const nodemailer = require('nodemailer');

class EmailService {
  constructor() {
    this.transporter = null;
    this.initializeTransporter();
  }

  initializeTransporter() {
    try {
      this.transporter = nodemailer.createTransport({
        host: process.env.SMTP_HOST,
        port: parseInt(process.env.SMTP_PORT) || 587,
        secure: process.env.SMTP_PORT === '465', // true for 465, false for other ports
        auth: {
          user: process.env.SMTP_USER,
          pass: process.env.SMTP_PASS
        },
        tls: {
          rejectUnauthorized: false
        }
      });

      console.log('Email transporter initialized successfully');
    } catch (error) {
      console.error('Failed to initialize email transporter:', error);
    }
  }

  async testConnection() {
    try {
      if (!this.transporter) {
        throw new Error('Email transporter not initialized');
      }

      await this.transporter.verify();
      return {
        success: true,
        message: 'SMTP connection verified successfully'
      };
    } catch (error) {
      return {
        success: false,
        message: 'SMTP connection failed',
        error: error.message
      };
    }
  }

  async sendEmail(emailOptions) {
    try {
      if (!this.transporter) {
        throw new Error('Email transporter not initialized');
      }

      const mailOptions = {
        from: `"${emailOptions.from.name}" <${emailOptions.from.email}>`,
        to: emailOptions.to,
        replyTo: emailOptions.replyTo,
        subject: emailOptions.subject,
        text: emailOptions.text,
        html: emailOptions.html
      };

      const info = await this.transporter.sendMail(mailOptions);
      
      console.log('Email sent successfully:', info.messageId);
      
      return {
        success: true,
        messageId: info.messageId,
        response: info.response
      };
    } catch (error) {
      console.error('Email send error:', error);
      return {
        success: false,
        error: error.message
      };
    }
  }

  async sendBulkEmails(emails) {
    const results = [];
    
    for (const email of emails) {
      try {
        const result = await this.sendEmail(email);
        results.push({
          to: email.to,
          success: result.success,
          messageId: result.messageId,
          error: result.error
        });
        
        // Add a small delay between emails to avoid overwhelming the SMTP server
        await new Promise(resolve => setTimeout(resolve, 1000));
      } catch (error) {
        results.push({
          to: email.to,
          success: false,
          error: error.message
        });
      }
    }
    
    return results;
  }

  formatEmailTemplate(template, data) {
    let formattedTemplate = template;
    
    // Replace placeholders with actual data
    Object.keys(data).forEach(key => {
      const placeholder = `{{${key}}}`;
      formattedTemplate = formattedTemplate.replace(new RegExp(placeholder, 'g'), data[key]);
    });
    
    return formattedTemplate;
  }

  validateEmailAddress(email) {
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    return emailRegex.test(email);
  }
}

module.exports = new EmailService();