package com.mathlearning.util;

import javax.mail.*;
import javax.mail.internet.*;
import javax.swing.JOptionPane;
import java.util.Properties;
import java.util.Random;

public class EmailUtil {
    private static final Random random = new Random();
    
  
    public static String sendVerificationCode(String toEmail) {
        if (!EmailConfig.isConfigured()) {
            JOptionPane.showMessageDialog(null, 
                "邮箱配置未完成！\n请修改 email_config.properties 文件，配置您的邮箱信息。", 
                "配置错误", 
                JOptionPane.ERROR_MESSAGE);
            return null;
        }
        
        String verificationCode = generateVerificationCode();
        
        try {
            boolean sendSuccess = sendEmail(toEmail, verificationCode);
            
            if (sendSuccess) {
                JOptionPane.showMessageDialog(
                    null,
                    "验证码已发送到您的邮箱！\n\n" +
                    "收件邮箱: " + toEmail + "\n" +
                    "请查看您的邮箱并输入验证码。",
                    "验证码发送成功",
                    JOptionPane.INFORMATION_MESSAGE
                );
                return verificationCode;
            } else {
                JOptionPane.showMessageDialog(null, 
                    "验证码发送失败，请检查邮箱地址是否正确或稍后重试", 
                    "发送失败", 
                    JOptionPane.ERROR_MESSAGE);
                return null;
            }
        } catch (Exception e) {
            JOptionPane.showMessageDialog(null, 
                "发送验证码时发生错误: " + e.getMessage(), 
                "错误", 
                JOptionPane.ERROR_MESSAGE);
            return null;
        }
    }
    
   
    private static boolean sendEmail(String toEmail, String verificationCode) {
        Properties props = new Properties();
        props.put("mail.smtp.host", EmailConfig.getSmtpHost());
        props.put("mail.smtp.port", EmailConfig.getSmtpPort());
        props.put("mail.smtp.auth", "true");
        
        if (EmailConfig.isSslEnabled()) {
            props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
            props.put("mail.smtp.socketFactory.port", EmailConfig.getSmtpPort());
        }
        
        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(EmailConfig.getFrom(), EmailConfig.getPassword());
            }
        });
        
        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(EmailConfig.getFrom()));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(toEmail));
            message.setSubject("数学学习软件 - 邮箱验证码");
            
            String emailContent = "尊敬的用户：\n\n" +
                                "您正在注册数学学习软件，验证码为：" + verificationCode + "\n\n" +
                                "验证码有效期为10分钟，请尽快完成注册。\n\n" +
                                "如果不是您本人操作，请忽略此邮件。\n\n" +
                                "数学学习软件团队";
            
            message.setText(emailContent);
            
            Transport.send(message);
            System.out.println("验证码邮件已发送到: " + toEmail);
            return true;
            
        } catch (MessagingException e) {
            System.err.println("发送邮件失败: " + e.getMessage());
            e.printStackTrace();
            return false;
        }
    }
    
  
    private static String generateVerificationCode() {
        return String.format("%06d", random.nextInt(1000000));
    }
    
    
    public static boolean isValidEmail(String email) {
        if (email == null || email.trim().isEmpty()) {
            return false;
        }
        
        String emailRegex = "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$";
        return email.matches(emailRegex);
    }
    

    public static String getEmailRequirements() {
        return "请输入有效的邮箱地址，例如：username@example.com";
    }
}