package main

import (
	"log"
	"sync"
	"time"

	"github.com/gorilla/websocket"
)

const TIMEOUT = 6
const IDLE_TIMEOUT = TIMEOUT * time.Second
const PING_INTERVAL = (TIMEOUT / 2) * time.Second

type WSConnection struct {
	alive     bool
	url       string
	conn      *websocket.Conn
	errChan   chan error
	writeLock sync.Mutex
	ReadChan  chan string
	WriteChan chan string
	Dead      chan error
}

func (ws *WSConnection) messageReader() {
	log.Printf("Starting reader")
	for {
		if !ws.alive {
			break
		}

		_, message, err := ws.conn.ReadMessage()
		ws.conn.SetReadDeadline(time.Now().Add(IDLE_TIMEOUT))
		if err != nil {
			ws.errChan <- err
			break
		}

		log.Printf("Received: %s, %d in output channel", message, len(ws.ReadChan))
		ws.ReadChan <- string(message)
	}
	log.Printf("Reader done")
}

func (ws *WSConnection) messageSender() {
	log.Printf("Starting sender")
	for {
		msg, ok := <-ws.WriteChan
		if !ok {
			break
		}
		ws.doSend(msg)
	}
	log.Printf("Sender done")
}

func (ws *WSConnection) doSend(msg string) {
	ws.writeLock.Lock()
	defer ws.writeLock.Unlock()

	ws.conn.SetWriteDeadline(time.Now().Add(IDLE_TIMEOUT))
	log.Printf("Sending: %s, %d in input channel", msg, len(ws.WriteChan))
	err := ws.conn.WriteMessage(websocket.TextMessage, []byte(msg))
	if err != nil {
		log.Printf("Error during message writing: %v", err)
		ws.errChan <- err
		return
	}
}

func (ws *WSConnection) pinger() {
	log.Printf("Starting pinger, sleeping for %v", PING_INTERVAL)
	for {
		if !ws.alive {
			break
		}
		ws.doPing()
		time.Sleep(PING_INTERVAL)
	}
	log.Printf("Pinger done")
}

func (ws *WSConnection) doPing() {
	ws.writeLock.Lock()
	defer ws.writeLock.Unlock()

	// log.Printf("Ping")
	err := ws.conn.WriteMessage(websocket.PingMessage, nil)
	if err != nil {
		log.Println("Error during ping:", err)
		ws.errChan <- err
		return
	}
	ws.conn.SetWriteDeadline(time.Now().Add(IDLE_TIMEOUT))
	// log.Printf("Ping OK")
}

func (ws *WSConnection) handleError() {
	for {
		err := <-ws.errChan
		log.Printf("Client error: %+v", err)
		ws.alive = false
		ws.conn.Close()
		close(ws.ReadChan)
		close(ws.WriteChan)
		close(ws.errChan)
		ws.Dead <- err
		return
	}
}

func (ws *WSConnection) Open() {
	log.Printf("Connecting to %s", ws.url)
	ws.Dead = make(chan error, 1)

	conn, _, err := websocket.DefaultDialer.Dial(ws.url, nil)
	if err != nil {
		log.Println("Error during connection:", err)
		ws.Dead <- err
		return
	}
	log.Printf("Connected")
	ws.conn = conn
	ws.alive = true

	ws.errChan = make(chan error, 1)
	ws.ReadChan = make(chan string, 128)
	ws.WriteChan = make(chan string, 128)

	ws.conn.SetReadDeadline(time.Now().Add(IDLE_TIMEOUT))
	ws.conn.SetWriteDeadline(time.Now().Add(IDLE_TIMEOUT))
	ws.conn.SetPongHandler(func(string) error {
		// log.Println("Pong")
		ws.conn.SetReadDeadline(time.Now().Add(IDLE_TIMEOUT))
		return nil
	})

	go ws.handleError()
	go ws.messageReader()
	go ws.messageSender()
	go ws.pinger()
}