// go/main.go
package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha256"
	"crypto/x509"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

// 与 Java 保持一致的 RSA 公钥/私钥（Base64）
var publicKeyStr = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqmdgZjjpySFAd+3Go33tshTOhRcSl6Sl4x8bR5vrEzsvFqQQW+VXLco0E1jy9dIR4NguRIGWOowi/4EU5PEM3ZVrXQCxCnyyqIuuDtY9QNTh5DTn60aDOLEL2X7+mvICgFg+VAKPik+8fBSUfzcGiLqFlx+VhUAkq9hCyd/wtYInuAxPSoCr8F2cmI4/V6sAhVUkHUZhJvWlyDLUpYKOGgYM4rXjCXXKrPO0FNf1iY70AWACSJmXUwBVuIRYWfTRVOvzEPWkp/tuqir/XcvMfKKVU5/eCr8abNVIG99HTF1iKvQPdQUldAyk5z9YPV5IwAbrjlEACmJ5JvuT3bypewIDAQAB"
var privateKeyStr = "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"

// parsePublicKey 解析 Java Base64 公钥为 rsa.PublicKey
// 返回 rsa.PublicKey 或错误
func parsePublicKey(b64 string) (*rsa.PublicKey, error) {
	der, err := base64.StdEncoding.DecodeString(b64)
	if err != nil {
		return nil, err
	}
	pub, err := x509ParsePublicKey(der)
	return pub, err
}

// parsePrivateKey 解析 Java Base64 私钥为 rsa.PrivateKey
// 返回 rsa.PrivateKey 或错误
func parsePrivateKey(b64 string) (*rsa.PrivateKey, error) {
	der, err := base64.StdEncoding.DecodeString(b64)
	if err != nil {
		return nil, err
	}
	priv, err := x509ParsePrivateKey(der)
	return priv, err
}

// x509ParsePublicKey X509 公钥解析（PKCS#8）
func x509ParsePublicKey(der []byte) (*rsa.PublicKey, error) {
	key, err := x509.ParsePKIXPublicKey(der)
	if err != nil {
		return nil, err
	}
	pub, ok := key.(*rsa.PublicKey)
	if !ok {
		return nil, errors.New("公钥类型错误")
	}
	return pub, nil
}

// x509ParsePrivateKey PKCS#8 私钥解析
func x509ParsePrivateKey(der []byte) (*rsa.PrivateKey, error) {
	key, err := x509.ParsePKCS8PrivateKey(der)
	if err != nil {
		return nil, err
	}
	priv, ok := key.(*rsa.PrivateKey)
	if !ok {
		return nil, errors.New("私钥类型错误")
	}
	return priv, nil
}

// EncryptHybrid 混合加密：随机 AES-256-GCM + RSA-OAEP(SHA-256) 加密 AES 密钥
// 输出 Base64(iv || rsa(aesKey) || gcmCiphertext) 与 Java 完全一致
func EncryptHybrid(plaintext []byte) (string, error) {
	pub, err := parsePublicKey(publicKeyStr)
	if err != nil {
		return "", err
	}
	aesKey := make([]byte, 32)
	if _, err = rand.Read(aesKey); err != nil {
		return "", err
	}
	block, err := aes.NewCipher(aesKey)
	if err != nil {
		return "", err
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}
	iv := make([]byte, 12)
	if _, err = rand.Read(iv); err != nil {
		return "", err
	}
	ciphertext := gcm.Seal(nil, iv, plaintext, nil)
	label := []byte{}
	encKey, err := rsa.EncryptOAEP(sha256.New(), rand.Reader, pub, aesKey, label)
	if err != nil {
		return "", err
	}
	buf := bytes.Join([][]byte{iv, encKey, ciphertext}, nil)
	return base64.StdEncoding.EncodeToString(buf), nil
}

// DecryptHybrid 混合解密：拆分 iv、RSA 加密的 AES 密钥、GCM 密文
// 使用 RSA-OAEP(SHA-256) 解密 AES 密钥，再用 AES-256-GCM 解密数据
func DecryptHybrid(token string) ([]byte, error) {
	log.Println("=== 开始解密 DecryptHybrid ===")
	log.Println("原始 token:", token)

	// 兼容 Java 的 " "→"+"
	token = strings.ReplaceAll(token, " ", "+")
	log.Println("空格替换后的 token:", token)

	data, err := base64.StdEncoding.DecodeString(token)
	if err != nil {
		log.Println("Base64 解码失败:", err)
		return nil, err
	}
	log.Println("Base64 解码成功，长度:", len(data))

	if len(data) < 12+256 {
		log.Println("密文长度非法:", len(data))
		return nil, errors.New("密文长度非法")
	}

	iv := data[:12]
	encKey := data[12 : 12+256]
	ct := data[12+256:]

	log.Println("IV 长度:", len(iv))
	log.Println("RSA 加密的 AES Key 长度:", len(encKey))
	log.Println("GCM 密文长度:", len(ct))

	priv, err := parsePrivateKey(privateKeyStr)
	if err != nil {
		log.Println("解析私钥失败:", err)
		return nil, err
	}

	// RSA PKCS1Padding 解密
	aesKey, err := rsa.DecryptPKCS1v15(rand.Reader, priv, encKey)
	if err != nil {
		log.Println("RSA PKCS1 解密失败:", err)
		return nil, err
	}
	log.Println("RSA 解密 AES Key 成功，长度:", len(aesKey))

	block, err := aes.NewCipher(aesKey)
	if err != nil {
		log.Println("AES Cipher 创建失败:", err)
		return nil, err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		log.Println("GCM 创建失败:", err)
		return nil, err
	}

	pt, err := gcm.Open(nil, iv, ct, nil)
	if err != nil {
		log.Println("GCM 解密失败:", err)
		return nil, err
	}

	log.Println("解密成功，明文长度:", len(pt))
	log.Println("=== 解密结束 ===")
	return pt, nil
}

