import crypto from "crypto";

export function nowIso() {
  return new Date().toISOString();
}

export async function sleep(ms: number) {
  if (ms <= 0) return;
  await new Promise<void>((resolve) => setTimeout(resolve, ms));
}

export function normalizeUrl(url: string) {
  const u = url.trim();
  if (u.startsWith("//")) return `https:${u}`;
  if (u.startsWith("http://") || u.startsWith("https://")) return u;
  return `https://${u}`;
}

export function parsePrice(text: string | null) {
  if (!text) return null;
  const t = text.replace(/[¥￥,\s]/g, "");
  const m = t.match(/(\d+(?:\.\d+)?)/);
  if (!m) return null;
  const n = Number(m[1]);
  return Number.isFinite(n) ? n : null;
}

export function parseSales(text: string | null) {
  if (!text) return null;
  const t = text.replace(/[,，\s]/g, "");
  const m = t.match(/(\d+(?:\.\d+)?)(万|千)?/);
  if (!m) return null;
  const base = Number(m[1]);
  if (!Number.isFinite(base)) return null;
  const unit = m[2];
  if (unit === "万") return Math.round(base * 10_000);
  if (unit === "千") return Math.round(base * 1000);
  return Math.round(base);
}

export function parseScore(text: string | null) {
  if (!text) return null;
  const t = text.replace(/[^\d.]/g, "");
  const n = Number(t);
  if (!Number.isFinite(n)) return null;
  if (n > 10) return null;
  return n;
}

export function stableId(input: string) {
  return crypto.createHash("sha256").update(input).digest("hex").slice(0, 16);
}

export function computeGroupKey(title: string) {
  const t = title
    .toLowerCase()
    .replace(/[【】\[\]（）()]/g, " ")
    .replace(/[^\p{L}\p{N}]+/gu, " ")
    .trim();
  const tokens = t.split(/\s+/).filter(Boolean);
  const core = tokens.slice(0, 8).join("-");
  return core.slice(0, 64) || stableId(title);
}

export function clamp(n: number, min: number, max: number) {
  return Math.min(max, Math.max(min, n));
}

export async function asyncPool<T, R>(items: T[], concurrency: number, fn: (item: T) => Promise<R>) {
  const limit = Math.max(1, Math.floor(concurrency));
  const out: R[] = new Array(items.length);
  let i = 0;

  async function worker() {
    while (true) {
      const idx = i;
      i += 1;
      if (idx >= items.length) return;
      out[idx] = await fn(items[idx]!);
    }
  }

  const workers = Array.from({ length: Math.min(limit, items.length) }, () => worker());
  await Promise.all(workers);
  return out;
}

export async function withRetry<T>(fn: () => Promise<T>, opts: { retries: number; baseMs: number; maxMs: number; jitter: number }) {
  let attempt = 0;
  while (true) {
    try {
      return await fn();
    } catch (e) {
      if (attempt >= opts.retries) throw e;
      const exp = opts.baseMs * 2 ** attempt;
      const ms = Math.min(opts.maxMs, exp);
      const j = Math.floor(ms * opts.jitter * Math.random());
      await sleep(ms + j);
      attempt += 1;
    }
  }
}

export function createRateLimiter(qps: number) {
  const intervalMs = qps <= 0 ? 0 : Math.floor(1000 / qps);
  let last = 0;
  return async () => {
    if (intervalMs <= 0) return;
    const now = Date.now();
    const wait = Math.max(0, last + intervalMs - now);
    last = now + wait;
    await sleep(wait);
  };
}