use crate::status::FileStatus;
use crate::SHORT_SHA_LENGTH;
use crate::{blame::Blame, status::GitStatus};
use anyhow::{anyhow, Context, Result};
use askpass::{AskPassResult, AskPassSession};
use collections::{HashMap, HashSet};
use futures::future::BoxFuture;
use futures::{select_biased, AsyncWriteExt, FutureExt as _};
use git2::BranchType;
use gpui::{AppContext, AsyncApp, SharedString};
use parking_lot::Mutex;
use rope::Rope;
use schemars::JsonSchema;
use serde::Deserialize;
use std::borrow::Borrow;
use std::process::Stdio;
use std::sync::LazyLock;
use std::{
    cmp::Ordering,
    path::{Component, Path, PathBuf},
    sync::Arc,
};
use sum_tree::MapSeekTarget;
use util::command::new_smol_command;
use util::ResultExt;

pub const REMOTE_CANCELLED_BY_USER: &str = "Operation cancelled by user";

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct Branch {
    pub is_head: bool,
    pub name: SharedString,
    pub upstream: Option<Upstream>,
    pub most_recent_commit: Option<CommitSummary>,
}

impl Branch {
    pub fn tracking_status(&self) -> Option<UpstreamTrackingStatus> {
        self.upstream
            .as_ref()
            .and_then(|upstream| upstream.tracking.status())
    }

    pub fn priority_key(&self) -> (bool, Option<i64>) {
        (
            self.is_head,
            self.most_recent_commit
                .as_ref()
                .map(|commit| commit.commit_timestamp),
        )
    }
}

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct Upstream {
    pub ref_name: SharedString,
    pub tracking: UpstreamTracking,
}

impl Upstream {
    pub fn remote_name(&self) -> Option<&str> {
        self.ref_name
            .strip_prefix("refs/remotes/")
            .and_then(|stripped| stripped.split("/").next())
    }
}

#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
pub enum UpstreamTracking {
    /// Remote ref not present in local repository.
    Gone,
    /// Remote ref present in local repository (fetched from remote).
    Tracked(UpstreamTrackingStatus),
}

impl From<UpstreamTrackingStatus> for UpstreamTracking {
    fn from(status: UpstreamTrackingStatus) -> Self {
        UpstreamTracking::Tracked(status)
    }
}

impl UpstreamTracking {
    pub fn is_gone(&self) -> bool {
        matches!(self, UpstreamTracking::Gone)
    }

    pub fn status(&self) -> Option<UpstreamTrackingStatus> {
        match self {
            UpstreamTracking::Gone => None,
            UpstreamTracking::Tracked(status) => Some(*status),
        }
    }
}

#[derive(Debug, Clone)]
pub struct RemoteCommandOutput {
    pub stdout: String,
    pub stderr: String,
}

impl RemoteCommandOutput {
    pub fn is_empty(&self) -> bool {
        self.stdout.is_empty() && self.stderr.is_empty()
    }
}

#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
pub struct UpstreamTrackingStatus {
    pub ahead: u32,
    pub behind: u32,
}

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct CommitSummary {
    pub sha: SharedString,
    pub subject: SharedString,
    /// This is a unix timestamp
    pub commit_timestamp: i64,
    pub has_parent: bool,
}

#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct CommitDetails {
    pub sha: SharedString,
    pub message: SharedString,
    pub commit_timestamp: i64,
    pub committer_email: SharedString,
    pub committer_name: SharedString,
}

impl CommitDetails {
    pub fn short_sha(&self) -> SharedString {
        self.sha[..SHORT_SHA_LENGTH].to_string().into()
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct Remote {
    pub name: SharedString,
}

pub enum ResetMode {
    // reset the branch pointer, leave index and worktree unchanged
    // (this will make it look like things that were committed are now
    // staged)
    Soft,
    // reset the branch pointer and index, leave worktree unchanged
    // (this makes it look as though things that were committed are now
    // unstaged)
    Mixed,
}

pub trait GitRepository: Send + Sync {
    fn reload_index(&self);

    /// Returns the contents of an entry in the repository's index, or None if there is no entry for the given path.
    ///
    /// Also returns `None` for symlinks.
    fn load_index_text(&self, path: RepoPath, cx: AsyncApp) -> BoxFuture<Option<String>>;

    /// Returns the contents of an entry in the repository's HEAD, or None if HEAD does not exist or has no entry for the given path.
    ///
    /// Also returns `None` for symlinks.
    fn load_committed_text(&self, path: RepoPath, cx: AsyncApp) -> BoxFuture<Option<String>>;

    fn set_index_text(
        &self,
        path: RepoPath,
        content: Option<String>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<anyhow::Result<()>>;

    /// Returns the URL of the remote with the given name.
    fn remote_url(&self, name: &str) -> Option<String>;

    /// Returns the SHA of the current HEAD.
    fn head_sha(&self) -> Option<String>;

    fn merge_head_shas(&self) -> Vec<String>;

