const Sequelize = require('sequelize');
const path = require('path');
const readdir = require('fs/promises').readdir;

class Database {

    constructor() {

    }

    async initialize() {
        this.connection = await this.#connect();
        this.models = await this.#getModels();
        await this.#createTables();
    }

    async #connect() {
        if (this.connection !== undefined) {
            return this.connection;
        }
        if (config?.database === undefined) {
            throw new Error('missing database config');
        }
        let connection = new Sequelize(config.database.database, config.database.username, config.database.password, {
            dialect: config.database.dialect,
            host: config.database.host,
            port: config.database.port,
            storage: config.database.storage,
            logging: false
        });
        await connection.authenticate();
        logger.info('successfully connected to the database');
        return connection;
    }

    async #getModels() {
        let modelsDirectory = path.resolve(path.join(__dirname, '../models'));
        const files = await readdir(modelsDirectory);
        const models = {};
        for (let index = 0; index < files.length; index++) {
            let modelFile = path.join(modelsDirectory, files[index]);
            if (path.extname(modelFile) !== '.js') {
                continue;
            }
            const model = require(modelFile);
            if (model.prototype?.createTable === undefined || model.name === 'Base') {
                continue;
            }
            modelFile = path.basename(modelFile);
            modelFile = modelFile.substring(0, modelFile.indexOf(path.extname(modelFile)));
            models[modelFile] = model;
        }
        return models;
    }

    async #createTables() {
        if (this.models === undefined || this.models.size === 0) {
            return;
        }
        const models = Object.values(this.models);
        for (let index = 0; index < models.length; index++) {
            const model = models[index];
            try {
                const timestamp = new Date().getTime();
                await model.prototype.createTable();
                logger.debug('creation/alteration of table \'' + model.name + '\' finished after ' + (new Date().getTime() - timestamp) + 'ms');
            } catch (err) {
                logger.error('an error occured creating table \'' + model.name + '\' > ' + err);
            }
        }

    }
}

module.exports = Database;