/**
 * WhatsApp notification service using Baileys (WhatsApp Web unofficial API)
 * Manages one WhatsApp session per clinic (identified by clinicId).
 * Sessions are stored in $WHATSAPP_SESSION_DIR/<clinicId>/, which defaults
 * to /app/data/whatsapp-sessions inside the container so credentials survive
 * container restarts (the path must live on a persistent Docker volume).
 *
 * ⚠️  Disclaimer: Baileys uses the WhatsApp Web protocol which is unofficial.
 *     Use at low volume (< 500 msg/day) to minimise ban risk.
 */

import makeWASocket, {
  DisconnectReason,
  fetchLatestBaileysVersion,
  makeCacheableSignalKeyStore,
  useMultiFileAuthState,
} from "@whiskeysockets/baileys";
import { Boom } from "@hapi/boom";
import * as fs from "fs";
import * as path from "path";
import pino from "pino";
import { EventEmitter } from "events";
import PQueue from "p-queue";
import { insertWhatsAppLog, maskPhone } from "../db.js";
import { childLogger } from "../_core/logger.js";

const waLog = childLogger("whatsapp");

// ─── Types ────────────────────────────────────────────────────────────────────
export type WAStatus = "disconnected" | "connecting" | "qr_ready" | "connected";

interface WASession {
  socket: ReturnType<typeof makeWASocket> | null;
  status: WAStatus;
  qrCode: string | null; // base64 QR image data URL
  qrRaw: string | null;  // raw QR string for display
  retryCount: number;
  events: EventEmitter;
}

// ─── In-memory session store ──────────────────────────────────────────────────
const sessions = new Map<number, WASession>();

// ─── Rate limiting : une queue p-queue par cabinet ───────────────────────────
// Intervalle de 2.5s entre messages pour éviter les bans WhatsApp
const messageQueues = new Map<number, PQueue>();

function getMessageQueue(clinicId: number): PQueue {
  if (!messageQueues.has(clinicId)) {
    messageQueues.set(clinicId, new PQueue({
      concurrency: 1,
      interval: 2500,
      intervalCap: 1,
    }));
  }
  return messageQueues.get(clinicId)!;
}

const SESSION_DIR = process.env.WHATSAPP_SESSION_DIR ?? "/app/data/whatsapp-sessions";
try {
  fs.mkdirSync(SESSION_DIR, { recursive: true });
} catch (err) {
  waLog.error({ err, sessionDir: SESSION_DIR }, "failed to create session dir");
}

// Silent logger to avoid spamming server logs
const logger = pino({ level: "silent" });

// ─── Helpers ──────────────────────────────────────────────────────────────────
function sessionPath(clinicId: number) {
  return path.join(SESSION_DIR, String(clinicId));
}

function getOrCreateSession(clinicId: number): WASession {
  if (!sessions.has(clinicId)) {
    sessions.set(clinicId, {
      socket: null,
      status: "disconnected",
      qrCode: null,
      qrRaw: null,
      retryCount: 0,
      events: new EventEmitter(),
    });
  }
  return sessions.get(clinicId)!;
}

// ─── QR code as base64 data URL ───────────────────────────────────────────────
async function qrToDataUrl(qrString: string): Promise<string> {
  // Dynamically import qrcode to avoid circular deps
  const QRCode = await import("qrcode");
  return QRCode.default.toDataURL(qrString, {
    width: 300,
    margin: 2,
    color: { dark: "#128C7E", light: "#FFFFFF" },
  });
}

// ─── Connect / start session ──────────────────────────────────────────────────
export async function connectWhatsApp(clinicId: number): Promise<void> {
  const session = getOrCreateSession(clinicId);

  if (session.status === "connected" || session.status === "connecting") return;

  session.status = "connecting";
  session.qrCode = null;
  session.qrRaw = null;

  const authDir = sessionPath(clinicId);
  fs.mkdirSync(authDir, { recursive: true });

  const { state, saveCreds } = await useMultiFileAuthState(authDir);
  const { version } = await fetchLatestBaileysVersion();

  const sock = makeWASocket({
    version,
    logger,
    auth: {
      creds: state.creds,
      keys: makeCacheableSignalKeyStore(state.keys, logger),
    },
    printQRInTerminal: false,
    generateHighQualityLinkPreview: false,
    browser: ["Salle d'attente", "Chrome", "1.0.0"],
  });

  session.socket = sock;

