use crate::pb::*;
use crate::pb::diff_service_client::DiffServiceClient;

use super::{GitksService, cache, into_status, into_stream};

async fn remote_diff_client(
    svc: &GitksService,
    header: Option<&RepositoryHeader>,
) -> Result<Option<DiffServiceClient<tonic::transport::Channel>>, tonic::Status> {
    let header = match header {
        Some(h) => h,
        None => return Ok(None),
    };
    let Some(route) = svc.route_repository(header).await? else {
        return Ok(None);
    };
    tracing::info!(storage_name = %route.storage_name, relative_path = %route.relative_path, actor_name = %route.actor_name, grpc_addr = %route.grpc_addr, "forwarding diff rpc");
    let endpoint = super::remote_endpoint(&route.grpc_addr).await?;
    let client = DiffServiceClient::connect(endpoint)
        .await
        .map_err(|e| tonic::Status::unavailable(e.to_string()))?;
    Ok(Some(client))
}

#[tonic::async_trait]
impl diff_service_server::DiffService for GitksService {
    type GetPatchStream =
        tokio_stream::wrappers::ReceiverStream<Result<GetPatchResponse, tonic::Status>>;

    async fn get_diff(
        &self,
        request: tonic::Request<GetDiffRequest>,
    ) -> Result<tonic::Response<GetDiffResponse>, tonic::Status> {
        let inner = request.into_inner();
        let repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("diff.get_diff", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(inner.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_diff_client(self, inner.repository.as_ref()).await? {
                    return client.get_diff(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = if cache::selectors_are_oid(&inner.base, &inner.head) {
            cache::cached_response("diff.get_diff", &inner, || {
                gb.get_diff(inner.clone()).map_err(into_status)
            })?
        } else {
            gb.get_diff(inner).map_err(into_status)?
        };
        tracing::info!(%repo, files = resp.files.len(), overflow = resp.overflow, "get_diff done");
        Ok(tonic::Response::new(resp))
    }

    async fn get_commit_diff(
        &self,
        request: tonic::Request<GetCommitDiffRequest>,
    ) -> Result<tonic::Response<GetDiffResponse>, tonic::Status> {
        let inner = request.into_inner();
        let repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("diff.get_commit_diff", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(inner.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_diff_client(self, inner.repository.as_ref()).await? {
                    return client.get_commit_diff(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = if cache::selector_is_oid(&inner.commit) {
            cache::cached_response("diff.get_commit_diff", &inner, || {
                gb.get_commit_diff(inner.clone()).map_err(into_status)
            })?
        } else {
            gb.get_commit_diff(inner).map_err(into_status)?
        };
        tracing::info!(%repo, files = resp.files.len(), "get_commit_diff done");
        Ok(tonic::Response::new(resp))
    }

    async fn get_patch(
        &self,
        request: tonic::Request<GetPatchRequest>,
    ) -> Result<tonic::Response<Self::GetPatchStream>, tonic::Status> {
        let inner = request.into_inner();
        let repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("diff.get_patch", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(inner.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_diff_client(self, inner.repository.as_ref()).await? {
                    let resp = client.get_patch(inner).await?;
                    let stream = super::bridge_server_stream(resp.into_inner());
                    return Ok(tonic::Response::new(stream));
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let items = if cache::selectors_are_oid(&inner.base, &inner.head) {
            cache::cached_vec_response("diff.get_patch", &inner, || {
                gb.get_patch(inner.clone()).map_err(into_status)
            })?
        } else {
            gb.get_patch(inner).map_err(into_status)?
        };
        Ok(tonic::Response::new(into_stream(items)))
    }

    async fn get_diff_stats(
        &self,
        request: tonic::Request<GetDiffStatsRequest>,
    ) -> Result<tonic::Response<DiffStats>, tonic::Status> {
        let inner = request.into_inner();
        let repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("diff.get_diff_stats", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(inner.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_diff_client(self, inner.repository.as_ref()).await? {
                    return client.get_diff_stats(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = if cache::selectors_are_oid(&inner.base, &inner.head) {
            cache::cached_response("diff.get_diff_stats", &inner, || {
                gb.get_diff_stats(inner.clone()).map_err(into_status)
            })?
        } else {
            gb.get_diff_stats(inner).map_err(into_status)?
        };
        Ok(tonic::Response::new(resp))
    }
}