package sms

import (
	"context"
	"crypto/rand"
	"encoding/json"
	"fmt"
	"math/big"
	"time"

	"github.com/aliyun/alibaba-cloud-sdk-go/services/dysmsapi"
	"go.uber.org/zap"

	"hyapi-server/internal/config"
)

// AliSMSService 阿里云短信服务
type AliSMSService struct {
	client *dysmsapi.Client
	config config.SMSConfig
	logger *zap.Logger
}

// NewAliSMSService 创建阿里云短信服务
func NewAliSMSService(cfg config.SMSConfig, logger *zap.Logger) (*AliSMSService, error) {
	client, err := dysmsapi.NewClientWithAccessKey("cn-hangzhou", cfg.AccessKeyID, cfg.AccessKeySecret)
	if err != nil {
		return nil, fmt.Errorf("创建短信客户端失败: %w", err)
	}
	return &AliSMSService{
		client: client,
		config: cfg,
		logger: logger,
	}, nil
}

// SendVerificationCode 发送验证码
func (s *AliSMSService) SendVerificationCode(ctx context.Context, phone string, code string) error {
	request := dysmsapi.CreateSendSmsRequest()
	request.Scheme = "https"
	request.PhoneNumbers = phone
	request.SignName = s.config.SignName
	request.TemplateCode = s.config.TemplateCode
	request.TemplateParam = fmt.Sprintf(`{"code":"%s"}`, code)

	response, err := s.client.SendSms(request)
	if err != nil {
		s.logger.Error("Failed to send SMS",
			zap.String("phone", phone),
			zap.Error(err))
		return fmt.Errorf("短信发送失败: %w", err)
	}

	if response.Code != "OK" {
		s.logger.Error("SMS send failed",
			zap.String("phone", phone),
			zap.String("code", response.Code),
			zap.String("message", response.Message))
		return fmt.Errorf("短信发送失败: %s - %s", response.Code, response.Message)
	}

	s.logger.Info("SMS sent successfully",
		zap.String("phone", phone),
		zap.String("bizId", response.BizId))

	return nil
}

// SendBalanceAlert 发送余额预警短信（低余额与欠费共用 balance_alert_template_code；模板需包含 name、time、money）
func (s *AliSMSService) SendBalanceAlert(ctx context.Context, phone string, balance float64, threshold float64, alertType string, enterpriseName ...string) error {
	request := dysmsapi.CreateSendSmsRequest()
	request.Scheme = "https"
	request.PhoneNumbers = phone
	request.SignName = s.config.SignName

	name := "海宇数据用户"
	if len(enterpriseName) > 0 && enterpriseName[0] != "" {
		name = enterpriseName[0]
	}
	t := time.Now().Format("2006-01-02 15:04:05")
	var money float64
	if alertType == "low_balance" {
		money = threshold
	} else {
		money = balance
	}

	templateCode := s.config.BalanceAlertTemplateCode
	if templateCode == "" {
		templateCode = "SMS_500565339"
	}
	tp, err := json.Marshal(struct {
		Name  string `json:"name"`
		Time  string `json:"time"`
		Money string `json:"money"`
	}{Name: name, Time: t, Money: fmt.Sprintf("%.2f", money)})
	if err != nil {
		return fmt.Errorf("构建短信模板参数失败: %w", err)
	}
	request.TemplateCode = templateCode
	request.TemplateParam = string(tp)

	response, err := s.client.SendSms(request)
	if err != nil {
		s.logger.Error("发送余额预警短信失败",
			zap.String("phone", phone),
			zap.String("alert_type", alertType),
			zap.Error(err))
		return fmt.Errorf("短信发送失败: %w", err)
	}

	if response.Code != "OK" {
		s.logger.Error("余额预警短信发送失败",
			zap.String("phone", phone),
			zap.String("alert_type", alertType),
			zap.String("code", response.Code),
			zap.String("message", response.Message))
		return fmt.Errorf("短信发送失败: %s - %s", response.Code, response.Message)
	}

	s.logger.Info("余额预警短信发送成功",
		zap.String("phone", phone),
		zap.String("alert_type", alertType),
		zap.String("bizId", response.BizId))

	return nil
}

// GenerateCode 生成验证码
func (s *AliSMSService) GenerateCode(length int) string {
	if length <= 0 {
		length = 6
	}

	max := big.NewInt(int64(pow10(length)))
	n, _ := rand.Int(rand.Reader, max)

	format := fmt.Sprintf("%%0%dd", length)
	return fmt.Sprintf(format, n.Int64())
}

func pow10(n int) int {
	result := 1
	for i := 0; i < n; i++ {
		result *= 10
	}
	return result
}