/*
 * *****************************************************************************
 * Copyright (C) 2019-2021 Chrystian Huot <chrystian.huot@saubeo.solutions>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 * ****************************************************************************
 */

'use strict';

import { spawnSync } from 'child_process';
import compression from 'compression';
import cors from 'cors';
import EventEmitter from 'events';
import dotenv from 'dotenv';
import express from 'express';
import fs from 'fs';
import helmet from 'helmet';
import http from 'http';
import https from 'https';
import path from 'path';
import Sequelize from 'sequelize';
import url from 'url';

import { RdioScanner } from './lib/rdio-scanner/main.js';

export class App extends EventEmitter {
    constructor() {
        super();

        const dirname = path.dirname(url.fileURLToPath(import.meta.url));

        const configFile = path.resolve(process.env.APP_DATA || dirname, 'config.json');

        const staticFile = 'index.html';

        const staticDir = fs.existsSync(path.resolve(dirname, `../client/${staticFile}`))
            ? path.resolve(dirname, '../client')
            : path.resolve(dirname, '../client/dist/rdio-scanner');

        const openssl = !spawnSync('openssl', ['version']).error;

        dotenv.config();

        if (fs.existsSync(configFile)) {
            this.config = JSON.parse(fs.readFileSync(configFile));
        }

        if (this.config === null || typeof this.config !== 'object') {
            this.config = {};
        }

        const nodejs = this.config.nodejs || {};

        this.config.nodejs = {
            env: typeof nodejs.env === 'string' && nodejs.env.length ? nodejs.env : 'production',
            host: typeof nodejs.host === 'string' && nodejs.host.length ? nodejs.host : '0.0.0.0',
            port: typeof nodejs.port === 'number' ? nodejs.port : 3000,
            ssl: typeof nodejs.ssl === 'boolean' ? nodejs.ssl : false,
            sslCa: typeof nodejs.sslCa === 'string' && nodejs.sslCa.length ? nodejs.sslCa : 'ca.crt',
            sslCert: typeof nodejs.sslCert === 'string' && nodejs.sslCert.length ? nodejs.sslCert : 'server.crt',
            sslKey: typeof nodejs.sslKey === 'string' && nodejs.sslKey.length ? nodejs.sslKey : 'server.key',
        };

        const sequelize = this.config.sequelize || {};

        this.config.sequelize = typeof sequelize.dialect === 'string' && sequelize.dialect.length && sequelize.dialect !== 'sqlite' ? {
            dialect: sequelize.dialect,
            database: typeof sequelize.database === 'string' && sequelize.database.length ? sequelize.database : 'db',
            host: typeof sequelize.host === 'string' && sequelize.host.length ? sequelize.host : '',
            port: typeof sequelize.port === 'number' ? sequelize.port : 3306,
            username: typeof sequelize.username === 'string' && sequelize.username.length ? sequelize.username : 'user',
            password: typeof sequelize.password === 'string' && sequelize.password.length ? sequelize.password : 'pass',

        } : {
            dialect: 'sqlite',
            storage: typeof sequelize.storage === 'string' && sequelize.storage.length ? sequelize.storage : 'database.sqlite',
        };

        const sslCaCert = path.resolve(process.env.APP_DATA || dirname, this.config.nodejs.sslCa);
        const sslServerCert = path.resolve(process.env.APP_DATA || dirname, this.config.nodejs.sslCert);
        const sslServerKey = path.resolve(process.env.APP_DATA || dirname, this.config.nodejs.sslKey);

        if (openssl && !(fs.existsSync(sslCaCert) && fs.existsSync(sslServerCert) && fs.existsSync(sslServerKey))) {
            const sslCaKey = sslCaCert.replace(/\..*$/, '.key');
            const sslCaSerial = sslCaCert.replace(/\..*$/, '.srl');
            const sslServerCsr = sslServerCert.replace(/\..*$/, '.csr');

            spawnSync('openssl', [
                'req', '-new', '-newkey', 'rsa:4096', '-batch', '-nodes', '-x509', '-days', '7305',
                '-subj', '/CN=Rdio Scanner CA', '-keyout', sslCaKey, '-out', sslCaCert
            ]);

