define(["jquery", "jquery.ui", "underscore", "gettext", "draggabilly",
"js/utils/module", "common/js/components/views/feedback_notification"],
function ($, ui, _, gettext, Draggabilly, ModuleUtils, NotificationView) {
'use strict';
var contentDragger = {
droppableClasses: 'drop-target drop-target-prepend drop-target-before drop-target-after',
validDropClass: "valid-drop",
expandOnDropClass: "expand-on-drop",
collapsedClass: "is-collapsed",
/*
* Determine information about where to drop the currently dragged
* element. Returns the element to attach to and the method of
* attachment ('before', 'after', or 'prepend').
*/
findDestination: function (ele, yChange) {
var eleY = ele.offset().top;
var eleYEnd = eleY + ele.outerHeight();
var containers = $(ele.data('droppable-class'));
var isSibling = function () {
return $(this).data('locator') !== undefined && !$(this).is(ele);
};
for (var i = 0; i < containers.length; i++) {
var container = $(containers[i]);
// Exclude the 'new unit' buttons, and make sure we don't
// prepend an element to itself
var siblings = container.children().filter(isSibling);
// If the container is collapsed, check to see if the
// element is on top of its parent list -- don't check the
// position of the container
var parentList = container.parents(ele.data('parent-location-selector')).first();
if (parentList.hasClass(this.collapsedClass)) {
var parentListTop = parentList.offset().top;
// To make it easier to drop subsections into collapsed sections (which have
// a lot of visual padding around them), allow a fudge factor around the
// parent element.
var collapseFudge = 10;
if (Math.abs(eleY - parentListTop) < collapseFudge ||
(eleY > parentListTop &&
eleYEnd - collapseFudge <= parentListTop + parentList.outerHeight())
) {
return {
ele: container,
attachMethod: 'prepend',
parentList: parentList
};
}
}
// Otherwise, do check the container
else {
// If the list is empty, we should prepend to it,
// unless both elements are at the same location --
// this prevents the user from being unable to expand
// a section
var containerY = container.offset().top;
if (siblings.length === 0 &&
containerY !== eleY &&
Math.abs(eleY - containerY) < 50) {
return {
ele: container,
attachMethod: 'prepend'
};
}
// Otherwise the list is populated, and we should attach before/after a sibling
else {
for (var j = 0; j < siblings.length; j++) {
var $sibling = $(siblings[j]);
var siblingY = $sibling.offset().top;
var siblingHeight = $sibling.outerHeight();
var siblingYEnd = siblingY + siblingHeight;
// Facilitate dropping into the beginning or end of a list
// (coming from opposite direction) via a "fudge factor". Math.min is for Jasmine test.
var fudge = Math.min(Math.ceil(siblingHeight / 2), 35);
// Dragging to top or bottom of a list with only one element is tricky
// because the element being dragged may be the same size as the sibling.
if (siblings.length === 1) {
// Element being dragged is within the drop target. Use the direction
// of the drag (yChange) to determine before or after.
if (eleY + fudge >= siblingY && eleYEnd - fudge <= siblingYEnd) {
return {
ele: $sibling,
attachMethod: yChange > 0 ? 'after' : 'before'
};
}
// Element being dragged is before the drop target.
else if (Math.abs(eleYEnd - siblingY) <= fudge) {
return {
ele: $sibling,
attachMethod: 'before'
};
}
// Element being dragged is after the drop target.
else if (Math.abs(eleY - siblingYEnd) <= fudge) {
return {
ele: $sibling,
attachMethod: 'after'
};
}
}
else {
// Dragging up into end of list.
if (j === siblings.length - 1 && yChange < 0 &&
Math.abs(eleY - siblingYEnd) <= fudge) {
return {
ele: $sibling,
attachMethod: 'after'
};
}
// Dragging up or down into beginning of list.
else if (j === 0 && Math.abs(eleY - siblingY) <= fudge) {
return {
ele: $sibling,
attachMethod: 'before'
};
}
// Dragging down into end of list. Special handling required because
// the element being dragged may be taller then the element being dragged over
// (if eleY can never be >= siblingY, general case at the end does not work).
