// ws-server/ws-core.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}`);

(async () => {
  try {
    console.log(
      "🧹 [WS CLEANUP] Pulizia sessioni e pending al riavvio server...",
    );
    await dbWs.deleteAllSessions();
    await dbWs.deleteAllPendingEvents();
    console.log("🧹 [WS CLEANUP] Completata");
  } catch (err) {
    console.error("❌ [WS CLEANUP ERROR]:", err);
  }
})();

const wsBySession = new Map();
const WS_DORMANT_MS = 2 * 60 * 1000;

function sendToClient(ws, msg) {
  const json = JSON.stringify(msg);
  console.log(`📤 [WS SEND] → user=${ws.user}: ${json}`);
  ws.send(json);
}

async function decideAuthRecovery({ session_id, user, device_id }) {
  const sessionRow = await dbWs.getSession(session_id, device_id);

  let needFull = false;
  let needRecovery = false;
  let reason = "none";

  if (!sessionRow) {
    needRecovery = true;
    reason = "session not found after cleanup";
  } else {
    const lastAck = sessionRow.last_ack || 0;
    const dormancy = lastAck > 0 ? Date.now() - lastAck : 0;

    if (sessionRow.need_full_sync) {
      needRecovery = true;
      reason = "db recovery flag";
    } else if (lastAck > 0 && dormancy >= WS_DORMANT_MS) {
      needRecovery = true;
      reason = "dormant";
    } else {
      needRecovery = false;
      reason = "recent or clean auth";
    }
  }

  await dbWs.setSessionNeedFullSync(session_id, device_id, needRecovery);

  console.log("🧪 [WS AUTH DECISION]", {
    user,
    session_id,
    device_id,
    needFull,
    needRecovery,
    reason,
    last_ack: sessionRow?.last_ack,
    last_sync: sessionRow?.last_sync,
    db_need_full_sync: sessionRow?.need_full_sync,
  });

  return { needFull, needRecovery, reason };
}

wss.on("connection", (ws) => {
  console.log("🔌 [WS CONNECT] Nuovo client");

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

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

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

    if (data.type === "auth") {
      let payload;

      try {
        payload = jwt.verify(data.token, JWT_SECRET);
        const user = payload.name;
        const session_id = data.session_id || randomUUID();
        const device_id = data.device_id || "default-device";
        const request_id = data.request_id || null;

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

        if (!wsBySession.has(session_id)) {
          wsBySession.set(session_id, new Map());
        }
        wsBySession.get(session_id).set(device_id, ws);

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

        await dbWs.upsertSession(session_id, user, device_id);

        const decision = await decideAuthRecovery({
          session_id,
          user,
          device_id,
        });

        sendToClient(ws, {
          type: "auth_ok",
          user,
          session_id,
          need_full_sync: decision.needFull,
          need_recovery: decision.needRecovery,
          reason: decision.reason,
        });
      } catch (err) {
        if (err.name === "TokenExpiredError") {
          sendToClient(ws, {
            type: "token_expired",
          });

          return;
        }

        console.error("❌ [WS AUTH ERROR]:", err);

        sendToClient(ws, {
          type: "auth_error",
          error: err.message,
        });

        ws.close();
      }
      return;
    }

    if (!ws.authenticated) {
      sendToClient(ws, { type: "error", message: "Not authenticated" });
      return;
    }

    if (data.type === "ack" && data.event_id) {
      console.log(`🟢 [WS ACK] user=${ws.user} event=${data.event_id}`);
      await dbWs.updateSessionAck(ws.session_id, ws.device_id);
      await dbWs.deletePendingEvent({
        user_id: ws.user,
        session_id: ws.session_id,
        device_id: ws.device_id,
        event_id: data.event_id,
      });
      return;
    }

    if (data.type === "client_recovered") {
      console.log(`🔄 [WS CLIENT RECOVERED] user=${ws.user}`);

      const session = await dbWs.getSession(ws.session_id, ws.device_id);

      if (!session) {
        sendToClient(ws, { type: "need_recovery", reason: "session missing" });
        return;
      }

      const lastAck = session.last_ack || 0;
      const dormancy = lastAck > 0 ? Date.now() - lastAck : 0;

      if (dormancy >= WS_DORMANT_MS || session.need_full_sync) {
        sendToClient(ws, {
          type: "need_recovery",
          reason: dormancy >= WS_DORMANT_MS ? "dormant" : "db recovery flag",
        });
        return;
      }

      const pending = await dbWs.getPendingEvents(
        ws.user,
        ws.session_id,
        ws.device_id,
      );

      for (const ev of pending) {
        ws.send(ev.payload);
      }

      return;
    }

    if (data.type === "pong") {
      await dbWs.updateSessionAck(ws.session_id, ws.device_id);
      return;
    }

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

    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}`);

    if (ws.session_id && ws.device_id) {
      const devices = wsBySession.get(ws.session_id);

      if (devices) {
        devices.delete(ws.device_id);

        if (devices.size === 0) {
          wsBySession.delete(ws.session_id);
        }
      }
    }
  });
});

module.exports = { wss, wsBySession };