signalk-plugin/plugin/telegram/callbacks/backupfile.js

const fs = require('fs');
const fsPromises = require('fs').promises;
const readline = require('readline');
const { listDataFiles, formatSize, buildPage } = require('../commands/backuplogs');

/**
 * Conta le righe di un file in modo efficiente (stream)
 */
function countLines(filePath) {
    return new Promise((resolve) => {
        let count = 0;
        const stream = fs.createReadStream(filePath);
        const rl = readline.createInterface({ input: stream, crlfDelay: Infinity });
        rl.on('line', () => count++);
        rl.on('close', () => resolve(count));
        rl.on('error', () => resolve(-1));
    });
}

module.exports = {
    prefix: 'bkfile:',
    handler: async (bot, query) => {
        const chatId = query.message.chat.id;
        const botMessageId = query.message.message_id;

        const parts = query.data.split(':');
        const fileIdx = parseInt(parts[1]);
        const userMessageId = parts[2];

        const files = await listDataFiles();
        const file = files[fileIdx];

        if (!file || !fs.existsSync(file.path)) {
            bot.answerCallbackQuery(query.id, { text: 'File non trovato', show_alert: true });
            return;
        }

        // Conta righe
        let lineCount = '—';
        try {
            const ext = file.name.split('.').pop().toLowerCase();
            if (['csv', 'txt', 'log', 'json'].includes(ext)) {
                lineCount = await countLines(file.path);
            }
        } catch (e) {}

        const modified = new Date(file.modified).toLocaleDateString('it-IT', {
            day: '2-digit', month: 'long', year: 'numeric',
            hour: '2-digit', minute: '2-digit'
        });

        const text = `*File:* \`${file.name}\`\n\n` +
            `*Dimensione:* ${formatSize(file.size)}\n` +
            `*Ultima modifica:* ${modified}\n` +
            `*Righe:* ${lineCount}\n`;

        const keyboard = [
            [{ text: 'Scarica file', callback_data: `bkdl:${fileIdx}:${userMessageId}` }],
            [{ text: '<- Torna alla lista', callback_data: `bkback:0:${userMessageId}` }]
        ];

        try {
            await bot.editMessageText(text, {
                chat_id: chatId,
                message_id: botMessageId,
                parse_mode: 'Markdown',
                reply_markup: { inline_keyboard: keyboard }
            });
        } catch (e) {}

        bot.answerCallbackQuery(query.id);
    }
};