/// Single-machine mode: no cluster forwarding.
macro_rules! remote_client {
    ($fn_name:ident, $client:ty, $svc_label:literal) => {
        async fn $fn_name(
            _svc: &super::GitksService,
            _header: Option<&crate::pb::RepositoryHeader>,
            _is_write: bool,
        ) -> Result<Option<$client>, tonic::Status> {
            Ok(None)
        }
    };
}

mod archive;
mod blame;
mod branch;
mod cache;
mod commit;
mod diff;
mod merge;
mod pack;
mod refs;
mod remote;
mod repository;
mod repository_maint;
mod tag;
mod tree;

use gix::discover::is_git;
use std::path::{Path, PathBuf};
use tokio_stream::wrappers::ReceiverStream;

use crate::bare::GitBare;
use crate::error::{GitError, GitResult};
use crate::pb::{
    archive_service_server, blame_service_server, branch_service_server, commit_service_server,
    diff_service_server, merge_service_server, pack_service_server, ref_service_server,
    remote_service_server, repository_service_server, tag_service_server, tree_service_server,
};

#[derive(Clone)]
pub struct GitksService {
    pub repo_prefix: PathBuf,
    pub grpc_addr: String,
    pub disk_cache: Option<crate::disk_cache::DiskCache>,
    pub pack_cache: Option<crate::pack_cache::PackCache>,
    pub hook_manager: Option<crate::hooks::HookManager>,
}

impl GitksService {
    pub fn new(repo_prefix: PathBuf) -> Self {
        Self {
            repo_prefix,
            grpc_addr: String::new(),
            disk_cache: None,
            pack_cache: None,
            hook_manager: None,
        }
    }

    pub fn with_disk_cache(mut self, dc: crate::disk_cache::DiskCache) -> Self {
        self.disk_cache = Some(dc);
        self
    }

    pub fn with_pack_cache(mut self, pc: crate::pack_cache::PackCache) -> Self {
        self.pack_cache = Some(pc);
        self
    }

    pub fn with_hook_manager(mut self, hm: crate::hooks::HookManager) -> Self {
        self.hook_manager = Some(hm);
        self
    }

    pub fn with_grpc_addr(mut self, grpc_addr: String) -> Self {
        self.grpc_addr = grpc_addr;
        self
    }

    pub fn scan_all_repo(&self) -> GitResult<Vec<String>> {
        let root = self.repo_prefix.as_ref();
        let mut repos = Vec::new();
        if is_bare_git_repo(root) {
            repos.push(root.to_path_buf());
        } else {
            scan_bare_repos_recursively(root, &mut repos)?;
        }
        Ok(repos
            .into_iter()
            .filter_map(|path| path.to_str().map(str::to_owned))
            .collect())
    }
    fn repo_label(&self, header: Option<&crate::pb::RepositoryHeader>) -> String {
        header
            .and_then(|h| {
                if h.relative_path.is_empty() {
                    None
                } else {
                    Some(h.relative_path.clone())
                }
            })
            .unwrap_or_else(|| "unknown".into())
    }

    /// Get the relative path from a repository header, if any.
    pub(crate) fn repo_relative_path<'a>(
        &self,
        header: Option<&'a crate::pb::RepositoryHeader>,
    ) -> Option<&'a str> {
        header.and_then(|h| {
            if h.relative_path.is_empty() {
                None
            } else {
                Some(h.relative_path.as_str())
            }
        })
    }

    /// Acquire a rate-limit permit for the repository in this request.
    /// Returns a guard that releases the permit on drop.
    pub(crate) async fn acquire_rate_limit(
        &self,
        header: Option<&crate::pb::RepositoryHeader>,
    ) -> Result<Option<crate::rate_limit::RateLimitGuard>, tonic::Status> {
        crate::rate_limit::acquire_or_reject(self.repo_relative_path(header)).await
    }

    pub(crate) fn resolve(
        &self,
        header: Option<&crate::pb::RepositoryHeader>,
    ) -> Result<GitBare, tonic::Status> {
        let header =
            header.ok_or_else(|| tonic::Status::invalid_argument("repository is required"))?;
        let header = self.prefixed_header(header);
        let gb = GitBare::from_repository_header(&header).map_err(into_status)?;
        tracing::debug!(
            repo = %gb.bare_dir.display(),
            "resolved repository"
        );
        Ok(gb)
    }

    pub(crate) fn resolve_for_init(
        &self,
        header: Option<&crate::pb::RepositoryHeader>,
    ) -> Result<PathBuf, tonic::Status> {
        let header =
            header.ok_or_else(|| tonic::Status::invalid_argument("repository is required"))?;
        let relative_path = header.relative_path.trim();
        if relative_path.is_empty() {
            return Err(tonic::Status::invalid_argument("relative_path is required"));
        }
        // Validate early to reject '..' and other traversal patterns
        crate::sanitize::validate_relative_path(relative_path)
            .map_err(|e| tonic::Status::invalid_argument(e.to_string()))?;

        let candidate = self.repo_prefix.join(relative_path);
        // Canonicalize repo_prefix (which should exist) for a reliable check
        let prefix_canon = self
            .repo_prefix
            .canonicalize()
            .unwrap_or_else(|_| self.repo_prefix.clone());

