package cellnet

import (
	"errors"
	"reflect"
)

type DecodePacketHandler struct {
}

func (self *DecodePacketHandler) Call(ev *Event) {

	var err error
	ev.Msg, err = DecodeMessage(ev.MsgID, ev.Data)

	r := errToResult(err)
	if r != Result_OK {
		ev.Msg, _ = DecodeMessage(ev.MsgID, ev.Data)

		ev.SetResult(r)
	}

}

var defaultDecodePacketHandler = new(DecodePacketHandler)

func StaticDecodePacketHandler() EventHandler {
	return defaultDecodePacketHandler
}

var ErrCodecNotFound = errors.New("codec not found")

func DecodeMessage(msgid uint32, data []byte) (interface{}, error) {
	meta := MessageMetaByID(msgid)

	if meta == nil {
		return nil, ErrMessageNotFound
	}
	if meta.Codec == nil {
		return nil, ErrCodecNotFound
	}

	// 创建消息
	msg := reflect.New(meta.Type).Interface()

	// 解析消息
	err := meta.Codec.Decode(data, msg)
	if err != nil {
		return nil, err
	}

	return msg, nil
}

func errToResult(err error) Result {

	if err == nil {
		return Result_OK
	}

	return Result_CodecError
}