// PricingLinkHandler 处理 GET /pricingLink
// 构造与 Java 相同结构的载荷：number(=numbers*100)、total、qureyApiUrl、taskMapList，并进行混合加密
func PricingLinkHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "仅支持 GET", http.StatusMethodNotAllowed)
		return
	}
	q := r.URL.Query()
	numbers := atoi(q.Get("numbers"))
	total := atoi(q.Get("total"))

	res := map[string]any{
		"number":      strconv.Itoa(numbers * 100),
		"total":       strconv.Itoa(total),
		"qureyApiUrl": buildQueryApiUrl(q),
		"taskMapList": buildTaskMapList(q),
	}

	body, err := json.Marshal(res)
	if err != nil {
		http.Error(w, "序列化失败", http.StatusInternalServerError)
		return
	}
	token, err := EncryptHybrid(body)
	if err != nil {
		http.Error(w, "加密失败", http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, token)
}

// PricingLinkDecHandler 处理 GET /pricingLinkDec
// 解密并返回原始 Map，兼容 Java 的 Base64 空格替换逻辑
func PricingLinkDecHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("进入 /pricingLinkDec")

	if r.Method != http.MethodGet {
		log.Println("方法非法:", r.Method)
		http.Error(w, "仅支持 GET", http.StatusMethodNotAllowed)
		return
	}

	link := r.URL.Query().Get("link")
	log.Println("收到 link 参数:", link)

	if strings.TrimSpace(link) == "" {
		log.Println("缺少 link 参数")
		http.Error(w, "缺少参数 link", http.StatusBadRequest)
		return
	}

	pt, err := DecryptHybrid(link)
	if err != nil {
		log.Println("解密失败:", err)
		http.Error(w, "解密失败", http.StatusBadRequest)
		return
	}

	var payload map[string]any
	if err := json.Unmarshal(pt, &payload); err != nil {
		log.Println("JSON 解析失败:", err)
		http.Error(w, "载荷解析失败", http.StatusBadRequest)
		return
	}

	log.Println("解密成功，返回 payload:", payload)
	writeJSON(w, http.StatusOK, payload)
}

// buildQueryApiUrl 生成 qureyApiUrl，与 Java 的 getUrl 逻辑一致（按字段编码并拼接）
// 基础路径固定为 https://api.buzhiyushu.cn/zhishu/baseInfo/pricing/list
func buildQueryApiUrl(q url.Values) string {
	base := "https://api.buzhiyushu.cn/zhishu/baseInfo/pricing/list?"
	add := func(k string) string {
		v := strings.TrimSpace(q.Get(k))
		if v == "" {
			return ""
		}
		return fmt.Sprintf("%s=%s&", k, url.QueryEscape(v))
	}
	var b strings.Builder
	b.WriteString(base)
	// 字段与 Java 对齐
	b.WriteString(add("bookName"))
	b.WriteString(add("bookPic"))
	b.WriteString(add("isbn"))
	b.WriteString(add("author"))
	b.WriteString(add("publisher"))
	if v := q.Get("vio_book"); v != "" {
		b.WriteString(fmt.Sprintf("vio_book=%s&", url.QueryEscape(v)))
	}
	if v := q.Get("book_set"); v != "" {
		b.WriteString(fmt.Sprintf("book_set=%s&", url.QueryEscape(v)))
	}
	if v := q.Get("onenum_mbooks"); v != "" {
		b.WriteString(fmt.Sprintf("onenum_mbooks=%s&", url.QueryEscape(v)))
	}
	if v := q.Get("ill_publisher"); v != "" {
		b.WriteString(fmt.Sprintf("ill_publisher=%s&", url.QueryEscape(v)))
	}
	b.WriteString(add("saleSelect"))
	b.WriteString(add("category"))
	if v := q.Get("ill_author"); v != "" {
		b.WriteString(fmt.Sprintf("ill_author=%s&", url.QueryEscape(v)))
	}
	b.WriteString(add("publiction_times"))
	b.WriteString(add("buy_counts"))
	// sell_counts 最后一个不加 &
	if v := strings.TrimSpace(q.Get("sell_counts")); v != "" {
		b.WriteString(fmt.Sprintf("sell_counts=%s", url.QueryEscape(v)))
	}
	// 去除可能的尾部 &
	u := b.String()
	if strings.HasSuffix(u, "&") {
		u = strings.TrimSuffix(u, "&")
	}
	return u
}

// buildTaskMapList 构造 taskMapList（无数据库，仅透传 shopIds 形成占位）
// 兼容 Java 的数组元素形态：{ "taskId": "", "shopId": "<id>", "shopType": "<type>" }
func buildTaskMapList(q url.Values) []map[string]string {
	ids := strings.TrimSpace(q.Get("shopIds"))
	types := q["shopType"] // 可选：与 shopIds 对应
	if ids == "" {
		return []map[string]string{}
	}
	idList := strings.Split(ids, ",")
	out := make([]map[string]string, 0, len(idList))
	for i, id := range idList {
		m := map[string]string{
			"taskId":   "", // 无任务系统，留空
			"shopId":   strings.TrimSpace(id),
			"shopType": "",
		}
		if i < len(types) {
			m["shopType"] = strings.TrimSpace(types[i])
		}
		out = append(out, m)
	}
	return out
}

// writeJSON 写出 JSON 响应
func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}

// atoi 安全转换
func atoi(s string) int {
	v, _ := strconv.Atoi(strings.TrimSpace(s))
	return v
}