  // ── QR code event ──────────────────────────────────────────────────────────
  sock.ev.on("connection.update", async (update) => {
    const { connection, lastDisconnect, qr } = update;

    if (qr) {
      session.qrRaw = qr;
      session.status = "qr_ready";
      try {
        session.qrCode = await qrToDataUrl(qr);
      } catch {
        session.qrCode = null;
      }
      waLog.info({ clinicId, event: "qr_ready" }, "QR code generated");
      session.events.emit("qr", { qrCode: session.qrCode, qrRaw: qr });
    }

    if (connection === "open") {
      session.status = "connected";
      session.qrCode = null;
      session.qrRaw = null;
      session.retryCount = 0;
      waLog.info({ clinicId, event: "connected" }, "session connected");
      session.events.emit("connected");
    }

    if (connection === "close") {
      const statusCode = (lastDisconnect?.error as Boom)?.output?.statusCode;
      const shouldReconnect = statusCode !== DisconnectReason.loggedOut;

      session.status = "disconnected";
      session.socket = null;

      waLog.warn(
        { clinicId, event: "disconnected", statusCode, shouldReconnect, retryCount: session.retryCount },
        "session disconnected"
      );

      if (shouldReconnect && session.retryCount < 5) {
        session.retryCount++;
        setTimeout(() => connectWhatsApp(clinicId), 3000 * session.retryCount);
      } else if (!shouldReconnect) {
        // Logged out – clear saved credentials
        clearSession(clinicId);
      }
      session.events.emit("disconnected", { statusCode });
    }
  });

  sock.ev.on("creds.update", saveCreds);
}

// ─── Disconnect / logout ──────────────────────────────────────────────────────
export async function disconnectWhatsApp(clinicId: number): Promise<void> {
  const session = sessions.get(clinicId);
  if (!session) return;

  try {
    await session.socket?.logout();
  } catch {
    // ignore
  }
  clearSession(clinicId);
}

function clearSession(clinicId: number) {
  const session = sessions.get(clinicId);
  if (session) {
    session.socket = null;
    session.status = "disconnected";
    session.qrCode = null;
    session.qrRaw = null;
  }
  // Remove saved auth files
  const authDir = sessionPath(clinicId);
  if (fs.existsSync(authDir)) {
    fs.rmSync(authDir, { recursive: true, force: true });
  }
}

// ─── Status getter ────────────────────────────────────────────────────────────
export function getWhatsAppStatus(clinicId: number): {
  status: WAStatus;
  qrCode: string | null;
  qrRaw: string | null;
} {
  const session = sessions.get(clinicId);
  if (!session) return { status: "disconnected", qrCode: null, qrRaw: null };
  return {
    status: session.status,
    qrCode: session.qrCode,
    qrRaw: session.qrRaw,
  };
}

/** Returns the number of currently connected WhatsApp sessions across all clinics. */
export function getActiveWhatsAppSessionsCount(): number {
  let count = 0;
  for (const session of sessions.values()) {
    if (session.status === "connected") count += 1;
  }
  return count;
}

// ─── Send message ─────────────────────────────────────────────────────────────
/**
 * Send a WhatsApp text message to a phone number.
 * @param clinicId  The clinic whose WhatsApp session to use
 * @param phone     Phone number in international format without + (e.g. "33612345678")
 * @param message   Text content
 */
export async function sendWhatsAppMessage(
  clinicId: number,
  phone: string,
  message: string
): Promise<{ success: boolean; error?: string }> {
  const session = sessions.get(clinicId);
  if (!session || session.status !== "connected" || !session.socket) {
    return { success: false, error: "WhatsApp non connecté pour ce cabinet" };
  }

  // Normalize phone: strip leading +, spaces, dashes
  const normalized = phone.replace(/[^0-9]/g, "");
  const jid = `${normalized}@s.whatsapp.net`;

  try {
    await session.socket.sendMessage(jid, { text: message });
    return { success: true };
  } catch (err: unknown) {
    const errorMessage = err instanceof Error ? err.message : String(err);
    return { success: false, error: errorMessage };
  }
}

// ─── Template-based message builders ─────────────────────────────────────────
import {
  buildMessage,
  type TemplateContext,
  type TemplateType,
} from "../../shared/whatsappTemplates.js";

export type { TemplateContext, TemplateType };

/**
 * Custom templates from the clinic DB record (null = use default).
 */
export type ClinicTemplates = Partial<Record<TemplateType, string | null>>;

export function buildJoinMessage(
  clinicName: string, ticketNumber: number, position: number, estimatedWait: number,
  customTemplates?: ClinicTemplates
): string {
  return buildMessage("joined", {
    nom: "", ticket: ticketNumber, position, attente: estimatedWait, cabinet: clinicName,
  }, customTemplates);
}

export function buildSoonMessage(
  clinicName: string, ticketNumber: number, minutesLeft: number,
  customTemplates?: ClinicTemplates
): string {
  return buildMessage("soon", {
    nom: "", ticket: ticketNumber, position: 0, attente: minutesLeft, cabinet: clinicName,
  }, customTemplates);
}

export function buildCalledMessage(
  clinicName: string, ticketNumber: number,
  customTemplates?: ClinicTemplates
): string {
  return buildMessage("called", {
    nom: "", ticket: ticketNumber, position: 0, attente: 0, cabinet: clinicName,
  }, customTemplates);
}

export function buildWithdrawnMessage(
  clinicName: string, ticketNumber: number,
  customTemplates?: ClinicTemplates
): string {
  return buildMessage("withdrawn", {
    nom: "", ticket: ticketNumber, position: 0, attente: 0, cabinet: clinicName,
  }, customTemplates);
}