package httpUtils

import (
	"bytes"
	"errors"
	"io"
	"io/ioutil"
	"mime/multipart"
	"net/http"
	"time"
)

var (
	client = http.Client{
		Timeout: 30 * time.Second,
		Transport: &http.Transport{
			MaxIdleConnsPerHost: 5,
			MaxConnsPerHost:     100,
		},
	}
)

type ByteSize int64

const (
	_           = iota // ignore first value by assigning to blank identifier
	KB ByteSize = 1 << (10 * iota)
	MB
)

var (
	outOfBodySizeErr = errors.New("out of body size limit")
)

type ResponseBody struct {
	StatusCode int
	Data       []byte
}

type RequestFormData map[string]string

// Post
// Note: 只会读取小于1M的数据
func Post(url string, header map[string]string, body io.Reader) (fr *ResponseBody, err error) {
	fr, err = do(http.MethodPost, url, header, body, int64(1024*MB))
	return
}

// PostFormData 提交标准的form表单
func PostFormData(url string, fromdata RequestFormData) (fr *ResponseBody, err error) {
	var b bytes.Buffer
	writer := multipart.NewWriter(&b)

	for k, v := range fromdata {
		if err = writer.WriteField(k, v); err != nil {
			return
		}
	}
	if err = writer.Close(); err != nil {
		return
	}

	header := map[string]string{"Content-Type": writer.FormDataContentType()}
	fr, err = do(http.MethodPost, url, header, &b, 2*int64(KB))
	return
}

// Get
// Note: 只会读取小于1M的数据
func Get(url string, header map[string]string) (fr *ResponseBody, err error) {
	fr, err = do(http.MethodGet, url, header, nil, int64(KB))
	return
}

// GetLargeFile 获取大文件。8M
func GetLargeFile(url string, header map[string]string) (fr *ResponseBody, err error) {
	fr, err = do(http.MethodGet, url, header, nil, int64(8*MB))
	return
}

func do(method string, url string, header map[string]string, body io.Reader, size int64) (fr *ResponseBody, err error) {
	req, err := http.NewRequest(method, url, body)
	if err != nil {
		return
	}
	for k, v := range header {
		req.Header.Set(k, v)
	}

	resp, err := client.Do(req)
	if err != nil {
		return
	}
	defer resp.Body.Close()

	if resp.ContentLength > size {
		err = outOfBodySizeErr
		return
	}

	data, err := ioutil.ReadAll(io.LimitReader(resp.Body, size))
	if err != nil {
		return
	}
	fr = &ResponseBody{
		StatusCode: resp.StatusCode,
		Data:       data,
	}
	return
}