/**
 * Creates an instance of Oracle, representing an interface to an
 * Oracle database.
 *
 * @constructor
 * @this {Oracle}
 * @param {string} user The database username
 * @param {string} password The database password
 * @param {string} connectString The Oracle connection string
 */
var q = require('q');
var oracledb = require('oracledb');
oracledb.outFormat = oracledb.OBJECT;
oracledb.poolMax = 10;
oracledb.poolMin = 2;

function Oracle(user, password, connectString) {
    this.credentials = {
        user: user,
        password: password,
        connectString: connectString
    };
    var that = this;
    this.poolPromise = oracledb.createPool(this.credentials)
        .then(function(pool) {
            console.log(pool.poolAlias);
            that.pool = pool;
        });
};


/**
 * Returns a promise, the result being an object containing
 * the results returned from the query
 *
 * @this {Oracle}
 * @param {string} queryString The query to be executed
 * @return {promise} The promise returned with the query results
 */
Oracle.prototype.query = function(queryString) {
    var deferred = q.defer();

    if (!this.pool) {

    }

    this.pool.getConnection()
        .then(function(conn) {
            console.log("Executing query");
            conn.execute(queryString)
                .then(function(result) {
                    conn.close()
                    deferred.resolve(result);
                    console.log("should be returning results");
                })
                .catch(function(err) {
                    console.error(err);
                    conn.close();
                });
        });
        return deferred.promise;
};

module.exports = {
    Oracle: Oracle
};