    // Note: this method blocks the current thread!
    fn status(&self, path_prefixes: &[RepoPath]) -> Result<GitStatus>;

    fn branches(&self) -> BoxFuture<Result<Vec<Branch>>>;

    fn change_branch(&self, _: String, _: AsyncApp) -> BoxFuture<Result<()>>;
    fn create_branch(&self, _: String, _: AsyncApp) -> BoxFuture<Result<()>>;

    fn reset(
        &self,
        commit: String,
        mode: ResetMode,
        env: HashMap<String, String>,
    ) -> BoxFuture<Result<()>>;

    fn checkout_files(
        &self,
        commit: String,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
    ) -> BoxFuture<Result<()>>;

    fn show(&self, commit: String, cx: AsyncApp) -> BoxFuture<Result<CommitDetails>>;

    fn blame(
        &self,
        path: RepoPath,
        content: Rope,
        cx: AsyncApp,
    ) -> BoxFuture<Result<crate::blame::Blame>>;

    /// Returns the absolute path to the repository. For worktrees, this will be the path to the
    /// worktree's gitdir within the main repository (typically `.git/worktrees/<name>`).
    fn path(&self) -> PathBuf;

    /// Returns the absolute path to the ".git" dir for the main repository, typically a `.git`
    /// folder. For worktrees, this will be the path to the repository the worktree was created
    /// from. Otherwise, this is the same value as `path()`.
    ///
    /// Git documentation calls this the "commondir", and for git CLI is overridden by
    /// `GIT_COMMON_DIR`.
    fn main_repository_path(&self) -> PathBuf;

    /// Updates the index to match the worktree at the given paths.
    ///
    /// If any of the paths have been deleted from the worktree, they will be removed from the index if found there.
    fn stage_paths(
        &self,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>>;
    /// Updates the index to match HEAD at the given paths.
    ///
    /// If any of the paths were previously staged but do not exist in HEAD, they will be removed from the index.
    fn unstage_paths(
        &self,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>>;

    fn commit(
        &self,
        message: SharedString,
        name_and_email: Option<(SharedString, SharedString)>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>>;

    fn push(
        &self,
        branch_name: String,
        upstream_name: String,
        options: Option<PushOptions>,
        askpass: AskPassSession,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>>;

    fn pull(
        &self,
        branch_name: String,
        upstream_name: String,
        askpass: AskPassSession,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>>;

    fn fetch(
        &self,
        askpass: AskPassSession,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>>;

    fn get_remotes(
        &self,
        branch_name: Option<String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<Vec<Remote>>>;

    /// returns a list of remote branches that contain HEAD
    fn check_for_pushed_commit(&self, cx: AsyncApp) -> BoxFuture<Result<Vec<SharedString>>>;

    /// Run git diff
    fn diff(&self, diff: DiffType, cx: AsyncApp) -> BoxFuture<Result<String>>;
}

pub enum DiffType {
    HeadToIndex,
    HeadToWorktree,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, JsonSchema)]
pub enum PushOptions {
    SetUpstream,
    Force,
}

impl std::fmt::Debug for dyn GitRepository {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("dyn GitRepository<...>").finish()
    }
}

pub struct RealGitRepository {
    pub repository: Arc<Mutex<git2::Repository>>,
    pub git_binary_path: PathBuf,
}

impl RealGitRepository {
    pub fn new(repository: git2::Repository, git_binary_path: Option<PathBuf>) -> Self {
        Self {
            repository: Arc::new(Mutex::new(repository)),
            git_binary_path: git_binary_path.unwrap_or_else(|| PathBuf::from("git")),
        }
    }

    fn working_directory(&self) -> Result<PathBuf> {
        self.repository
            .lock()
            .workdir()
            .context("failed to read git work directory")
            .map(Path::to_path_buf)
    }
}

// https://git-scm.com/book/en/v2/Git-Internals-Git-Objects
const GIT_MODE_SYMLINK: u32 = 0o120000;

impl GitRepository for RealGitRepository {
    fn reload_index(&self) {
        if let Ok(mut index) = self.repository.lock().index() {
            _ = index.read(false);
        }
    }

    fn path(&self) -> PathBuf {
        let repo = self.repository.lock();
        repo.path().into()
    }

    fn main_repository_path(&self) -> PathBuf {
        let repo = self.repository.lock();
        repo.commondir().into()
    }

    fn show(&self, commit: String, cx: AsyncApp) -> BoxFuture<Result<CommitDetails>> {
        let repo = self.repository.clone();
        cx.background_spawn(async move {
            let repo = repo.lock();
            let Ok(commit) = repo.revparse_single(&commit)?.into_commit() else {
                anyhow::bail!("{} is not a commit", commit);
            };
            let details = CommitDetails {
                sha: commit.id().to_string().into(),
                message: String::from_utf8_lossy(commit.message_raw_bytes())
                    .to_string()
                    .into(),
                commit_timestamp: commit.time().seconds(),
                committer_email: String::from_utf8_lossy(commit.committer().email_bytes())
                    .to_string()
                    .into(),
                committer_name: String::from_utf8_lossy(commit.committer().name_bytes())
                    .to_string()
                    .into(),
            };
            Ok(details)
        })
        .boxed()
    }

    fn reset(
        &self,
        commit: String,
        mode: ResetMode,
        env: HashMap<String, String>,
    ) -> BoxFuture<Result<()>> {
        async move {
            let working_directory = self.working_directory();

