kettle/htp/client.go

package htp

import (
	"bytes"
	"io/ioutil"
	"net/http"
	"one.com/kettle/utl"
	"time"
)

type ClientOption func(*Client)

func WithUserAgent(ua string) ClientOption {
	return func(c *Client){
		c.ua = ua
	}
}

type Client struct {
	c   *http.Client
	req *http.Request
	ua  string
}

func NewClient(options ...ClientOption) *Client {
	c := &http.Client{
		Transport: &http.Transport{
			TLSHandshakeTimeout: 3 * time.Second,
			MaxIdleConnsPerHost: 20,
			MaxIdleConns:        20,
			IdleConnTimeout:     90 * time.Second,
		},
		Timeout: 3 * time.Second,
	}
	clt := &Client{
		c: c,
	}

	for _, opt := range options {
		opt(clt)
	}

	return clt
}

func (self *Client) Get(url string) ([]byte, error) {
	return self.request(http.MethodGet, url, nil, nil)
}

func (self *Client) Post(url string, headers map[string]string, body []byte) ([]byte, error) {
	return self.request(http.MethodPost, url, headers, body)
}

func (self *Client) request(method, url string, headers map[string]string, body []byte) ([]byte, error) {
	params := bytes.NewReader(body)
	req, err := http.NewRequest(method, url, params)
	if err != nil {
		return nil, err
	}

	if len(self.ua) > 0 {
		req.Header.Set("User-Agent", self.ua)
	}

	for k, v := range headers {
		req.Header.Add(k, v)
	}

	resp, err := self.c.Do(req)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode != http.StatusOK { // sometime StatusCode <> 200 may not represents an error
		return nil, utl.ErrForCode(resp.StatusCode)
	}
	if resp == nil {
		return nil, utl.ErrContainerEmpty
	}
	defer resp.Body.Close()

	return ioutil.ReadAll(resp.Body)
}

/////////////////////// chaining call