import { WITH_DATA_RE } from '../constants/methods'
import { isFunction, isString } from '../helpers/isTypes'
import { assert } from '../helpers/error'
import { AxiosRequestConfig, AxiosResponse } from '../core/Axios'
import { Cancel, isCancel, isCancelToken } from './cancel'
import { flattenHeaders } from './flattenHeaders'
import { AxiosTransformer, transformData } from './transformData'
import { request } from './request'
import { AxiosErrorResponse } from './createError'

/**
 * 发送请求
 *
 * 校验配置，转换配置，转换数据，捕获取消请求。
 *
 * @param config 请求配置
 */
export function dispatchRequest(config: AxiosRequestConfig) {
	throwIfCancellationRequested(config)

	assert(isFunction(config.adapter), 'adapter 不是一个 function')
	assert(isString(config.url), 'url 不是一个 string')
	assert(isString(config.method), 'method 不是一个 string')

	config.headers = flattenHeaders(config)

	// 可以携带 data 的请求方法，转换 data
	// 否则，删除 data
	if (WITH_DATA_RE.test(config.method!)) {
		dataTransformer(config, config.transformRequest)
	} else {
		delete config.data
	}

	function onSuccess(response: AxiosResponse) {
		throwIfCancellationRequested(config)
		dataTransformer(response, config.transformResponse)

		return response
	}

	function onError(error: Cancel | AxiosErrorResponse) {
		if (!isCancel(error)) {
			throwIfCancellationRequested(config)
			dataTransformer(error.response, config.transformResponse)
		}

		return Promise.reject(error)
	}

	function dataTransformer<TData = unknown>(
		obj: { data?: TData; headers?: AnyObject },
		fn?: AxiosTransformer<TData>,
	) {
		obj.data = transformData(obj.data, obj.headers, fn)
	}

	return request(config).then(onSuccess, onError)
}

function throwIfCancellationRequested(config: AxiosRequestConfig) {
	const { cancelToken } = config
	if (isCancelToken(cancelToken)) {
		cancelToken.throwIfRequested()
	}
}