(function(define) {
    'use strict';
    define(['jquery', 'underscore', 'backbone', 'gettext', 'js/groups/models/cohort',
            'js/groups/models/verified_track_settings',
            'js/groups/views/cohort_editor', 'js/groups/views/cohort_form',
            'js/groups/views/course_cohort_settings_notification',
            'js/groups/views/cohort_discussions_inline', 'js/groups/views/cohort_discussions_course_wide',
            'js/groups/views/verified_track_settings_notification',
            'edx-ui-toolkit/js/utils/html-utils',
            'js/views/file_uploader', 'js/models/notification', 'js/views/notification', 'string_utils'],
        function($, _, Backbone, gettext, CohortModel, VerifiedTrackSettingsModel, CohortEditorView, CohortFormView,
                CourseCohortSettingsNotificationView, InlineDiscussionsView, CourseWideDiscussionsView,
                 VerifiedTrackSettingsNotificationView, HtmlUtils) {
            var hiddenClass = 'is-hidden',
                disabledClass = 'is-disabled',
                enableCohortsSelector = '.cohorts-state';


            var CohortsView = Backbone.View.extend({
                events: {
                    'change .cohort-select': 'onCohortSelected',
                    'change .cohorts-state': 'onCohortsEnabledChanged',
                    'click .action-create': 'showAddCohortForm',
                    'click .cohort-management-add-form .action-save': 'saveAddCohortForm',
                    'click .cohort-management-add-form .action-cancel': 'cancelAddCohortForm',
                    'click .link-cross-reference': 'showSection',
                    'click .toggle-cohort-management-secondary': 'showCsvUpload',
                    'click .toggle-cohort-management-discussions': 'showDiscussionTopics'
                },

                initialize: function(options) {
                    var model = this.model;

                    this.template = HtmlUtils.template($('#cohorts-tpl').text());
                    this.selectorTemplate = HtmlUtils.template($('#cohort-selector-tpl').text());
                    this.context = options.context;
                    this.contentGroups = options.contentGroups;
                    this.cohortSettings = options.cohortSettings;
                    model.on('sync', this.onSync, this);

                    // Update cohort counts when the user clicks back on the cohort management tab
                    // (for example, after uploading a csv file of cohort assignments and then
                    // checking results on data download tab).
                    $(this.getSectionCss('cohort_management')).click(function() {
                        model.fetch();
                    });
                },

                render: function() {
                    HtmlUtils.setHtml(this.$el, this.template({
                        cohorts: this.model.models,
                        cohortsEnabled: this.cohortSettings.get('is_cohorted')
                    }));
                    this.onSync();
                    // Don't create this view until the first render is called, as at that point the
                    // various other models whose state is required to properly view the notification
                    // will have completed their fetch operations.
                    if (!this.verifiedTrackSettingsNotificationView) {
                        var verifiedTrackSettingsModel = new VerifiedTrackSettingsModel();
                        verifiedTrackSettingsModel.url = this.context.verifiedTrackCohortingUrl;
                        verifiedTrackSettingsModel.fetch({
                            success: _.bind(this.renderVerifiedTrackSettingsNotificationView, this)
                        });
                        this.verifiedTrackSettingsNotificationView = new VerifiedTrackSettingsNotificationView({
                            model: verifiedTrackSettingsModel
                        });
                    }
                    return this;
                },

                renderSelector: function(selectedCohort) {
                    HtmlUtils.setHtml(this.$('.cohort-select'), this.selectorTemplate({
                        cohorts: this.model.models,
                        selectedCohort: selectedCohort
                    }));
                },

                renderCourseCohortSettingsNotificationView: function() {
                    var cohortStateMessageNotificationView = new CourseCohortSettingsNotificationView({
                        el: $('.cohort-state-message'),
                        cohortEnabled: this.getCohortsEnabled()
                    });
                    cohortStateMessageNotificationView.render();
                },

                renderVerifiedTrackSettingsNotificationView: function() {
                    if (this.verifiedTrackSettingsNotificationView) {
                        this.verifiedTrackSettingsNotificationView.validateSettings(
                            this.getCohortsEnabled(), this.model.models, this.$(enableCohortsSelector)
                        );
                    }
                },