            let mode_flag = match mode {
                ResetMode::Mixed => "--mixed",
                ResetMode::Soft => "--soft",
            };

            let output = new_smol_command(&self.git_binary_path)
                .envs(env)
                .current_dir(&working_directory?)
                .args(["reset", mode_flag, &commit])
                .output()
                .await?;
            if !output.status.success() {
                return Err(anyhow!(
                    "Failed to reset:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }
            Ok(())
        }
        .boxed()
    }

    fn checkout_files(
        &self,
        commit: String,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
    ) -> BoxFuture<Result<()>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        async move {
            if paths.is_empty() {
                return Ok(());
            }

            let output = new_smol_command(&git_binary_path)
                .current_dir(&working_directory?)
                .envs(env)
                .args(["checkout", &commit, "--"])
                .args(paths.iter().map(|path| path.as_ref()))
                .output()
                .await?;
            if !output.status.success() {
                return Err(anyhow!(
                    "Failed to checkout files:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }
            Ok(())
        }
        .boxed()
    }

    fn load_index_text(&self, path: RepoPath, cx: AsyncApp) -> BoxFuture<Option<String>> {
        let repo = self.repository.clone();
        cx.background_spawn(async move {
            fn logic(repo: &git2::Repository, path: &RepoPath) -> Result<Option<String>> {
                const STAGE_NORMAL: i32 = 0;
                let index = repo.index()?;

                // This check is required because index.get_path() unwraps internally :(
                check_path_to_repo_path_errors(path)?;

                let oid = match index.get_path(path, STAGE_NORMAL) {
                    Some(entry) if entry.mode != GIT_MODE_SYMLINK => entry.id,
                    _ => return Ok(None),
                };

                let content = repo.find_blob(oid)?.content().to_owned();
                Ok(Some(String::from_utf8(content)?))
            }
            match logic(&repo.lock(), &path) {
                Ok(value) => return value,
                Err(err) => log::error!("Error loading index text: {:?}", err),
            }
            None
        })
        .boxed()
    }

    fn load_committed_text(&self, path: RepoPath, cx: AsyncApp) -> BoxFuture<Option<String>> {
        let repo = self.repository.clone();
        cx.background_spawn(async move {
            let repo = repo.lock();
            let head = repo.head().ok()?.peel_to_tree().log_err()?;
            let entry = head.get_path(&path).ok()?;
            if entry.filemode() == i32::from(git2::FileMode::Link) {
                return None;
            }
            let content = repo.find_blob(entry.id()).log_err()?.content().to_owned();
            let content = String::from_utf8(content).log_err()?;
            Some(content)
        })
        .boxed()
    }

    fn set_index_text(
        &self,
        path: RepoPath,
        content: Option<String>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<anyhow::Result<()>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        cx.background_spawn(async move {
            let working_directory = working_directory?;
            if let Some(content) = content {
                let mut child = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .envs(&env)
                    .args(["hash-object", "-w", "--stdin"])
                    .stdin(Stdio::piped())
                    .stdout(Stdio::piped())
                    .spawn()?;
                child
                    .stdin
                    .take()
                    .unwrap()
                    .write_all(content.as_bytes())
                    .await?;
                let output = child.output().await?.stdout;
                let sha = String::from_utf8(output)?;

                log::debug!("indexing SHA: {sha}, path {path:?}");

                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .envs(env)
                    .args(["update-index", "--add", "--cacheinfo", "100644", &sha])
                    .arg(path.as_ref())
                    .output()
                    .await?;

                if !output.status.success() {
                    return Err(anyhow!(
                        "Failed to stage:\n{}",
                        String::from_utf8_lossy(&output.stderr)
                    ));
                }
            } else {
                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .envs(env)
                    .args(["update-index", "--force-remove"])
                    .arg(path.as_ref())
                    .output()
                    .await?;

                if !output.status.success() {
                    return Err(anyhow!(
                        "Failed to unstage:\n{}",
                        String::from_utf8_lossy(&output.stderr)
                    ));
                }
            }

            Ok(())
        })
        .boxed()
    }

    fn remote_url(&self, name: &str) -> Option<String> {
        let repo = self.repository.lock();
        let remote = repo.find_remote(name).ok()?;
        remote.url().map(|url| url.to_string())
    }

    fn head_sha(&self) -> Option<String> {
        Some(self.repository.lock().head().ok()?.target()?.to_string())
    }

    fn merge_head_shas(&self) -> Vec<String> {
        let mut shas = Vec::default();
        self.repository
            .lock()
            .mergehead_foreach(|oid| {
                shas.push(oid.to_string());
                true
            })
            .ok();
        if let Some(oid) = self
            .repository
            .lock()
            .find_reference("CHERRY_PICK_HEAD")
            .ok()
            .and_then(|reference| reference.target())
        {
            shas.push(oid.to_string())
        }
        shas
    }

    fn status(&self, path_prefixes: &[RepoPath]) -> Result<GitStatus> {
        let working_directory = self
            .repository
            .lock()
            .workdir()
            .context("failed to read git work directory")?
            .to_path_buf();
        GitStatus::new(&self.git_binary_path, &working_directory, path_prefixes)
    }