        // Unified path validation to avoid TOCTOU
        let canonical = match candidate.canonicalize() {
            Ok(canon) => {
                // Path exists and was canonicalized
                canon
            }
            Err(_) => {
                // Path doesn't exist yet — validate via parent
                let parent = candidate.parent().unwrap_or(&self.repo_prefix);
                let filename = candidate.file_name().ok_or_else(|| {
                    tonic::Status::invalid_argument("invalid path: missing filename")
                })?;

                let parent_canon = parent
                    .canonicalize()
                    .unwrap_or_else(|_| parent.to_path_buf());
                let constructed = parent_canon.join(filename);

                // String-level verification for non-existent paths
                let constructed_str = constructed.to_string_lossy();
                let prefix_str = prefix_canon.to_string_lossy();

                if !constructed_str.starts_with(&*prefix_str) {
                    return Err(tonic::Status::invalid_argument(
                        "path traversal detected: relative_path escapes repo prefix",
                    ));
                }

                constructed
            }
        };

        // Final check: canonical must be under prefix
        if !canonical.starts_with(&prefix_canon) {
            return Err(tonic::Status::invalid_argument(
                "path traversal detected: relative_path escapes repo prefix",
            ));
        }

        Ok(canonical)
    }

    pub fn notify_ref_update(
        &self,
        relative_path: &str,
        _ref_name: &str,
        _old_oid: &str,
        _new_oid: &str,
    ) {
        // Invalidate moka caches
        crate::server::cache::invalidate_repo(relative_path);

        // Invalidate disk cache
        if let Some(ref pc) = self.pack_cache {
            pc.invalidate_repo(relative_path);
        }
    }

    /// Inject repo_prefix as storage_path into the client-provided header
    fn prefixed_header(&self, header: &crate::pb::RepositoryHeader) -> crate::pb::RepositoryHeader {
        crate::pb::RepositoryHeader {
            storage_path: self.repo_prefix.to_string_lossy().into_owned(),
            relative_path: header.relative_path.clone(),
            storage_name: header.storage_name.clone(),
        }
    }
}

pub(super) fn bridge_server_stream<T: Send + 'static>(
    mut remote: tonic::Streaming<T>,
) -> tokio_stream::wrappers::ReceiverStream<Result<T, tonic::Status>> {
    let (tx, rx) = tokio::sync::mpsc::channel(16);
    tokio::spawn(async move {
        use tokio_stream::StreamExt;
        while let Some(item) = remote.next().await {
            if tx.send(item).await.is_err() {
                break;
            }
        }
    });
    tokio_stream::wrappers::ReceiverStream::new(rx)
}

fn scan_bare_repos_recursively(dir: &Path, repos: &mut Vec<PathBuf>) -> GitResult<()> {
    for entry in std::fs::read_dir(dir)? {
        let entry = entry?;
        let path = entry.path();

        if is_bare_git_repo(&path) {
            repos.push(path);
            continue;
        }

        if path.is_dir() {
            scan_bare_repos_recursively(&path, repos)?;
        }
    }

    Ok(())
}

fn is_bare_git_repo(path: &Path) -> bool {
    match is_git(path) {
        Ok(repo) => repo.is_bare(),
        Err(_) => false,
    }
}

pub(crate) fn into_status(e: GitError) -> tonic::Status {
    match &e {
        GitError::NotFound(_)
        | GitError::ObjectNotFound(_)
        | GitError::RefNotFound(_)
        | GitError::RepoNotFound => tonic::Status::not_found(e.to_string()),
        GitError::InvalidArgument(_) => tonic::Status::invalid_argument(e.to_string()),
        GitError::PermissionDenied(_) => tonic::Status::permission_denied(e.to_string()),
        GitError::Locked(_) => tonic::Status::failed_precondition(e.to_string()),
        GitError::AuthFailed(_) => tonic::Status::unauthenticated(e.to_string()),
        GitError::NotBareRepository => tonic::Status::failed_precondition(e.to_string()),
        _ => tonic::Status::internal(e.to_string()),
    }
}

impl From<GitError> for tonic::Status {
    fn from(e: GitError) -> Self {
        into_status(e)
    }
}

pub(crate) fn into_stream<T: Send + 'static>(
    items: Vec<T>,
) -> ReceiverStream<Result<T, tonic::Status>> {
    let (tx, rx) = tokio::sync::mpsc::channel(items.len().max(1));
    for item in items {
        let _ = tx.try_send(Ok(item));
    }
    ReceiverStream::new(rx)
}

pub(crate) fn git_cmd(gb: &GitBare, args: &[&str]) -> GitResult<std::process::Output> {
    let mut full_args: Vec<String> = vec![
        "--git-dir".into(),
        gb.bare_dir.to_string_lossy().into_owned(),
    ];
    full_args.extend(args.iter().map(|s| s.to_string()));
    let cmd_name = args.first().copied().unwrap_or("unknown");
    tracing::debug!(
        repo = %gb.bare_dir.display(),
        args = %full_args.iter().skip(2).cloned().collect::<Vec<_>>().join(" "),
        "spawning git subprocess"
    );
    let start = std::time::Instant::now();
    let result = std::process::Command::new("git")
        .args(&full_args)
        .output()
        .map_err(|e| {
            tracing::error!(
                repo = %gb.bare_dir.display(),
                error = %e,
                "failed to spawn git subprocess"
            );
            GitError::Internal(format!("failed to spawn git: {e}"))
        })?;
    let elapsed = start.elapsed();
    let elapsed_ms = elapsed.as_millis() as u64;

