const { Pool } = require('pg');

const cache = {
  global: [],
  byGuild: new Map(), // guildId -> rows[]
  ready: false
};

function inWindow(row, now = new Date()) {
  if (row.starts_at && now < new Date(row.starts_at)) return false;
  if (row.ends_at && now > new Date(row.ends_at))   return false;
  return true;
}

function pickWeighted(list) {
  if (!list.length) return null;
  const total = list.reduce((a, r) => a + (r.weight || 1), 0);
  let rnd = Math.random() * total;
  for (const r of list) {
    rnd -= (r.weight || 1);
    if (rnd <= 0) return r;
  }
  return list[0];
}

async function loadAll(pool) {
  const { rows } = await pool.query(
    `SELECT id, name, activity_type, enabled, weight, scope, guild_id, starts_at, ends_at
     FROM bot_statuses
     WHERE enabled = TRUE`
  );

  const now = new Date();
  cache.global = rows.filter(r => r.scope === 'global' && inWindow(r, now));
  cache.byGuild.clear();
  for (const r of rows) {
    if (r.scope === 'guild' && inWindow(r, now) && r.guild_id) {
      const arr = cache.byGuild.get(r.guild_id) || [];
      arr.push(r);
      cache.byGuild.set(r.guild_id, arr);
    }
  }
  cache.ready = true;
}

async function initStatusCache(pool) {
  await loadAll(pool);

  // Live refresh when table changes (if you created the trigger)
  const client = await pool.connect();
  await client.query('LISTEN status_change');
  client.on('notification', async () => {
    try {
      await loadAll(pool);
      console.log('[status] cache refreshed via NOTIFY');
    } catch (e) {
      console.error('[status] refresh error:', e);
    }
  });

  // Safety: periodic refresh in case NOTIFY is missed
  setInterval(() => loadAll(pool).catch(() => {}), 5 * 60 * 1000);
}

function getNextStatus(guildId) {
  const rows = (guildId && cache.byGuild.get(guildId))?.length
    ? cache.byGuild.get(guildId)
    : cache.global;

  return pickWeighted(rows || []);
}

module.exports = {
  initStatusCache,
  getNextStatus
};