package gameplatform

import (
	"crypto/md5"
	"crypto/sha1"
	"crypto/subtle"
	"encoding/hex"
	"kra/internal/biz/business"
	"os"
	"strings"
)

type Passwords struct{ AuthCode, MigrateAuthCode, TablePrefix string }

func NewPasswords() business.PlatformPasswordVerifier {
	return loadPasswords()
}
func NewPasswordEncoder() business.PlatformPasswordEncoder {
	return loadPasswords()
}
func loadPasswords() *Passwords {
	prefix := os.Getenv("SW_SDK_TABLE_PREFIX")
	if prefix == "" {
		prefix = "sys_"
	}
	return &Passwords{AuthCode: os.Getenv("SW_SDK_AUTH_CODE"), MigrateAuthCode: os.Getenv("SW_SDK_MIGRATE_AUTH_CODE"), TablePrefix: prefix}
}

// Encode 保留源平台 cmfPassword 的存储格式，新增渠道不能改用 Kra 账号密码格式。
func (p *Passwords) Encode(password string) (string, error) {
	if p.AuthCode == "" {
		return "", business.ErrPlatformPasswordConfig
	}
	return "###" + md5Hex(md5Hex(p.AuthCode+password)), nil
}
func md5Hex(value string) string { sum := md5.Sum([]byte(value)); return hex.EncodeToString(sum[:]) }

func (p *Passwords) Verify(password, stored string) (bool, error) {
	if strings.TrimSpace(password) == "" || strings.TrimSpace(stored) == "" {
		return false, nil
	}
	var expected string
	switch {
	case strings.HasPrefix(stored, "###"):
		if p.AuthCode == "" {
			return false, business.ErrPlatformPasswordConfig
		}
		expected = "###" + md5Hex(md5Hex(p.AuthCode+password))
	case strings.HasPrefix(stored, "##$##"):
		if p.MigrateAuthCode == "" {
			return false, business.ErrPlatformPasswordConfig
		}
		sha := sha1.Sum([]byte(password))
		expected = "##$##" + md5Hex(hex.EncodeToString(sha[:])+p.MigrateAuthCode)
	default:
		decor := md5Hex(p.TablePrefix)
		expected = decor[:12] + md5Hex(password) + decor[len(decor)-4:]
	}
	return subtle.ConstantTimeCompare([]byte(expected), []byte(stored)) == 1, nil
}