/**
 * Loiter plugin for Discord (or any Node.js) bots.
 *
 * Monetize your bot's "working…" / loading messages. Fail-safe: every method
 * swallows errors — if Loiter is unreachable your bot behaves as before.
 *
 * Setup (one time):   node loiter-discord.js register [serverUrl] [refCode]
 * Usage:
 *   const { Loiter } = require('./loiter-discord');
 *   const sb = Loiter.load();                 // reads ~/.loiter/discord_bot.json
 *   const line = await sb.line();               // "Sponsored · …" or null
 *   // append to your embed footer / status message, then when it's done:
 *   await sb.report(displaySeconds);
 */
const fs = require('fs');
const os = require('os');
const path = require('path');

const DEFAULT_SERVER = 'http://127.0.0.1:8787';
const DEFAULT_CONF = path.join(os.homedir(), '.loiter', 'discord_bot.json');
const SECONDS_PER_IMPRESSION = 5;
const REFRESH_MS = 600_000;

async function api(server, method, p, body, params) {
  let url = server + p;
  if (params) url += '?' + new URLSearchParams(params);
  const r = await fetch(url, {
    method,
    headers: { 'Content-Type': 'application/json' },
    body: body ? JSON.stringify(body) : undefined,
    signal: AbortSignal.timeout(4000),
  });
  if (!r.ok) throw new Error(`HTTP ${r.status}`);
  return r.json();
}

class Loiter {
  constructor(server, deviceKey) {
    this.server = server;
    this.deviceKey = deviceKey;
    this.ads = [];
    this.fetched = 0;
    this.i = 0;
    this.shown = new Map();
  }

  static load(conf = DEFAULT_CONF) {
    const c = JSON.parse(fs.readFileSync(conf, 'utf8'));
    return new Loiter(c.server, c.device_key);
  }

  async line() {
    try {
      if (Date.now() - this.fetched > REFRESH_MS || !this.ads.length) {
        const r = await api(this.server, 'GET', '/api/serve', null,
                            { device_key: this.deviceKey, n: 6 });
        this.ads = r.ads || [];
        this.fetched = Date.now();
      }
      if (!this.ads.length) return null;
      const ad = this.ads[this.i++ % this.ads.length];
      this.shown.set(ad.ad_id, (this.shown.get(ad.ad_id) || 0) + 1);
      return `Sponsored · ${ad.text}${ad.url ? ' → ' + ad.url : ''}`;
    } catch { return null; }
  }

  async report(displaySeconds) {
    try {
      const total = Math.floor(Math.max(0, displaySeconds) / SECONDS_PER_IMPRESSION);
      if (!total || !this.shown.size) { this.shown.clear(); return; }
      const weights = [...this.shown.values()].reduce((a, b) => a + b, 0);
      const entries = [...this.shown.entries()].sort((a, b) => a[0] - b[0]);
      const items = [];
      let left = total;
      entries.forEach(([adId, w], j) => {
        let n = j < entries.length - 1 ? Math.floor((total * w) / weights) : left;
        n = Math.min(n, left);
        if (n > 0) items.push({ ad_id: adId, count: n });
        left -= n;
      });
      this.shown.clear();
      if (items.length) {
        await api(this.server, 'POST', '/api/impressions',
                  { device_key: this.deviceKey, items, active_seconds: Math.floor(displaySeconds) });
      }
    } catch { this.shown.clear(); }
  }
}

async function register(argv) {
  const server = argv[0] || DEFAULT_SERVER;
  const ref = argv[1] || null;
  const r = await api(server, 'POST', '/api/register', { platform: 'discord-bot', ref });
  fs.mkdirSync(path.dirname(DEFAULT_CONF), { recursive: true });
  fs.writeFileSync(DEFAULT_CONF,
    JSON.stringify({ server, device_key: r.device_key, ref_code: r.ref_code }, null, 2),
    { mode: 0o600 });
  console.log(`Registered. Config: ${DEFAULT_CONF}\nReferral code: ${r.ref_code}`);
}

if (require.main === module) {
  if (process.argv[2] === 'register') register(process.argv.slice(3));
  else console.log('Usage: node loiter-discord.js register [serverUrl] [refCode]');
}