package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"sync"
	"time"

	"github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{}
var wsBroadcast = make(chan []byte, 100)

const TIMEOUT = 6
const IDLE_TIMEOUT = TIMEOUT * time.Second
const PING_INTERVAL = (TIMEOUT - 1) * time.Second

type WSConnection struct {
	conn      *websocket.Conn
	writeLock sync.Mutex
	ReadChan  chan string
	WriteChan chan string
}

func (ws *WSConnection) messageReader() {
	log.Printf("Reading messages")
	for {
		_, message, err := ws.conn.ReadMessage()
		ws.conn.SetReadDeadline(time.Now().Add(IDLE_TIMEOUT))
		if err != nil {
			return
		}
		log.Printf("Received: %s", message)
		ws.ReadChan <- string(message)
	}
}

func (ws *WSConnection) messageSender() {
	log.Printf("Sending messages")
	for {
		msg := <-ws.WriteChan
		ws.writeLock.Lock()

		ws.conn.SetWriteDeadline(time.Now().Add(IDLE_TIMEOUT))
		log.Printf("Sending: %s", msg)
		err := ws.conn.WriteMessage(websocket.TextMessage, []byte(msg))
		if err != nil {
			log.Printf("Error during message writing: %v", err)
			return
		}
		ws.writeLock.Unlock()
	}
}

func (ws *WSConnection) pinger() {
	log.Printf("Starting pinger, sleeping for %v", PING_INTERVAL)
	for {
		time.Sleep(PING_INTERVAL)

		// log.Printf("Ping")
		ws.writeLock.Lock()
		err := ws.conn.WriteMessage(websocket.PingMessage, nil)
		if err != nil {
			log.Println("Error during ping:", err)
			return
		}
		ws.writeLock.Unlock()
	}
}

func (ws *WSConnection) Open() {
	log.Printf("Client connected")
	ws.ReadChan = make(chan string, 1024)
	ws.WriteChan = make(chan string, 1024)

	ws.conn.SetReadLimit(1024)
	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))
		ws.conn.SetWriteDeadline(time.Now().Add(IDLE_TIMEOUT))
		return nil
	})

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

func wsHandler(responseWriter http.ResponseWriter, request *http.Request) {
	conn, err := upgrader.Upgrade(responseWriter, request, nil)
	if err != nil {
		fmt.Println("Error during connection upgrade:", err)
		return
	}

	ws := new(WSConnection)
	ws.conn = conn
	ws.Open()
}

type DownloadReq struct {
	Link string `json:"link"`
}

func handleDownload(responseWriter http.ResponseWriter, request *http.Request) {
	body, err := io.ReadAll(request.Body)
	if err != nil {
		log.Printf("Error reading request body: %v", err)
		http.Error(responseWriter, "Error reading request body", http.StatusBadRequest)
		return
	}
	defer request.Body.Close()

	req := DownloadReq{}
	err = json.Unmarshal(body, &req)
	if err != nil {
		log.Printf("Error parsing JSON: %v", err)
		http.Error(responseWriter, "Error parsing JSON", http.StatusBadRequest)
		return
	}

	log.Printf("Received download request: %s", req.Link)
	wsBroadcast <- []byte(req.Link)
}

func main() {
	log.SetFlags(log.Lmicroseconds)

	http.HandleFunc("/ws", wsHandler)
	http.HandleFunc("/download", handleDownload)
	log.Println("Server starting on :8080")
	err := http.ListenAndServe(":8080", nil)
	if err != nil {
		log.Println("Error starting server:", err)
	}
}