/**
 * This page is used to show the user an outline of the course.
 */
define([
    'jquery', 'underscore', 'gettext', 'js/views/pages/base_page', 'js/views/utils/xblock_utils',
    'js/views/course_outline', 'common/js/components/utils/view_utils', 'common/js/components/views/feedback_alert',
    'common/js/components/views/feedback_notification', 'js/views/course_highlights_enable', 'js/views/course_video_sharing_enable'],
function($, _, gettext, BasePage, XBlockViewUtils, CourseOutlineView, ViewUtils, AlertView, NoteView,
    CourseHighlightsEnableView,
    CourseVideoSharingEnableView
) {
    'use strict';

    var expandedLocators, CourseOutlinePage;

    CourseOutlinePage = BasePage.extend({
        // takes XBlockInfo as a model

        events: {
            'click .button-toggle-expand-collapse': 'toggleExpandCollapse'
        },

        /**
             * keep a running timeout counter of 5,000 milliseconds
             * for finding an element; see afterRender and scrollToElement function
             */
        findElementPollingTimeout: 5000,

        /**
             * used as the delay parameter to setTimeout in scrollToElement
             * function for polling for an element
             */
        pollingDelay: 100,

        options: {
            collapsedClass: 'is-collapsed'
        },

        // Extracting this to a variable allows comprehensive themes to replace or extend `CourseOutlineView`.
        outlineViewClass: CourseOutlineView,

        initialize: function() {
            var self = this;
            this.initialState = this.options.initialState;
            BasePage.prototype.initialize.call(this);
            this.$('.button-new').click(function(event) {
                self.outlineView.handleAddEvent(event);
            });
            this.$('.button.button-reindex').click(function(event) {
                self.handleReIndexEvent(event);
            });
            this.model.on('change', this.setCollapseExpandVisibility, this);
            $('.dismiss-button').bind('click', ViewUtils.deleteNotificationHandler(function() {
                $('.wrapper-alert-announcement').removeClass('is-shown').addClass('is-hidden');
            }));
        },

        setCollapseExpandVisibility: function() {
            var has_content = this.hasContent(),
                $collapseExpandButton = $('.button-toggle-expand-collapse');
            if (has_content) {
                $collapseExpandButton.removeClass('is-hidden');
            } else {
                $collapseExpandButton.addClass('is-hidden');
            }
        },

        renderPage: function() {
            var setInitialExpandState = function(xblockInfo, expandedLocators) {
                if (xblockInfo.isCourse() || xblockInfo.isChapter()) {
                    expandedLocators.add(xblockInfo.get('id'));
                }
            };

            this.setCollapseExpandVisibility();
            this.expandedLocators = expandedLocators;
            this.expandedLocators.clear();
            if (this.model.get('child_info')) {
                _.each(this.model.get('child_info').children, function(childXBlockInfo) {
                    setInitialExpandState(childXBlockInfo, this.expandedLocators);
                }, this);
            }
            setInitialExpandState(this.model, this.expandedLocators);

            if (this.initialState && this.initialState.expanded_locators) {
                this.expandedLocators.addAll(this.initialState.expanded_locators);
            }

            /* globals course */
            if (this.model.get('highlights_enabled')) {
                this.highlightsEnableView = new CourseHighlightsEnableView({
                    el: this.$('.status-highlights-enabled'),
                    model: this.model
                });
                this.highlightsEnableView.render();
            }

            // if video sharing enable
            if (this.model.get('video_sharing_enabled')) {
                this.videoSharingEnableView = new CourseVideoSharingEnableView({
                    el: this.$('.status-video-sharing-enabled'),
                    model: this.model
                });
                this.videoSharingEnableView.render();
            }

            this.outlineView = new this.outlineViewClass({
                el: this.$('.outline'),
                model: this.model,
                isRoot: true,
                initialState: this.initialState,
                expandedLocators: this.expandedLocators
            });
            this.outlineView.render();
            this.outlineView.setViewState(this.initialState || {});
            return $.Deferred().resolve().promise();
        },

        afterRender: function() {
            this.scrollToElement();
        },

        /**
             * recursively poll for element specified by the URL fragment
             * at 100 millisecond intervals until element is found or
             * Polling is reached
             */
        scrollToElement: function() {
            this.findElementPollingTimeout -= this.pollingDelay;

            const elementID = window.location.hash.replace('#', '');

            if (this.findElementPollingTimeout > 0) {
                if (elementID) {
                    const element = document.getElementById(elementID);
                    if (element) {
                        element.scrollIntoView();
                    } else {
                        setTimeout(this.scrollToElement, this.pollingDelay);
                    }
                }
            }
        },

        hasContent: function() {
            return this.model.hasChildren();
        },

        toggleExpandCollapse: function(event) {
            var toggleButton = this.$('.button-toggle-expand-collapse'),
                collapse = toggleButton.hasClass('collapse-all');
            event.preventDefault();
            toggleButton.toggleClass('collapse-all expand-all');
            this.$('.list-sections > li').each(function(index, domElement) {
                var $element = $(domElement);
                if (collapse) {
                    $element.addClass('is-collapsed');
                } else {
                    $element.removeClass('is-collapsed');
                }
            });
            if (this.model.get('child_info')) {
                _.each(this.model.get('child_info').children, function(childXBlockInfo) {
                    if (collapse) {
                        this.expandedLocators.remove(childXBlockInfo.get('id'));
                    } else {
                        this.expandedLocators.add(childXBlockInfo.get('id'));
                    }
                }, this);
            }
        },

        handleReIndexEvent: function(event) {
            var self = this;
            event.preventDefault();
            var $target = $(event.currentTarget);
            $target.css('cursor', 'wait');
            this.startReIndex($target.attr('href'))
                .done(function(data) { self.onIndexSuccess(data); })
                .fail(function(data) { self.onIndexError(data); })
                .always(function() { $target.css('cursor', 'pointer'); });
        },

        startReIndex: function(reindex_url) {
            return $.ajax({
                url: reindex_url,
                method: 'GET',
                global: false,
                contentType: 'application/json; charset=utf-8',
                dataType: 'json'
            });
        },

        onIndexSuccess: function(data) {
            var msg = new AlertView.Announcement({
                title: gettext('Course Index'),
                message: data.user_message
            });
            msg.show();
        },

        onIndexError: function(data) {
            var msg = new NoteView.Error({
                title: gettext('There were errors reindexing course.'),
                message: data.user_message
            });
            msg.show();
        }
    });

    /**
         * Represents the set of locators that should be expanded for the page.
         */
    expandedLocators = {
        locators: [],

        /**
             * Add the locator to the set if it is not already present.
             */
        add: function(locator) {
            if (!this.contains(locator)) {
                this.locators.push(locator);
            }
        },

        /**
             * Accepts an array of locators and adds them all to the set if not already present.
             */
        addAll: function(locators) {
            _.each(locators, function(locator) {
                this.add(locator);
            }, this);
        },

        /**
             * Remove the locator from the set if it is present.
             */
        remove: function(locator) {
            var index = this.locators.indexOf(locator);
            if (index >= 0) {
                this.locators.splice(index, 1);
            }
        },

        /**
             * Returns true iff the locator is present in the set.
             */
        contains: function(locator) {
            return this.locators.indexOf(locator) >= 0;
        },

        /**
             * Clears all expanded locators from the set.
             */
        clear: function() {
            this.locators = [];
        }
    };

    return CourseOutlinePage;
}); // end define();