/*
 Licensed to the Apache Software Foundation (ASF) under one
 or more contributor license agreements.  See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you under the Apache License, Version 2.0 (the
 "License"); you may not use this file except in compliance
 with the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

package common

import (
	"fmt"
	"net"
	"os"
	"strings"
	"sync"

	"go.uber.org/zap"
	"golang.org/x/net/context"
	"google.golang.org/grpc"

	"github.com/apache/yunikorn-core/pkg/log"
	"github.com/apache/yunikorn-scheduler-interface/lib/go/si"
)

// Defines Non blocking GRPC server interfaces
type NonBlockingGRPCServer interface {
	// Start services at the endpoint
	Start(endpoint string, ss si.SchedulerServer)
	// Waits for the service to stop
	Wait()
	// Stops the service gracefully
	Stop()
	// Stops the service forcefully
	ForceStop()
}

func NewNonBlockingGRPCServer() NonBlockingGRPCServer {
	return &nonBlockingGRPCServer{}
}

// NonBlocking server
type nonBlockingGRPCServer struct {
	wg     sync.WaitGroup
	server *grpc.Server
}

func (s *nonBlockingGRPCServer) Start(endpoint string, ss si.SchedulerServer) {
	s.wg.Add(1)

	go s.serve(endpoint, ss)
}

func (s *nonBlockingGRPCServer) Wait() {
	s.wg.Wait()
}

func (s *nonBlockingGRPCServer) Stop() {
	s.server.GracefulStop()
}

func (s *nonBlockingGRPCServer) ForceStop() {
	s.server.Stop()
}

func ParseEndpoint(ep string) (string, string, error) {
	if strings.HasPrefix(strings.ToLower(ep), "unix://") || strings.HasPrefix(strings.ToLower(ep), "tcp://") {
		s := strings.SplitN(ep, "://", 2)
		if s[1] != "" {
			return s[0], s[1], nil
		}
	}
	return "", "", fmt.Errorf("invalid endpoint: %v", ep)
}

// Logging unary interceptor function to log every RPC call
func logGRPC(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
	log.Log(log.RPC).Debug("GPRC call",
		zap.String("method", info.FullMethod))
	log.Log(log.RPC).Debug("GPRC request",
		zap.String("request", fmt.Sprintf("%+v", req)))
	resp, err := handler(ctx, req)
	if err != nil {
		log.Log(log.RPC).Debug("GPRC error", zap.Error(err))
	} else {
		log.Log(log.RPC).Debug("GPRC response",
			zap.String("response", fmt.Sprintf("%+v", resp)))
	}
	return resp, err
}

// Returns unary interceptor that will be used to intercept the execution of a unary RPC on the gRPC server
func withServerUnaryInterceptor() grpc.ServerOption {
	return grpc.UnaryInterceptor(logGRPC)
}

func (s *nonBlockingGRPCServer) serve(endpoint string, ss si.SchedulerServer) {
	proto, addr, err := ParseEndpoint(endpoint)
	if err != nil {
		log.Log(log.RPC).Fatal("fatal error", zap.Error(err))
	}

	if proto == "unix" {
		addr = "/" + addr
		if err = os.Remove(addr); err != nil && !os.IsNotExist(err) {
			log.Log(log.RPC).Fatal("failed to remove unix domain socket",
				zap.String("uds", addr),
				zap.Error(err))
		}
	}

	var listener net.Listener
	listener, err = net.Listen(proto, addr)
	if err != nil {
		log.Log(log.RPC).Fatal("failed to listen to address",
			zap.Error(err))
	}

	server := grpc.NewServer(withServerUnaryInterceptor())
	s.server = server

	if ss != nil {
		si.RegisterSchedulerServer(server, ss)
	}

	log.Log(log.RPC).Info("listening for connections",
		zap.Stringer("address", listener.Addr()))

	if err = server.Serve(listener); err != nil {
		log.Log(log.RPC).Fatal("failed to serve", zap.Error(err))
	}
}
