/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
 * Copyright © 2017 Amdocs
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 *
 * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 */
package org.onap.aai.datarouter.util;

import java.util.ArrayList;
import java.util.List;

public class SearchSuggestionPermutation {
    /*
     * Will return all the unique combinations of the suggestions provided.
     * The order of the permutation is not taken into account when computing
     * the uniqueness.
     * e.g.: A list of A,B,C,D will return
     * [[A], [A, B, C, D], [A, C, D], [A, D], [B], [B, C, D], [B, D], [C], [C, D], [D]]
     *
     * @param list The list of statuses to create permutations of
     * @return     A list which contains a array list of all possible combinations
     */
    public static ArrayList<ArrayList<String>> getUniqueListForSuggestions(
            List<String> originalList) {
        ArrayList<ArrayList<String>> lists = new ArrayList<>();
        if (originalList.isEmpty()) {
            lists.add(new ArrayList<String>());
            return lists;
        }
        List<String> list = new ArrayList<>(originalList);
        String head = list.get(0);
        ArrayList<String> rest = new ArrayList<>(list.subList(1, list.size()));

        for (ArrayList<String> activeList : getUniqueListForSuggestions(rest)) {
            ArrayList<String> newList = new ArrayList<>();
            newList.add(head);
            newList.addAll(activeList);
            lists.add(newList);
            lists.add(activeList);
        }
        return lists;
    }

    public static ArrayList<ArrayList<String>> getNonEmptyUniqueLists(List<String> list) {
        ArrayList<ArrayList<String>> lists = getUniqueListForSuggestions(list);
        // remove empty list from the power set
        for (ArrayList<String> emptyList : lists) {
            if (emptyList.isEmpty()) {
                lists.remove(emptyList);
                break;
            }
        }
        return lists;
    }

    public static List<List<String>> getListPermutations(List<String> list) {
        List<String> inputList = new ArrayList<>();
        inputList.addAll(list);
        if (inputList.isEmpty()) {
            List<List<String>> result = new ArrayList<>();
            result.add(new ArrayList<String>());
            return result;
        }

        List<List<String>> listOfLists = new ArrayList<>();

        String firstElement = inputList.remove(0);

        List<List<String>> recursiveReturn = getListPermutations(inputList);
        for (List<String> li : recursiveReturn) {

            for (int index = 0; index <= li.size(); index++) {
                List<String> temp = new ArrayList<>(li);
                temp.add(index, firstElement);
                listOfLists.add(temp);
            }

        }
        return listOfLists;
    }

}