import { env } from '$env/dynamic/private';

// In-memory store: Map<ip, { count, windowStart }>
const publishStore = new Map();
const readStore    = new Map();

const PUBLISH_LIMIT = parseInt(env.RATE_LIMIT_PUBLISH  ?? '5');
const READ_LIMIT    = parseInt(env.RATE_LIMIT_READ     ?? '100');
const PUBLISH_WINDOW_MS = 60 * 60 * 1000; // 1 hour
const READ_WINDOW_MS    = 60 * 1000;       // 1 minute

function check(store, ip, limit, windowMs) {
  const now = Date.now();
  const entry = store.get(ip);

  if (!entry || now - entry.windowStart > windowMs) {
    store.set(ip, { count: 1, windowStart: now });
    return { allowed: true, remaining: limit - 1 };
  }

  if (entry.count >= limit) {
    const retryAfter = Math.ceil((entry.windowStart + windowMs - now) / 1000);
    return { allowed: false, remaining: 0, retryAfter };
  }

  entry.count += 1;
  return { allowed: true, remaining: limit - entry.count };
}

export function checkPublishRate(ip) {
  return check(publishStore, ip, PUBLISH_LIMIT, PUBLISH_WINDOW_MS);
}

export function checkReadRate(ip) {
  return check(readStore, ip, READ_LIMIT, READ_WINDOW_MS);
}

export function getClientIp(request) {
  return (
    request.headers.get('x-forwarded-for')?.split(',')[0].trim() ??
    request.headers.get('x-real-ip') ??
    '127.0.0.1'
  );
}

// Cleanup old entries every 10 minutes to prevent memory leak
setInterval(() => {
  const now = Date.now();
  for (const [ip, entry] of publishStore) {
    if (now - entry.windowStart > PUBLISH_WINDOW_MS) publishStore.delete(ip);
  }
  for (const [ip, entry] of readStore) {
    if (now - entry.windowStart > READ_WINDOW_MS) readStore.delete(ip);
  }
}, 10 * 60 * 1000);