tab, double-quote, non-ASCII).
    #[test]
    fn parse_new_files_from_porcelain_extracts_new_files() {
        let porcelain = PORCELAIN_INPUT;

        let files = parse_new_files_from_porcelain(porcelain);

        assert_eq!(files.len(), 9);
        assert!(files.contains(&"new_file.rs".to_string()));
        assert!(files.contains(&"another_new.py".to_string()));
        assert!(files.contains(&"staged_new.js".to_string()));
        assert!(files.contains(&"dir/untracked.txt".to_string()));
        assert!(files.contains(&"temp.log".to_string()));
        assert!(files.contains(&"staged_then_modified.js".to_string()));
        // C-quoted paths should be properly unquoted:
        assert!(files.contains(&"file\tname.rs".to_string()));
        assert!(files.contains(&"staged\"file.js".to_string()));
        // Backslash in filename (\\) unquotes to single backslash:
        assert!(files.contains(&"file\\backslash.rs".to_string()));
        // These should be excluded:
        assert!(!files.contains(&"modified.rs".to_string()));
        assert!(!files.contains(&"working_tree_only.txt".to_string()));
        assert!(!files.contains(&"working_tree_new.txt".to_string()));
    }

    /// Verify that porcelain parsing returns empty for both clean output
    /// (no new/untracked files) and malformed/truncated lines.
    #[test]
    fn parse_new_files_from_porcelain_returns_empty() {
        let porcelain = "\
M  modified.rs
 M working_tree_only.txt
D  deleted.rs
 A working_tree_new.txt
";

        let files = parse_new_files_from_porcelain(porcelain);
        assert!(
            files.is_empty(),
            "Should be empty when no new/untracked files"
        );

        // Malformed/truncated lines that match the filter but are too short
        // for path extraction should also produce empty results without panicking.
        let short_lines = ["A", "A ", "?? ", "??"];
        for &bad_line in &short_lines {
            let files = parse_new_files_from_porcelain(bad_line);
            assert!(
                files.is_empty(),
                "Malformed line {bad_line:?} should produce empty result, got {files:?}"
            );
        }

        // Also test the ??-only variant with the same short lines.
        for &bad_line in &short_lines {
            let files = parse_untracked_from_porcelain(bad_line);
            assert!(
                files.is_empty(),
                "Malformed line {bad_line:?} should produce empty result from ??-only parser, got {files:?}"
            );
        }
    }

    // ── parse_untracked_from_porcelain — ??-only untracked parsing ──

    /// Verify that `parse_untracked_from_porcelain` catches only `?? ` (truly
    /// untracked) entries and excludes `A ` (staged-as-new) files.
    #[test]
    fn parse_untracked_from_porcelain_returns_only_untracked() {
        let porcelain = PORCELAIN_INPUT;

        let files = parse_untracked_from_porcelain(porcelain);

        // Should include only ??-prefixed entries (6 total)
        assert_eq!(files.len(), 6);
        assert!(files.contains(&"new_file.rs".to_string()));
        assert!(files.contains(&"another_new.py".to_string()));
        assert!(files.contains(&"dir/untracked.txt".to_string()));
        assert!(files.contains(&"temp.log".to_string()));
        // C-quoted paths should be properly unquoted:
        assert!(files.contains(&"file\tname.rs".to_string()));
        assert!(files.contains(&"file\\backslash.rs".to_string()));
        // These should be excluded:
        assert!(!files.contains(&"staged_new.js".to_string()));
        assert!(!files.contains(&"staged_then_modified.js".to_string()));
        assert!(!files.contains(&"modified.rs".to_string()));
        assert!(!files.contains(&"working_tree_only.txt".to_string()));
        assert!(!files.contains(&"working_tree_new.txt".to_string()));
        assert!(!files.contains(&"staged\"file.js".to_string()));
    }

    /// Verify that `parse_untracked_from_porcelain` returns empty for output
    /// containing only staged-as-new or modified files (no ?? entries).
    #[test]
    fn parse_untracked_from_porcelain_no_untracked() {
        let porcelain = "\
M  modified.rs
A  staged_new.js
 M working_tree_only.txt
AM staged_then_modified.js
 A working_tree_new.txt
";

        let files = parse_untracked_from_porcelain(porcelain);
        assert!(
            files.is_empty(),
            "Should be empty when no `?? ` entries present"
        );
    }