                onSync: function(model, response, options) {
                    var selectedCohort = this.lastSelectedCohortId && this.model.get(this.lastSelectedCohortId),
                        hasCohorts = this.model.length > 0,
                        cohortNavElement = this.$('.cohort-management-nav'),
                        additionalCohortControlElement = this.$('.wrapper-cohort-supplemental'),
                        isModelUpdate;
                    isModelUpdate = function() {
                        // Distinguish whether this is a sync event for just one model, or if it is for
                        // an entire collection.
                        return options && options.patch && response.hasOwnProperty('user_partition_id');
                    };
                    this.hideAddCohortForm();
                    if (isModelUpdate()) {
                        // Refresh the selector in case the model's name changed
                        this.renderSelector(selectedCohort);
                    } else if (hasCohorts) {
                        cohortNavElement.removeClass(hiddenClass);
                        additionalCohortControlElement.removeClass(hiddenClass);
                        this.renderSelector(selectedCohort);
                        if (selectedCohort) {
                            this.showCohortEditor(selectedCohort);
                        }
                    } else {
                        cohortNavElement.addClass(hiddenClass);
                        additionalCohortControlElement.addClass(hiddenClass);
                        this.showNotification({
                            type: 'warning',
                            title: gettext('You currently have no cohorts configured'),
                            actionText: gettext('Add Cohort'),
                            actionClass: 'action-create',
                            actionIconClass: 'fa-plus'
                        });
                    }
                    this.renderVerifiedTrackSettingsNotificationView();
                },

                getSelectedCohort: function() {
                    var id = this.$('.cohort-select').val();
                    return id && this.model.get(parseInt(id));
                },

                onCohortSelected: function(event) {
                    event.preventDefault();
                    var selectedCohort = this.getSelectedCohort();
                    this.lastSelectedCohortId = selectedCohort.get('id');
                    this.showCohortEditor(selectedCohort);
                },

                onCohortsEnabledChanged: function(event) {
                    event.preventDefault();
                    this.saveCohortSettings();
                },

                saveCohortSettings: function() {
                    var self = this,
                        cohortSettings,
                        fieldData = {is_cohorted: this.getCohortsEnabled()};
                    cohortSettings = this.cohortSettings;
                    cohortSettings.save(
                        fieldData, {patch: true, wait: true}
                    ).done(function() {
                        self.render();
                        self.renderCourseCohortSettingsNotificationView();
                    }).fail(function(result) {
                        self.showNotification({
                            type: 'error',
                            title: gettext("We've encountered an error. Refresh your browser and then try again.")},
                            self.$('.cohorts-state-section')
                        );
                    });
                },

                getCohortsEnabled: function() {
                    return this.$(enableCohortsSelector).prop('checked');
                },

                showCohortEditor: function(cohort) {
                    this.removeNotification();
                    if (this.editor) {
                        this.editor.setCohort(cohort);
                        $('.cohort-management-group .group-header-title').focus();
                    } else {
                        this.editor = new CohortEditorView({
                            el: this.$('.cohort-management-group'),
                            model: cohort,
                            cohorts: this.model,
                            contentGroups: this.contentGroups,
                            context: this.context
                        });
                        this.editor.render();
                        $('.cohort-management-group .group-header-title').focus();
                    }
                },

                showNotification: function(options, beforeElement) {
                    var model = new NotificationModel(options);
                    this.removeNotification();
                    this.notification = new NotificationView({
                        model: model
                    });

                    if (!beforeElement) {
                        beforeElement = this.$('.cohort-management-group');
                    }
                    beforeElement.before(this.notification.$el);

                    this.notification.render();
                },

                removeNotification: function() {
                    if (this.notification) {
                        this.notification.remove();
                    }
                    if (this.cohortFormView) {
                        this.cohortFormView.removeNotification();
                    }
                },

                showAddCohortForm: function(event) {
                    var newCohort;
                    event.preventDefault();
                    this.removeNotification();
                    newCohort = new CohortModel();
                    newCohort.url = this.model.url;
                    this.cohortFormView = new CohortFormView({
                        model: newCohort,
                        contentGroups: this.contentGroups,
                        context: this.context
                    });
                    this.cohortFormView.render();
                    this.$('.cohort-management-add-form').append(this.cohortFormView.$el);
                    this.cohortFormView.$('.cohort-name').focus();
                    this.setCohortEditorVisibility(false);
                },

