/**
 * 新一代版本
 * @author yutent<yutent.io@gmail.com>
 * @date 2020/07/31 18:59:47
 */

import { Format, toS } from './lib/format.js'

const nativeFetch = window.fetch
const NOBODY_METHODS = ['GET', 'HEAD']
const FORM_TYPES = {
  form: 'application/x-www-form-urlencoded; charset=UTF-8',
  json: 'application/json; charset=UTF-8',
  text: 'text/plain; charset=UTF-8'
}
const ERRORS = {
  10001: 'Argument url is required',
  10012: 'Parse error',
  10100: 'Request canceled',
  10104: 'Request pending...',
  10200: 'Ok',
  10204: 'No content',
  10304: 'Not modified',
  10500: 'Internal Server Error',
  10504: 'Connected timeout'
}

class _Request {
  constructor(url = '', options = {}, owner) {
    if (!url) {
      throw new Error(ERRORS[10001])
    }

    // url规范化
    url = url.replace(/#.*$/, '')

    if (owner.BASE_URL) {
      if (!/^([a-z]+:|\/\/)/.test(url)) {
        url = owner.BASE_URL + url
      }
    }

    options.method = (options.method || 'get').toUpperCase()

    this._owner = owner

    this.options = {
      headers: {
        'X-Requested-With': 'XMLHttpRequest',
        'content-type': FORM_TYPES.form
      },
      body: null,
      cache: 'default',
      signal: null, // 超时信号, 配置该项时, timeout不再生效
      timeout: 30000 // 超时时间, 单位毫秒, 默认30秒
    }

    if (!options.signal) {
      this.control = new AbortController()
      options.signal = this.control.signal
    }

    if (options.headers) {
      let headers = this.options.headers
      Object.assign(headers, options.headers)
      options.headers = headers
    }

    Object.assign(this.options, options, { url })

    if (owner._inject_req) {
      owner._inject_req(this.options)
    }

    return this.__next__()
  }

  __next__() {
    var options = this.options
    var params = null
    var hasAttach = false // 是否有附件
    var crossDomain = false // 是否跨域
    var noBody = NOBODY_METHODS.includes(options.method)

    /* --------------------------  1»» 请求的内容 --------------------- */
    if (options.body) {
      var type = typeof options.body
      switch (type) {
        case 'number':
        case 'string':
          this.__type__('text')
          params = options.body
          break
        case 'object':
          // 解析表单DOM
          if (options.body.nodeName === 'FORM') {
            options.method = options.body.method.toUpperCase() || 'POST'

            params = Format.parseForm(options.body)
            hasAttach = params.constructor === FormData

            // 如果是一个 FormData对象,且为不允许携带body的方法,则直接改为POST
          } else if (options.body.constructor === FormData) {
            hasAttach = true
            if (noBody) {
              options.method = 'POST'
            }
            params = options.body
          } else {
            for (let k in options.body) {
              if (toS.call(options.body[k]) === '[object File]') {
                hasAttach = true
                break
              }
            }
            // 有附件,则改为FormData
            if (hasAttach) {
              if (noBody) {
                options.method = 'POST'
              }
              params = Format.mkFormData(options.body)
            } else {
              params = options.body
            }
          }
      }
    }
    if (hasAttach) {
      delete options.headers['content-type']
    }

    /* --------------------------  2»» 处理跨域  --------------------- */
    try {
      let $a = document.createElement('a')
      $a.href = options.url

      crossDomain = location.protocol !== $a.protocol || location.host !== $a.host
      $a = null
    } catch (err) {}

    if (crossDomain && options.credentials === 'omit') {
      delete options.headers['X-Requested-With']
    }

    /* ------------- 3»» 根据method类型, 处理表单数据  ---------------- */

    // 拼接到url上
    if (noBody) {
      params = Format.param(params)
      if (params) {
        options.url += (~options.url.indexOf('?') ? '&' : '?') + params
      }
    } else {
      if (!hasAttach) {
        if (~options.headers['content-type'].indexOf('json')) {
          params = JSON.stringify(params)
        } else {
          params = Format.param(params)
        }
      }
    }

    /* -----------------   4»» 超时处理  -----------------------*/
    if (options.timeout && options.timeout > 0) {
      this.timer = setTimeout(_ => {
        this.abort()
      }, options.timeout)

      delete options.timeout
    }

    /* -----------------    5»» 构造请求    ------------------- */
    var url = options.url
    delete options.url
    for (let k in options) {
      if (options[k] === null || options[k] === undefined || options[k] === '') {
        delete options[k]
      }
    }
    return nativeFetch(url, options)
      .then(r => {
        clearTimeout(this.timer)
        let isSucc = r.status >= 200 && r.status < 400
        if (this._owner._inject_res) {
          r = this._owner._inject_res(r)
        }
        if (isSucc) {
          return r
        } else {
          return Promise.reject(r)
        }
      })
      .catch(e => {
        clearTimeout(this.timer)
        return Promise.reject(e)
      })
  }

  abort() {
    this.control.abort()
  }

  __type__(type) {
    this.options.headers['content-type'] = FORM_TYPES[type]
  }
}

function inject(target) {
  target.inject = {
    request(callback) {
      target._inject_req = callback
    },
    response(callback) {
      target._inject_res = callback
    }
  }
}

const _fetch = function (url, options) {
  return new _Request(url, options, _fetch)
}

_fetch.create = function () {
  var another = function (url, options) {
    return new _Request(url, options, another)
  }
  inject(another)
  return another
}

inject(_fetch)

export default _fetch