use crate::pb::{self, *};
use async_stream::try_stream;
use futures_util::{stream, StreamExt, TryStreamExt};
use std::pin::Pin;
use std::time::{Duration, Instant};
use tonic::{Code, Request, Response, Status};

pub use pb::server::{TestServiceServer, UnimplementedServiceServer};

#[derive(Default, Clone)]
pub struct TestService;

type Result<T> = std::result::Result<Response<T>, Status>;
type Streaming<T> = Request<tonic::Streaming<T>>;
type Stream<T> =
    Pin<Box<dyn futures_core::Stream<Item = std::result::Result<T, Status>> + Send + 'static>>;

#[tonic::async_trait]
impl pb::server::TestService for TestService {
    async fn empty_call(&self, _request: Request<Empty>) -> Result<Empty> {
        Ok(Response::new(Empty {}))
    }

    async fn unary_call(&self, request: Request<SimpleRequest>) -> Result<SimpleResponse> {
        let req = request.into_inner();

        if let Some(echo_status) = req.response_status {
            let status = Status::new(Code::from_i32(echo_status.code), echo_status.message);
            return Err(status);
        }

        let res_size = if req.response_size >= 0 {
            req.response_size as usize
        } else {
            let status = Status::new(Code::InvalidArgument, "response_size cannot be negative");
            return Err(status);
        };

        let res = SimpleResponse {
            payload: Some(Payload {
                body: vec![0; res_size],
                ..Default::default()
            }),
            ..Default::default()
        };

        Ok(Response::new(res))
    }

    async fn cacheable_unary_call(&self, _: Request<SimpleRequest>) -> Result<SimpleResponse> {
        unimplemented!()
    }

    type StreamingOutputCallStream = Stream<StreamingOutputCallResponse>;

    async fn streaming_output_call(
        &self,
        req: Request<StreamingOutputCallRequest>,
    ) -> Result<Self::StreamingOutputCallStream> {
        let StreamingOutputCallRequest {
            response_parameters,
            ..
        } = req.into_inner();

        let stream = try_stream! {
            for param in response_parameters {
                let deadline = Instant::now() + Duration::from_micros(param.interval_us as u64);
                tokio::timer::delay(deadline).await;

                let payload = crate::server_payload(param.size as usize);
                yield StreamingOutputCallResponse { payload: Some(payload) };
            }
        };

        Ok(Response::new(
            Box::pin(stream) as Self::StreamingOutputCallStream
        ))
    }

    async fn streaming_input_call(
        &self,
        req: Streaming<StreamingInputCallRequest>,
    ) -> Result<StreamingInputCallResponse> {
        let mut stream = req.into_inner();

        let mut aggregated_payload_size = 0 as i32;
        while let Some(msg) = stream.try_next().await? {
            aggregated_payload_size += msg.payload.unwrap().body.len() as i32;
        }

        let res = StreamingInputCallResponse {
            aggregated_payload_size,
        };

        Ok(Response::new(res))
    }

    type FullDuplexCallStream = Stream<StreamingOutputCallResponse>;

    async fn full_duplex_call(
        &self,
        req: Streaming<StreamingOutputCallRequest>,
    ) -> Result<Self::FullDuplexCallStream> {
        let mut stream = req.into_inner();

        if let Some(first_msg) = stream.message().await? {
            if let Some(echo_status) = first_msg.response_status {
                let status = Status::new(Code::from_i32(echo_status.code), echo_status.message);
                return Err(status);
            }

            let single_message = stream::iter(vec![Ok(first_msg)]);
            let mut stream = single_message.chain(stream);

            let stream = try_stream! {
                while let Some(msg) = stream.try_next().await? {
                    if let Some(echo_status) = msg.response_status {
                        let status = Status::new(Code::from_i32(echo_status.code), echo_status.message);
                        Err(status)?;
                    }

                    for param in msg.response_parameters {
                        let deadline = Instant::now() + Duration::from_micros(param.interval_us as u64);
                        tokio::timer::delay(deadline).await;

                        let payload = crate::server_payload(param.size as usize);
                        yield StreamingOutputCallResponse { payload: Some(payload) };
                    }
                }
            };

            Ok(Response::new(Box::pin(stream) as Self::FullDuplexCallStream))
        } else {
            let stream = stream::empty();
            Ok(Response::new(Box::pin(stream) as Self::FullDuplexCallStream))
        }
    }

    type HalfDuplexCallStream = Stream<StreamingOutputCallResponse>;

    async fn half_duplex_call(
        &self,
        _: Streaming<StreamingOutputCallRequest>,
    ) -> Result<Self::HalfDuplexCallStream> {
        Err(Status::unimplemented("TODO"))
    }

    async fn unimplemented_call(&self, _: Request<Empty>) -> Result<Empty> {
        Err(Status::unimplemented(""))
    }
}

pub struct UnimplementedService;

#[tonic::async_trait]
impl pb::server::UnimplementedService for UnimplementedService {
    async fn unimplemented_call(&self, _req: Request<Empty>) -> Result<Empty> {
        Err(Status::unimplemented(""))
    }
}