    // ── parse_git_status_porcelain — per-file status map ─────────

    #[expect(clippy::too_many_lines)]
    #[test]
    fn test_parse_git_status_porcelain() {
        struct Case {
            /// Short label for failure messages.
            name: &'static str,
            /// Raw git status --porcelain output.
            input: &'static str,
            /// Expected entries: (path, Some(status)) asserts the file has that
            /// status; (path, None) asserts the file is absent from the map.
            /// An empty slice asserts the entire map is empty.
            expected: &'static [(&'static str, Option<GitFileStatus>)],
        }
        let cases: &[Case] = &[
            Case {
                name: "unstaged modified file",
                input: " M src/main.rs\n",
                expected: &[("src/main.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "staged added file",
                input: "A  new_file.rs\n",
                expected: &[("new_file.rs", Some(GitFileStatus::Added))],
            },
            Case {
                name: "untracked file",
                input: "?? new_file.rs\n",
                expected: &[("new_file.rs", Some(GitFileStatus::Added))],
            },
            Case {
                name: "staged and unstaged modified (MM)",
                input: "MM both.rs\n",
                expected: &[("both.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "staged added + unstaged modified (AM)",
                input: "AM partial.rs\n",
                expected: &[("partial.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "rename (old -> new)",
                input: "R  old.rs -> new.rs\n",
                expected: &[("new.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "rename with arrow in old path",
                input: "R  \"old -> name.rs\" -> \"new -> name.rs\"\n",
                expected: &[("new -> name.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "untracked directory (trailing slash stripped)",
                input: "?? new_dir/\n",
                expected: &[("new_dir", Some(GitFileStatus::Added))],
            },
            Case {
                name: "quoted path with spaces",
                input: " M \"path with spaces.rs\"\n",
                expected: &[("path with spaces.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "deleted file (unstaged) skipped",
                input: " D gone.rs\n",
                expected: &[],
            },
            Case {
                name: "deleted file (staged) skipped",
                input: "D  gone.rs\n",
                expected: &[],
            },
            Case {
                name: "clean (unrecognized status) not present",
                input: "   clean.rs\n",
                expected: &[("clean.rs", None)],
            },
            Case {
                name: "multiple entries same file — modified wins over added",
                input: "A  dup.rs\n M dup.rs\n",
                expected: &[("dup.rs", Some(GitFileStatus::Modified))],
            },
            Case {
                name: "multiple entries same file — added sticks",
                input: "?? dup.rs\nA  dup.rs\n",
                expected: &[("dup.rs", Some(GitFileStatus::Added))],
            },
            Case {
                name: "empty output",
                input: "",
                expected: &[],
            },
            Case {
                name: "mixed statuses",
                input: concat!(
                    " M src/main.rs\n",
                    "?? new_file.rs\n",
                    "A  staged.rs\n",
                    " D deleted.rs\n",
                ),
                expected: &[
                    ("src/main.rs", Some(GitFileStatus::Modified)),
                    ("new_file.rs", Some(GitFileStatus::Added)),
                    ("staged.rs", Some(GitFileStatus::Added)),
                    ("deleted.rs", None),
                ],
            },
        ];

        for case in cases {
            let map = parse_git_status_porcelain(case.input);

            if case.expected.is_empty() {
                assert!(
                    map.is_empty(),
                    "case '{}' (input={:?}): expected empty map, got {:#?}",
                    case.name,
                    case.input,
                    map
                );
            } else {
                let expected_count = case.expected.iter().filter(|(_, s)| s.is_some()).count();
                assert_eq!(
                    map.len(),
                    expected_count,
                    "case '{}' (input={:?}): map has unexpected entries",
                    case.name,
                    case.input,
                );
                for &(path, expected_status) in case.expected {
                    match expected_status {
                        Some(status) => {
                            assert_eq!(
                                map.get(path),
                                Some(&status),
                                "case '{}' (input={:?}): path={:?}",
                                case.name,
                                case.input,
                                path
                            );
                        }
                        None => {
                            assert!(
                                !map.contains_key(path),
                                "case '{}' (input={:?}): path={:?} should be absent, got {:?}",
                                case.name,
                                case.input,
                                path,
                                map.get(path)
                            );
                        }
                    }
                }
            }
        }
    }

    // ── parse_numstat_lines — numstat line parsing ──

    /// numstat line parsing: normal, binary, malformed-skip, and empty inputs.
    #[test]
    fn parse_numstat_lines_cases() {
        let cases: &[(&str, &str, Vec<NumstatEntry>)] = &[
            (
                "normal",
                "10\t3\tsrc/main.rs\n0\t1\tsrc/lib.rs\n42\t7\tCargo.toml\n",
                vec![
                    NumstatEntry {
                        additions: Some(10),
                        deletions: Some(3),
                        path: "src/main.rs".to_string(),
                    },
                    NumstatEntry {
                        additions: Some(0),
                        deletions: Some(1),
                        path: "src/lib.rs".to_string(),
                    },
                    NumstatEntry {
                        additions: Some(42),
                        deletions: Some(7),
                        path: "Cargo.toml".to_string(),
                    },
                ],
            ),
            (
                "binary",
                "-\t-\timage.png\n42\t7\tsrc/main.rs\n",
                vec![
                    NumstatEntry {
                        additions: None,
                        deletions: None,
                        path: "image.png".to_string(),
                    },
                    NumstatEntry {
                        additions: Some(42),
                        deletions: Some(7),
                        path: "src/main.rs".to_string(),
                    },
                ],
            ),
            (
                "skips_malformed",
                "\n\n10\t3\tsrc/main.rs\n\t\t\nnot-enough-fields\n",
                vec![NumstatEntry {
                    additions: Some(10),
                    deletions: Some(3),
                    path: "src/main.rs".to_string(),
                }],
            ),
            ("empty_string", "", vec![]),
            ("empty_lines", "\n\n\n", vec![]),
        ];
        for (name, input, expected) in cases {
            assert_eq!(parse_numstat_lines(input), *expected, "case: {name}");
        }
    }

