import { normalizeConfig } from './helpers'
import { AjaxInstance, AjaxOption, AxiosMethods } from './types'
import { cancellerCalled } from './canceller'
type AnyObject = Record<string, any>

// GDataShape通过initAjax的第二个泛型参数传入，单独的请求如果不传返回数据的类型，则默认使用GDataShape
// DataType通过ajax.get, ajax.post等方法的泛型参数传入，如果定义了这个参数，会将GDataShape覆盖
export interface RequestCreator<COPT extends AnyObject, GDataShape extends AnyObject = any> {
  // request = ajax.get(url, options_1)
  <DataType = GDataShape>(url: string, options?: Partial<AjaxOption | COPT>): {
    // request(params, options_2)
    (params?: AnyObject | null, opts?: Partial<AjaxOption | COPT>): Promise<DataType>
  }
}

const postLikeMethods = ['PUT', 'POST', 'DELETE' , 'PATCH']
export const generateMethod = <COPT extends AnyObject, GDataShape extends AnyObject = any>(ajax: AjaxInstance, method: AxiosMethods): RequestCreator<COPT, GDataShape> =>
  /**
   * 
   * @param url 完整的请求url链接
   * @param options ajax配置
   * @returns 返回一个发送请求的函数
   */
  <DataType = GDataShape>(url: string, options?: Partial<AjaxOption | COPT>) =>
    /**
     * 发送请求
     * @param params get类请求的url参数 or post类请求的请求体数据
     * @param opts ajax参数，拥有最高优先级
     * @returns 请求数据
     */
    async (params?: AnyObject | null, opts?: Partial<AjaxOption | COPT>) => {
      const mergedOptions = { ...options, ...opts }

      const isPostLikeMethod =  postLikeMethods.includes(method)

      const config = {
        ...mergedOptions,
        params: isPostLikeMethod ? undefined : params,
        data: isPostLikeMethod ? params : undefined,
        url,
        method
      }

      // 处理取消请求逻辑
      const needCancel = typeof mergedOptions.cancelKey !== 'undefined'

      if (needCancel) {
        if (typeof AbortController !== 'undefined') {
          // 环境支持AbortController
          const controller = new AbortController()
          config.signal = controller.signal
          ajax.canceller[mergedOptions.cancelKey] = () => {
            controller.abort.call(controller)
            // 删除挂载在ajax上的请求中断函数
            Reflect.deleteProperty(ajax.canceller, mergedOptions.cancelKey)
          }
        } else {
          // 环境如果不支持AbortController，取消函数挂载到ajax只能交给adapter里面去实现了
          config.signal = undefined
          // 默认的取消函数，因为异步的关系，逻辑可能还没走到adapter中去，取消函数就已经被调用了，此时取消函数还是undefined
          // 默认函数将已经调用的取消函数名称记录下来，在adapter中走到发送请求的逻辑时，直接中断即可
          ajax.canceller[mergedOptions.cancelKey] = () => {
            cancellerCalled.push(mergedOptions.cancelKey)
            Reflect.deleteProperty(ajax.canceller, mergedOptions.cancelKey)
          }
        }
      }

      const finalOpts = normalizeConfig(ajax, config)

      // mock
      const mock = finalOpts.mock
      if (mock) {
        return Promise.resolve(mock)
      }

      const res = await ajax.request<any, DataType>(finalOpts)

      return res
    }