            spawnSync('openssl', [
                'req', '-new', '-newkey', 'rsa:4096', '-batch', '-nodes', '-subj', '/CN=Rdio Scanner',
                '-keyout', sslServerKey, '-out', sslServerCsr,
            ]);

            spawnSync('openssl', [
                'x509', '-in', sslServerCsr, '-days', '7305', '-req', '-CA', sslCaCert,
                '-CAkey', sslCaKey, '-CAcreateserial', '-CAserial', sslCaSerial, '-out', sslServerCert,
            ]);

            fs.rmSync(sslCaSerial);
            fs.rmSync(sslServerCsr);
        }

        if (this.config.sequelize === null || typeof this.config.sequelize !== 'object') {
            this.config.sequelize = {};
        }

        if (typeof this.config.sequelize.dialect !== 'string' || !this.config.sequelize.dialect.length) {
            this.config.sequelize.dialect = 'sqlite';
        }

        if (this.config.sequelize.dialect === 'sqlite' &&
            (typeof this.config.sequelize.storage !== 'string' || !this.config.sequelize.storage.length)) {
            this.config.sequelize.storage = 'database.sqlite';
        }

        this.router = express();
        this.router.disable('x-powered-by');
        this.router.use(compression());
        this.router.use(cors());
        this.router.use(express.json({ limit: '10mb' }));
        this.router.use(express.urlencoded({ extended: false, limit: '10mb' }));
        this.router.use(helmet({ contentSecurityPolicy: false, frameguard: false }));
        this.router.use(express.static(staticDir));
        this.router.use((req, res, next) => {
            if (
                req.path.startsWith('/api') ||
                req.accepts('html', 'json', 'xml') !== 'html' ||
                path.extname(req.path) !== ''
            ) {
                return next();
            }

            if (fs.existsSync(path.join(staticDir, staticFile))) {
                return res.sendFile(staticFile, { root: staticDir });

            } else {
                return res.send('A new build is being prepared. Please check back in a few minutes.');
            }
        });
        this.router.set(this.config.nodejs.port);

        this.sequelize = new Sequelize(Object.assign({}, this.config.sequelize, {
            logging: false,
            storage: this.config.sequelize.storage
                ? path.resolve(process.env.APP_DATA || process.env.DB_STORAGE || dirname, this.config.sequelize.storage)
                : '',
        }));

        if (
            this.config.nodejs.env !== 'development' && this.config.nodejs.ssl === true &&
            fs.existsSync(sslServerCert) && fs.existsSync(sslServerKey)
        ) {
            const options = {
                cert: fs.readFileSync(sslServerCert),
                key: fs.readFileSync(sslServerKey),
            };

            if (fs.existsSync(this.config.nodejs.sslCA)) {
                options.ca = fs.readFileSync(sslCaCert);
            }

            this.httpServer = https.createServer(options, this.router);

        } else {
            this.httpServer = http.createServer(this.router);
        }

        this.once('ready', () => {
            let config = Object.keys(this.config)
                .sort((a, b) => a.localeCompare(b))
                .reduce((conf, key) => {
                    conf[key] = this.config[key];
                    return conf;
                }, {});

            try {
                fs.writeFileSync(configFile, JSON.stringify(config, null, 2));

            } catch (error) {
                console.error(error.message);
            }
        });

        RdioScanner.migrate(this.sequelize).then(() => {
            this.rdioScanner = new RdioScanner(this);

            this.rdioScanner.once('ready', () => {
                // Starting from v5.1, config is now in the database.
                // Delete obsolete config from the config.json file.
                if ('rdioScanner' in this.config) {
                    delete this.config.rdioScanner;
                }

                this.httpServer.listen(this.config.nodejs.port, this.config.nodejs.host, () => {
                    const scheme = this.httpServer instanceof https.Server ? 'https' : 'http';

                    this.url = `${scheme}://${this.config.nodejs.host}:${this.config.nodejs.port}`;

                    console.log(`Server is running at ${this.url}`);
                });

                this.emit('ready');
            });
        });
    }
}

export const app = new App();