                hideAddCohortForm: function() {
                    this.setCohortEditorVisibility(true);
                    if (this.cohortFormView) {
                        this.cohortFormView.remove();
                        this.cohortFormView = null;
                    }
                },

                setCohortEditorVisibility: function(showEditor) {
                    if (showEditor) {
                        this.$('.cohorts-state-section').removeClass(disabledClass).attr('aria-disabled', false);
                        this.$('.cohort-management-group').removeClass(hiddenClass);
                        this.$('.cohort-management-nav').removeClass(disabledClass).attr('aria-disabled', false);
                    } else {
                        this.$('.cohorts-state-section').addClass(disabledClass).attr('aria-disabled', true);
                        this.$('.cohort-management-group').addClass(hiddenClass);
                        this.$('.cohort-management-nav').addClass(disabledClass).attr('aria-disabled', true);
                    }
                },

                saveAddCohortForm: function(event) {
                    var self = this,
                        newCohort = this.cohortFormView.model;
                    event.preventDefault();
                    this.removeNotification();
                    this.cohortFormView.saveForm()
                        .done(function() {
                            self.lastSelectedCohortId = newCohort.id;
                            self.model.fetch().done(function() {
                                self.showNotification({
                                    type: 'confirmation',
                                    title: interpolate_text(
                                        gettext('The {cohortGroupName} cohort has been created. You can manually add students to this cohort below.'),
                                        {cohortGroupName: newCohort.get('name')}
                                    )
                                });
                            });
                        });
                },

                cancelAddCohortForm: function(event) {
                    event.preventDefault();
                    this.removeNotification();
                    this.onSync();
                },

                showSection: function(event) {
                    event.preventDefault();
                    var section = $(event.currentTarget).data('section');
                    $(this.getSectionCss(section)).click();
                    $(window).scrollTop(0);
                },

                showCsvUpload: function(event) {
                    event.preventDefault();

                    $(event.currentTarget).addClass(hiddenClass);
                    var uploadElement = this.$('.csv-upload').removeClass(hiddenClass);

                    if (!this.fileUploaderView) {
                        this.fileUploaderView = new FileUploaderView({
                            el: uploadElement,
                            title: gettext('Assign students to cohorts by uploading a CSV file.'),
                            inputLabel: gettext('Choose a .csv file'),
                            inputTip: gettext('Only properly formatted .csv files will be accepted.'),
                            submitButtonText: gettext('Upload File and Assign Students'),
                            extensions: '.csv',
                            url: this.context.uploadCohortsCsvUrl,
                            successNotification: function(file, event, data) {
                                var message = interpolate_text(gettext(
                                    "Your file '{file}' has been uploaded. Allow a few minutes for processing."
                                ), {file: file});
                                return new NotificationModel({
                                    type: 'confirmation',
                                    title: message
                                });
                            }
                        }).render();
                    }
                },
                showDiscussionTopics: function(event) {
                    event.preventDefault();

                    $(event.currentTarget).addClass(hiddenClass);
                    var cohortDiscussionsElement = this.$('.cohort-discussions-nav').removeClass(hiddenClass);

                    if (!this.CourseWideDiscussionsView) {
                        this.CourseWideDiscussionsView = new CourseWideDiscussionsView({
                            el: cohortDiscussionsElement,
                            model: this.context.discussionTopicsSettingsModel,
                            cohortSettings: this.cohortSettings
                        }).render();
                    }
                    if (!this.InlineDiscussionsView) {
                        this.InlineDiscussionsView = new InlineDiscussionsView({
                            el: cohortDiscussionsElement,
                            model: this.context.discussionTopicsSettingsModel,
                            cohortSettings: this.cohortSettings
                        }).render();
                    }
                },

                getSectionCss: function(section) {
                    return ".instructor-nav .nav-item [data-section='" + section + "']";
                }
            });
            return CohortsView;
        });
}).call(this, define || RequireJS.define);
