var HOME_BUTTON = 36;
var LEFT_ARROW = 37;
var UP_ARROW = 38;
var RIGHT_ARROW = 39;
var DOWN_ARROW = 40;

function handleHotKeys(e) {
    key = window.event ? e.keyCode : e.which;
    var newLocation = "";
    switch (key) {
        case HOME_BUTTON:
            newLocation = "gallery.php";
            break;
        case LEFT_ARROW:
            if (document.getElementById('prev')) {
                newLocation = document.getElementById('prev').href;
            }
            break;
        case UP_ARROW:
            if (document.getElementById('first')) {
                newLocation = document.getElementById('first').href;
            }
            break;
        case RIGHT_ARROW:
            if (document.getElementById('next')) {
                newLocation = document.getElementById('next').href;
            }
            break;
        case DOWN_ARROW:
            if (document.getElementById('last')) {
                newLocation = document.getElementById('last').href;
            }
    }
    if (newLocation) {
        window.location = newLocation;
    }
}

function init(e) {
    if (window.location.href.indexOf("gallery.php?img=") != -1) {
        if (window.addEventListener) {
            window.addEventListener('keydown', handleHotKeys, false);
        } else if (document.addEventListener) {
            document.addEventListener('keydown', handleHotKeys, false);
        } else if (window.attachEvent) {
            document.attachEvent('onkeydown', handleHotKeys);
        }
    }
}

if (window.addEventListener) {
    window.addEventListener('load', init, false);
} else if (document.addEventListener) {
    document.addEventListener('load', init, false);
} else if (window.attachEvent) {
    window.attachEvent('onload', init);
}