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/*
 * Collapser:  Takes two elements and creates a visual "expando:" clicking on one element expands/collapses the other.
 * Required properties:
 *      clicker: The element that will be clicked on.
 *      content: The element that will expand or collapse as the clicker is clicked on.
 * Optional properties:
 *      isCollapsed: Is the content collapsed.  Set to true on serialization (or initialization) to start content in collapsed state.
 *          Can be manually set as well.
 *      collapsibleClass: The CSS class to apply to the content and the clicker when collapsed.  Defaults to "collapsible-collapsed".
 *      isAnimated: Set to true to apply a transition to expand/collapse (defaults to false).
 *      transitionClass: If isAnimated is set to true, the component will apply transitionClass to the content during the
 *          collapse process.  You can then define transitionClass in your style sheet with the desired CSS transitions.
 *          Defaults to "collapsible-transition".
 *      contentHeight: If both isAnimated and isCollapsedAtStart are set to true, set contentHeight to the height of the content
 *          (in pixels, but without the "px") when not collapsed.  If this value is not set, the first time the content is expanded
 *          the transition will not work. Subsequent collapses (and expansions) will transition as expected.
 *      isLabelClickable: Boolean that indicates whether or not the clicker should have listener events. Defaults to true; set to
 *          false for collapsers that will only be operated remotely.
 *      isToggling: Set this anually toggle the expand/collapse of the content.
 *
 */
var Montage = require("montage/core/core").Montage,
    Component = require("montage/ui/component").Component,
    Collapser = exports.Collapser = Montage.create(Component, {

    // This component has no template.
    hasTemplate:{
        value: false
    },

    /* === BEGIN: Models === */

    // contentHeight: Stores the height of the content just before collapse.
    _contentHeight: {
        value: 0
    },
    contentHeight: {
        serializable: true,
        get: function() {
            return this._contentHeight;
        },
        set: function(newVal) {
            this._contentHeight = newVal;
        }
    },

    // isCollapsing: true if the collapser is collapsing (or expanding); used in the draw cycle.
    _isCollapsing: {
        value: false
    },

    // isAnimated: boolean to apply transition to expand/collapse
    _isAnimated : {
        value: false
    },
    isAnimated: {
        serializable: true,
        get: function() {
            return this._isAnimated;
        },
        set: function(newVal) {
            this._isAnimated = newVal;
        }
    },

    _bypassAnimation : {
        value: true
    },
    bypassAnimation: {
        serializable: true,
        get: function() {
            return this._bypassAnimation;
        },
        set: function(newVal) {
            this._bypassAnimation= newVal;
            //console.log('bypassAnimation setter ' + newVal)
        }
    },
     _oldAnimated : {
        value: false
     },

    // transitionClass: The CSS class to apply to the content during collapse to provide CSS transition.
    // Note that this CSS class must be defined in your style sheet with the desired transitions.
    _transitionClass : {
        value: "collapsible-transition"
    },
    transitionClass: {
        get: function() {
            return this._transitionClass;
        },
        set: function(newVal) {
            this._transitionClass = newVal;
        }
    },

    // isCollapsed: is the content actually collapsed at this moment
    _isCollapsed: {
        value: ""
    },
    isCollapsed : {
        serializable: true,
        get: function() {
            return this._isCollapsed;
        },
        set: function(newVal) {
            if (newVal !== this._isCollapsed) {
                this._isCollapsed = newVal;
                //this.needsDraw = true;
            }
        }
    },

    // collapsedClass:  the class to apply to the clicker and content when the content is collapsed.
    _collapsedClass : {
        value: "collapsible-collapsed"
    },
    collapsedClass: {
        get: function() {
            return this._collapsedClass;
        },
        set: function(newVal) {
            this._collapsedClass = newVal;
        }
    },

    // _origOverflowValue: Stores the original overflow value of the collapsible element.
    // Why store the value? While the collapsible element is collapsed, obviously we will need overflow: hidden.
    // But when the collapsible element is open, we will need overflow to return to its original value.
    _origOverflowValue : {
        value: false
    },

    // isLabelClickable: Boolean for whether or not the label is clickable. If set to false,
    // the label click listener is never applied.  For collapsibles that will only be operated remotely.
    // Defaults to true.
    _isLabelClickable : {
        value: true
    },
    isLabelClickable : {
        serializable: true,
        get: function() {
            return this._isLabelClickable;
        },
        set: function(newVal) {
            this._isLabelClickable = newVal;
        }
    },

    _myContent:{
        value:null
    },

    myContent:{
            serializable:true,
            get:function () {
                return this._myContent;
            },
            set:function (newVal) {
                this._myContent = newVal;
            }
        },

        _clicker:{
            value:null
        },

        clicker:{
            serializable:true,
            get:function () {
                return this._clicker;
            },
            set:function (newVal) {
                this._clicker = newVal;
            }
        },