    // Record metrics
    crate::metrics::record_git_cmd(cmd_name, elapsed);

    // Slow operation warning
    if elapsed.as_secs() >= 1 {
        tracing::warn!(
            repo = %gb.bare_dir.display(),
            command = cmd_name,
            elapsed_ms,
            "slow git subprocess"
        );
    }

    if !result.status.success() {
        let stderr_str = String::from_utf8_lossy(&result.stderr);
        tracing::warn!(
            repo = %gb.bare_dir.display(),
            command = cmd_name,
            status = ?result.status.code(),
            stderr = %stderr_str.trim(),
            elapsed_ms,
            "git subprocess exited with non-zero status"
        );
        return Err(structured_git_error(&stderr_str, result.status.code()));
    }

    tracing::debug!(
        repo = %gb.bare_dir.display(),
        command = cmd_name,
        elapsed_ms,
        "git subprocess completed"
    );
    Ok(result)
}

/// Map git subprocess stderr to a structured GitError variant.
fn structured_git_error(stderr: &str, code: Option<i32>) -> GitError {
    let stderr_trimmed = stderr.trim();
    if stderr_trimmed.contains("not a git repository") || stderr_trimmed.contains("does not exist")
    {
        GitError::RepoNotFound
    } else if stderr_trimmed.contains("Permission denied") || stderr_trimmed.contains("denied") {
        GitError::PermissionDenied(stderr_trimmed.to_string())
    } else if stderr_trimmed.contains("is locked") || stderr_trimmed.contains("Could not acquire") {
        GitError::Locked(stderr_trimmed.to_string())
    } else if stderr_trimmed.contains("not found") || stderr_trimmed.contains("do not have") {
        GitError::NotFound(stderr_trimmed.to_string())
    } else {
        GitError::CommandFailed {
            status_code: code,
            stderr: stderr_trimmed.to_string(),
        }
    }
}

pub async fn serve(
    addr: std::net::SocketAddr,
    svc: GitksService,
) -> Result<(), tonic::transport::Error> {
    let span = tracing::info_span!("gitks.server", %addr);
    let _enter = span.enter();
    tracing::info!("registering gRPC services");

    let (health_reporter, health_service) = tonic_health::server::health_reporter();

    let repo_svc = repository_service_server::RepositoryServiceServer::new(svc.clone());
    let archive_svc = archive_service_server::ArchiveServiceServer::new(svc.clone());
    let blame_svc = blame_service_server::BlameServiceServer::new(svc.clone());
    let branch_svc = branch_service_server::BranchServiceServer::new(svc.clone());
    let commit_svc = commit_service_server::CommitServiceServer::new(svc.clone());
    let diff_svc = diff_service_server::DiffServiceServer::new(svc.clone());
    let merge_svc = merge_service_server::MergeServiceServer::new(svc.clone());
    let pack_svc = pack_service_server::PackServiceServer::new(svc.clone());
    let ref_svc = ref_service_server::RefServiceServer::new(svc.clone());
    let remote_svc = remote_service_server::RemoteServiceServer::new(svc.clone());
    let tag_svc = tag_service_server::TagServiceServer::new(svc.clone());
    let tree_svc = tree_service_server::TreeServiceServer::new(svc);

    health_reporter
        .set_serving::<repository_service_server::RepositoryServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<archive_service_server::ArchiveServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<blame_service_server::BlameServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<branch_service_server::BranchServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<commit_service_server::CommitServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<diff_service_server::DiffServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<merge_service_server::MergeServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<pack_service_server::PackServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<ref_service_server::RefServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<remote_service_server::RemoteServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<tag_service_server::TagServiceServer<GitksService>>()
        .await;
    health_reporter
        .set_serving::<tree_service_server::TreeServiceServer<GitksService>>()
        .await;

    let server = tonic::transport::Server::builder()
        .add_service(health_service)
        .add_service(repo_svc)
        .add_service(archive_svc)
        .add_service(blame_svc)
        .add_service(branch_svc)
        .add_service(commit_svc)
        .add_service(diff_svc)
        .add_service(merge_svc)
        .add_service(pack_svc)
        .add_service(ref_svc)
        .add_service(remote_svc)
        .add_service(tag_svc)
        .add_service(tree_svc);
    tracing::info!("server ready, starting to accept connections");
    server.serve(addr).await
}