// Xiapan Cloud (虾盘云) client for U-Claw open-source edition.
// Provides only: apiKey derivation, balance lookup, recharge URL.
// Intentionally does NOT call /recharge/activate — open-source users do not get free quota.

const DEFAULT_API_BASE = 'https://api.u-claw.org/v1';
const DEFAULT_RECHARGE_PAGE = 'https://u-claw.org/cloud.html';
const QUOTA_PER_USD = 500_000; // 1 USD = 500k tokens (matches new-api convention)
const REQUEST_TIMEOUT_MS = 10_000;

// sk-uc- prefix marks keys generated by the u-claw open-source edition.
// ClawX commercial keys use plain sk-<hash> and the cloud.html flow uses sk-xp-,
// so the three namespaces never collide and the backend can audit by prefix.
export function buildApiKey(fingerprint) {
  if (!fingerprint || !/^[0-9a-f]{64}$/i.test(fingerprint)) {
    throw new Error('Fingerprint must be 64-character hex.');
  }
  return `sk-uc-${fingerprint.toLowerCase()}`;
}

function getApiBase() {
  return (process.env.UCLAW_CLOUD_API_BASE || DEFAULT_API_BASE).replace(/\/+$/, '');
}

function getRechargePage() {
  return process.env.UCLAW_CLOUD_RECHARGE_PAGE || DEFAULT_RECHARGE_PAGE;
}

async function fetchWithTimeout(url, init) {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
  try {
    return await fetch(url, { ...init, signal: controller.signal });
  } finally {
    clearTimeout(timer);
  }
}

export async function getBalance(apiKey) {
  if (!apiKey) throw new Error('apiKey is required.');
  const base = getApiBase();
  const headers = { Authorization: `Bearer ${apiKey}` };

  const [subRes, usageRes] = await Promise.all([
    fetchWithTimeout(`${base}/dashboard/billing/subscription`, { headers }).catch(() => null),
    fetchWithTimeout(
      `${base}/dashboard/billing/usage?start_date=2020-01-01&end_date=${new Date().toISOString().slice(0, 10)}`,
      { headers },
    ).catch(() => null),
  ]);

  if (!subRes || !subRes.ok) {
    return {
      ok: false,
      reason: subRes ? `subscription HTTP ${subRes.status}` : 'subscription request failed',
      hardLimitUsd: 0,
      usedUsd: 0,
      remainingUsd: 0,
      remainingTokens: 0,
    };
  }

  const subscription = await subRes.json().catch(() => ({}));
  let usedUsd = 0;
  if (usageRes && usageRes.ok) {
    const usage = await usageRes.json().catch(() => ({}));
    // total_usage is in cents (USD * 100), per new-api convention
    usedUsd = Number(usage.total_usage || 0) / 100;
  }

  const hardLimitUsd = Number(subscription.hard_limit_usd || 0);
  const remainingUsd = Math.max(0, hardLimitUsd - usedUsd);
  const remainingTokens = Math.round(remainingUsd * QUOTA_PER_USD);

  return {
    ok: true,
    reason: null,
    hardLimitUsd,
    usedUsd,
    remainingUsd,
    remainingTokens,
  };
}

export function getRechargeUrl(apiKey) {
  if (!apiKey) throw new Error('apiKey is required.');
  const page = getRechargePage();
  const url = new URL(page);
  url.searchParams.set('key', apiKey);
  // Page already has #recharge anchor; preserve it
  return `${url.toString()}#recharge`;
}