package service

import (
	"accounting-app/internal/config"
	"fmt"
	"net/smtp"
)

// EmailService handles email notifications
type EmailService struct {
	host     string
	port     int
	username string
	password string
	from     string
	enabled  bool
}

// NewEmailService creates a new EmailService instance
func NewEmailService(cfg *config.Config) *EmailService {
	if cfg.SMTPHost == "" || cfg.SMTPUser == "" {
		return &EmailService{enabled: false}
	}
	return &EmailService{
		host:     cfg.SMTPHost,
		port:     cfg.SMTPPort,
		username: cfg.SMTPUser,
		password: cfg.SMTPPassword,
		from:     cfg.SMTPFrom,
		enabled:  true,
	}
}

// SendAllocationNotification sends an email notification for auto allocation
func (s *EmailService) SendAllocationNotification(to string, amount float64, ruleName string) error {
	if !s.enabled || to == "" {
		return nil
	}

	subject := "Auto Allocation Executed"
	body := fmt.Sprintf("Your automatic allocation rule '%s' has been executed.\nAmount: %.2f", ruleName, amount)

	// Simple text email
	msg := []byte(fmt.Sprintf("To: %s\r\n"+
		"From: %s\r\n"+
		"Subject: %s\r\n"+
		"Content-Type: text/plain; charset=UTF-8\r\n"+
		"\r\n"+
		"%s\r\n", to, s.from, subject, body))

	auth := smtp.PlainAuth("", s.username, s.password, s.host)
	addr := fmt.Sprintf("%s:%d", s.host, s.port)

	if err := smtp.SendMail(addr, auth, s.from, []string{to}, msg); err != nil {
		return fmt.Errorf("failed to send email: %w", err)
	}

	return nil
}