    fn branches(&self) -> BoxFuture<Result<Vec<Branch>>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        async move {
            let fields = [
                "%(HEAD)",
                "%(objectname)",
                "%(parent)",
                "%(refname)",
                "%(upstream)",
                "%(upstream:track)",
                "%(committerdate:unix)",
                "%(contents:subject)",
            ]
            .join("%00");
            let args = vec!["for-each-ref", "refs/heads/**/*", "--format", &fields];
            let working_directory = working_directory?;
            let output = new_smol_command(&git_binary_path)
                .current_dir(&working_directory)
                .args(args)
                .output()
                .await?;

            if !output.status.success() {
                return Err(anyhow!(
                    "Failed to git git branches:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }

            let input = String::from_utf8_lossy(&output.stdout);

            let mut branches = parse_branch_input(&input)?;
            if branches.is_empty() {
                let args = vec!["symbolic-ref", "--quiet", "--short", "HEAD"];

                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .args(args)
                    .output()
                    .await?;

                // git symbolic-ref returns a non-0 exit code if HEAD points
                // to something other than a branch
                if output.status.success() {
                    let name = String::from_utf8_lossy(&output.stdout).trim().to_string();

                    branches.push(Branch {
                        name: name.into(),
                        is_head: true,
                        upstream: None,
                        most_recent_commit: None,
                    });
                }
            }

            Ok(branches)
        }
        .boxed()
    }

    fn change_branch(&self, name: String, cx: AsyncApp) -> BoxFuture<Result<()>> {
        let repo = self.repository.clone();
        cx.background_spawn(async move {
            let repo = repo.lock();
            let revision = repo.find_branch(&name, BranchType::Local)?;
            let revision = revision.get();
            let as_tree = revision.peel_to_tree()?;
            repo.checkout_tree(as_tree.as_object(), None)?;
            repo.set_head(
                revision
                    .name()
                    .ok_or_else(|| anyhow!("Branch name could not be retrieved"))?,
            )?;
            Ok(())
        })
        .boxed()
    }

    fn create_branch(&self, name: String, cx: AsyncApp) -> BoxFuture<Result<()>> {
        let repo = self.repository.clone();
        cx.background_spawn(async move {
            let repo = repo.lock();
            let current_commit = repo.head()?.peel_to_commit()?;
            repo.branch(&name, &current_commit, false)?;
            Ok(())
        })
        .boxed()
    }

    fn blame(
        &self,
        path: RepoPath,
        content: Rope,
        cx: AsyncApp,
    ) -> BoxFuture<Result<crate::blame::Blame>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();

        const REMOTE_NAME: &str = "origin";
        let remote_url = self.remote_url(REMOTE_NAME);

        cx.background_spawn(async move {
            crate::blame::Blame::for_path(
                &git_binary_path,
                &working_directory?,
                &path,
                &content,
                remote_url,
            )
            .await
        })
        .boxed()
    }

    fn diff(&self, diff: DiffType, cx: AsyncApp) -> BoxFuture<Result<String>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        cx.background_spawn(async move {
            let args = match diff {
                DiffType::HeadToIndex => Some("--staged"),
                DiffType::HeadToWorktree => None,
            };

            let output = new_smol_command(&git_binary_path)
                .current_dir(&working_directory?)
                .args(["diff"])
                .args(args)
                .output()
                .await?;

            if !output.status.success() {
                return Err(anyhow!(
                    "Failed to run git diff:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }
            Ok(String::from_utf8_lossy(&output.stdout).to_string())
        })
        .boxed()
    }

    fn stage_paths(
        &self,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        cx.background_spawn(async move {
            if !paths.is_empty() {
                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory?)
                    .envs(env)
                    .args(["update-index", "--add", "--remove", "--"])
                    .args(paths.iter().map(|p| p.as_ref()))
                    .output()
                    .await?;

                if !output.status.success() {
                    return Err(anyhow!(
                        "Failed to stage paths:\n{}",
                        String::from_utf8_lossy(&output.stderr)
                    ));
                }
            }
            Ok(())
        })
        .boxed()
    }

    fn unstage_paths(
        &self,
        paths: Vec<RepoPath>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();

        cx.background_spawn(async move {
            if !paths.is_empty() {
                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory?)
                    .envs(env)
                    .args(["reset", "--quiet", "--"])
                    .args(paths.iter().map(|p| p.as_ref()))
                    .output()
                    .await?;

                if !output.status.success() {
                    return Err(anyhow!(
                        "Failed to unstage:\n{}",
                        String::from_utf8_lossy(&output.stderr)
                    ));
                }
            }
            Ok(())
        })
        .boxed()
    }

    fn commit(
        &self,
        message: SharedString,
        name_and_email: Option<(SharedString, SharedString)>,
        env: HashMap<String, String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        let working_directory = self.working_directory();
        cx.background_spawn(async move {
            let mut cmd = new_smol_command("git");
            cmd.current_dir(&working_directory?)
                .envs(env)
                .args(["commit", "--quiet", "-m"])
                .arg(&message.to_string())
                .arg("--cleanup=strip");

