<?php
    /**
     * Gasteizko Margolariak API v3 - Location
     *
     * Used to get notifications.
     * This file is to be called directly from a URL request.
     *
     * https://margolariak.com/API/v3/help/
     *
     * @since 1.0.0
     */


    //Posible notification target
    define('TARGET_ALL', 'all');
    define('TARGET_GM', 'gm');

    //Default target
    define('DEF_TARGET', TARGET_ALL);

    //$_GET valid parameters
    define('GET_TARGET', 'target');

    //Error messages
    define('ERR_TARGET', '-TARGET:');


    /**
     * Initializes the MySQL database connection.
     * 
     * Called at the beggining of the script. It connects to the database using the
     * parameters in the .htpasswd file. It also sets database and page encodings.
     * 
     * @since 1.0.0
     * @return object Database connection.
     */
    function startdb(){
        //Include the db configuration file. It's somehow like this
        /*
        <?php
            $host = 'XXXX';
            $db_name = 'XXXX';
            $username_ro = 'XXXX';
            $username_rw = 'XXXX';
            $pass_ro = 'XXXX';
            $pass_rw = 'XXXX';
        ?>
        */
        include('../../.htpasswd');

        //Connect to to database
        $con = mysqli_connect($host, $username_rw, $pass_rw, $db_name);

        //Set encoding options
        mysqli_set_charset($con, 'utf-8');
        header('Content-Type: text/html; charset=utf8');
        mysqli_query($con, 'SET NAMES utf8;');

        //Return the db connection
        return $con;
    }


    /**
     * Discerns the type of notifications requested.
     *
     * Determines which notificatios the request is looking for: public
     * notification or members-only notifications. To do so, it looks for a
     * request parameter keyed 'target'
     * 
     * @since 3.0.0
     * @param array $get Array with the request parameters.
     * @return string 'all' or 'gm' if it was passed as the 'target' GET
     *                parameter. 'gm' if there was no 'target' parameter or
     *                null if some invalid value was passed as the 'target'
     *                parameter.
     */
    function get_target($get){
        $target = $get[GET_TARGET];
        if (strlen($target) < 1){
            return DEF_TARGET;
        }
        else{
            if ($target != TARGET_ALL && $target != TARGET_GM){
                return null;
            }
            else{
                return $target;
            }
        }
    }


    /**
     * Retrieves the notifications
     *
     * Retrieves the notificatios for the selected target that are still on
     * time to be delivered and formats them as a JSON object.
     * 
     * @since 3.0.0
     * @param object $con Open database connection.
     * @param string $target Optional. 'gm' or 'all'. Default is 'all'.
     * @return string JSON object with the fetched notifications.
     */
    function select_notifications($con, $target = TARGET_ALL){
        if ($target == TARGET_GM){
            $query = "SELECT id, title_es, title_en, title_eu, text_es, text_en, text_eu, dtime, internal AS gm, duration, action, 0 AS seen FROM notification WHERE internal = 1 AND dtime > NOW() - INTERVAL duration MINUTE ORDER BY dtime DESC";
        }
        else{
            $query = "SELECT id, title_es, title_en, title_eu, text_es, text_en, text_eu, dtime, internal AS gm, duration, action, 0 AS seen FROM notification WHERE dtime > NOW() - INTERVAL duration MINUTE ORDER BY dtime DESC";
        }
        $q = mysqli_query($con, $query);
        if (mysqli_num_rows($q) == 0){
            return null;
        }
        else{
            $rows = array();
            while($r = mysqli_fetch_assoc($q)) {
                $rows[] = $r;
            }
            return(json_encode($rows));
        }
    }


    /**
     * Prints the notifications. 
     * 
     * @since 3.0.0
     * @param string $notifications JSON object with the notifications,
     *                              as generated by 
     *                              {@see select_notifications($con, $target)}
     */
    function print_notifications($notifications){
        echo($notifications);
    }


    // SCRIPT START


    // Connect to the database
    $con = startdb('rw');

    // Select target
    $target = get_target($_GET);
    if ($target == null){
        // Bad request
        http_response_code(400);
        exit(-1);
    }

    // Get notifications
    $notifications = select_notifications($con, $_GET[GET_TARGET]);
    if ($notifications == null){
        // No content
        http_response_code(204);
    }
    else{
        print_notifications($notifications);
    }
?>