import { DEFAULT_BASE_URL, DEFAULT_TIMEOUT, SUCCESS_CODE } from '@/constants/request'
import { clearAuth, getToken, isAuthEnabled, redirectToLogin } from '@/utils/auth'
import { showToast } from '@/utils/toast'

let baseURL = DEFAULT_BASE_URL

function buildUrl(url = '') {
  if (!url) {
    return baseURL
  }

  if (/^https?:\/\//.test(url)) {
    return url
  }

  if (url.startsWith('/')) {
    return `${baseURL}${url}`
  }

  return `${baseURL}/${url}`
}

/**
 * 构造请求头。
 * @param {Record<string, string>} customHeader 自定义请求头
 * @param {boolean} needAuth 是否需要携带 token
 * @param {boolean} withJson 是否设置 JSON Content-Type
 * @returns {Record<string, string>}
 */
function buildHeaders(customHeader = {}, needAuth = true, withJson = true) {
  const headers = {
    ...(withJson ? { 'Content-Type': 'application/json' } : {}),
    ...customHeader
  }

  if (needAuth && isAuthEnabled()) {
    const token = getToken()
    if (token) {
      headers.Authorization = `Bearer ${token}`
    }
  }

  return headers
}

function handleUnauthorized() {
  if (!isAuthEnabled()) {
    return
  }

  clearAuth()
  redirectToLogin()
}

/**
 * 统一解析后端响应结构。
 * 约定：`code === 0` 为成功，最终返回 `data` 字段。
 */
function resolveResponseData(responseData) {
  const code = typeof responseData?.code === 'number' ? responseData.code : SUCCESS_CODE

  if (code !== SUCCESS_CODE) {
    const error = new Error(responseData?.message || '业务处理失败')
    error.code = code
    throw error
  }

  return responseData?.data !== undefined ? responseData.data : responseData
}

/**
 * 通用请求方法。
 * @param {object} options uni.request 参数扩展
 * @returns {Promise<any>}
 */
function request(options = {}) {
  const {
    url,
    method = 'GET',
    data,
    header,
    timeout = DEFAULT_TIMEOUT,
    needAuth = true,
    showErrorToast = true,
    showToast: showToastLegacy
  } = options

  const shouldShowErrorToast = typeof showToastLegacy === 'boolean'
    ? showToastLegacy
    : showErrorToast

  return new Promise((resolve, reject) => {
    uni.request({
      url: buildUrl(url),
      method: String(method).toUpperCase(),
      data,
      timeout,
      header: buildHeaders(header, needAuth, true),
      success: (res) => {
        const { statusCode = 0, data: responseData = {} } = res

        if (statusCode === 401) {
          handleUnauthorized()
          reject(new Error('登录状态已失效'))
          return
        }

        if (statusCode < 200 || statusCode >= 300) {
          const message = responseData?.message || `网络错误(${statusCode})`
          if (shouldShowErrorToast) {
            showToast(message)
          }
          reject(new Error(message))
          return
        }

        try {
          const finalData = resolveResponseData(responseData)
          resolve(finalData)
        } catch (error) {
          if (error.code === 401) {
            handleUnauthorized()
          }
          if (shouldShowErrorToast) {
            showToast(error.message)
          }
          reject(error)
        }
      },
      fail: (error) => {
        if (shouldShowErrorToast) {
          showToast('网络异常，请稍后重试')
        }
        reject(error)
      }
    })
  })
}

request.get = (url, params = {}, config = {}) => {
  return request({
    url,
    method: 'GET',
    data: params,
    ...config
  })
}

request.post = (url, data = {}, config = {}) => {
  return request({
    url,
    method: 'POST',
    data,
    ...config
  })
}

request.put = (url, data = {}, config = {}) => {
  return request({
    url,
    method: 'PUT',
    data,
    ...config
  })
}

request.delete = (url, data = {}, config = {}) => {
  return request({
    url,
    method: 'DELETE',
    data,
    ...config
  })
}

request.upload = (url, filePath, name = 'file', formData = {}, config = {}) => {
  const {
    header = {},
    needAuth = true,
    showErrorToast = true,
    showToast: showToastLegacy
  } = config

  const shouldShowErrorToast = typeof showToastLegacy === 'boolean'
    ? showToastLegacy
    : showErrorToast

  return new Promise((resolve, reject) => {
    uni.uploadFile({
      url: buildUrl(url),
      filePath,
      name,
      formData,
      header: buildHeaders(header, needAuth, false),
      success: (res) => {
        if (res.statusCode === 401) {
          handleUnauthorized()
          reject(new Error('登录状态已失效'))
          return
        }

        if (res.statusCode < 200 || res.statusCode >= 300) {
          const message = `上传失败(${res.statusCode})`
          if (shouldShowErrorToast) {
            showToast(message)
          }
          reject(new Error(message))
          return
        }

        let responseData = {}
        try {
          responseData = JSON.parse(res.data || '{}')
        } catch (error) {
          if (shouldShowErrorToast) {
            showToast('上传返回数据格式错误')
          }
          reject(error)
          return
        }

        try {
          const finalData = resolveResponseData(responseData)
          resolve(finalData)
        } catch (error) {
          if (error.code === 401) {
            handleUnauthorized()
          }
          if (shouldShowErrorToast) {
            showToast(error.message)
          }
          reject(error)
        }
      },
      fail: (error) => {
        if (shouldShowErrorToast) {
          showToast('上传失败，请稍后重试')
        }
        reject(error)
      }
    })
  })
}

/**
 * 动态设置 API 基础地址。
 */
request.setBaseUrl = (url) => {
  if (!url || typeof url !== 'string') {
    return
  }

  baseURL = url.replace(/\/$/, '')
}

request.getBaseUrl = () => baseURL

export default request