            if let Some((name, email)) = name_and_email {
                cmd.arg("--author").arg(&format!("{name} <{email}>"));
            }

            let output = cmd.output().await?;

            if !output.status.success() {
                return Err(anyhow!(
                    "Failed to commit:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }
            Ok(())
        })
        .boxed()
    }

    fn push(
        &self,
        branch_name: String,
        remote_name: String,
        options: Option<PushOptions>,
        ask_pass: AskPassSession,
        env: HashMap<String, String>,
        // note: git push *must* be started on the main thread for
        // git-credentials manager to work (hence taking an AsyncApp)
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        let working_directory = self.working_directory();
        async move {
            let working_directory = working_directory?;

            let mut command = new_smol_command("git");
            command
                .envs(env)
                .env("GIT_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS_REQUIRE", "force")
                .env("GIT_HTTP_USER_AGENT", "Zed")
                .current_dir(&working_directory)
                .args(["push"])
                .args(options.map(|option| match option {
                    PushOptions::SetUpstream => "--set-upstream",
                    PushOptions::Force => "--force-with-lease",
                }))
                .arg(remote_name)
                .arg(format!("{}:{}", branch_name, branch_name))
                .stdin(smol::process::Stdio::null())
                .stdout(smol::process::Stdio::piped())
                .stderr(smol::process::Stdio::piped());
            let git_process = command.spawn()?;

            run_remote_command(ask_pass, git_process).await
        }
        .boxed()
    }

    fn pull(
        &self,
        branch_name: String,
        remote_name: String,
        ask_pass: AskPassSession,
        env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        let working_directory = self.working_directory();
        async {
            let mut command = new_smol_command("git");
            command
                .envs(env)
                .env("GIT_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS_REQUIRE", "force")
                .current_dir(&working_directory?)
                .args(["pull"])
                .arg(remote_name)
                .arg(branch_name)
                .stdout(smol::process::Stdio::piped())
                .stderr(smol::process::Stdio::piped());
            let git_process = command.spawn()?;

            run_remote_command(ask_pass, git_process).await
        }
        .boxed()
    }

    fn fetch(
        &self,
        ask_pass: AskPassSession,
        env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        let working_directory = self.working_directory();
        async {
            let mut command = new_smol_command("git");
            command
                .envs(env)
                .env("GIT_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS", ask_pass.script_path())
                .env("SSH_ASKPASS_REQUIRE", "force")
                .current_dir(&working_directory?)
                .args(["fetch", "--all"])
                .stdout(smol::process::Stdio::piped())
                .stderr(smol::process::Stdio::piped());
            let git_process = command.spawn()?;

            run_remote_command(ask_pass, git_process).await
        }
        .boxed()
    }

    fn get_remotes(
        &self,
        branch_name: Option<String>,
        cx: AsyncApp,
    ) -> BoxFuture<Result<Vec<Remote>>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        cx.background_spawn(async move {
            let working_directory = working_directory?;
            if let Some(branch_name) = branch_name {
                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .args(["config", "--get"])
                    .arg(format!("branch.{}.remote", branch_name))
                    .output()
                    .await?;

                if output.status.success() {
                    let remote_name = String::from_utf8_lossy(&output.stdout);

                    return Ok(vec![Remote {
                        name: remote_name.trim().to_string().into(),
                    }]);
                }
            }

            let output = new_smol_command(&git_binary_path)
                .current_dir(&working_directory)
                .args(["remote"])
                .output()
                .await?;

            if output.status.success() {
                let remote_names = String::from_utf8_lossy(&output.stdout)
                    .split('\n')
                    .filter(|name| !name.is_empty())
                    .map(|name| Remote {
                        name: name.trim().to_string().into(),
                    })
                    .collect();

                return Ok(remote_names);
            } else {
                return Err(anyhow!(
                    "Failed to get remotes:\n{}",
                    String::from_utf8_lossy(&output.stderr)
                ));
            }
        })
        .boxed()
    }

    fn check_for_pushed_commit(&self, cx: AsyncApp) -> BoxFuture<Result<Vec<SharedString>>> {
        let working_directory = self.working_directory();
        let git_binary_path = self.git_binary_path.clone();
        cx.background_spawn(async move {
            let working_directory = working_directory?;
            let git_cmd = async |args: &[&str]| -> Result<String> {
                let output = new_smol_command(&git_binary_path)
                    .current_dir(&working_directory)
                    .args(args)
                    .output()
                    .await?;
                if output.status.success() {
                    Ok(String::from_utf8(output.stdout)?)
                } else {
                    Err(anyhow!(String::from_utf8_lossy(&output.stderr).to_string()))
                }
            };

            let head = git_cmd(&["rev-parse", "HEAD"])
                .await
                .context("Failed to get HEAD")?
                .trim()
                .to_owned();

            let mut remote_branches = vec![];
            let mut add_if_matching = async |remote_head: &str| {
                if let Ok(merge_base) = git_cmd(&["merge-base", &head, remote_head]).await {
                    if merge_base.trim() == head {
                        if let Some(s) = remote_head.strip_prefix("refs/remotes/") {
                            remote_branches.push(s.to_owned().into());
                        }
                    }
                }
            };

