import { Server } from 'socket.io'
import jwt from 'jsonwebtoken'

// Simple in-memory structures keyed by eventId
const events = {}

const QUEUE_THRESHOLD = parseInt(process.env.QUEUE_THRESHOLD || "100", 10)
const CONCURRENT_ACTIVE = parseInt(process.env.CONCURRENT_ACTIVE || "50", 10)
const TOKEN_TTL_SECONDS = parseInt(process.env.TOKEN_TTL_SECONDS || `${15 * 60}`, 10)

function ensureEvent(eventId) {
  if (!events[eventId]) {
    events[eventId] = {
      sockets: new Set(), // connected socket ids
      queue: [], // array of socket ids in order
      active: new Set(), // sockets that currently hold a token (allowed to buy)
      queueOn: false,
    }
  }
  return events[eventId]
}

function broadcastUpdate(eventId, io) {
  const ev = events[eventId]
  if (!ev) return
  // notify all connected sockets in room
  for (const sid of ev.sockets) {
    const pos = ev.queue.indexOf(sid)
    io.to(sid).emit("queue_update", {
      activeCount: ev.sockets.size,
      position: pos === -1 ? null : pos + 1,
      estimatedWait: pos === -1 ? null : ev.queue.length * 5,
    })
  }
}

function evaluateQueue(eventId, io) {
  const ev = events[eventId]
  if (!ev) return

  // ensure active set size <= CONCURRENT_ACTIVE
  while (ev.active.size < CONCURRENT_ACTIVE && ev.queue.length > 0) {
    const next = ev.queue.shift()
    if (!next) break
    // sign token
    const token = jwt.sign({ sid: next, eventId }, process.env.JWT_SECRET || "dev-secret", {
      expiresIn: TOKEN_TTL_SECONDS,
    })
    ev.active.add(next)
    io.to(next).emit("granted", { token, expiresAt: new Date(Date.now() + TOKEN_TTL_SECONDS * 1000).toISOString() })
  }

  // If too many active (rare), revoke oldest
  if (ev.active.size > CONCURRENT_ACTIVE) {
    const toRevoke = Array.from(ev.active).slice(CONCURRENT_ACTIVE)
    toRevoke.forEach((sid) => {
      ev.active.delete(sid)
      io.to(sid).emit("revoked")
    })
  }

  // If queue no longer needed, clear it
  if (ev.sockets.size < QUEUE_THRESHOLD) ev.queueOn = false

  // broadcast
  broadcastUpdate(eventId, io)
}

export async function GET(req) {
  if (global.io) {
    console.log("Socket.IO már fut")
    return Response.json({ message: "Socket.IO már inicializálva" })
  }

  console.log("Socket.IO inicializálása...")
  
  try {
    // Get the HTTP server instance from Next.js
    const server = req.nextUrl.protocol === 'https:' 
      ? require('https').createServer()
      : require('http').createServer()

    const io = new Server(server, {
      cors: {
        origin: "*",
        methods: ["GET", "POST"]
      }
    })

    global.io = io

    io.on("connection", (socket) => {
      console.log("Csatlakozott:", socket.id)

      socket.on("join_event", async ({ eventId }) => {
        if (!eventId) return
        const ev = ensureEvent(eventId)
        ev.sockets.add(socket.id)
        socket.join(eventId)

        // compute counts
        const activeCount = ev.sockets.size
        // turn on queue if threshold reached
        if (activeCount >= QUEUE_THRESHOLD) ev.queueOn = true

        // if queueOn and socket not active, add to queue
        if (ev.queueOn && !ev.active.has(socket.id)) {
          if (!ev.queue.includes(socket.id)) ev.queue.push(socket.id)
        }

        // evaluate granting
        evaluateQueue(eventId, io)

        // send initial update
        const pos = ev.queue.indexOf(socket.id)
        io.to(socket.id).emit("queue_update", {
          activeCount: ev.sockets.size,
          position: pos === -1 ? null : pos + 1,
          estimatedWait: pos === -1 ? null : ev.queue.length * 5,
        })
      })

      socket.on("disconnect", () => {
        console.log("Lecsatlakozott:", socket.id)
        // remove from every event
        for (const [eventId, ev] of Object.entries(events)) {
          if (ev.sockets.has(socket.id)) ev.sockets.delete(socket.id)
          const qi = ev.queue.indexOf(socket.id)
          if (qi !== -1) ev.queue.splice(qi, 1)
          if (ev.active.has(socket.id)) ev.active.delete(socket.id)
          // re-evaluate to grant next in line
          evaluateQueue(eventId, io)
          // notify remaining sockets
          broadcastUpdate(eventId, io)
        }
      })
    })

    // Start the Socket.IO server on a different port
    const SOCKET_PORT = process.env.SOCKET_PORT || 4000
    server.listen(SOCKET_PORT, () => {
      console.log(`Socket.IO szerver fut a ${SOCKET_PORT} porton`)
    })

    return Response.json({ 
      message: "Socket.IO szerver inicializálva", 
      port: SOCKET_PORT 
    })
    
  } catch (error) {
    console.error("Socket.IO inicializálási hiba:", error)
    return Response.json({ error: "Nem sikerült inicializálni a Socket.IO szervert" }, { status: 500 })
  }
}