else if (j === siblings.length - 1 && yChange > 0 &&
Math.abs(eleYEnd - siblingYEnd) <= fudge) {
return {
ele: $sibling,
attachMethod: 'after'
};
}
else if (eleY >= siblingY && eleY <= siblingYEnd) {
return {
ele: $sibling,
attachMethod: eleY - siblingY <= siblingHeight / 2 ? 'before' : 'after'
};
}
}
}
}
}
}
// Failed drag
return {
ele: null,
attachMethod: ''
};
},
// Information about the current drag.
dragState: {},
onDragStart: function (draggable) {
var ele = $(draggable.element);
this.dragState = {
// Which element will be dropped into/onto on success
dropDestination: null,
// How we attach to the destination: 'before', 'after', 'prepend'
attachMethod: '',
// If dragging to an empty section, the parent section
parentList: null,
// The y location of the last dragMove event (to determine direction).
lastY: 0,
// The direction the drag is moving in (negative means up, positive down).
dragDirection: 0
};
if (!ele.hasClass(this.collapsedClass)) {
ele.addClass(this.collapsedClass);
ele.find('.expand-collapse').first().addClass('expand').removeClass('collapse');
// onDragStart gets called again after the collapse, so we can't
// just store a variable in the dragState.
ele.addClass(this.expandOnDropClass);
}
// We should remove this class name before start dragging to
// avoid performance issues.
ele.removeClass('was-dragging');
},
onDragMove: function (draggable, event, pointer) {
// Handle scrolling of the browser.
var scrollAmount = 0;
var dragBuffer = 10;
if (window.innerHeight - dragBuffer < pointer.clientY) {
scrollAmount = dragBuffer;
}
else if (dragBuffer > pointer.clientY) {
scrollAmount = -(dragBuffer);
}
if (scrollAmount !== 0) {
window.scrollBy(0, scrollAmount);
return;
}
var yChange = draggable.dragPoint.y - this.dragState.lastY;
if (yChange !== 0) {
this.dragState.direction = yChange;
}
this.dragState.lastY = draggable.dragPoint.y;
var ele = $(draggable.element);
var destinationInfo = this.findDestination(ele, this.dragState.direction);
var destinationEle = destinationInfo.ele;
this.dragState.parentList = destinationInfo.parentList;
// Clear out the old destination
if (this.dragState.dropDestination) {
this.dragState.dropDestination.removeClass(this.droppableClasses);
}
// Mark the new destination
if (destinationEle && this.pointerInBounds(pointer, ele)) {
ele.addClass(this.validDropClass);
destinationEle.addClass('drop-target drop-target-' + destinationInfo.attachMethod);
this.dragState.attachMethod = destinationInfo.attachMethod;
this.dragState.dropDestination = destinationEle;
}
else {
ele.removeClass(this.validDropClass);
this.dragState.attachMethod = '';
this.dragState.dropDestination = null;
}
},
onDragEnd: function (draggable, event, pointer) {
var ele = $(draggable.element);
var destination = this.dragState.dropDestination;
// Clear dragging state in preparation for the next event.
if (destination) {
destination.removeClass(this.droppableClasses);
}
ele.removeClass(this.validDropClass);
// If the drag succeeded, rearrange the DOM and send the result.
if (destination && this.pointerInBounds(pointer, ele)) {
// Make sure we don't drop into a collapsed element
if (this.dragState.parentList) {
this.expandElement(this.dragState.parentList);
}
var method = this.dragState.attachMethod;
destination[method](ele);
this.handleReorder(ele);
}
// If the drag failed, send it back
else {
$('.was-dragging').removeClass('was-dragging');
ele.addClass('was-dragging');
}
if (ele.hasClass(this.expandOnDropClass)) {
this.expandElement(ele);
ele.removeClass(this.expandOnDropClass);
}
// Everything in its right place
ele.css({
top: 'auto',
left: 'auto'
});
this.dragState = {};
},
pointerInBounds: function (pointer, ele) {
return pointer.clientX >= ele.offset().left && pointer.clientX < ele.offset().left + ele.outerWidth();
},
expandElement: function (ele) {
// Verify all children of the element are rendered.
var ensureChildrenRendered = ele.data('ensureChildrenRendered');
if (_.isFunction(ensureChildrenRendered)) { ensureChildrenRendered(); }
// Update classes.
ele.removeClass(this.collapsedClass);
ele.find('.expand-collapse').first().removeClass('expand').addClass('collapse');
},
/*
* Find all parent-child changes and save them.
