function parsePayParams(rawValue) {
  try {
    const params = JSON.parse(decodeURIComponent(String(rawValue || '')));
    if (!params || typeof params !== 'object') {
      return null;
    }
    return params;
  } catch (error) {
    console.error('[wechat-pay] parse params failed', error);
    return null;
  }
}

function requestPayment(payParams) {
  return new Promise((resolve) => {
    wx.requestPayment({
      timeStamp: String(payParams.timeStamp || ''),
      nonceStr: String(payParams.nonceStr || ''),
      package: String(payParams.package || ''),
      signType: payParams.signType || 'RSA',
      paySign: String(payParams.paySign || ''),
      success() {
        resolve('success');
      },
      fail(error) {
        const errMsg = error && error.errMsg ? error.errMsg : '';
        resolve(/cancel/i.test(errMsg) ? 'cancel' : 'fail');
      },
    });
  });
}

function appendPayResult(url, requestId, status) {
  const value = `${requestId}:${status}`;
  const hashIndex = String(url || '').indexOf('#');
  const baseUrl =
    hashIndex >= 0 ? String(url).slice(0, hashIndex) : String(url || '');
  const rawHash = hashIndex >= 0 ? String(url).slice(hashIndex + 1) : '';
  const params = new URLSearchParams(rawHash);
  params.set('wx_pay_result', value);
  return `${baseUrl}#${params.toString()}`;
}

function notifyPreviousWebView(requestId, status) {
  const pages = getCurrentPages();
  const previousPage = pages.length >= 2 ? pages[pages.length - 2] : null;
  if (previousPage && typeof previousPage.setData === 'function') {
    previousPage.setData({
      webViewUrl: appendPayResult(
        previousPage.data.webViewUrl,
        requestId,
        status,
      ),
    });
  }
}

Page({
  data: {
    title: '正在拉起支付',
    errorMessage: '',
  },

  async onLoad(query) {
    const requestId = String(query.requestId || '');
    const payParams = parsePayParams(query.payParams);
    if (!requestId || !payParams) {
      this.setData({
        title: '支付失败',
        errorMessage: '缺少支付参数。',
      });
      return;
    }

    const status = await requestPayment(payParams);
    notifyPreviousWebView(requestId, status);
    wx.navigateBack();
  },

  handleBack() {
    wx.navigateBack();
  },
});