import { getDb, WatchedItem } from './database';
import { checkStockStatus } from './scraper';
import { sendTelegramAlert } from './telegram';

const MIN_INTERVAL_SECONDS = 30;
const timers = new Map<number, NodeJS.Timeout>();

async function runCheck(itemId: number): Promise<void> {
  const db = getDb();
  const item = db.prepare('SELECT * FROM watched_items WHERE id = ?').get(itemId) as WatchedItem | undefined;

  if (!item || !item.is_active) return;

  console.log(`[Scheduler] Checking item ${itemId} — ${item.name || item.url}`);

  try {
    const result = await checkStockStatus(item.url);

    const now = new Date().toISOString();
    let alertSent = item.alert_sent;

    // Fire alert only on transition to in_stock when no alert has been sent yet
    if (result.status === 'in_stock' && !item.alert_sent) {
      const displayName = result.name || item.name || item.url;
      await sendTelegramAlert(
        `🟢 <b>Back in Stock!</b>\n\n` +
        `<b>${displayName}</b>\n\n` +
        `<a href="${item.url}">Open in Store →</a>`
      );
      alertSent = 1;
    }

    // Build update payload
    const updates: Record<string, string | number> = {
      last_status: result.status,
      alert_sent: alertSent,
      check_count: item.check_count + 1,
      last_checked_at: now,
    };

    // Populate name and thumbnail on first successful scrape
    if (result.name && !item.name) updates.name = result.name;
    if (result.thumbnail && !item.thumbnail_url) updates.thumbnail_url = result.thumbnail;

    const setClause = Object.keys(updates).map(k => `${k} = @${k}`).join(', ');
    db.prepare(`UPDATE watched_items SET ${setClause} WHERE id = @id`).run({ ...updates, id: itemId });

    console.log(`[Scheduler] Item ${itemId} → ${result.status} (check #${item.check_count + 1})`);
  } catch (err) {
    console.error(`[Scheduler] Error checking item ${itemId}:`, err);
    // Still increment count so the UI shows activity
    db.prepare('UPDATE watched_items SET check_count = check_count + 1, last_checked_at = ? WHERE id = ?')
      .run(new Date().toISOString(), itemId);
  }
}

export function startItem(item: WatchedItem): void {
  stopItem(item.id);

  const intervalMs = Math.max(MIN_INTERVAL_SECONDS, item.check_interval) * 1000;
  const timer = setInterval(() => runCheck(item.id), intervalMs);
  timers.set(item.id, timer);

  console.log(`[Scheduler] Started item ${item.id} — interval ${intervalMs / 1000}s`);
}

export function stopItem(id: number): void {
  const timer = timers.get(id);
  if (timer) {
    clearInterval(timer);
    timers.delete(id);
    console.log(`[Scheduler] Stopped item ${id}`);
  }
}

export function initScheduler(): void {
  const db = getDb();
  const activeItems = db.prepare('SELECT * FROM watched_items WHERE is_active = 1').all() as WatchedItem[];

  for (const item of activeItems) {
    startItem(item);
  }

  console.log(`[Scheduler] Initialized — ${activeItems.length} active item(s)`);
}