package servlet

import (
	"context"
	"sync"

	logging "git.loafle.net/commons/logging-go"
	crp "git.loafle.net/commons/rpc-go/protocol"
	"git.loafle.net/commons/server-go"
	css "git.loafle.net/commons/server-go/socket"
	cssw "git.loafle.net/commons/server-go/socket/web"
	oe "git.loafle.net/overflow/external-go"
	oeg "git.loafle.net/overflow/external-go/grpc"
	og "git.loafle.net/overflow/gateway"
	"github.com/valyala/fasthttp"
	"google.golang.org/grpc/metadata"
)

type RPCServlet interface {
	cssw.Servlet
}

type RPCServlets struct {
	cssw.Servlets

	RPCServerCodec crp.ServerCodec
	UseSession     bool

	sessions sync.Map
}

func (s *RPCServlets) Handshake(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx) (*fasthttp.ResponseHeader, error) {
	return nil, nil
}

func (s *RPCServlets) OnConnect(servletCtx server.ServletCtx, conn css.Conn) {
	s.Servlets.OnConnect(servletCtx, conn)

	if s.UseSession {
		sessionID := servletCtx.GetAttribute(og.SessionIDKey)
		targetID := servletCtx.GetAttribute(og.SessionTargetIDKey)
		if nil != sessionID && nil != targetID {
			s.sessions.Store(sessionID.(string), RetainSession(targetID.(string), servletCtx))
		}
	}
}

func (s *RPCServlets) OnDisconnect(servletCtx server.ServletCtx) {
	s.Servlets.OnDisconnect(servletCtx)

	if s.UseSession {
		sessionID := servletCtx.GetAttribute(og.SessionIDKey)
		if nil != sessionID {
			s.sessions.Delete(sessionID.(string))
		}
	}
}

func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
	stopChan <-chan struct{}, doneChan chan<- struct{},
	readChan <-chan css.SocketMessage, writeChan chan<- css.SocketMessage) {
	defer func() {
		doneChan <- struct{}{}
	}()

	var (
		md          metadata.MD
		src         crp.ServerRequestCodec
		messageType int
		message     []byte
		method      string
		params      []string
		grpcCtx     context.Context
		grpcReply   string
		replyBuff   []byte
		err         error
	)

	_clientType := servletCtx.GetAttribute(og.SessionClientTypeKey)
	_sessionID := servletCtx.GetAttribute(og.SessionIDKey)
	_targetID := servletCtx.GetAttribute(og.SessionTargetIDKey)

	if nil != _clientType && nil != _sessionID && nil != _targetID {
		md = metadata.Pairs(
			oe.GRPCClientTypeKey.String(), _clientType.(oe.ClientType).String(),
			oe.GRPCSessionIDKey.String(), _sessionID.(string),
			oe.GRPCTargetIDKey.String(), _targetID.(string),
		)
	}

	servletCtx.SetAttribute(og.SessionWriteChanKey, writeChan)

	for {
		select {
		case socketMessage, ok := <-readChan:
			if !ok {
				return
			}

			messageType, message = socketMessage()

			// grpc exec method call
			src, err = s.RPCServerCodec.NewRequest(messageType, message)
			if nil != err {
				logging.Logger().Error(err)
				break
			}

			method = src.Method()
			params, err = src.Params()
			if nil != err {
				logging.Logger().Error(err)
				s.writeError(src, writeChan, crp.E_BAD_PARAMS, "", err)
				break
			}

			grpcCtx = metadata.NewOutgoingContext(context.Background(), md)
			grpcReply, err = oeg.Exec(grpcCtx, method, params...)
			if nil != err {
				logging.Logger().Error(err)
			}

			if !src.HasResponse() {
				break
			}
			messageType, replyBuff, err = src.NewResponseWithString(grpcReply, err)
			if nil != err {
				logging.Logger().Error(err)
				s.writeError(src, writeChan, crp.E_INTERNAL, "", err)
				break
			}

			writeChan <- css.MakeSocketMessage(messageType, replyBuff)
		case <-stopChan:
			return
		}

	}

}

func (s *RPCServlets) writeError(src crp.ServerRequestCodec, writeChan chan<- css.SocketMessage, code crp.ErrorCode, message string, data interface{}) {
	if !src.HasResponse() {
		return
	}

	pErr := &crp.Error{
		Code:    code,
		Message: message,
		Data:    data,
	}

	messageType, buf, err := src.NewResponse(nil, pErr)
	if nil != err {
		logging.Logger().Error(err)
		return
	}
	writeChan <- css.MakeSocketMessage(messageType, buf)
}

func (s *RPCServlets) GetSessions(sessionIDs []string) []*Session {
	var sessions []*Session

	if nil == sessionIDs || 0 == len(sessionIDs) {
		return sessions
	}

	for _, sessionID := range sessionIDs {
		session, ok := s.sessions.Load(sessionID)
		if ok {
			sessions = append(sessions, session.(*Session))
		}
	}

	return sessions
}

func (s *RPCServlets) GetSessionsByTargetIDs(targetIDs []string) []*Session {
	var sessions []*Session
	if nil == targetIDs || 0 == len(targetIDs) {
		return sessions
	}

	s.sessions.Range(func(k, v interface{}) bool {
		session := v.(*Session)

		for _, targetID := range targetIDs {
			if session.TargetID == targetID {
				sessions = append(sessions, session)
				break
			}
		}

		return true
	})

	return sessions
}