/**!
 *
 *  Copyright 2015 Netflix, Inc.
 *
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 *
 */

/*jslint node: true*/
/*global angular*/
/*jslint plusplus: true */

'use strict';

/* Filters */

angular.module('app.filters', []);

var uniqueItems = function (data, key) {
    var result = [],
        i,
        value;
    for (i = 0; i < data.length; i++) {
        value = data[i][key];
        if (result.indexOf(value) === -1) {
            result.push(value);
        }
    }
    return result;
};

angular
    .module('app.filters')
    .filter('groupBy', function () {
        return function (collection, key) {
            if (collection === null) {
                return;
            }
            return uniqueItems(collection, key);
        };
    })
;

angular
    .module('app.filters')
    .filter('groupFilter', function () {
        return function (collection, group) {
            var result = [],
                i;
            for (i = 0; i < collection.length; i++) {
                if (collection[i].group === group) {
                    result.push(collection[i]);
                }
            }
            return result;
        };
    })
;

/**!
 *
 *  Copyright 2015 Netflix, Inc.
 *
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 *
 */

/*jslint node: true*/
/*global angular*/
/*jslint plusplus: true */

'use strict';

/* Filters */

angular.module('app.filters', []);

var uniqueItems = function (data, key) {
    var result = [],
        i,
        value;
    for (i = 0; i < data.length; i++) {
        value = data[i][key];
        if (result.indexOf(value) === -1) {
            result.push(value);
        }
    }
    return result;
};

angular
    .module('app.filters')
    .filter('groupBy', function () {
        return function (collection, key) {
            if (collection === null) {
                return;
            }
            return uniqueItems(collection, key);
        };
    })
;

angular
    .module('app.filters')
    .filter('groupFilter', function () {
        return function (collection, group) {
            return collection.filter(function (item) {
                return item.group === group;
            });
        };
    })
;

Use Array filter func instead of mutation