package srpc

import (
	"bytes"
	"errors"
	"fmt"
	"net"
	"olznet.de/slog"
	"reflect"
	"sync"
)

type parseInputsFunc func(in []byte) (ret []reflect.Value, err error)
type parseOutputsFunc func(in []reflect.Value) (ret []byte, err error)

type service struct {
	f    reflect.Value
	fin  parseInputsFunc
	fout parseOutputsFunc
}

type Server struct {
	ed         IEncoderDecoder
	serviceMap sync.Map
}

func (server *Server) ServeConn(conn net.Conn) {
	var fs service
	var request *RPCRequest
	var err error

	tcpConn := NewTCPConn(conn, server.ed)
	defer tcpConn.Close()

	if request, err = tcpConn.ReceiveRequest(); err != nil {
		slog.LOG_ERROR("srpc - Malformed request received: '%s'\n", err.Error())
		return
	}

	var response RPCResponse
	response.Status = RPCOK
	response.Error = ""

	if fsRaw, ok := server.serviceMap.Load(request.FuncName); !ok {
		slog.LOG_ERROR("srpc - Call to unknown method: '%s'\n", request.FuncName)
		err := fmt.Sprintf("Unknown method: '%s'", request.FuncName)
		response.Status = RPCERR
		response.Error = err
	} else {
		fs = fsRaw.(service)
		if inputs, err := fs.fin(request.Payload); err != nil {
			slog.LOG_ERROR("srpc - Error parsing inputs '%s'\n", err.Error())
			response.Status = RPCERR
			response.Error = err.Error()
		} else {
			outputs := fs.f.Call(inputs)
			if payload, err := fs.fout(outputs); err != nil {
				slog.LOG_ERROR("srpc - Error parsing outputs '%s'\n", err.Error())
				response.Status = RPCERR
				response.Error = err.Error()
			} else {
				slog.LOG_DEBUG("%v\n", outputs)
				response.Payload = append([]byte{}, payload...)
			}
		}
	}

	if err = tcpConn.SendResponse(&response); err != nil {
		slog.LOG_ERROR("srpc - Error sending response '%s'\n", err.Error())
	}
}

func (server *Server) Accept(ln net.Listener) {
	for {
		conn, err := ln.Accept()
		if err != nil {
			slog.LOG_INFO("srpc - Accept: '%s'\n", err.Error())
			return
		}
		go server.ServeConn(conn)
	}
}

func (server *Server) RegisterName(name string, rcvr interface{}) (err error) {
	if _, ok := server.serviceMap.Load(name); ok {
		return errors.New("srpc: Function with name '" + name + "' already registerd")
	}
	ft := reflect.TypeOf(rcvr)
	fv := reflect.ValueOf(rcvr)

	nIn := ft.NumIn()

	fs := service{}

	fs.fin = func(in []byte) (ret []reflect.Value, err error) {
		var b bytes.Buffer
		if _, err = b.Write(in); err != nil {
			return nil, err
		}
		decoder := server.ed.NewDecoder(&b)

		ret = make([]reflect.Value, nIn)
		for i := 0; i < nIn; i++ {
			arg := reflect.New(ft.In(i))
			if err = decoder.Decode(arg.Interface()); err != nil {
				return nil, err
			}
			ret[i] = reflect.Indirect(arg)
		}

		return ret, nil
	}

	fs.fout = func(in []reflect.Value) (ret []byte, err error) {
		var b bytes.Buffer
		encoder := server.ed.NewEncoder(&b)

		for _, v := range in {
			if v.Type() == reflect.TypeOf((*error)(nil)).Elem() {
				if v.IsNil() {
					if err = encoder.Encode(string("")); err != nil {
						return nil, err
					}
				} else {
					if err = encoder.Encode(v.Interface().(error).Error()); err != nil {
						fmt.Println(err)
						return nil, err
					}
				}
			} else {
				if err = encoder.Encode(v.Interface()); err != nil {
					return nil, err
				}
			}
		}

		return b.Bytes(), nil
	}

	fs.f = fv
	server.serviceMap.Store(name, fs)

	return nil
}

func (server *Server) CallName(name string, args ...interface{}) (ret []byte, err error) {
	var b bytes.Buffer
	var fs service
	encoder := server.ed.NewEncoder(&b)

	if fsRaw, ok := server.serviceMap.Load(name); !ok {
		return nil, errors.New("srpc - Call to unknown method: '" + name + "'")
	} else {
		fs = fsRaw.(service)
	}

	for _, a := range args {
		if err := encoder.Encode(a); err != nil {
			return nil, errors.New("srpc - Error: '" + err.Error() + "'")
		}
	}
	if inputs, err := fs.fin(b.Bytes()); err != nil {
		return nil, err
	} else {
		outputs := fs.f.Call(inputs)
		return fs.fout(outputs)
	}
}

func NewServer(ed IEncoderDecoder) *Server {
	ret := &Server{}
	ret.ed = ed
	return ret
}

func NewDefaultServer() *Server {
	ret := NewServer(NewEncoderDecoder())
	return ret
}

var DefaultServer = NewDefaultServer()