(function () {
    'use strict';

    var serviceId = 'search';
    angular.module('app').factory(serviceId, [ search]);

    //service to wrap lunr.js for angular usage - currently handles searching items
    function search() {

        var index = lunr(function() {
            this.field('title');
            this.field('details');
            this.field('itemType');
            this.field('displayType');
            this.field('tags');
            this.ref('itemId');
        });
        var service = {
            indexItems: indexItems,
            searchItem: searchItem
        };

        //There is an issue in lunr.js where if your query string is a certain length you don't get results where you should
        //e.g. if you have a document containing 'styling' then searching for 'styl' will yield a result,
        //but then searching 'styli' or 'stylin' yield nothing
        //This is to do with the stemmer(?) in the code, so the workaround is to remove the stemmer
        //*reference: https://github.com/olivernn/lunr.js/issues/38
        index.pipeline.remove(index.stemmer);
        
        return service;

        //index all items
        function indexItems(items) {
            items.forEach(function (item) {
                var mappedItem = itemMapper(item);
                index.add(mappedItem);
      
            });
            return ;
        }

        //tells lunr what item properties to index
        function itemMapper (item) {
            return {
                "itemId": item.itemId,
                "summary": item.summary,
                "details": item.details,
                "title": item.title,
                "itemType": item.itemType,
                "displayType": item.displayType,
                "tags": $.map(item.tags, function(tag) {
                    return tag.text;
                }).join(' ')
            }
        }

        //search items using the text attribute
        function searchItem(text) {
  
            if(text)
                return index.search(text);
            return null;
        }
    }
})();