<?php

    /**
     * functions.php
     *
     * Computer Science 50
     * Problem Set 8
     *
     * Helper functions.
     */

    require_once(__DIR__ . "/constants.php");

    /**
     * Executes SQL statement, possibly with parameters, returning
     * an array of all rows in result set or false on (non-fatal) error.
     */
    function query(/* $sql [, ... ] */)
    {
        // SQL statement
        $sql = func_get_arg(0);

        // parameters, if any
        $parameters = array_slice(func_get_args(), 1);

        // try to connect to database
        static $handle;
        if (!isset($handle))
        {
            try
            {
                // connect to database
                $handle = new PDO("mysql:dbname=" . DATABASE . ";host=" . SERVER, USERNAME, PASSWORD);

                // ensure that PDO::prepare returns false when passed invalid SQL
                $handle->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); 
            }
            catch (Exception $e)
            {
                trigger_error($e->getMessage(), E_USER_ERROR);
                exit;
            }
        }

        // prepare SQL statement
        $statement = $handle->prepare($sql);
        if ($statement === false)
        {
            trigger_error($handle->errorInfo()[2], E_USER_ERROR);
            exit;
        }

        // execute SQL statement
        $results = $statement->execute($parameters);
        if ($results === false)
        {
            trigger_error($statement->errorInfo()[2], E_USER_ERROR);
            exit;
        }

        // return result set's rows
        return $statement->fetchAll(PDO::FETCH_ASSOC);
    }

?>