// ws-server.js
require("dotenv").config();
const WebSocket = require("ws");
const jwt = require("jsonwebtoken");
const { randomUUID } = require("crypto");
const dbWs = require("./db/dbWs");

const PORT = process.env.WS_PORT || 4002;
const HOST = process.env.WS_HOST || "0.0.0.0";
const JWT_SECRET = process.env.JWT_SECRET;

if (!JWT_SECRET) {
  console.error("❌ ERRORE: JWT_SECRET non definito nel .env");
  process.exit(1);
}

const wss = new WebSocket.Server({ port: PORT, host: HOST });
console.log(`🚀 WebSocket server attivo su ws://${HOST}:${PORT}`);

// =====================================================
// PULIZIA SESSIONI E PENDING AL RIAVVIO SERVER
// =====================================================
(async () => {
  try {
    console.log("🧹 [WS CLEANUP] Pulizia sessioni e pending al riavvio server...");

    await dbWs.deleteAllSessions();
    await dbWs.deleteAllPendingEvents();

    console.log("🧹 [WS CLEANUP] Completata: tutte le sessioni e pending rimossi");
  } catch (err) {
    console.error("❌ [WS CLEANUP ERROR]:", err);
  }
})();


// Mappa session_id → ws
const wsBySession = new Map();

// =====================================================
// COSTANTI
// =====================================================
const WS_DORMANT_MS = 2 * 60 * 1000;              // 2 minuti
const WS_RETENTION_MS = 30 * 24 * 60 * 60 * 1000; // 30 giorni

const RETRY_INTERVAL_MS = 3000; // OK così
const MAX_RETRIES = 40;         // OK così
const MAX_RETRY_BATCH = 500;    // OK così


// =====================================================
// HELPER: calcolo dormancy sessione
// =====================================================
async function getSessionDormancyMs(session_id) {
  const s = await dbWs.getSession(session_id);
  if (!s || !s.last_ack) return Infinity;
  return Date.now() - s.last_ack;
}

// =====================================================
// FUNZIONE DI INVIO CON LOG
// =====================================================
function sendToClient(ws, msg) {
  const json = JSON.stringify(msg);
  console.log(`📤 [WS SEND] at=${new Date().toISOString()} → user=${ws.user || "??"}: ${json}`);
  ws.send(json);
}

// =====================================================
// CONNESSIONE CLIENT
// =====================================================
wss.on("connection", (ws) => {
  console.log(`🔌 [WS CONNECT] Nuovo client at=${new Date().toISOString()}`);

  ws.authenticated = false;
  ws.user = null;
  ws.session_id = null;

  ws.on("message", async (msg) => {
    console.log(`📩 [WS RAW] at=${new Date().toISOString()} msg=${msg.toString()}`);

    let data;
    try {
      data = JSON.parse(msg.toString());
    } catch (err) {
      console.error("❌ Errore parsing JSON:", err);
      return;
    }

    // -----------------------------
    // AUTENTICAZIONE JWT
    // -----------------------------
    if (data.type === "auth") {
      console.log(`🔐 [WS AUTH] Richiesta auth at=${new Date().toISOString()}`);

      try {
        const payload = jwt.verify(data.token, JWT_SECRET);
        const user = payload.name;
        const session_id = data.session_id || randomUUID();

        ws.user = user;
        ws.session_id = session_id;
        ws.authenticated = true;

        wsBySession.set(session_id, ws);

        console.log(`🔐 [WS AUTH OK] user=${user} session=${session_id}`);

        const existing = await dbWs.getSession(session_id);
        if (!existing) {
          console.log(`🆕 [WS SESSION] Creo nuova sessione=${session_id}`);
          await dbWs.createSession(session_id, user);
        } else {
          console.log(`♻️ [WS SESSION] Sessione esistente, aggiorno last_ack`);
          await dbWs.updateSessionAck(session_id);
        }

        const sessionRow = await dbWs.getSession(session_id);

        sendToClient(ws, {
          type: "auth_ok",
          user,
          session_id,
          need_full_sync: !!sessionRow.need_full_sync,
        });

      } catch (err) {
        console.error("❌ [WS AUTH ERROR]:", err);
        sendToClient(ws, { type: "auth_error", error: err.message });
        ws.close();
      }
      return;
    }

    // -----------------------------
    // MESSAGGI NON AUTORIZZATI
    // -----------------------------
    if (!ws.authenticated) {
      sendToClient(ws, {
        type: "error",
        message: "Not authenticated",
      });
      return;
    }

    // -----------------------------
    // ACK evento
    // -----------------------------
    if (data.type === "ack" && data.event_id) {
      console.log(`🟢 [WS ACK] user=${ws.user} session=${ws.session_id} event_id=${data.event_id}`);
      await dbWs.deletePendingEvent(data.event_id);
      await dbWs.updateSessionAck(ws.session_id);
      return;
    }

    // -----------------------------
    // PONG (keepalive)
    // -----------------------------
    if (data.type === "pong") {
      console.log(`🏓 [WS PONG] user=${ws.user} session=${ws.session_id}`);
      await dbWs.updateSessionAck(ws.session_id);
      return;
    }

    // -----------------------------
    // RECOVERY DONE
    // -----------------------------
    if (data.type === "recovery_done") {
      console.log(`🔄 [WS RECOVERY DONE] user=${ws.user} session=${ws.session_id}`);
      await dbWs.clearNeedFullSync(ws.session_id);
      await dbWs.updateSessionAck(ws.session_id);
      return;
    }