            // check the main branch of each remote
            let remotes = git_cmd(&["remote"])
                .await
                .context("Failed to get remotes")?;
            for remote in remotes.lines() {
                if let Ok(remote_head) =
                    git_cmd(&["symbolic-ref", &format!("refs/remotes/{remote}/HEAD")]).await
                {
                    add_if_matching(remote_head.trim()).await;
                }
            }

            // ... and the remote branch that the checked-out one is tracking
            if let Ok(remote_head) = git_cmd(&["rev-parse", "--symbolic-full-name", "@{u}"]).await {
                add_if_matching(remote_head.trim()).await;
            }

            Ok(remote_branches)
        })
        .boxed()
    }
}

async fn run_remote_command(
    mut ask_pass: AskPassSession,
    git_process: smol::process::Child,
) -> std::result::Result<RemoteCommandOutput, anyhow::Error> {
    select_biased! {
        result = ask_pass.run().fuse() => {
            match result {
                AskPassResult::CancelledByUser => {
                    Err(anyhow!(REMOTE_CANCELLED_BY_USER))?
                }
                AskPassResult::Timedout => {
                    Err(anyhow!("Connecting to host timed out"))?
                }
            }
        }
        output = git_process.output().fuse() => {
            let output = output?;
            if !output.status.success() {
                Err(anyhow!(
                    "{}",
                    String::from_utf8_lossy(&output.stderr)
                ))
            } else {
                Ok(RemoteCommandOutput {
                    stdout: String::from_utf8_lossy(&output.stdout).to_string(),
                    stderr: String::from_utf8_lossy(&output.stderr).to_string(),
                })
            }
        }
    }
}

#[derive(Debug, Clone)]
pub struct FakeGitRepository {
    state: Arc<Mutex<FakeGitRepositoryState>>,
}

#[derive(Debug, Clone)]
pub struct FakeGitRepositoryState {
    pub path: PathBuf,
    pub event_emitter: smol::channel::Sender<PathBuf>,
    pub head_contents: HashMap<RepoPath, String>,
    pub index_contents: HashMap<RepoPath, String>,
    pub blames: HashMap<RepoPath, Blame>,
    pub statuses: HashMap<RepoPath, FileStatus>,
    pub current_branch_name: Option<String>,
    pub branches: HashSet<String>,
    pub simulated_index_write_error_message: Option<String>,
}

impl FakeGitRepository {
    pub fn open(state: Arc<Mutex<FakeGitRepositoryState>>) -> Arc<dyn GitRepository> {
        Arc::new(FakeGitRepository { state })
    }
}

impl FakeGitRepositoryState {
    pub fn new(path: PathBuf, event_emitter: smol::channel::Sender<PathBuf>) -> Self {
        FakeGitRepositoryState {
            path,
            event_emitter,
            head_contents: Default::default(),
            index_contents: Default::default(),
            blames: Default::default(),
            statuses: Default::default(),
            current_branch_name: Default::default(),
            branches: Default::default(),
            simulated_index_write_error_message: None,
        }
    }
}

impl GitRepository for FakeGitRepository {
    fn reload_index(&self) {}

    fn load_index_text(&self, path: RepoPath, _: AsyncApp) -> BoxFuture<Option<String>> {
        let state = self.state.lock();
        let content = state.index_contents.get(path.as_ref()).cloned();
        async { content }.boxed()
    }

    fn load_committed_text(&self, path: RepoPath, _: AsyncApp) -> BoxFuture<Option<String>> {
        let state = self.state.lock();
        let content = state.head_contents.get(path.as_ref()).cloned();
        async { content }.boxed()
    }

    fn set_index_text(
        &self,
        path: RepoPath,
        content: Option<String>,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<anyhow::Result<()>> {
        let mut state = self.state.lock();
        if let Some(message) = state.simulated_index_write_error_message.clone() {
            return async { Err(anyhow::anyhow!(message)) }.boxed();
        }
        if let Some(content) = content {
            state.index_contents.insert(path.clone(), content);
        } else {
            state.index_contents.remove(&path);
        }
        state
            .event_emitter
            .try_send(state.path.clone())
            .expect("Dropped repo change event");
        async { Ok(()) }.boxed()
    }

    fn remote_url(&self, _name: &str) -> Option<String> {
        None
    }

    fn head_sha(&self) -> Option<String> {
        None
    }

    fn merge_head_shas(&self) -> Vec<String> {
        vec![]
    }

    fn show(&self, _: String, _: AsyncApp) -> BoxFuture<Result<CommitDetails>> {
        unimplemented!()
    }

    fn reset(&self, _: String, _: ResetMode, _: HashMap<String, String>) -> BoxFuture<Result<()>> {
        unimplemented!()
    }

    fn checkout_files(
        &self,
        _: String,
        _: Vec<RepoPath>,
        _: HashMap<String, String>,
    ) -> BoxFuture<Result<()>> {
        unimplemented!()
    }

    fn path(&self) -> PathBuf {
        let state = self.state.lock();
        state.path.clone()
    }

    fn main_repository_path(&self) -> PathBuf {
        self.path()
    }

    fn status(&self, path_prefixes: &[RepoPath]) -> Result<GitStatus> {
        let state = self.state.lock();

        let mut entries = state
            .statuses
            .iter()
            .filter_map(|(repo_path, status)| {
                if path_prefixes
                    .iter()
                    .any(|path_prefix| repo_path.0.starts_with(path_prefix))
                {
                    Some((repo_path.to_owned(), *status))
                } else {
                    None
                }
            })
            .collect::<Vec<_>>();
        entries.sort_unstable_by(|(a, _), (b, _)| a.cmp(&b));

