/**
 * Logger locale + invio realtime.
 *
 * Scrive una riga ogni secondo in un CSV locale (1 sessione = 1 file) e
 * contemporaneamente invia i field via WebSocket al realtime per InfluxDB.
 *
 * Path-list dinamica: i path letti ad ogni tick vengono presi dal ruleset
 * 'logs' (cores/rulesets). Quando il ruleset cambia (push WS o cambio remoto):
 *   - la sessione corrente viene chiusa (CSV finalizzato)
 *   - si manda `session_reset` al server (nuovo session_id su Influx)
 *   - si apre un nuovo CSV con i nuovi path
 *   - lo storico Influx resta coerente: tag `session` cambia, tag
 *     `ruleset_version` riflette la nuova versione applicata.
 */
const fs = require('fs').promises;
const fsSync = require('fs');
const pth = require('path');
const skFlow = require('../config/skFlow');
const realtime = require('./realtime/core');
const rulesets = require('./rulesets');

const logsDirectory = pth.join(__dirname, '../../data/logs/');
const WRITE_INTERVAL = 1000;

let session = null;
let writeInterval = null;
let logPaths = [];

const SPECIAL_RESOLVERS = {
    'navigation.position.latitude': () => skFlow.get('navigation.position')?.latitude ?? null,
    'navigation.position.longitude': () => skFlow.get('navigation.position')?.longitude ?? null,
    'system.uptime': () => Math.floor(process.uptime()),
};

function resolveValue(p) {
    if (SPECIAL_RESOLVERS[p]) return SPECIAL_RESOLVERS[p]();
    return skFlow.get(p);
}

/**
 * Init: prende i path iniziali dal ruleset attivo e si sottoscrive ai cambi.
 * @param {Array<String>} [fallback] - opzionale, lista path se non c'e' ruleset
 */
function init(fallback) {
    logPaths = rulesets.getEnabledPaths('logs');
    if ((!logPaths || logPaths.length === 0) && Array.isArray(fallback)) {
        logPaths = fallback;
    }
    console.log(`[LOGS] init: ${logPaths.length} path da ruleset v=${rulesets.versionStr('logs') || '?'}`);

    rulesets.onUpdateOf('logs', async (next) => {
        const newPaths = (next.content || []).filter(it => it.enabled !== false).map(it => it.path);
        console.log(`[LOGS] ruleset update: ${newPaths.length} path → restart recording`);
        const wasRecording = !!session;
        try {
            if (wasRecording) await stopRecording();
            logPaths = newPaths;
            if (realtime.isConnected()) realtime.sendRaw({ _t: 'session_reset' });
            if (wasRecording) await startRecording();
        } catch (err) {
            console.error('[LOGS] restart on ruleset update failed:', err.message);
        }
    });
}

async function ensureDir() {
    try { await fs.mkdir(logsDirectory, { recursive: true }); } catch (e) {}
}

async function startRecording(name) {
    if (session) await stopRecording();
    if (!name) name = new Date().toISOString().replace(/[:.]/g, '-');
    if (logPaths.length === 0) console.warn('[LOGS] nessun path configurato');

    await ensureDir();
    const header = ['timestamp', ...logPaths].join(',') + '\n';
    const filePath = pth.join(logsDirectory, `${name}.csv`);
    await fs.writeFile(filePath, header);

    session = { name, paths: logPaths.slice(), startTime: new Date(), elements: 0, filePath };
    writeInterval = setInterval(() => { writeLog(); }, WRITE_INTERVAL);
    console.log(`[LOGS] started: ${name} (${logPaths.length} cols)`);
    return session;
}

async function writeLog() {
    if (!session) return;
    try {
        const timestamp = new Date().toISOString();
        const fields = {};
        const csvValues = [];
        for (const p of session.paths) {
            const val = resolveValue(p);
            fields[p] = val;
            if (val === null || val === undefined) csvValues.push('');
            else if (typeof val === 'object') csvValues.push(JSON.stringify(val).replace(/,/g, ';'));
            else csvValues.push(val);
        }
        const row = [timestamp, ...csvValues].join(',') + '\n';
        await fs.appendFile(session.filePath, row);
        session.elements++;
        if (realtime.isConnected()) realtime.send([Date.now(), 'logs', fields]);
    } catch (err) {
        console.error('[LOGS] write error:', err.message);
    }
}

async function stopRecording() {
    if (writeInterval) { clearInterval(writeInterval); writeInterval = null; }
    if (session) {
        console.log(`[LOGS] stopped ${session.name} (${session.elements} righe)`);
        session = null;
    }
}

async function getLog(name) {
    try { return await fs.readFile(pth.join(logsDirectory, `${name}.csv`), 'utf-8'); }
    catch (err) { console.error('[LOGS] read err:', err.message); return null; }
}

function getLogFile(name) {
    const p = pth.join(logsDirectory, `${name}.csv`);
    return fsSync.existsSync(p) ? p : null;
}

async function listLogs() {
    await ensureDir();
    try {
        const files = await fs.readdir(logsDirectory);
        const csv = files.filter(f => f.endsWith('.csv'));
        const out = [];
        for (const file of csv) {
            const p = pth.join(logsDirectory, file);
            const stat = await fs.stat(p);
            out.push({
                name: file.replace('.csv', ''),
                filename: file,
                size: (stat.size / (1024 * 1024)).toFixed(2),
                created: stat.birthtime,
                modified: stat.mtime,
            });
        }
        return out.sort((a, b) => b.modified - a.modified);
    } catch (err) {
        console.error('[LOGS] list err:', err.message);
        return [];
    }
}

function getSession() {
    if (!session) return null;
    return {
        name: session.name, paths: session.paths, startTime: session.startTime,
        elements: session.elements, delay: WRITE_INTERVAL,
    };
}

module.exports = { init, startRecording, stopRecording, getLog, getLogFile, getSession, listLogs };