package rpc

import (
	"context"
	"net"
	"net/http"
	"sync"
	"sync/atomic"

	"git.nspix.com/golang/micro/log"
)

type HandleFunc func(ctx *Context) error

type Server struct {
	ctx        context.Context
	listener   net.Listener
	ch         chan *Request
	ctxPool    sync.Pool
	serviceMap sync.Map // map[string]HandleFunc
	sessions   sync.Map
	exitFlag   int32
	exitChan   chan struct{}
}

func (svr *Server) getContext() *Context {
	if v := svr.ctxPool.Get(); v != nil {
		return v.(*Context)
	} else {
		return &Context{}
	}
}

func (svr *Server) putContext(c *Context) {
	svr.ctxPool.Put(c)
}

func (svr *Server) wrkLoop() {
	for {
		select {
		case req, ok := <-svr.ch:
			if ok {
				svr.handleRequest(req)
			}
		case <-svr.exitChan:
			return
		}
	}
}

func (svr *Server) handleRequest(req *Request) {
	var (
		ok  bool
		err error
		cb  HandleFunc
		val interface{}
		ctx *Context
	)
	if val, ok = svr.serviceMap.Load(req.Method); ok {
		cb = val.(HandleFunc)
		ctx = svr.getContext()
		ctx.Reset(req, NewResponse())
		if err = cb(ctx); err == nil {
			if err = writeFrame(req.conn, &Frame{
				Func:     FuncResponse,
				Sequence: req.Sequence,
				Data:     ctx.Response().Bytes(),
			}); err != nil {
				log.Warnf("RPC: write request(%s@%d) response error: %s", req.Method, req.Sequence, err.Error())
			}
		} else {
			log.Warnf("RPC: handle request(%s@%d) error: %s", req.Method, req.Sequence, err.Error())
			resp := NewResponse()
			resp.code = http.StatusServiceUnavailable
			resp.message = http.StatusText(http.StatusServiceUnavailable)
			ctx.Reset(req, resp)
			if err = writeFrame(req.conn, &Frame{
				Func:     FuncResponse,
				Sequence: req.Sequence,
				Data:     ctx.Response().Bytes(),
			}); err != nil {
				log.Warnf("RPC: write request(%s@%d) response error: %s", req.Method, req.Sequence, err.Error())
			}
		}
	} else {
		ctx = svr.getContext()
		resp := NewResponse()
		resp.code = http.StatusNotFound
		resp.message = http.StatusText(http.StatusNotFound)
		ctx.Reset(req, resp)
		if err = writeFrame(req.conn, &Frame{
			Func:     FuncResponse,
			Sequence: req.Sequence,
			Data:     ctx.Response().Bytes(),
		}); err != nil {
			log.Warnf("RPC: write request(%s@%d) response failed cause by: %s", req.Method, req.Sequence, err.Error())
		}
	}
}

func (svr *Server) process(conn net.Conn) {
	var (
		err   error
		frame *Frame
	)
	svr.sessions.Store(conn.LocalAddr().String(), conn)
	defer func() {
		svr.sessions.Delete(conn.LocalAddr().String())
		_ = conn.Close()
	}()
	for {
		if frame, err = readFrame(conn); err != nil {
			return
		}
		switch frame.Func {
		case FuncPing:
			if err = writeFrame(conn, &Frame{Func: FuncPing}); err != nil {
				return
			}
		case FuncRequest:
			if req, err2 := ReadRequest(frame.Data); err2 == nil {
				req.reset(frame.Sequence, conn)
				select {
				case svr.ch <- req:
				default:
				}
			}
		}
	}
}

func (svr *Server) Handle(method string, f HandleFunc) {
	svr.serviceMap.Store(method, f)
	return
}

func (svr *Server) Serve(l net.Listener) (err error) {
	svr.listener = l
	go func() {
		svr.wrkLoop()
	}()
	for {
		if conn, err2 := svr.listener.Accept(); err2 == nil {
			go svr.process(conn)
		} else {
			err = err2
			break
		}
	}
	return
}

func (svr *Server) Close() (err error) {
	if atomic.CompareAndSwapInt32(&svr.exitFlag, 0, 1) {
		//clear sessions
		svr.sessions.Range(func(key, value interface{}) bool {
			c := value.(net.Conn)
			_ = c.Close()
			return true
		})
		err = svr.listener.Close()
		close(svr.exitChan)
	}
	return
}

func New(ctx context.Context) *Server {
	return &Server{
		ctx:      ctx,
		ch:       make(chan *Request, 10),
		exitChan: make(chan struct{}),
	}
}