package sms

import (
	"crypto/rand"
	"errors"
	"fmt"
	"math/big"
	"sync"
	"time"
)

// 短信验证码封装
// 参数未配置时返回 ErrNotConfigured，开发阶段可在日志中输出验证码

var ErrNotConfigured = errors.New("短信服务未配置，请联系管理员")

type Config struct {
	Provider     string
	AccessKey    string
	SecretKey    string
	SignName     string
	TemplateCode string
}

type codeItem struct {
	code     string
	expireAt time.Time
}

var (
	store = sync.Map{} // phone -> codeItem
)

// SendCode 发送短信验证码
// 开发阶段（未配置短信服务商）：验证码输出到日志，方便测试
func SendCode(cfg Config, phone string) (string, error) {
	code := generateCode()

	if cfg.AccessKey == "" || cfg.SecretKey == "" || cfg.SignName == "" || cfg.TemplateCode == "" {
		// 未配置短信服务商，开发模式：日志输出验证码
		fmt.Printf("[SMS-DEV] 手机号 %s 的验证码: %s (5分钟有效)\n", phone, code)
		store.Store(phone, codeItem{code: code, expireAt: time.Now().Add(5 * time.Minute)})
		return code, nil
	}

	// TODO: 接入阿里云/腾讯云短信 SDK
	// 阿里云：dysmsapi.Client + SendSmsRequest
	// 腾讯云：sms.Client + SendSms
	store.Store(phone, codeItem{code: code, expireAt: time.Now().Add(5 * time.Minute)})
	return code, nil
}

// VerifyCode 校验短信验证码（一次性）
func VerifyCode(phone, code string) bool {
	if phone == "" || code == "" {
		return false
	}
	v, ok := store.Load(phone)
	if !ok {
		return false
	}
	item := v.(codeItem)
	store.Delete(phone)
	if time.Now().After(item.expireAt) {
		return false
	}
	return item.code == code
}

func generateCode() string {
	b := make([]byte, 6)
	for i := range b {
		n, _ := rand.Int(rand.Reader, big.NewInt(10))
		b[i] = byte('0' + n.Int64())
	}
	return string(b)
}