    // -----------------------------
    // ALTRI MESSAGGI
    // -----------------------------
    console.log(`📨 [WS MESSAGE] user=${ws.user} data=${JSON.stringify(data)}`);
  });

  ws.on("close", () => {
    console.log(`❌ [WS DISCONNECT] user=${ws.user} session=${ws.session_id} at=${new Date().toISOString()}`);
    if (ws.session_id) wsBySession.delete(ws.session_id);
  });
});

// =====================================================
// BROADCAST AFFIDABILE PER UTENTE
// =====================================================
wss.broadcastToUserReliable = async function (user, payload) {
  console.log(`📣 [WS BROADCAST] user=${user} payload=${JSON.stringify(payload)} at=${new Date().toISOString()}`);

  const sessions = await dbWs.getSessionsByUser(user);
  if (!sessions || sessions.length === 0) {
    console.log(`⚠️ [WS BROADCAST] Nessuna sessione attiva per user=${user}`);
    return;
  }

  for (const s of sessions) {
    const ws = wsBySession.get(s.session_id);

    const event_id = randomUUID();
    const msg = { ...payload, event_id };
    const json = JSON.stringify(msg);


    const dormancy = await getSessionDormancyMs(s.session_id);

    if (ws && ws.readyState === WebSocket.OPEN && ws.authenticated) {
      console.log(`   📤 consegnato a session=${s.session_id}`);
      ws.send(json);
      await dbWs.addPendingEvent(event_id, s.session_id, msg);
      continue;
    }

    if (dormancy < WS_DORMANT_MS) {
      console.log(`   🟦 session=${s.session_id} offline <2min → salvo in pending`);
      await dbWs.addPendingEvent(event_id, s.session_id, msg);
      continue;
    }

    if (dormancy < WS_RETENTION_MS) {
      console.log(`   🟨 session=${s.session_id} offline >2min → need_full_sync`);
      await dbWs.setSessionNeedFullSync(s.session_id, true);
      continue;
    }

    console.log(`   🟥 session=${s.session_id} offline >30gg → need_full_sync (full)`);
    await dbWs.setSessionNeedFullSync(s.session_id, true);

  }
};

wss.broadcastToUser = wss.broadcastToUserReliable;

// =====================================================
// BROADCAST PER ADMIN
// =====================================================
wss.broadcastToAdmins = function (msg) {
  const json = JSON.stringify(msg);
  console.log(`📣 [WS BROADCAST ADMINS] → ${json}`);

  for (const client of wss.clients) {
    if (
      client.readyState === WebSocket.OPEN &&
      client.authenticated &&
      client.user === "Admin"
    ) {
      console.log(`   ↳ inviato a Admin`);
      client.send(json);
    }
  }
};

// =====================================================
// RETRY LOOP
// =====================================================
setInterval(async () => {
  console.log(`⏱️ [WS RETRY LOOP] tick at=${new Date().toISOString()}`);

  const pending = await dbWs.getPendingEventsOlderThan(RETRY_INTERVAL_MS, MAX_RETRY_BATCH);

  for (const ev of pending) {
    const ws = wsBySession.get(ev.session_id);

    if (ev.retries >= MAX_RETRIES) {
      console.warn(`⏱️ [WS TIMEOUT] event_id=${ev.event_id} session=${ev.session_id} → recovery`);
      await dbWs.setSessionNeedFullSync(ev.session_id, true);
      await dbWs.deletePendingEvent(ev.event_id);
      continue;
    }

    if (ws && ws.readyState === WebSocket.OPEN && ws.authenticated) {
      console.log(`🔁 [WS RETRY] event_id=${ev.event_id} retries=${ev.retries} session=${ev.session_id}`);
      const payload = typeof ev.payload === "string" ? ev.payload : JSON.stringify(ev.payload);
      ws.send(payload);
      await dbWs.updatePendingEventRetry(ev.event_id);
      continue;
    }

    const sessionRow = await dbWs.getSession(ev.session_id);
    const lastAck = sessionRow?.last_ack || 0;
    const dormant = !lastAck || (Date.now() - lastAck) > WS_DORMANT_MS;

const dormancy = await getSessionDormancyMs(ev.session_id);

if (ws && ws.readyState === WebSocket.OPEN && ws.authenticated) {
  console.log(`🔁 [WS RETRY] event_id=${ev.event_id} retries=${ev.retries} session=${ev.session_id}`);
  const payload = typeof ev.payload === "string" ? ev.payload : JSON.stringify(ev.payload);
  ws.send(payload);
  await dbWs.updatePendingEventRetry(ev.event_id);
  continue;
}

if (dormancy < WS_DORMANT_MS) {
  console.log(`🟦 [WS WAIT] session=${ev.session_id} offline <2min → pending conservato`);
  continue;
}

if (dormancy < WS_RETENTION_MS) {
  console.log(`🟨 [WS DORMANT] session=${ev.session_id} offline >2min → need_full_sync`);
  await dbWs.setSessionNeedFullSync(ev.session_id, true);
  await dbWs.deletePendingEvent(ev.event_id);
  continue;
}

console.log(`🟥 [WS EXPIRED] session=${ev.session_id} offline >30gg → need_full_sync`);
await dbWs.setSessionNeedFullSync(ev.session_id, true);
await dbWs.deletePendingEvent(ev.event_id);




  }
}, RETRY_INTERVAL_MS);

module.exports = wss;