import nodemailer from 'nodemailer';

// Email configuration
// Required environment variables:
// - SMTP_HOST: Your SMTP server host (e.g. smtp.gmail.com)
// - SMTP_PORT: Your SMTP server port (e.g. 587 for TLS, 465 for SSL)
// - SMTP_USER: Your SMTP server username/email
// - SMTP_PASSWORD: Your SMTP server password or app password
// - EMAIL_FROM: The email address that will appear as sender
const smtpConfig = {
  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_PASSWORD,
  },
};

// For development, if SMTP credentials aren't provided, log messages instead of sending
const devMode = process.env.NODE_ENV !== 'production' && 
  (!process.env.SMTP_HOST || !process.env.SMTP_USER || !process.env.SMTP_PASSWORD);

// Create a reusable transporter object
let transporter: nodemailer.Transporter;

// Initialize the transporter
export const initializeEmailTransporter = () => {
  if (devMode) {
    console.log('Email dev mode active: emails will be logged instead of sent');
    // Use Nodemailer's testing account for development
    return nodemailer.createTransport({
      jsonTransport: true // This outputs the email to the console instead of sending it
    });
  }
  
  if (!transporter) {
    transporter = nodemailer.createTransport(smtpConfig);
  }
  return transporter;
};

// Send location sharing email
export const sendLocationSharingEmail = async ({
  to,
  senderName,
  locationUrl,
  expiryTime,
}: {
  to: string;
  senderName: string;
  locationUrl: string;
  expiryTime?: Date;
}) => {
  const emailTransporter = initializeEmailTransporter();

  const expiryMessage = expiryTime
    ? `This location share will expire on ${expiryTime.toLocaleString()}.`
    : 'This location share does not expire.';

  const mailOptions = {
    from: process.env.EMAIL_FROM || `"Location Tracker" <${process.env.SMTP_USER || 'noreply@locationtracker.com'}>`,
    to,
    subject: `${senderName} shared their location with you`,
    text: `
      ${senderName} has shared their real-time location with you.
      
      Click the link below to view their current location:
      ${locationUrl}
      
      ${expiryMessage}
      
      This is an automated message, please do not reply.
    `,
    html: `
      <div style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto;">
        <h2 style="color: #4a5568;">Location Shared with You</h2>
        <p>${senderName} has shared their real-time location with you.</p>
        
        <div style="margin: 20px 0;">
          <a href="${locationUrl}" style="background-color: #4299e1; color: white; padding: 10px 15px; text-decoration: none; border-radius: 5px; display: inline-block;">
            View Location
          </a>
        </div>
        
        <p style="color: #718096; font-size: 14px;">${expiryMessage}</p>
        
        <hr style="border: none; border-top: 1px solid #e2e8f0; margin: 20px 0;" />
        
        <p style="color: #a0aec0; font-size: 12px;">
          This is an automated message from Real-Time Location Tracker. Please do not reply.
        </p>
      </div>
    `,
  };

  try {
    if (devMode) {
      // In dev mode, log the email details instead of sending
      console.log('DEV MODE: Email would be sent with the following details:');
      console.log('To:', to);
      console.log('Subject:', mailOptions.subject);
      console.log('Location URL:', locationUrl);
      return { success: true, messageId: 'dev-mode-email', devMode: true };
    }
    
    const info = await emailTransporter.sendMail(mailOptions);
    return { success: true, messageId: info.messageId };
  } catch (error) {
    console.error('Error sending email:', error);
    throw new Error('Failed to send email. Please check your SMTP settings.');
  }
};