// API工具函数

// 定义后端服务URL和OAuth2配置
import {cookies} from 'next/headers'
import {redirect} from 'next/navigation'

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
}

// ======================
// region device token
// ======================

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 = `${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 ${await accessToken}`,
      },
      body: JSON.stringify(data),
    }
    let response = await fetch(`${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 ${await accessToken}`
      response = await fetch(`${API_BASE_URL}${endpoint}`, requestOptions)
    }

    // 检查响应状态
    if (!response.ok) {
      console.log('响应不成功', `status=${response.status}`, await response.text())
      return {
        success: false,
        status: response.status,
        message: '请求失败',
      }
    }

    // 检查响应状态
    return handleResponse(response)
  }
  catch (e) {
    console.error('API call failed:', e)
    throw new Error('服务调用失败', {cause: e})
  }
}


// endregion

// ======================
// region user token
// ======================

async function getUserToken(refresh = false): Promise<string> {
  // 从 cookie 中获取用户令牌
  const cookie = await cookies()
  const userToken = cookie.get('auth_token')?.value
  const userRefresh = cookie.get('auth_refresh')?.value

  // 检查缓存的令牌是否可用
  if (!refresh && userToken) {
    return userToken
  }

  // 如果没有刷新令牌，抛出异常
  if (!userRefresh) {
    throw UnauthorizedError
  }

  // 请求刷新访问令牌
  const addr = `${API_BASE_URL}/api/auth/token`
  const body = {
    grant_type: 'refresh_token',
    client_id: CLIENT_ID,
    client_secret: CLIENT_SECRET,
    refresh_token: userRefresh,
  }

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

  if (!response.ok) {
    console.log('刷新令牌失败', `status=${response.status}`, await response.text())
    throw UnauthorizedError
  }

  // 保存新的用户令牌到 cookie
  const data = await response.json()
  const nextAccessToken = data.access_token
  const nextRefreshToken = data.refresh_token
  const expiresIn = data.expires_in

  cookie.set('auth_token', nextAccessToken, {
    httpOnly: true,
    sameSite: 'strict',
    secure: process.env.NODE_ENV === 'production',
    maxAge: Math.max(expiresIn, 0),
  })
  cookie.set('auth_refresh', nextRefreshToken, {
    httpOnly: true,
    sameSite: 'strict',
    secure: process.env.NODE_ENV === 'production',
    maxAge: 7 * 24 * 3600, // 7天
  })

  return nextAccessToken
}

// 使用用户令牌的API调用函数
export async function callWithUserToken<R = undefined>(
  endpoint: string,
  data: unknown,
): Promise<ApiResponse<R>> {
  try {
    let token = await getUserToken()

    // 发送请求
    let response: Response
    const requestOptions = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${token}`,
      },
      body: JSON.stringify(data),
    }

    response = await fetch(`${API_BASE_URL}${endpoint}`, requestOptions)

    if (response.status === 401) {
      token = await getUserToken(true)
      requestOptions.headers['Authorization'] = `Bearer ${token}`
      response = await fetch(`${API_BASE_URL}${endpoint}`, requestOptions)
    }

    // 检查响应状态
    if (!response.ok) {
      if (response.status === 401) {
        throw UnauthorizedError
      }

      console.log('响应不成功', `status=${response.status}`, await response.text())
      return {
        success: false,
        status: response.status,
        message: '请求失败',
      }
    }

    return handleResponse(response)
  }
  catch (e) {
    // 重定向到登录页面
    if (e === UnauthorizedError) {
      redirect('/login')
    }

    console.error('API call with user token failed:', e)
    throw new Error('服务调用失败', {cause: e})
  }
}

// endregion

// 统一响应解析
async function handleResponse<R = undefined>(response: Response): Promise<ApiResponse<R>> {

  // 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}`)
  }
}

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

export type PageRecord<T = unknown> = {
  total: number
  page: number
  size: number
  list: T[]
}

export const UnauthorizedError = new Error('未授权访问')