// models/notificationModel.js
const { getPool } = require('./userModel');

// Web Push (lazy init)
let webpush = null;
let vapidConfigured = false;

function getWebPush() {
  if (!webpush) {
    try {
      webpush = require('web-push');
      if (process.env.VAPID_PUBLIC_KEY && process.env.VAPID_PRIVATE_KEY) {
        webpush.setVapidDetails(
          process.env.VAPID_SUBJECT || 'mailto:admin@technicalkorea.net',
          process.env.VAPID_PUBLIC_KEY,
          process.env.VAPID_PRIVATE_KEY
        );
        vapidConfigured = true;
      }
    } catch (e) {
      console.warn('[notifications] web-push 모듈 로드 실패:', e.message);
    }
  }
  return vapidConfigured ? webpush : null;
}

// Push 전송 헬퍼 — 알림 생성 후 호출 (ntfy 우선, 나머지 Web Push)
async function sendPushToUsers(userIds, payload) {
  const pushModel = require('./pushSubscriptionModel');
  const { sendNtfy } = require('../utils/ntfySender');

  try {
    // 1) ntfy 구독자 분리
    const ntfyUserIds = userIds && userIds.length > 0
      ? await pushModel.getNtfyUserIds(userIds)
      : await pushModel.getAllNtfyUserIds();

    const ntfySet = new Set(ntfyUserIds);

    // 2) ntfy 병렬 발송
    if (ntfyUserIds.length > 0) {
      await Promise.allSettled(
        ntfyUserIds.map(uid =>
          sendNtfy(uid, { title: payload.title, body: payload.body, url: payload.url })
        )
      );
    }

    // 3) Web Push — ntfy 구독자 제외
    const wp = getWebPush();
    if (!wp) return;

    let subscriptions;
    if (userIds && userIds.length > 0) {
      const webPushUserIds = userIds.filter(id => !ntfySet.has(id));
      subscriptions = webPushUserIds.length > 0
        ? await pushModel.getByUserIds(webPushUserIds)
        : [];
    } else {
      // broadcast: 전체 구독 가져온 뒤 ntfy 사용자 제외
      subscriptions = (await pushModel.getAll()).filter(s => !ntfySet.has(s.user_id));
    }

    const payloadStr = JSON.stringify(payload);
    for (const sub of subscriptions) {
      try {
        await wp.sendNotification({
          endpoint: sub.endpoint,
          keys: { p256dh: sub.p256dh, auth: sub.auth }
        }, payloadStr);
      } catch (err) {
        if (err.statusCode === 410 || err.statusCode === 404) {
          await pushModel.deleteByEndpoint(sub.endpoint).catch(() => {});
        }
      }
    }
  } catch (e) {
    console.error('[notifications] Push 전송 오류:', e.message);
  }
}

async function getRecipientIds(notificationType) {
  const pool = getPool();
  const [rows] = await pool.query(
    `SELECT user_id FROM notification_recipients
     WHERE notification_type = ? AND is_active = 1`,
    [notificationType]
  );
  return rows.map(r => r.user_id);
}

const notificationModel = {
  // 알림 생성
  async create(notificationData) {
    const pool = getPool();
    const { user_id, type, title, message, link_url, reference_type, reference_id, created_by } = notificationData;

    const [result] = await pool.query(
      `INSERT INTO notifications (user_id, type, title, message, link_url, reference_type, reference_id, created_by)
       VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
      [user_id || null, type || 'system', title, message || null, link_url || null, reference_type || null, reference_id || null, created_by || null]
    );

    this._invalidateCache(user_id);

    return result.insertId;
  },

  // 읽지 않은 알림 조회 (특정 사용자 또는 전체)
  async getUnread(userId = null) {
    const pool = getPool();
    const [rows] = await pool.query(
      `SELECT * FROM notifications
       WHERE is_read = 0
       AND (user_id IS NULL OR user_id = ?)
       ORDER BY created_at DESC
       LIMIT 50`,
      [userId || 0]
    );
    return rows;
  },

  // 전체 알림 조회 (페이징)
  async getAll(userId = null, page = 1, limit = 20) {
    const pool = getPool();
    const offset = (page - 1) * limit;

    const [rows] = await pool.query(
      `SELECT * FROM notifications
       WHERE (user_id IS NULL OR user_id = ?)
       ORDER BY created_at DESC
       LIMIT ? OFFSET ?`,
      [userId || 0, limit, offset]
    );

    const [[{ total }]] = await pool.query(
      `SELECT COUNT(*) as total FROM notifications
       WHERE (user_id IS NULL OR user_id = ?)`,
      [userId || 0]
    );

    return { notifications: rows, total, page, limit };
  },

  // 알림 읽음 처리
  async markAsRead(notificationId) {
    const pool = getPool();
    const [[row]] = await pool.query('SELECT user_id FROM notifications WHERE notification_id = ?', [notificationId]);
    const [result] = await pool.query(
      `UPDATE notifications SET is_read = 1, read_at = NOW() WHERE notification_id = ?`,
      [notificationId]
    );
    if (row) this._invalidateCache(row.user_id);
    return result.affectedRows > 0;
  },

