// 示例：使用Node.js获取访问令牌
const axios = require('axios');

const getAccessToken = async (code) => {
  const params = new URLSearchParams();
  params.append('grant_type', 'authorization_code');
  params.append('code', code);
  params.append('redirect_uri', 'YOUR_REDIRECT_URI');
  
  const response = await axios.post('https://identity.xero.com/connect/token', params, {
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded',
      'Authorization': 'Basic ' + Buffer.from(`${CLIENT_ID}:${CLIENT_SECRET}`).toString('base64')
    }
  });
  
  return response.data.access_token;
};

// 示例：获取账单列表
const getBills = async (accessToken, tenantId) => {
  try {
    const response = await axios.get('https://api.xero.com/api.xro/2.0/Bills', {
      headers: {
        'Authorization': `Bearer ${accessToken}`,
        'xero-tenant-id': tenantId,
        'Accept': 'application/json'
      }
    });
    return response.data;
  } catch (error) {
    console.error('Error fetching bills:', error.response.data);
    throw error;
  }
};

// 示例：带筛选条件的账单查询
const getFilteredBills = async (accessToken, tenantId, params = {}) => {
  const queryString = new URLSearchParams(params).toString();
  const url = `https://api.xero.com/api.xro/2.0/Bills?${queryString}`;
  
  const response = await axios.get(url, {
    headers: {
      'Authorization': `Bearer ${accessToken}`,
      'xero-tenant-id': tenantId
    }
  });
  
  return response.data;
};

// 使用示例
const bills = await getFilteredBills(accessToken, tenantId, {
  page: 1,
  where: 'Status=="AUTHORISED"',
  order: 'Date DESC'
});

// 分页处理示例
const getAllBills = async (accessToken, tenantId) => {
  let allBills = [];
  let page = 1;
  let hasMore = true;
  
  while (hasMore) {
    const response = await getFilteredBills(accessToken, tenantId, { page });
    allBills = [...allBills, ...response.Bills];
    hasMore = response.Bills.length === 100; // Xero每页最多返回100条记录
    page++;
  }
  
  return allBills;
};