const { simpleParser } = require('mailparser');
const db = require('./db');
const emitter = require('./eventEmitter');
const logger = require('./logger');

// Helper function to convert stream to buffer
function streamToBuffer(stream) {
    return new Promise((resolve, reject) => {
        const chunks = [];
        stream.on('data', (chunk) => chunks.push(chunk));
        stream.on('error', reject);
        stream.on('end', () => resolve(Buffer.concat(chunks)));
    });
}

async function saveEmail(stream) {
    try {
        // First, buffer the entire stream
        const emailBuffer = await streamToBuffer(stream);
        
        // Now, parse the buffered email content
        const parsed = await simpleParser(emailBuffer);
        // const rawEmail = emailBuffer.toString(); // We are not saving the raw email content for now.

        const recipient = parsed.to ? parsed.to.text : 'undisclosed-recipients';
        const sender = parsed.from ? parsed.from.text : 'unknown-sender';
        const subject = parsed.subject || 'No Subject';
        const body = parsed.text || (parsed.html || '');

        // Manually create a timestamp for 'Asia/Shanghai' timezone
        const received_at = new Date().toLocaleString('sv-SE', {
            timeZone: 'Asia/Shanghai'
        });

        const [result] = await db.execute(
            'INSERT INTO emails (recipient, sender, subject, body, received_at) VALUES (?, ?, ?, ?, ?)',
            [recipient, sender, subject, body, received_at]
        );
        const newEmailId = result.insertId;

        logger.info(`Email from <${sender}> to <${recipient}> saved with ID: ${newEmailId}`);

        if (parsed.attachments && parsed.attachments.length > 0) {
            for (const attachment of parsed.attachments) {
                await db.execute(
                    'INSERT INTO email_attachments (email_id, filename, content_type, content) VALUES (?, ?, ?, ?)',
                    [newEmailId, attachment.filename, attachment.contentType, attachment.content]
                );
                logger.info(`Attachment ${attachment.filename} saved for email ID: ${newEmailId}`);
            }
        }

        // Emit an event with the new email's main information
        const [rows] = await db.execute('SELECT id, sender, recipient, subject, body, received_at FROM emails WHERE id = ?', [newEmailId]);
        if (rows.length > 0) {
            emitter.emit('newEmail', rows[0]);
            logger.info(`Event 'newEmail' emitted for email ID: ${newEmailId}`);
        }

    } catch (error) {
        logger.error('Failed to save email:', {
            errorMessage: error.message,
            errorStack: error.stack
        });
        // Re-throw the error so the caller (SMTPServer) can handle it.
        throw error;
    }
}

module.exports = { saveEmail };