// API工具函数

// 定义后端服务URL和OAuth2配置
const API_BASE_URL = process.env.API_BASE_URL
const CLIENT_ID = process.env.CLIENT_ID
const CLIENT_SECRET = process.env.CLIENT_SECRET

// OAuth令牌缓存
interface TokenCache {
  token: string
  expires: number // 过期时间戳
}

let tokenCache: TokenCache | null = null

// 获取OAuth2访问令牌
export async function getAccessToken(forceRefresh = false): Promise<string> {
  try {
    // 检查缓存的令牌是否可用
    if (!forceRefresh && tokenCache && tokenCache.expires > Date.now()) {
      return tokenCache.token
    }

    const addr = `http://${API_BASE_URL}/api/auth/token`
    const body = {
      client_id: CLIENT_ID,
      client_secret: CLIENT_SECRET,
      grant_type: 'client_credentials',
    }

    const response = await fetch(addr, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(body),
    })

    if (!response.ok) {
      throw new Error(`OAuth token request failed: ${response.status} ${await response.text()}`)
    }

    const data = await response.json()

    // 缓存令牌和过期时间
    // 通常后端会返回expires_in（秒为单位）
    tokenCache = {
      token: data.access_token,
      expires: Date.now() + data.expires_in * 1000,
    }

    return tokenCache.token
  }
  catch (error) {
    console.error('Failed to get access token:', error)
    throw new Error('认证服务暂时不可用')
  }
}

// 通用的API调用函数
export async function call<R = undefined>(endpoint: string, data: unknown): Promise<ApiResponse<R>> {
  try {
    // 发送请求
    let accessToken = getAccessToken()
    const requestOptions = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${await accessToken}`,
      },
      body: JSON.stringify(data),
    }
    let response = await fetch(`http://${API_BASE_URL}${endpoint}`, requestOptions)

    // 如果返回401未授权，尝试刷新令牌并重试一次
    if (response.status === 401) {
      accessToken = getAccessToken(true) // 强制刷新令牌

      // 使用新令牌重试请求
      requestOptions.headers['Authorization'] = `Bearer ${await accessToken}`
      response = await fetch(`http://${API_BASE_URL}${endpoint}`, requestOptions)
    }

    // 解析响应数据
    const type = response.headers.get('Content-Type') ?? 'text/plain'
    if (type.indexOf('application/json') !== -1) {
      const json = await response.json()
      if (!response.ok) {
        console.log('响应不成功', `status=${response.status}`, json)
        return {
          success: false,
          status: response.status,
          message: json.message || '请求失败',
        }
      }
      return {
        success: true,
        data: json,
      }
    }
    else if (type.indexOf('text/plain') !== -1) {
      const text = await response.text()
      if (!response.ok) {
        console.log('响应不成功', `status=${response.status}`, text)
        return {
          success: false,
          status: response.status,
          message: text || '请求失败',
        }
      }
      return {
        success: true,
        data: undefined as unknown as R, // 强转类型，考虑优化
      }
    }
    else {
      throw new Error(`无法解析响应数据，未处理的 Content-Type: ${type}`)
    }
  }
  catch (e) {
    console.error('API call failed:', e)
    throw new Error('服务调用失败', {cause: e})
  }
}

// 使用用户令牌的API调用函数
export async function callWithUserToken<R = undefined>(
  endpoint: string, 
  data: unknown, 
  userToken: string,
  onTokenExpired?: () => void
): Promise<ApiResponse<R>> {
  try {
    // 发送请求
    const requestOptions = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${userToken}`,
      },
      body: JSON.stringify(data),
    }
    
    const response = await fetch(`http://${API_BASE_URL}${endpoint}`, requestOptions)

    // 如果返回401未授权，可能是用户令牌过期
    if (response.status === 401) {
      // 通知调用者令牌已过期，需要刷新或重新登录
      if (onTokenExpired) {
        onTokenExpired()
      }
      
      return {
        success: false,
        status: response.status,
        message: '用户会话已过期，请重新登录',
      }
    }

    // 解析响应数据
    const type = response.headers.get('Content-Type') ?? 'text/plain'
    if (type.indexOf('application/json') !== -1) {
      const json = await response.json()
      if (!response.ok) {
        console.log('响应不成功', `status=${response.status}`, json)
        return {
          success: false,
          status: response.status,
          message: json.message || '请求失败',
        }
      }
      return {
        success: true,
        data: json,
      }
    }
    else if (type.indexOf('text/plain') !== -1) {
      const text = await response.text()
      if (!response.ok) {
        console.log('响应不成功', `status=${response.status}`, text)
        return {
          success: false,
          status: response.status,
          message: text || '请求失败',
        }
      }
      return {
        success: true,
        data: undefined as unknown as R,
      }
    }
    else {
      throw new Error(`无法解析响应数据，未处理的 Content-Type: ${type}`)
    }
  }
  catch (e) {
    console.error('API call with user token failed:', e)
    throw new Error('服务调用失败', {cause: e})
  }
}

// 统一的API响应类型
export type ApiResponse<T = undefined> = {
  success: false
  status: number
  message: string
} | {
  success: true
  data: T
}