  // 모든 알림 읽음 처리
  async markAllAsRead(userId = null) {
    const pool = getPool();
    const [result] = await pool.query(
      `UPDATE notifications SET is_read = 1, read_at = NOW()
       WHERE is_read = 0 AND (user_id IS NULL OR user_id = ?)`,
      [userId || 0]
    );
    this._invalidateCache(userId);
    return result.affectedRows;
  },

  // 알림 삭제
  async delete(notificationId) {
    const pool = getPool();
    const [result] = await pool.query(
      `DELETE FROM notifications WHERE notification_id = ?`,
      [notificationId]
    );
    return result.affectedRows > 0;
  },

  // 오래된 알림 삭제 (30일 이상)
  async deleteOld(days = 30) {
    const pool = getPool();
    const [result] = await pool.query(
      `DELETE FROM notifications WHERE created_at < DATE_SUB(NOW(), INTERVAL ? DAY)`,
      [days]
    );
    return result.affectedRows;
  },

  // 읽지 않은 알림 개수 (캐싱)
  async getUnreadCount(userId = null) {
    const cacheKey = `notif:unread:${userId || 0}`;
    try {
      const cache = require('../utils/cache');
      const cached = await cache.get(cacheKey);
      if (cached !== null && cached !== undefined) return cached;
    } catch (e) { /* 무시 */ }

    const pool = getPool();
    const [[{ count }]] = await pool.query(
      `SELECT COUNT(*) as count FROM notifications
       WHERE is_read = 0 AND (user_id IS NULL OR user_id = ?)`,
      [userId || 0]
    );

    try {
      const cache = require('../utils/cache');
      await cache.set(cacheKey, count, 30);
    } catch (e) { /* 무시 */ }

    return count;
  },

  // 캐시 무효화
  _invalidateCache(userId) {
    try {
      const cache = require('../utils/cache');
      cache.del(`notif:unread:${userId || 0}`).catch(() => {});
      if (userId) cache.del('notif:unread:0').catch(() => {});
    } catch (e) { /* 무시 */ }
  },

  // 수리 신청 알림 생성 헬퍼 (지정된 수신자에게 전송)
  async createRepairNotification(repairData) {
    const { equipment_id, equipment_name, repair_type, request_id, created_by } = repairData;

    const recipientIds = await getRecipientIds('repair');

    if (recipientIds.length === 0) {
      const id = await this.create({
        type: 'repair',
        title: `수리 신청: ${equipment_name || '설비'}`,
        message: `${repair_type} 수리가 신청되었습니다.`,
        link_url: `/pages/admin/repair-management.html`,
        reference_type: 'work_issue_reports',
        reference_id: request_id,
        created_by
      });
      sendPushToUsers([], {
        title: `수리 신청: ${equipment_name || '설비'}`,
        body: `${repair_type} 수리가 신청되었습니다.`,
        url: `/pages/admin/repair-management.html`
      });
      return id;
    }

    const results = [];
    for (const userId of recipientIds) {
      const notificationId = await this.create({
        user_id: userId,
        type: 'repair',
        title: `수리 신청: ${equipment_name || '설비'}`,
        message: `${repair_type} 수리가 신청되었습니다.`,
        link_url: `/pages/admin/repair-management.html`,
        reference_type: 'work_issue_reports',
        reference_id: request_id,
        created_by
      });
      results.push(notificationId);
    }

    sendPushToUsers(recipientIds, {
      title: `수리 신청: ${equipment_name || '설비'}`,
      body: `${repair_type} 수리가 신청되었습니다.`,
      url: `/pages/admin/repair-management.html`
    });

    return results;
  },

  // 일반 알림 생성 (유형별 지정된 수신자에게 전송)
  async createTypedNotification(notificationData) {
    const { type, title, message, link_url, reference_type, reference_id, created_by } = notificationData;

    const recipientIds = await getRecipientIds(type);

    if (recipientIds.length === 0) {
      const id = await this.create({
        type,
        title,
        message,
        link_url,
        reference_type,
        reference_id,
        created_by
      });
      sendPushToUsers([], { title, body: message || '', url: link_url || '/' });
      return id;
    }

    const results = [];
    for (const userId of recipientIds) {
      const notificationId = await this.create({
        user_id: userId,
        type,
        title,
        message,
        link_url,
        reference_type,
        reference_id,
        created_by
      });
      results.push(notificationId);
    }

    sendPushToUsers(recipientIds, { title, body: message || '', url: link_url || '/' });

    return results;
  },

  // 특정 사용자 직접 알림 (target_user_ids 기반, type 브로드캐스트 아님)
  async createTargetedNotification(notificationData) {
    const { type, title, message, link_url, reference_type, reference_id, created_by, target_user_ids } = notificationData;

    const results = [];
    for (const userId of target_user_ids) {
      const notificationId = await this.create({
        user_id: userId,
        type,
        title,
        message,
        link_url,
        reference_type,
        reference_id,
        created_by
      });
      results.push(notificationId);
    }

    // ntfy + WebPush 발송
    sendPushToUsers(target_user_ids, { title, body: message || '', url: link_url || '/' });

    return results;
  }
};

module.exports = notificationModel;