use tokio_stream::StreamExt;
use tokio_stream::wrappers::ReceiverStream;

use crate::pb::*;

use super::{GitksService, into_status, resolve};

#[tonic::async_trait]
impl pack_service_server::PackService for GitksService {
    type UploadPackStream = ReceiverStream<Result<UploadPackResponse, tonic::Status>>;
    type ReceivePackStream = ReceiverStream<Result<ReceivePackResponse, tonic::Status>>;
    type PackObjectsStream = ReceiverStream<Result<PackfileChunk, tonic::Status>>;

    async fn advertise_refs(
        &self,
        request: tonic::Request<AdvertiseRefsRequest>,
    ) -> Result<tonic::Response<AdvertiseRefsResponse>, tonic::Status> {
        let inner = request.into_inner();
        let gb = resolve(inner.repository.as_ref())?;
        let resp = gb.advertise_refs(inner).map_err(into_status)?;
        Ok(tonic::Response::new(resp))
    }

    async fn upload_pack(
        &self,
        request: tonic::Request<tonic::Streaming<UploadPackRequest>>,
    ) -> Result<tonic::Response<Self::UploadPackStream>, tonic::Status> {
        let mut stream = request.into_inner();
        let first = stream
            .next()
            .await
            .ok_or_else(|| tonic::Status::invalid_argument("empty upload-pack stream"))??;
        let gb = resolve(first.repository.as_ref())?;

        let (tx, rx) = tokio::sync::mpsc::channel(16);
        tx.send(Ok(first))
            .await
            .map_err(|_| tonic::Status::internal("channel closed"))?;
        tokio::spawn(async move {
            while let Some(msg) = stream.next().await {
                if tx.send(msg).await.is_err() {
                    break;
                }
            }
        });

        let result = gb.upload_pack(ReceiverStream::new(rx)).await?;
        Ok(tonic::Response::new(result))
    }

    async fn receive_pack(
        &self,
        request: tonic::Request<tonic::Streaming<ReceivePackRequest>>,
    ) -> Result<tonic::Response<Self::ReceivePackStream>, tonic::Status> {
        let mut stream = request.into_inner();
        let first = stream
            .next()
            .await
            .ok_or_else(|| tonic::Status::invalid_argument("empty receive-pack stream"))??;
        let gb = resolve(first.repository.as_ref())?;

        let (tx, rx) = tokio::sync::mpsc::channel(16);
        tx.send(Ok(first))
            .await
            .map_err(|_| tonic::Status::internal("channel closed"))?;
        tokio::spawn(async move {
            while let Some(msg) = stream.next().await {
                if tx.send(msg).await.is_err() {
                    break;
                }
            }
        });

        let result = gb.receive_pack(ReceiverStream::new(rx)).await?;
        Ok(tonic::Response::new(result))
    }

    async fn pack_objects(
        &self,
        request: tonic::Request<PackObjectsRequest>,
    ) -> Result<tonic::Response<Self::PackObjectsStream>, tonic::Status> {
        let inner = request.into_inner();
        let gb = resolve(inner.repository.as_ref())?;
        let stream = gb.pack_objects(inner).await?;
        Ok(tonic::Response::new(stream))
    }

    async fn index_pack(
        &self,
        request: tonic::Request<tonic::Streaming<IndexPackRequest>>,
    ) -> Result<tonic::Response<IndexPackResponse>, tonic::Status> {
        let mut stream = request.into_inner();
        let mut inputs = Vec::new();
        while let Some(msg) = stream.next().await {
            inputs.push(msg?);
        }
        let gb = resolve(inputs.first().and_then(|r| r.repository.as_ref()))?;
        let resp = gb.index_pack(inputs).map_err(into_status)?;
        Ok(tonic::Response::new(resp))
    }

    async fn list_packfiles(
        &self,
        request: tonic::Request<ListPackfilesRequest>,
    ) -> Result<tonic::Response<ListPackfilesResponse>, tonic::Status> {
        let inner = request.into_inner();
        let gb = resolve(inner.repository.as_ref())?;
        let resp = gb.list_packfiles(inner).map_err(into_status)?;
        Ok(tonic::Response::new(resp))
    }

    async fn fsck(
        &self,
        request: tonic::Request<FsckRequest>,
    ) -> Result<tonic::Response<FsckResponse>, tonic::Status> {
        let inner = request.into_inner();
        let gb = resolve(inner.repository.as_ref())?;
        let resp = gb.fsck(inner).map_err(into_status)?;
        Ok(tonic::Response::new(resp))
    }
}