DialogSystem = {
    _layers: []
};

DialogSystem.showDialog = function(elmt, onCancel) {
    var overlay = $('<div>&nbsp;</div>')
        .addClass("dialog-overlay")
        .css("z-index", 101 + DialogSystem._layers.length * 2)
        .appendTo(document.body);
        
    var container = $('<div></div>')
        .addClass("dialog-container")
        .css("z-index", 102 + DialogSystem._layers.length * 2)
        .appendTo(document.body);
        
    elmt.css("visibility", "hidden").appendTo(container);
    container.css("top", Math.round((overlay.height() - elmt.height()) / 2) + "px");
    elmt.css("visibility", "visible");
    
    container.draggable({ handle: '.dialog-header', cursor: 'move' });
    
    var layer = {
        overlay: overlay,
        container: container,
        onCancel: onCancel
    };
    DialogSystem._layers.push(layer);
    
    var level = DialogSystem._layers.length;
    
    layer.keyHandler = function(evt) {
        if (evt.keyCode == 27 && !evt.shiftKey && !evt.metaKey && !evt.altKey && !evt.ctrlKey &&
            evt.target.tagName.toLowerCase() != "input" &&
            evt.target.tagName.toLowerCase() != "textarea") {
            
            DialogSystem.dismissUntil(level - 1);
            evt.stopImmediatePropagation();
            evt.stopPropagation();
            evt.preventDefault();
            return false;
        }
    };
    $(document).stack("keydown", layer.keyHandler);
    
    return level;
};

DialogSystem.dismissAll = function() {
    DialogSystem.dismissUntil(0);
};

DialogSystem.dismissUntil = function(level) {
    for (var i = DialogSystem._layers.length - 1; i >= level; i--) {
        var layer = DialogSystem._layers[i];
        
        $(document).unbind("keydown", layer.keyHandler);
        
        layer.overlay.remove();
        layer.container.remove();
        layer.container.unbind();
        
        if (layer.onCancel) {
            try {
                layer.onCancel();
            } catch (e) {
                Refine.reportException(e);
            }
        }
    }
    DialogSystem._layers = DialogSystem._layers.slice(0, level);
};

DialogSystem.createDialog = function() {
    return $('<div></div>').addClass("dialog-frame");
};

DialogSystem.showBusy = function(message) {
    var frame = DialogSystem.createDialog();
    frame.addClass("dialog-busy");
    
    var body = $('<div>').attr('id', 'loading-message').appendTo(frame);
    $('<img>').attr("src", "images/large-spinner.gif").appendTo(body);
    $('<span>').text(" " + (message || "Working...")).appendTo(body);
    
    var level = DialogSystem.showDialog(frame);
    
    return function() {
        DialogSystem.dismissUntil(level - 1);
    };
};