'use strict';

const { randomBytes } = require('crypto');

const DEFAULT_PARSE_FUNCTIONS_URL = 'https://server.fmode.cn/parse/functions';
const DEFAULT_PAY_COMPANY = '1AiWpTEDH9';
const DEFAULT_NEW_API_CALLBACK = 'WbyPrzMI3A';

function createTradeNo(prefix = 'VOC') {
  const stamp = new Date().toISOString().replace(/[-:.TZ]/g, '');
  return `${prefix}${stamp}${randomBytes(4).toString('hex')}`;
}

function buildRechargePaymentRequest({ amount, title = 'VOC 数据调用充值', tradeNo, sessionToken } = {}) {
  const numericAmount = Number(amount);
  if (!Number.isFinite(numericAmount) || numericAmount <= 0) {
    throw new Error('充值金额必须大于 0');
  }
  const outTradeNo = tradeNo || createTradeNo();
  const parseFunctionsUrl = String(process.env.FMODE_PARSE_FUNCTIONS_URL || DEFAULT_PARSE_FUNCTIONS_URL).replace(/\/$/, '');
  const body = {
    company: process.env.FMODE_PAY_COMPANY || DEFAULT_PAY_COMPANY,
    out_trade_no: outTradeNo,
    total_fee: Number(numericAmount.toFixed(2)),
    body: String(title).slice(0, 80),
    fun_id: process.env.FMODE_NEWAPI_RECHARGE_CALLBACK_FUN_ID || DEFAULT_NEW_API_CALLBACK
  };
  return {
    endpoint: `${parseFunctionsUrl}/pay_code2`,
    method: 'POST',
    headers: sessionToken ? { 'X-Parse-Session-Token': sessionToken } : {},
    body,
    tradeNo: outTradeNo,
    amountCny: body.total_fee,
    polling: {
      endpoint: `${parseFunctionsUrl}/order_status2`,
      method: 'POST',
      body: {
        out_trade_no: outTradeNo,
        company: body.company
      }
    }
  };
}

async function requestPaymentQr({ amount, title, sessionToken, tradeNo, fetchImpl = fetch } = {}) {
  const request = buildRechargePaymentRequest({ amount, title, sessionToken, tradeNo });
  const response = await fetchImpl(request.endpoint, {
    method: request.method,
    headers: { Accept: 'application/json', 'Content-Type': 'application/json', ...request.headers },
    body: JSON.stringify(request.body)
  });
  const payload = await response.json().catch(() => ({}));
  const codeUrl = Array.isArray(payload?.code_url) ? payload.code_url[0] : payload?.code_url;
  if (!response.ok || !codeUrl) {
    const error = new Error(payload?.error || payload?.message || `pay_code2 HTTP ${response.status}`);
    error.httpStatus = response.status;
    throw error;
  }
  const nonceStr = payload?.nonce_str || '';
  return {
    ...request,
    paymentMode: 'qr',
    qrCodeUrl: String(codeUrl),
    nonceStr,
    polling: {
      ...request.polling,
      body: {
        ...request.polling.body,
        ...(nonceStr ? { nonce_str: nonceStr } : {})
      }
    }
  };
}

module.exports = {
  DEFAULT_PARSE_FUNCTIONS_URL,
  createTradeNo,
  buildRechargePaymentRequest,
  requestPaymentQr
};