package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"time"
)

func main() {

	// 命令行參數(shù) 參數(shù)名稱前面加個 -
    // 第一個參數(shù)為命令行參數(shù)，第二個默認值GET 第三個usage提示信息 
	method := flag.String("X", "GET", "GET POST")
	// 如果時GET請求不需要寫body
	body := flag.String("d", "{}", "json format")
	flag.Parse()

	// 沒有 - 的參數(shù),但是需要放到最末尾
	args := flag.Args()
	if len(args) != 1 {
		// 約定只有一個這樣子的參數(shù)，且必須是url
		fmt.Println("No parameter is passed, the url must be passed at the end")
		return
	}
	// 創(chuàng)建一個httpclient
	client := NewHttpClient()

	switch *method {
	// 只做GET POST支持
	case "POST", "GET":
		// 將body參數(shù)轉成map 必須要是json格式
		param := make(map[string]any)
		err := json.Unmarshal([]byte(*body), &param)
		if err != nil {
			fmt.Println("Json format is not valid", err.Error())
			return
		}

		data, err := client.Json(*method, args[0], param)
		if err != nil {
			fmt.Println(err.Error())
			return
		}
		// json格式化打印
		result := bytes.Buffer{}
		_ = json.Indent(&result, data, "", "\t")
		fmt.Println(result.String())
	default:
		fmt.Printf("No support %s", *method)
		return
	}
}

// HttpClient http客戶端
type HttpClient struct {
	client  http.Client
	Address string
}

func NewHttpClient() *HttpClient {
	client := http.Client{
		Timeout: time.Duration(3) * time.Second,
		Transport: &http.Transport{
			MaxIdleConnsPerHost:   5,
			MaxConnsPerHost:       100,
			IdleConnTimeout:       90 * time.Second,
			TLSHandshakeTimeout:   10 * time.Second,
			ExpectContinueTimeout: 1 * time.Second,
		},
	}
	return &HttpClient{client: client}
}

// Json 接收json格式返回
func (c *HttpClient) Json(method string, url string, args map[string]any) ([]byte, error) {
	jsonStr, _ := json.Marshal(args)
	req, err := http.NewRequest(method, url, bytes.NewReader(jsonStr))
	req.Header.Set("Content-Type", "application/json")
	if err != nil {
		return nil, err
	}
	return c.handleResponse(req)
}

func (c *HttpClient) handleResponse(req *http.Request) ([]byte, error) {
	// go原生方法 執(zhí)行http請求
	response, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}

	if response.StatusCode != http.StatusOK {
		return nil, errors.New(fmt.Sprintf("response code is %d", response.StatusCode))
	}

	// 以帶緩沖字節(jié)的方式讀取body 與其它語言類似
	buff := make([]byte, 128)
	var body []byte
	reader := bufio.NewReader(response.Body)
	for {
		n, err := reader.Read(buff)

		if err != nil && err != io.EOF {
			return nil, err
		}

		body = append(body, buff[:n]...)

		// 讀完了
		if err == io.EOF || n == 0 {
			break
		}

		if n < 128 {
			break
		}

	}
	defer response.Body.Close()
	return body, nil
}

// 將map轉成go中的url.Values
func (c *HttpClient) toValues(args map[string]any) string {
	if args != nil && len(args) > 0 {
		params := url.Values{}
		for k, v := range args {
			params.Set(k, fmt.Sprintf("%v", v))
		}
		return params.Encode()
	}
	return ""
}

PS D:\GoProject\curl> .\gocurl.exe -X=GET http://localhost:7001/product/get?pid=1001
{
        "code": "200",
        "msg": "ok",
        "data": {
                "pid": "1001",
                "pName": "iphone14-7676",
                "count": 0,
                "PType": ""
        }
}
PS D:\GoProject\curl> .\gocurl.exe -X=POST -d='{\"pid\":\"1002\"}' http://localhost:7001/product/post
{
        "code": "200",
        "msg": "ok",
        "data": {
                "pid": "1002",
                "pName": "iphone14-7676",
                "count": 0,
                "PType": ""
        }
}