/**
 * GET /api/calendar
 * Возвращает объединённый список событий за период:
 *   - user_posts (черновики / запланированные / опубликованные пользователем)
 *   - scheduled_posts (авто-публикации статей блога)
 *
 * Query params:
 *   from       — ISO date начала (включительно), default = начало текущего месяца
 *   to         — ISO date конца (включительно), default = конец следующего месяца
 *   channel_id — фильтр по каналу (опционально)
 *   user_id    — берётся из заголовка x-user-id
 */

const express = require('express');
const router = express.Router();
const { query } = require('../config/db');

const getUserId = (req) => parseInt(req.headers['x-user-id']) || null;

router.get('/', async (req, res) => {
  try {
    const userId = getUserId(req);
    if (!userId) return res.status(401).json({ error: 'Unauthorized' });

    // Диапазон дат
    const now = new Date();
    const defaultFrom = new Date(now.getFullYear(), now.getMonth(), 1);
    const defaultTo   = new Date(now.getFullYear(), now.getMonth() + 2, 0, 23, 59, 59);

    const from      = req.query.from ? new Date(req.query.from) : defaultFrom;
    const to        = req.query.to   ? new Date(req.query.to)   : defaultTo;
    const channelId = req.query.channel_id ? parseInt(req.query.channel_id) : null;

    const events = [];

    // ── user_posts ────────────────────────────────────────────────────────────
    // Берём посты юзера у которых scheduled_at или published_at попадает в диапазон
    const upParams = [userId, from, to];
    let upWhere = `up.user_id = $1
      AND (
        (up.scheduled_at IS NOT NULL AND up.scheduled_at BETWEEN $2 AND $3)
        OR
        (up.published_at IS NOT NULL AND up.published_at BETWEEN $2 AND $3)
        OR
        (up.scheduled_at IS NULL AND up.published_at IS NULL AND up.status='draft'
          AND up.created_at BETWEEN $2 AND $3)
      )`;

    if (channelId) {
      upParams.push(channelId);
      upWhere += ` AND up.channel_id = $${upParams.length}`;
    }

    const { rows: userPosts } = await query(
      `SELECT up.id, up.channel_id, up.status,
              up.scheduled_at, up.published_at, up.created_at,
              left(up.content, 120) AS content_preview,
              up.topic,
              up.image_url,
              c.name AS channel_name, c.platform
       FROM user_posts up
       JOIN channels c ON c.id = up.channel_id
       WHERE ${upWhere}
       ORDER BY COALESCE(up.scheduled_at, up.published_at, up.created_at) ASC
       LIMIT 500`,
      upParams
    );

    for (const p of userPosts) {
      events.push({
        id:            `up_${p.id}`,
        source:        'user_post',
        source_id:     p.id,
        channel_id:    p.channel_id,
        channel_name:  p.channel_name,
        platform:      p.platform,
        status:        p.status,            // draft | scheduled | published | failed
        date:          p.scheduled_at || p.published_at || p.created_at,
        scheduled_at:  p.scheduled_at,
        published_at:  p.published_at,
        title:         p.topic || null,
        preview:       p.content_preview,
        image_url:     p.image_url,
        editable:      true,                // можно перетаскивать / редактировать
      });
    }

    // ── scheduled_posts (авто-публикации статей блога) ────────────────────────
    // Отдаём только если нет фильтра по каналу, или канал совпадает
    const spParams = [from, to];
    let spWhere = `sp.scheduled_at BETWEEN $1 AND $2`;

    if (channelId) {
      spParams.push(channelId);
      spWhere += ` AND sp.channel_id = $${spParams.length}`;
    } else {
      // Только каналы этого юзера (или системные)
      spParams.push(userId);
      spWhere += ` AND (c.user_id = $${spParams.length} OR c.is_system = true)`;
    }

    const { rows: schedPosts } = await query(
      `SELECT sp.id, sp.channel_id, sp.status,
              sp.scheduled_at, sp.published_at,
              sp.error,
              a.title AS article_title, a.slug AS article_slug,
              a.category AS article_category, a.cover_url,
              c.name AS channel_name, c.platform
       FROM scheduled_posts sp
       JOIN channels c ON c.id = sp.channel_id
       LEFT JOIN articles a ON a.id = sp.article_id
       WHERE ${spWhere}
       ORDER BY sp.scheduled_at ASC
       LIMIT 500`,
      spParams
    );

    for (const p of schedPosts) {
      // Маппинг статусов: pending → scheduled, sent → published
      const status = p.status === 'sent' ? 'published'
                   : p.status === 'pending' ? 'scheduled'
                   : p.status; // failed

      events.push({
        id:            `sp_${p.id}`,
        source:        'scheduled_post',
        source_id:     p.id,
        channel_id:    p.channel_id,
        channel_name:  p.channel_name,
        platform:      p.platform,
        status,
        date:          p.published_at || p.scheduled_at,
        scheduled_at:  p.scheduled_at,
        published_at:  p.published_at,
        title:         p.article_title || null,
        preview:       p.article_title || null,
        image_url:     p.cover_url || null,
        article_slug:  p.article_slug || null,
        article_category: p.article_category || null,
        error:         p.error || null,
        editable:      p.status === 'pending', // pending можно отменить/перенести
      });
    }

    // Сортируем общий список по дате
    events.sort((a, b) => new Date(a.date) - new Date(b.date));

    res.json({
      from: from.toISOString(),
      to:   to.toISOString(),
      count: events.length,
      events,
    });
  } catch (err) {
    console.error('[Calendar] Error:', err);
    res.status(500).json({ error: err.message });
  }
});

module.exports = router;