package dx

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"sort"
	"strings"
	"time"

	"github.com/gogf/gf/v2/frame/g"
)

const (
	// DefaultBaseURL 电信API基础地址
	DefaultBaseURL = "https://cmp-api.ctwing.cn:20164"
)

// GetTimestampGMT 返回 GMT 时区的 yyyyMMddHHmmss 格式时间戳
func GetTimestampGMT() string {
	return time.Now().UTC().Format("20060102150405")
}

// OrderParams 将 URL params 按 key 字典序排序
// 输入如 "b=1&c=2&a=1"，输出 "a=1&b=1&c=2"
func OrderParams(params string) (string, error) {
	if params == "" {
		return "", nil
	}
	kvs := strings.Split(params, "&")
	m := make(map[string]string, len(kvs))
	for _, kv := range kvs {
		idx := strings.Index(kv, "=")
		if idx < 0 {
			continue
		}
		m[kv[:idx]] = kv[idx+1:]
	}
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	var parts []string
	for _, k := range keys {
		parts = append(parts, k+"="+m[k])
	}
	return strings.Join(parts, "&"), nil
}

// SignMD5 对 reqStr 做 MD5 加密，返回小写十六进制字符串
func SignMD5(reqStr string) string {
	h := md5.Sum([]byte(reqStr))
	return strings.ToLower(hex.EncodeToString(h[:]))
}

// BuildSign 构造签名：params 排序后拼接 params+body+secretKey+timestamp 再 MD5
// 注意：与参考项目一致，对 MD5 结果再做一次 hex 编码
func BuildSign(params, body, secretKey, timestamp string) (string, error) {
	ordered, err := OrderParams(params)
	if err != nil {
		return "", err
	}
	reqStr := ordered + body + secretKey + timestamp
	md5Str := SignMD5(reqStr)
	// 对 MD5 结果再做一次 hex 编码（与参考项目一致）
	hexStr := hex.EncodeToString([]byte(md5Str))
	return hexStr, nil
}

// BuildSignWithDebug 构造签名并输出调试信息
func BuildSignWithDebug(ctx context.Context, params, body, secretKey, timestamp, appKey string) (string, error) {
	ordered, err := OrderParams(params)
	if err != nil {
		return "", err
	}
	reqStr := ordered + body + secretKey + timestamp

	maskedSecret := secretKey

	g.Log().Debugf(ctx, "[签名调试] AppKey: %s", appKey)
	g.Log().Debugf(ctx, "[签名调试] SecretKey: %s", maskedSecret)
	g.Log().Debugf(ctx, "[签名调试] Timestamp: %s", timestamp)
	g.Log().Debugf(ctx, "[签名调试] 排序后参数: %s", ordered)
	g.Log().Debugf(ctx, "[签名调试] Body: '%s'", body)
	g.Log().Debugf(ctx, "[签名调试] 签名原串: %s%s[SecretKey]%s", ordered, body, timestamp)

	md5Str := SignMD5(reqStr)
	g.Log().Debugf(ctx, "[签名调试] MD5结果: %s", md5Str)

	// 对 MD5 结果再做一次 hex 编码
	hexStr := hex.EncodeToString([]byte(md5Str))
	g.Log().Debugf(ctx, "[签名调试] 最终签名(hex编码后): %s", hexStr)

	return hexStr, nil
}