package sign

import (
	"crypto"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha1"
	"crypto/x509"
	"encoding/base64"
	"fmt"
	"log"
	"net/url"
	"sort"
	"strings"
)

const APPID = "a23b2d45b0214f7ebbe167cd2e490435"
const PRI_KEY = "MIICeAIBADANBgkqhkiG9w0BAQEFAASCAmIwggJeAgEAAoGBAOAoyk5ot2KHo3hFga+ozeSO6XORk6wd4MkyETSGCDrha8klXfTukAJfYz3eS/PpkdLJTGrd34D21BkKzJ7Pc+ExMwTEc4xTaWU9vVJWlshVgHUsfbRhVps3IivtK9e268j+7xHf0I6j0zJ7zOLO6aADf76e/GqVfA+rz0DPPR3jAgMBAAECgYEA3blbSy2nX42dM6VE/zTw28hEwOzZbiFrrHearyJ4140MKb2Nb23eAorJxnOxG0YI2MAGl5p5rr331AFrnxbCnb4JZ5fnT1uBNtmH4uEnHhIhQm3CsSukFWvnO5KRD+9Zl3BKUSor2ynCs5/EO0hcKlKCYtHiXKzkkUi65rLuH4kCQQD2tlELA8YDMGgKNOF3ZpvRrTqKxGb4wwg+jUX4ns4oXutc57EfG4R96MWG5gu4x/3ZVrHPMHsmPClnK7hAyXP/AkEA6JkfBiLkhlCmkCn5F3qDwuQNzTHqdm/Ql71Hogk6+2itVgJ9ua+Eegw5cVynPqrEWW2e7VbNjuiVlkMLJE0GHQJBAKFCOCTf+YzaFhcdy4X1DsJ13T8Y80mEiZ4BT4wbmRswN92JH+/6V5bJEFuFgIHuTxHBpgWMZeJvDoz+Obg3NVcCQE+tdFUzyrjAE+66khua2lv+p0OtX7Xmo7v3GPzG0K+isg4OmGbtWyI74cmVha0P7mb8CD8hRxU3U1a/7Kcow3kCQQCky3My+Qr+offSBqBE1cuFbkJ09G6nlotlPlO0pVnXOHMsUBCkfocv6QJ25KooppU1C1Cktgf9BYJ9b/r+r1Lu"
const HOST = "http://openapi.hopewindcloud.com/"

// 对参数进行签名，并为 Map 添加 appid 和 sign 参数
func SignByRSA(params map[string]string) string {
	params["appid"] = APPID
	content := CreateLinkString(params)
	privateKeyBytes, err := base64.StdEncoding.DecodeString(PRI_KEY)
	if err != nil {
		return ""
	}
	pkcs8PrivateKey, err := x509.ParsePKCS8PrivateKey(privateKeyBytes)
	if err != nil {
		log.Fatalf("Failed to parse PKCS#8 private key: %v", err)
	}
	privateKey, ok := pkcs8PrivateKey.(*rsa.PrivateKey)
	if !ok {
		log.Fatal("Private key is not of type RSA")
	}
	h := sha1.New()
	_, err = h.Write([]byte(content))
	if err != nil {
		fmt.Println(err)
		return ""
	}
	hashed := h.Sum(nil)
	signed, err := rsa.SignPKCS1v15(rand.Reader, privateKey, crypto.SHA1, hashed)
	if err != nil {
		fmt.Println(err)
		return ""
	}
	sign := url.QueryEscape(base64.StdEncoding.EncodeToString(signed))
	params["sign"] = sign
	return sign
}

// paramsFilter 过滤参数
func paramsFilter(params map[string]interface{}) map[string]string {
	result := make(map[string]string)
	if params == nil || len(params) == 0 {
		return result
	}
	for key, value := range params {
		if value == nil || key == "sign" {
			continue
		}
		result[key] = value.(string)
	}
	return result
}

// createLinkString 创建链接字符串
func CreateLinkString(params map[string]string) string {
	if params == nil {
		return ""
	}
	// 排序键
	keys := make([]string, 0, len(params))
	for key := range params {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	sb := strings.Builder{}
	keyLastNum := len(keys) - 1
	for i, key := range keys {
		value := params[key]
		sb.WriteString(key)
		sb.WriteString("=")
		sb.WriteString(value)
		if i != keyLastNum {
			sb.WriteString("&")
		}
	}
	return sb.String()
}