'use strict';

exports = module.exports = {
    start,
    stop
};

const LOG_FILENAME = 'app.log';

const assert = require('assert'),
    debug = require('debug')('syslog:server'),
    dgram = require('dgram'),
    fs = require('fs'),
    path = require('path'),
    parser = require('nsyslog-parser'),
    util = require('util');

let server = null;

async function start(options) {
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof options.port, 'number');
    assert.strictEqual(typeof options.logFolder, 'string');

    debug('==========================================');
    debug('          Cloudron Syslog Daemon          ');
    debug('==========================================');

    server = dgram.createSocket('udp4');

    server.on('error', function (error) {
        console.error(`socket error: ${error}`);
    });

    server.on('message', function (msg /*, rinfo */) {
        const info = parser(msg.toString());

        if (!info || !info.appName) return debug('Ignore unknown app log:', msg.toString());

        // remove line breaks to avoid holes in the log file
        // we do not ignore empty log lines, to allow gaps for potential ease of readability
        const message = info.message.replace(/\n/g, '');

        const filePath = path.join(options.logFolder, info.appName);
        const fileName = path.join(filePath, LOG_FILENAME);

        try {
            fs.mkdirSync(filePath, { recursive: true });
            fs.appendFileSync(fileName, info.ts.toISOString() + ' ' + message + '\n');
        } catch (error) {
            console.error(error);
        }
    });

    await util.promisify(server.bind.bind(server))(options.port); // intentional double "bind"

    debug(`Listening on port ${options.port}`);
}

async function stop() {
    if (!server) return;
    await util.promisify(server.close.bind(server))();
    server = null;
}