        Ok(GitStatus {
            entries: entries.into(),
        })
    }

    fn branches(&self) -> BoxFuture<Result<Vec<Branch>>> {
        let state = self.state.lock();
        let current_branch = &state.current_branch_name;
        let result = Ok(state
            .branches
            .iter()
            .map(|branch_name| Branch {
                is_head: Some(branch_name) == current_branch.as_ref(),
                name: branch_name.into(),
                most_recent_commit: None,
                upstream: None,
            })
            .collect());

        async { result }.boxed()
    }

    fn change_branch(&self, name: String, _: AsyncApp) -> BoxFuture<Result<()>> {
        let mut state = self.state.lock();
        state.current_branch_name = Some(name.to_owned());
        state
            .event_emitter
            .try_send(state.path.clone())
            .expect("Dropped repo change event");
        async { Ok(()) }.boxed()
    }

    fn create_branch(&self, name: String, _: AsyncApp) -> BoxFuture<Result<()>> {
        let mut state = self.state.lock();
        state.branches.insert(name.to_owned());
        state
            .event_emitter
            .try_send(state.path.clone())
            .expect("Dropped repo change event");
        async { Ok(()) }.boxed()
    }

    fn blame(
        &self,
        path: RepoPath,
        _content: Rope,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<crate::blame::Blame>> {
        let state = self.state.lock();
        let result = state
            .blames
            .get(&path)
            .with_context(|| format!("failed to get blame for {:?}", path.0))
            .cloned();
        async { result }.boxed()
    }

    fn stage_paths(
        &self,
        _paths: Vec<RepoPath>,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        unimplemented!()
    }

    fn unstage_paths(
        &self,
        _paths: Vec<RepoPath>,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        unimplemented!()
    }

    fn commit(
        &self,
        _message: SharedString,
        _name_and_email: Option<(SharedString, SharedString)>,
        _env: HashMap<String, String>,
        _: AsyncApp,
    ) -> BoxFuture<Result<()>> {
        unimplemented!()
    }

    fn push(
        &self,
        _branch: String,
        _remote: String,
        _options: Option<PushOptions>,
        _ask_pass: AskPassSession,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        unimplemented!()
    }

    fn pull(
        &self,
        _branch: String,
        _remote: String,
        _ask_pass: AskPassSession,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        unimplemented!()
    }

    fn fetch(
        &self,
        _ask_pass: AskPassSession,
        _env: HashMap<String, String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<RemoteCommandOutput>> {
        unimplemented!()
    }

    fn get_remotes(
        &self,
        _branch: Option<String>,
        _cx: AsyncApp,
    ) -> BoxFuture<Result<Vec<Remote>>> {
        unimplemented!()
    }

    fn check_for_pushed_commit(&self, _cx: AsyncApp) -> BoxFuture<Result<Vec<SharedString>>> {
        unimplemented!()
    }

    fn diff(&self, _diff: DiffType, _cx: AsyncApp) -> BoxFuture<Result<String>> {
        unimplemented!()
    }
}

fn check_path_to_repo_path_errors(relative_file_path: &Path) -> Result<()> {
    match relative_file_path.components().next() {
        None => anyhow::bail!("repo path should not be empty"),
        Some(Component::Prefix(_)) => anyhow::bail!(
            "repo path `{}` should be relative, not a windows prefix",
            relative_file_path.to_string_lossy()
        ),
        Some(Component::RootDir) => {
            anyhow::bail!(
                "repo path `{}` should be relative",
                relative_file_path.to_string_lossy()
            )
        }
        Some(Component::CurDir) => {
            anyhow::bail!(
                "repo path `{}` should not start with `.`",
                relative_file_path.to_string_lossy()
            )
        }
        Some(Component::ParentDir) => {
            anyhow::bail!(
                "repo path `{}` should not start with `..`",
                relative_file_path.to_string_lossy()
            )
        }
        _ => Ok(()),
    }
}

pub static WORK_DIRECTORY_REPO_PATH: LazyLock<RepoPath> =
    LazyLock::new(|| RepoPath(Path::new("").into()));

#[derive(Clone, Debug, Ord, Hash, PartialOrd, Eq, PartialEq)]
pub struct RepoPath(pub Arc<Path>);

impl RepoPath {
    pub fn new(path: PathBuf) -> Self {
        debug_assert!(path.is_relative(), "Repo paths must be relative");

        RepoPath(path.into())
    }

    pub fn from_str(path: &str) -> Self {
        let path = Path::new(path);
        debug_assert!(path.is_relative(), "Repo paths must be relative");

