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

use crate::pb::*;
use crate::pb::pack_service_client::PackServiceClient;

use super::{GitksService, into_status};

async fn remote_pack_client(
    svc: &GitksService,
    header: Option<&RepositoryHeader>,
) -> Result<Option<PackServiceClient<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 pack rpc");
    let endpoint = super::remote_endpoint(&route.grpc_addr).await?;
    let client = PackServiceClient::connect(endpoint)
        .await
        .map_err(|e| tonic::Status::unavailable(e.to_string()))?;
    Ok(Some(client))
}

#[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 repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("pack.advertise_refs", %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_pack_client(self, inner.repository.as_ref()).await? {
                    return client.advertise_refs(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = gb.advertise_refs(inner).map_err(into_status)?;
        tracing::info!(%repo, refs = resp.references.len(), "advertise_refs done");
        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 repo = self.repo_label(first.repository.as_ref());
        let span = tracing::info_span!("pack.upload_pack", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(first.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_pack_client(self, first.repository.as_ref()).await? {
                    let (tx, rx) = tokio::sync::mpsc::channel(16);
                    let _ = tx.send(first).await;
                    tokio::spawn(async move {
                        use tokio_stream::StreamExt;
                        while let Some(msg) = stream.next().await {
                            match msg {
                                Ok(m) => { if tx.send(m).await.is_err() { break; } }
                                Err(_) => break,
                            }
                        }
                    });
                    let resp = client.upload_pack(tokio_stream::wrappers::ReceiverStream::new(rx)).await?;
                    let out = super::bridge_server_stream(resp.into_inner());
                    return Ok(tonic::Response::new(out));
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        tracing::info!(%repo, "upload-pack streaming started");

        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 repo = self.repo_label(first.repository.as_ref());
        let span = tracing::info_span!("pack.receive_pack", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(first.repository.as_ref()) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_pack_client(self, first.repository.as_ref()).await? {
                    let (tx, rx) = tokio::sync::mpsc::channel(16);
                    let _ = tx.send(first).await;
                    tokio::spawn(async move {
                        use tokio_stream::StreamExt;
                        while let Some(msg) = stream.next().await {
                            match msg {
                                Ok(m) => { if tx.send(m).await.is_err() { break; } }
                                Err(_) => break,
                            }
                        }
                    });
                    let resp = client.receive_pack(tokio_stream::wrappers::ReceiverStream::new(rx)).await?;
                    let out = super::bridge_server_stream(resp.into_inner());
                    return Ok(tonic::Response::new(out));
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        tracing::info!(%repo, "receive-pack streaming started");

        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 repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("pack.pack_objects", %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_pack_client(self, inner.repository.as_ref()).await? {
                    let resp = client.pack_objects(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 stream = gb.pack_objects(inner).await?;
        tracing::info!(%repo, "pack-objects streaming started");
        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 repo = self.repo_label(inputs.first().and_then(|r| r.repository.as_ref()));
        let span = tracing::info_span!("pack.index_pack", %repo);
        let _enter = span.enter();
        let gb = match self.resolve(inputs.first().and_then(|r| r.repository.as_ref())) {
            Ok(gb) => gb,
            Err(err) if err.code() == tonic::Code::NotFound => {
                if let Some(mut client) = remote_pack_client(self, inputs.first().and_then(|r| r.repository.as_ref())).await? {
                    return client.index_pack(tokio_stream::iter(inputs)).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = gb.index_pack(inputs).map_err(into_status)?;
        tracing::info!(%repo, objects = resp.object_count, "index_pack done");
        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 repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("pack.list_packfiles", %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_pack_client(self, inner.repository.as_ref()).await? {
                    return client.list_packfiles(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = gb.list_packfiles(inner).map_err(into_status)?;
        tracing::info!(%repo, count = resp.packfiles.len(), "list_packfiles done");
        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 repo = self.repo_label(inner.repository.as_ref());
        let span = tracing::info_span!("pack.fsck", %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_pack_client(self, inner.repository.as_ref()).await? {
                    return client.fsck(inner).await;
                }
                return Err(err);
            }
            Err(err) => return Err(err),
        };
        let resp = gb.fsck(inner).map_err(into_status)?;
        tracing::info!(%repo, ok = resp.ok, errors = resp.errors.len(), warnings = resp.warnings.len(), "fsck done");
        Ok(tonic::Response::new(resp))
    }
}