package fcast

import (
	"encoding/binary"
	"encoding/json"
	"errors"
	"log"
	"net"
	"strconv"
)

type Connection struct {
	net.Conn
}

func Connect(host string) (*Connection, error) {
	conn, err := net.Dial("tcp", host+":"+strconv.Itoa(DefaultPort))
	return &Connection{conn}, err
}

func (c *Connection) ListenForMessages(em *EventManager) error {

	c.addPingHandlerIfNotSet(em)

	for {

		var (
			bodyLenBuf = make([]byte, 4)
			opCodeBuf  [1]byte
			// bodyBuf's size depends on bodyLen's value
		)

		_, err := c.Read(bodyLenBuf)
		bodyBuf := make([]byte, binary.LittleEndian.Uint32(bodyLenBuf)-1)
		_, err = c.Read(opCodeBuf[:])
		_, err = c.Read(bodyBuf)

		if err != nil {
			if errors.Is(err, net.ErrClosed) {
				return nil
			}
			return err
		}

		rawMsg, err := DeserializeRaw(bodyLenBuf, opCodeBuf[:], bodyBuf)
		if err != nil {
			return err
		}

		err = em.dispatchMessage(rawMsg)
		if err != nil {
			return err
		}

	}

	return nil

}

func (c *Connection) addPingHandlerIfNotSet(em *EventManager) {
	if em.codes[Ping].handler == nil {
		em.SetHandler(PingMessage{}, func(message Message) {
			err := c.SendMessage(PongMessage{})
			if err != nil {
				log.Println("[ERROR} fcast: error in default pong responder:", err)
			}
		})
	}
}

func (c *Connection) SendMessage(message Message) error {
	body, _ := json.Marshal(message)
	rawMessage := NewMessage(message.getOpCode(), body)
	serialized := SerializeRaw(rawMessage)
	_, err := c.Write(serialized)
	return err
}