package meituan

import (
	"crypto/hmac"
	"crypto/md5"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"sort"
	"strings"
	"time"

	"repository.lenntc.com/lenntc/third-platform-sdk/util"
)

type Sign struct {
	AppKey    string // 应用key
	AppSecret string // 应用秘钥
}

func newSign(appKey, appSecret string) *Sign {
	return &Sign{
		AppKey:    appKey,
		AppSecret: appSecret,
	}
}

func (s *Sign) BuildHeader(methodType string, uri string, data map[string]any) map[string]string {
	headers := map[string]string{
		SCaApp:              s.AppKey,                                  // 应用app_key
		SCaTimestamp:        fmt.Sprintf("%d", time.Now().UnixMilli()), // 请求发起时间戳(毫秒)，有效时1分钟
		SCaSignatureHeaders: "S-Ca-Timestamp,S-Ca-App",                 // 将需要签名的header
		ContentMd5:          s.contentMD5(methodType, data),            // body数据Md5加密
		//"Content-Type":      "application/json",
	}
	headers[SCaSignature] = s.GetSign(methodType, uri, data, headers)
	return headers
}

func (s *Sign) GetSign(methodType string, uri string, data map[string]any, signHeaders map[string]string) string {
	httpMethod := s.httpMethod(methodType)
	contentMD5 := s.contentMD5(methodType, data)
	headers := s.headers(signHeaders)
	url := s.url(methodType, uri, data)
	strSign := httpMethod + "\n" + contentMD5 + "\n" + headers + url
	hm := hmac.New(sha256.New, []byte(s.AppSecret))
	hm.Write([]byte(strSign))
	signStr := base64.StdEncoding.EncodeToString(hm.Sum(nil))
	return signStr
}

// 请求方式大写
func (s *Sign) httpMethod(methodType string) string {
	return strings.ToUpper(methodType)
}

// 请求参数执行base64+md5的值
func (s *Sign) contentMD5(methodType string, data map[string]any) string {
	methodType = s.httpMethod(methodType)
	if (methodType == http.MethodPost || methodType == http.MethodPut) && data != nil {
		dataByte, _ := json.Marshal(data)
		h := md5.New()
		h.Write(dataByte)
		return base64.StdEncoding.EncodeToString(h.Sum(nil))
	} else {
		return ""
	}
}

// 签名计算Header的Key拼接
func (s *Sign) headers(signHeaders map[string]string) string {
	var str = ""
	// key排序
	sortData := sort.StringSlice{}
	for k := range signHeaders {
		if k != SCaSignature && k != SCaSignatureHeaders && k != ContentMd5 {
			sortData = append(sortData, k)
		}
	}
	sortData.Sort()

	for _, k := range sortData {
		str += k + ":" + signHeaders[k] + "\n"
	}
	return str
}

// url拼接
// post直接返回path，get有参数的情况下拼接url
func (s *Sign) url(methodType, uri string, data map[string]any) string {
	var query = ""
	methodType = s.httpMethod(methodType)
	// key排序
	sortData := sort.StringSlice{}
	for k := range data {
		sortData = append(sortData, k)
	}
	sortData.Sort()
	if len(sortData) > 0 && methodType == http.MethodGet {
		for num, key := range sortData {
			value, err := util.ToString(data[key])
			if err != nil {
				return ""
			}
			str1 := ""
			if len(sortData)-1 != num {
				str1 = "&"
			}
			if len(value) > 0 {
				query += fmt.Sprintf("%s=%s", key, value)
			} else {
				query += key
			}
			query += str1
		}
	}
	return fmt.Sprintf("%s%s", uri, query)
}