(function(define) {
    'use strict';
    define([
        'underscore', 'edx-ui-toolkit/js/pagination/paging-collection', 'js/edxnotes/models/note'
    ], function(_, PagingCollection, NoteModel) {
        return PagingCollection.extend({
            model: NoteModel,

            state: {
                pageSize: 10
            },

            queryParams: {},

            constructor: function(models, options) {
                this.url = options.url;
                this.state.pageSize = options.perPage;

                if (options.text) {
                    this.queryParams.text = options.text;
                }

                PagingCollection.prototype.constructor.call(this, models, options);
            },

        /**
         * Returns course structure from the list of notes.
         * @return {Object}
         */
            getCourseStructure: (function() {
                var courseStructure = null;
                return function() {
                    var chapters = {},
                        sections = {},
                        units = {};

                    this.each(function(note) {
                        var chapter = note.get('chapter'),
                            section = note.get('section'),
                            unit = note.get('unit');

                        chapters[chapter.location] = chapter;
                        sections[section.location] = section;
                        units[unit.location] = units[unit.location] || [];
                        units[unit.location].push(note);
                    });

                    courseStructure = {
                        chapters: _.sortBy(_.toArray(chapters), function(c) { return c.index; }),
                        sections: sections,
                        units: units
                    };

                    return courseStructure;
                };
            }())
        });
    });
}).call(this, define || RequireJS.define);