Added database interface module

lib/DatabaseConnectionPool.js

@@ -0,0 +1,65 @@
+'use strict';
+
+// Import required modules
+const mysql = require('mysql2/promise');
+const path = require('path');
+
+// Import the database connection options from config/db.json
+let defaultDbOptions;
+try {
+	defaultDbOptions = require(
+		path.join(__dirname, '../config/db.json'));
+} catch (e) {
+	console.log(e);
+	throw new Error('Missing or malformed config ' +
+		'(config/db.json)');
+}
+
+/**
+ * A class representing a pool of database connections
+ */
+class DatabaseConnectionPool {
+	#dbOptions;
+	#connectionPool;
+
+	/**
+	 * Create a database connection pool
+	 * @param {object} [dbOptions] Optional database params to connect with
+	 */
+	constructor(dbOptions) {
+		// Use default options if none are passed into the constructor
+		if (typeof dbOptions === 'undefined')
+			this.#dbOptions = defaultDbOptions;
+
+		return (async () => {
+			this.#connectionPool =
+				await mysql.createPool(this.#dbOptions);
+
+			return this;
+		})();
+	}
+
+	/**
+	 * Run a query against the database connection
+	 * @param {string} sql The query to be executed
+	 * @param {(Array<string|number>)} Values to replace prepared statement
+	 * @return {(Array<object>|object)} Data returned from the database
+	 */
+	async runQuery(sql, params) {
+		if (sql.slice(-1) !== ';')
+			throw new Error('Invalid query, needs ;');
+
+		// Execute as non-prepared if no params are supplied
+		if (typeof params === 'undefined') {
+			const [ data ] =
+				await this.#connectionPool.execute(sql);
+			return data;
+		}
+
+		const [ data ] =
+			await this.#connectionPool.execute(sql, params);
+		return data;
+	}
+}
+
+module.exports = DatabaseConnectionPool;