    // ── run_git_discard — discard modifications ──

    /// Discard changes to a modified tracked file — restores it to HEAD.
    #[tokio::test]
    async fn test_run_git_discard_modified_file() {
        let (_dir, repo_path) = init_temp_repo();

        // Modify the tracked file.
        std::fs::write(repo_path.join("test.txt"), b"modified content\n")
            .expect("write modified file");

        // Confirm file is dirty.
        let status = run_git_command(&repo_path, &["status", "--porcelain", "test.txt"])
            .await
            .expect("status before discard");
        assert!(
            !status.trim().is_empty(),
            "file should be dirty before discard"
        );

        // Discard the modification.
        run_git_discard(&repo_path, "test.txt", DiscardTarget::File)
            .await
            .expect("run_git_discard should succeed");

        // File should be clean now.
        let status = run_git_command(&repo_path, &["status", "--porcelain", "test.txt"])
            .await
            .expect("status after discard");
        assert!(
            status.trim().is_empty(),
            "file should be clean after discard"
        );

        // Content should match the committed version.
        let content = std::fs::read_to_string(repo_path.join("test.txt")).expect("read file");
        assert_eq!(
            content, "line1\nline2\nline3\n",
            "content should be restored to HEAD"
        );
    }

    /// Discard a new untracked file — removes it from the working tree.
    #[tokio::test]
    async fn test_run_git_discard_new_file() {
        let (_dir, repo_path) = init_temp_repo();

        // Create a new untracked file.
        let new_path = repo_path.join("new_file.rs");
        std::fs::write(&new_path, b"fn new() {}").expect("write new file");
        assert!(new_path.exists(), "new file should exist before discard");

        // Discard the untracked file.
        run_git_discard(&repo_path, "new_file.rs", DiscardTarget::File)
            .await
            .expect("run_git_discard should succeed");

        // File should be removed.
        assert!(
            !new_path.exists(),
            "new file should be removed after discard"
        );
    }

    /// Discard a directory with untracked content — recursively removes it.
    #[tokio::test]
    async fn test_run_git_discard_directory() {
        let (_dir, repo_path) = init_temp_repo();

        // Create a directory with an untracked file inside.
        let sub_dir = repo_path.join("subdir");
        std::fs::create_dir(&sub_dir).expect("create subdir");
        let sub_file = sub_dir.join("nested.rs");
        std::fs::write(&sub_file, b"fn nested() {}").expect("write nested file");
        assert!(sub_file.exists(), "nested file should exist before discard");

        // Discard the directory.
        run_git_discard(&repo_path, "subdir", DiscardTarget::Directory)
            .await
            .expect("run_git_discard should succeed");

        // Directory and its contents should be gone.
        assert!(
            !sub_dir.exists(),
            "directory should be removed after discard"
        );
    }

    /// Discard a clean file — succeeds as a no-op.
    #[tokio::test]
    async fn test_run_git_discard_clean_file() {
        let (_dir, repo_path) = init_temp_repo();

        let result = run_git_discard(&repo_path, "test.txt", DiscardTarget::File).await;
        assert!(result.is_ok(), "discarding a clean file should succeed");
    }

    // ── has_unstaged_changes ─────────────────────────────────────────

    /// Empty, fully-staged, unstaged, dual-status, untracked, mixed, and
    /// trailing-newline porcelain inputs.
    #[test]
    fn has_unstaged_changes_cases() {
        let cases: &[(&str, &str, bool)] = &[
            ("empty_string", "", false),
            ("empty_lines", "\n\n", false),
            ("fully_staged_modified", "M  Cargo.toml\n", false),
            ("fully_staged_added", "A  src/lib.rs\n", false),
            (
                "fully_staged_mixed",
                "M  Cargo.toml\nA  src/lib.rs\nD  old.rs\n",
                false,
            ),
            ("unstaged_modified", " M src/lib.rs\n", true),
            ("unstaged_deleted", " D src/old.rs\n", true),
            ("dual_status_modified", "MM src/lib.rs\n", true),
            ("dual_status_added", "AM src/new.rs\n", true),
            ("dual_status_deleted", "MD src/old.rs\n", true),
            ("untracked_file", "?? new_file.rs\n", true),
            ("untracked_directory", "?? dir/untracked.txt\n", true),
            (
                "mixed_only_staged",
                "M  Cargo.toml\nA  src/main.rs\n",
                false,
            ),
            (
                "mixed_staged_and_unstaged",
                "M  Cargo.toml\n M src/main.rs\n?? new.rs\n",
                true,
            ),
            ("trailing_newline_unstaged", " M file.rs\n", true),
            ("trailing_newline_staged", "M  file.rs\n", false),
        ];
        for (name, input, expected) in cases {
            assert_eq!(has_unstaged_changes(input), *expected, "case: {name}");
        }
    }
}