*/
handleReorder: function (element) {
var parentSelector = element.data('parent-location-selector'),
childrenSelector = element.data('child-selector'),
newParentEle = element.parents(parentSelector).first(),
newParentLocator = newParentEle.data('locator'),
oldParentLocator = element.data('parent'),
oldParentEle, saving, refreshParent;
refreshParent = function (element) {
var refresh = element.data('refresh');
// If drop was into a collapsed parent, the parent will have been
// expanded. Views using this class may need to track the
// collapse/expand state, so send it with the refresh callback.
var collapsed = element.hasClass(contentDragger.collapsedClass);
if (_.isFunction(refresh)) { refresh(collapsed); }
};
saving = new NotificationView.Mini({
title: gettext('Saving')
});
saving.show();
element.addClass('was-dropped');
// Timeout interval has to match what is in the CSS.
setTimeout(function () {
element.removeClass('was-dropped');
}, 1000);
this.saveItem(newParentEle, childrenSelector, function () {
saving.hide();
// Refresh new parent.
refreshParent(newParentEle);
// Refresh old parent.
if (newParentLocator !== oldParentLocator) {
oldParentEle = $(parentSelector).filter(function () {
return $(this).data('locator') === oldParentLocator;
});
refreshParent(oldParentEle);
element.data('parent', newParentLocator);
}
});
},
/*
* Actually save the update to the server. Takes the element
* representing the parent item to save, a CSS selector to find
* its children, and a success callback.
*/
saveItem: function (ele, childrenSelector, success) {
// Find all current child IDs.
var children = _.map(
ele.find(childrenSelector),
function (child) {
return $(child).data('locator');
}
);
$.ajax({
url: ModuleUtils.getUpdateUrl(ele.data('locator')),
type: 'PUT',
dataType: 'json',
contentType: 'application/json',
data: JSON.stringify({
children: children
}),
success: success
});
},
/*
* Make DOM element with class `type` draggable using `handleClass`, able to be dropped
* into `droppableClass`, and with parent type `parentLocationSelector`.
* @param {DOM element, jQuery element} element
* @param {Object} options The list of options. Possible options:
* `type` - class name of the element.
* `handleClass` - specifies on what element the drag interaction starts.
* `droppableClass` - specifies on what elements draggable element can be dropped.
* `parentLocationSelector` - class name of a parent element with data-locator.
* `refresh` - method that will be called after dragging to refresh
* views of the target and source xblocks.
*/
makeDraggable: function (element, options) {
var draggable;
options = _.defaults({
type: null,
handleClass: null,
droppableClass: null,
parentLocationSelector: null,
refresh: null,
ensureChildrenRendered: null
}, options);
if ($(element).data('droppable-class') !== options.droppableClass) {
$(element).data({
'droppable-class': options.droppableClass,
'parent-location-selector': options.parentLocationSelector,
'child-selector': options.type,
'refresh': options.refresh,
'ensureChildrenRendered': options.ensureChildrenRendered
});
draggable = new Draggabilly(element, {
handle: options.handleClass,
containment: '.wrapper-dnd'
});
draggable.on('dragStart', _.bind(contentDragger.onDragStart, contentDragger, draggable));
draggable.on('dragMove', _.bind(contentDragger.onDragMove, contentDragger, draggable));
draggable.on('dragEnd', _.bind(contentDragger.onDragEnd, contentDragger, draggable));
}
}
};
return contentDragger;
});