package sdk

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/hex"
	"sort"
	"strings"
)

func GenSignature(param *Params) string {
	if param.Headers() == nil {
		return ""
	}

	if param.secretKey == "" {
		panic("secretKey不能为空")
	}

	var sortedKeys []string
	for key, _ := range param.Headers() {
		sortedKeys = append(sortedKeys, key)
	}
	sort.Strings(sortedKeys)

	var params []string
	for _, key := range sortedKeys {
		if key != signatureHeader {
			params = append(params, key+"="+strings.Trim(param.Headers()[key], " "))
		}
	}
	params = append(params, "RequestMethod="+strings.Trim(param.requestMethod, " "))
	params = append(params, "Uri="+strings.Trim(param.uri, " "))
	if len(param.requestBody) <= 0 {
		params = append(params, "RequestBody=")
	} else {
		body := param.requestBody
		// 去除空格
		body = strings.Replace(body, " ", "", -1)
		// 去除换行符
		body = strings.Replace(body, "\n", "", -1)
		// 去除制表符
		body = strings.Replace(body, "\t", "", -1)
		// 去除回车符
		body = strings.Replace(body, "\r", "", -1)
		params = append(params, "RequestBody="+body)
	}

	return HmacSha256ToHex(param.secretKey+"&", strings.Trim(strings.Join(params, "&"), " "))
}

// HmacSha256 计算HmacSha256
// key 是加密所使用的key
// data 是加密的内容
func HmacSha256(key string, data string) []byte {
	mac := hmac.New(sha256.New, []byte(key))
	_, _ = mac.Write([]byte(data))

	return mac.Sum(nil)
}

// HmacSha256ToHex 将加密后的二进制转16进制字符串
func HmacSha256ToHex(key string, data string) string {
	return hex.EncodeToString(HmacSha256(key, data))
}

func RequestHeaders(params *Params) map[string]string {
	genSignature := GenSignature(params)
	params.Signature(genSignature)
	return params.Headers()
}