package fcast

import (
	"encoding/json"
	"log"
	"reflect"
	"sync"
)

type EventHandler func(message Message)
type CodeRegistry struct {
	handler     EventHandler
	constructor func() Message
}

type EventManager struct {
	codes map[OpCode]CodeRegistry
	mu    sync.RWMutex
}

func (em *EventManager) SetHandler(message Message, handler EventHandler) {
	em.mu.Lock()
	defer em.mu.Unlock()

	if em.codes == nil {
		em.codes = make(map[OpCode]CodeRegistry)
	}
	em.codes[message.getOpCode()] = CodeRegistry{
		handler: handler,
		constructor: func() Message {
			return reflect.New(reflect.TypeOf(message)).Interface().(Message)
		},
	}
}

func (em *EventManager) dispatchMessage(raw *RawMessage) error {

	if _, exists := em.codes[raw.Header.OpCode]; !exists {
		log.Printf("[INFO] fcast: Got a message without a listener - OpCode=%d, Size=%d, Body=%s\n", raw.Header.OpCode, raw.Header.Size, string(raw.Body))
		return nil
	}

	constructor := em.codes[raw.Header.OpCode].constructor
	handler := em.codes[raw.Header.OpCode].handler

	msg := constructor()
	if len(raw.Body) > 0 {
		if err := json.Unmarshal(raw.Body, msg); err != nil {
			return err
		}
	}

	handler(msg)
	return nil

}