    // isToggling: Bindable property. Set this (to anything) to trigger a toggle.
    _isToggling: {
        value: true
    },
    isToggling: {
        serializable: true,
        get: function() {
            return this._isToggling;
        },
        set: function(newVal) {
            if (newVal !== this._isToggling) {
                this._isToggling = newVal;

                if (this.bypassAnimation === true) {
                    this._oldAnimated = this.isAnimated;
                    this.isAnimated = false;
                }
                this.myContent.classList.remove(this.transitionClass);
                this.handleCollapserLabelClick();
            }
        }
    },

    /* === END: Models === */

    /* === BEGIN: Draw cycle === */

    prepareForDraw: {
        value: function() {
            // Get the original value of the overflow property:
            this._origOverflowValue = window.getComputedStyle(this.myContent, null).getPropertyValue("overflow");
            if (this.isCollapsed === false) {
                this.myContent.style.height = "auto";
            }


            // If the content area is supposed to start out collapsed:
            if (this.isCollapsed) {
                this.myContent.style.height = "0px";
                // Set the overflow to hidden if it's not already
                if (this._origOverflowValue !== "hidden") {
                    this.myContent.style.overflow = "hidden";
                }
                this.myContent.classList.add(this.collapsedClass);
                this.clicker.classList.add(this.collapsedClass);
            } else {
                this.myContent.style.height = "auto";
                this.myContent.classList.remove(this.collapsedClass);
                this.clicker.classList.remove(this.collapsedClass);
            }
        }
    },
    draw: {
        value: function() {
            // Is the content area expanding/collapsing?
            this.myContent.classList.remove(this.transitionClass);
            if (this._isCollapsing) {

                if (this.isAnimated) {
                    // Apply the transition class to the content.
                    this.myContent.classList.add(this.transitionClass);

                    // Add a handler for the end of the transition, so we can tidy things up after
                    // the transition completes
                    this.myContent.identifier = "myContent";
                    this.myContent.addEventListener("webkitTransitionEnd", this, false);

                    this.myContent.style.overflow = "hidden";
                }

                // Next, are we expanding or collapsing?
                if (this.myContent.classList.contains(this.collapsedClass)) {
                    // It's already collapsed so we are expanding
                    this.myContent.style.height = this.contentHeight + "px";
                    this.isCollapsed = false;

                } else {
                    // It's expanded so we are collapsing
                    this.myContent.style.height = "0px";
                    this.isCollapsed = true;

                    // Set the overflow to hidden if it isn't already
                    if (this._origOverflowValue !== "hidden") {
                        this.myContent.style.overflow = "hidden";
                    }
                }

                // Toggle the CSS class and deactivate the collapsing flag because we are now done.
                this.myContent.classList.toggle(this.collapsedClass);
                this.clicker.classList.toggle(this.collapsedClass);
                this._isCollapsing = false;

                // Special cases:  If transition does not happen (in the case of a contentHeight of 0
                // or isAnimated = false) we need to manually fire it here to do the cleanup.
                if ((this.contentHeight < 3) || (!this.isAnimated)) {
                    this.handleMyContentWebkitTransitionEnd();
                }
            }
        }
    },

    /* === END: Draw cycle === */

    /* === BEGIN: Event handlers === */

    // Handle a click on the label
    handleCollapserLabelClick: {
        value: function() {

            // The user has clicked on one of the expandos.  What should we do?
            // First, are we expanding or collapsing?
            if (!this.myContent.classList.contains(this.collapsedClass)) {
                // We are collapsing!
                // Save the current height of the content.
                this.contentHeight = this.myContent.offsetHeight;
                // Set the current height of the content to a pixel height instead of "auto"
                // so that the transition can happen.
                // (This doesn't actually change the appearance of the element,
                // so it's okay to do here, outside the draw cycle.)
                this.myContent.style.height = this.contentHeight + "px";

                this.isCollapsed = true;
            } else {
                this.isCollapsed = false;
            }

            // Set the collapsing flag so when the draw cycle begins
            // it will know to expand/collapse.
            this._isCollapsing = true;

            // Set the component to run its draw cycle.
            this.needsDraw = true;

        }
    },

    // This handler is bound to the transitionEnd event.  If transitions
    // are disabled, it is called manually.
    handleMyContentWebkitTransitionEnd: {
        value: function(event) {

            // Are we animating the transitions?
            if (this.isAnimated) {
                // Yes, transitions are animated.
                // Remove the event listener so it won't fire again.
                this.myContent.removeEventListener("webkitTransitionEnd", this, false);

                // remove the CSS class that supplies the transition
                this.myContent.classList.remove(this.transitionClass);
            }

            // Set the height of the content area to auto; this way it can expand/collapse as interactions
            // happen within.
            if (!this.myContent.classList.contains(this.collapsedClass)) {
                this.myContent.style.height = "auto";
                // Return the overflow to its original value if it wasn't hidden
                if (this._origOverflowValue !== "hidden") {
                    this.myContent.style.overflow = this._origOverflowValue;
                }

            }

            if (this.bypassAnimation === true) {
                this.isAnimated = this._oldAnimated;
            } else {
                this.bypassAnimation = true;
            }
        }
    }

    /* === END: Event handlers === */
});