package chanrpc

import (
	"errors"
	"fmt"
	"runtime"

	"gitee.com/nbcx/leaf/conf"
	"gitee.com/nbcx/leaf/log"
)

// one server per goroutine (goroutine not safe)
// one client per goroutine (goroutine not safe)
type Server struct {
	// id -> function
	//
	// function:
	// func(args []interface{})
	// func(args []interface{}) interface{}
	// func(args []interface{}) []interface{}
	functions map[interface{}]interface{}
	ChanCall  chan *CallInfo
}

type CallInfo struct {
	f       interface{}
	args    []interface{}
	chanRet chan *RetInfo
	cb      interface{}
}

func NewServer(l int) *Server {
	s := new(Server)
	s.functions = make(map[interface{}]interface{})
	s.ChanCall = make(chan *CallInfo, l)
	return s
}

// you must call the function before calling Open and Go
func (s *Server) Register(id interface{}, f interface{}) {
	switch f.(type) {
	case func([]interface{}):
	case func([]interface{}) interface{}:
	case func([]interface{}) []interface{}:
	default:
		panic(fmt.Sprintf("function id %v: definition of function is invalid", id))
	}

	if _, ok := s.functions[id]; ok {
		panic(fmt.Sprintf("function id %v: already registered", id))
	}

	s.functions[id] = f
}

func (s *Server) ret(ci *CallInfo, ri *RetInfo) (err error) {
	if ci.chanRet == nil {
		return
	}

	defer func() {
		if r := recover(); r != nil {
			err = r.(error)
		}
	}()

	ri.cb = ci.cb
	ci.chanRet <- ri
	return
}

func (s *Server) exec(ci *CallInfo) (err error) {
	defer func() {
		if r := recover(); r != nil {
			if conf.LenStackBuf > 0 {
				buf := make([]byte, conf.LenStackBuf)
				l := runtime.Stack(buf, false)
				err = fmt.Errorf("%v: %s", r, buf[:l])
			} else {
				err = fmt.Errorf("%v", r)
			}

			s.ret(ci, &RetInfo{err: fmt.Errorf("%v", r)})
		}
	}()

	// execute
	switch ci.f.(type) {
	case func([]interface{}):
		ci.f.(func([]interface{}))(ci.args)
		return s.ret(ci, &RetInfo{})
	case func([]interface{}) interface{}:
		ret := ci.f.(func([]interface{}) interface{})(ci.args)
		return s.ret(ci, &RetInfo{ret: ret})
	case func([]interface{}) []interface{}:
		ret := ci.f.(func([]interface{}) []interface{})(ci.args)
		return s.ret(ci, &RetInfo{ret: ret})
	}

	panic("bug")
}

func (s *Server) Exec(ci *CallInfo) {
	err := s.exec(ci)
	if err != nil {
		log.Error("%v", err)
	}
}

// goroutine safe
func (s *Server) Go(id interface{}, args ...interface{}) {
	f := s.functions[id]
	if f == nil {
		return
	}

	defer func() {
		recover()
	}()

	s.ChanCall <- &CallInfo{
		f:    f,
		args: args,
	}
}

// goroutine safe
func (s *Server) Call0(id interface{}, args ...interface{}) error {
	return s.Open(0).Call0(id, args...)
}

// goroutine safe
func (s *Server) Call1(id interface{}, args ...interface{}) (interface{}, error) {
	return s.Open(0).Call1(id, args...)
}

// goroutine safe
func (s *Server) CallN(id interface{}, args ...interface{}) ([]interface{}, error) {
	return s.Open(0).CallN(id, args...)
}

func (s *Server) Close() {
	close(s.ChanCall)

	for ci := range s.ChanCall {
		s.ret(ci, &RetInfo{
			err: errors.New("chanrpc server closed"),
		})
	}
}

// goroutine safe
func (s *Server) Open(l int) *Client {
	c := NewClient(l)
	c.Attach(s)
	return c
}