        RepoPath(path.into())
    }
}

impl std::fmt::Display for RepoPath {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        self.0.to_string_lossy().fmt(f)
    }
}

impl From<&Path> for RepoPath {
    fn from(value: &Path) -> Self {
        RepoPath::new(value.into())
    }
}

impl From<Arc<Path>> for RepoPath {
    fn from(value: Arc<Path>) -> Self {
        RepoPath(value)
    }
}

impl From<PathBuf> for RepoPath {
    fn from(value: PathBuf) -> Self {
        RepoPath::new(value)
    }
}

impl From<&str> for RepoPath {
    fn from(value: &str) -> Self {
        Self::from_str(value)
    }
}

impl Default for RepoPath {
    fn default() -> Self {
        RepoPath(Path::new("").into())
    }
}

impl AsRef<Path> for RepoPath {
    fn as_ref(&self) -> &Path {
        self.0.as_ref()
    }
}

impl std::ops::Deref for RepoPath {
    type Target = Path;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl Borrow<Path> for RepoPath {
    fn borrow(&self) -> &Path {
        self.0.as_ref()
    }
}

#[derive(Debug)]
pub struct RepoPathDescendants<'a>(pub &'a Path);

impl MapSeekTarget<RepoPath> for RepoPathDescendants<'_> {
    fn cmp_cursor(&self, key: &RepoPath) -> Ordering {
        if key.starts_with(self.0) {
            Ordering::Greater
        } else {
            self.0.cmp(key)
        }
    }
}

fn parse_branch_input(input: &str) -> Result<Vec<Branch>> {
    let mut branches = Vec::new();
    for line in input.split('\n') {
        if line.is_empty() {
            continue;
        }
        let mut fields = line.split('\x00');
        let is_current_branch = fields.next().context("no HEAD")? == "*";
        let head_sha: SharedString = fields.next().context("no objectname")?.to_string().into();
        let parent_sha: SharedString = fields.next().context("no parent")?.to_string().into();
        let ref_name: SharedString = fields
            .next()
            .context("no refname")?
            .strip_prefix("refs/heads/")
            .context("unexpected format for refname")?
            .to_string()
            .into();
        let upstream_name = fields.next().context("no upstream")?.to_string();
        let upstream_tracking = parse_upstream_track(fields.next().context("no upstream:track")?)?;
        let commiterdate = fields.next().context("no committerdate")?.parse::<i64>()?;
        let subject: SharedString = fields
            .next()
            .context("no contents:subject")?
            .to_string()
            .into();

        branches.push(Branch {
            is_head: is_current_branch,
            name: ref_name,
            most_recent_commit: Some(CommitSummary {
                sha: head_sha,
                subject,
                commit_timestamp: commiterdate,
                has_parent: !parent_sha.is_empty(),
            }),
            upstream: if upstream_name.is_empty() {
                None
            } else {
                Some(Upstream {
                    ref_name: upstream_name.into(),
                    tracking: upstream_tracking,
                })
            },
        })
    }

    Ok(branches)
}

fn parse_upstream_track(upstream_track: &str) -> Result<UpstreamTracking> {
    if upstream_track == "" {
        return Ok(UpstreamTracking::Tracked(UpstreamTrackingStatus {
            ahead: 0,
            behind: 0,
        }));
    }

    let upstream_track = upstream_track
        .strip_prefix("[")
        .ok_or_else(|| anyhow!("missing ["))?;
    let upstream_track = upstream_track
        .strip_suffix("]")
        .ok_or_else(|| anyhow!("missing ["))?;
    let mut ahead: u32 = 0;
    let mut behind: u32 = 0;
    for component in upstream_track.split(", ") {
        if component == "gone" {
            return Ok(UpstreamTracking::Gone);
        }
        if let Some(ahead_num) = component.strip_prefix("ahead ") {
            ahead = ahead_num.parse::<u32>()?;
        }
        if let Some(behind_num) = component.strip_prefix("behind ") {
            behind = behind_num.parse::<u32>()?;
        }
    }
    Ok(UpstreamTracking::Tracked(UpstreamTrackingStatus {
        ahead,
        behind,
    }))
}

#[test]
fn test_branches_parsing() {
    // suppress "help: octal escapes are not supported, `\0` is always null"
    #[allow(clippy::octal_escapes)]
    let input = "*\0060964da10574cd9bf06463a53bf6e0769c5c45e\0\0refs/heads/zed-patches\0refs/remotes/origin/zed-patches\0\01733187470\0generated protobuf\n";
    assert_eq!(
        parse_branch_input(&input).unwrap(),
        vec![Branch {
            is_head: true,
            name: "zed-patches".into(),
            upstream: Some(Upstream {
                ref_name: "refs/remotes/origin/zed-patches".into(),
                tracking: UpstreamTracking::Tracked(UpstreamTrackingStatus {
                    ahead: 0,
                    behind: 0
                })
            }),
            most_recent_commit: Some(CommitSummary {
                sha: "060964da10574cd9bf06463a53bf6e0769c5c45e".into(),
                subject: "generated protobuf".into(),
                commit_timestamp: 1733187470,
                has_parent: false,
            })
        }]
    )
}