/*
 * Copyright 2019 Red Hat, Inc. and/or its affiliates.
 *
 * 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.
 */

package org.optaweb.employeerostering.service.common.generator;

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

public class StringDataGenerator {

    public static StringDataGenerator buildFullNames() {
        return new StringDataGenerator()
                .addPart(true, 0,
                        "Amy",
                        "Beth",
                        "Chad",
                        "Dan",
                        "Elsa",
                        "Flo",
                        "Gus",
                        "Hugo",
                        "Ivy",
                        "Jay")
                .addPart(false, 1,
                        "A.",
                        "B.",
                        "C.",
                        "D.",
                        "E.",
                        "F.",
                        "G.",
                        "H.",
                        "I.",
                        "J.")
                .addPart(false, 1,
                        "O.",
                        "P.",
                        "Q.",
                        "R.",
                        "S.",
                        "T.",
                        "U.",
                        "V.",
                        "W.",
                        "X.")
                .addPart(false, 1,
                        "Cole",
                        "Fox",
                        "Green",
                        "Jones",
                        "King",
                        "Li",
                        "Poe",
                        "Rye",
                        "Smith",
                        "Watt");
    }

    public static StringDataGenerator buildCompanyNames() {
        return new StringDataGenerator()
                .addPart(true, 0,
                        "Steel",
                        "Paper",
                        "Stone",
                        "Wood",
                        "Water",
                        "Food",
                        "Oil",
                        "Car",
                        "Power",
                        "Computer")
                .addPart(true, 1,
                        "Inc",
                        "Corp",
                        "Limited",
                        "Express",
                        "Telco",
                        "Mobile",
                        "Soft",
                        "Mart",
                        "Bank",
                        "Labs")
                .addPart(false, 2,
                        "US",
                        "UK",
                        "JP",
                        "DE",
                        "FR",
                        "BE",
                        "NL",
                        "BR",
                        "IN",
                        "ES");
    }

    public static StringDataGenerator buildLocationNames() {
        return new StringDataGenerator()
                .addPart(true, 0,
                        "Los",
                        "San",
                        "Las",
                        "Santa",
                        "New",
                        "Fort",
                        "Mount",
                        "Saint",
                        "Little",
                        "El")
                .addPart(true, 1,
                        "Angeles",
                        "Francisco",
                        "Vegas",
                        "Barbara",
                        "York",
                        "Collins",
                        "Vernon",
                        "Peter",
                        "Rock",
                        "Paso")
                .addPart(false, 2,
                        "Town",
                        "City",
                        "Falls",
                        "Ville",
                        "Field",
                        "Polis",
                        "Shire",
                        "Berg",
                        "Borough",
                        "Island")
                .addPart(false, 3,
                        "AL",
                        "CA",
                        "DE",
                        "FL",
                        "GA",
                        "HI",
                        "IN",
                        "KS",
                        "LA",
                        "ME");
    }

    public static StringDataGenerator buildAssemblyLineNames() {
        return new StringDataGenerator()
                .addPart("Chassis",
                        "Engine",
                        "Battery",
                        "Radiator",
                        "Tires",
                        "Lights",
                        "Doors",
                        "Bumper",
                        "Windows",
                        "Sunroof",
                        "Spoiler",
                        "Seats",
                        "Radio",
                        "Airbag",
                        "GPS")
                .addPart("Factory A",
                        "Factory B",
                        "Factory C",
                        "Factory D",
                        "Factory E",
                        "Factory F",
                        "Factory G",
                        "Factory H",
                        "Factory I",
                        "Factory J",
                        "Factory K",
                        "Factory L",
                        "Factory M",
                        "Factory N",
                        "Factory O")
                .addPart("line 1",
                        "line 2",
                        "line 3",
                        "line 4",
                        "line 5",
                        "line 6",
                        "line 7",
                        "line 8",
                        "line 9",
                        "line 10",
                        "line 11",
                        "line 12",
                        "line 13",
                        "line 14",
                        "line 15");
    }

    /**
     * Determines how to go through the unique combinations to maximize uniqueness, even on small subsets.
     * It does not scroll per digit (0000, 1111, 2222, 0001, 1112, 2220, 0002, 1110, 2221, ...).
     * Instead, it scrolls per half (0000, 1111, 2222, 0011, 1122, 2200, 0022, 1100, 2211, ...).
     */
    private static final int[][] HALF_SEQUENCE_MAP = new int[][] { {}, { 0 }, { 0, 1 }, { 0, 2, 1 }, { 0, 2, 1, 3 } };
    /**
     * Determines which parts to eliminate first if maximumSize prediction doesn't need all parts.
     */
    private static final int[] DEFAULT_ELIMINATION_INDEX_MAP = new int[] { 0, 1, 1, 1 };

    private final boolean capitalizeFirstLetter;
    private final String delimiter;
    private List<String[]> partValuesList = new ArrayList<>();
    private int partValuesLength;
    private List<Integer> eliminationIndexMap = new ArrayList<>();
    private int requiredSize = 0;

    private List<String[]> filteredPartValuesList = partValuesList;
    private int index = 0;
    private int indexLimit;

    public StringDataGenerator() {
        this(false);
    }

    public StringDataGenerator(boolean capitalizeFirstLetter) {
        this(capitalizeFirstLetter, " ");
    }

    public StringDataGenerator(String delimiter) {
        this(false, delimiter);
    }

    public StringDataGenerator(boolean capitalizeFirstLetter, String delimiter) {
        this.capitalizeFirstLetter = capitalizeFirstLetter;
        this.delimiter = delimiter;
    }

    public StringDataGenerator addPart(String... partValues) {
        return addPart(false, DEFAULT_ELIMINATION_INDEX_MAP[partValuesList.size()], partValues);
    }

    public StringDataGenerator addAToZPart() {
        return addAToZPart(false, DEFAULT_ELIMINATION_INDEX_MAP[partValuesList.size()]);
    }

    public StringDataGenerator addAToZPart(boolean required, int eliminationIndex) {
        return addPart(required, eliminationIndex,
                "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S",
                "T", "U", "V", "W", "X", "Y", "Z");
    }

    public StringDataGenerator addNumericPart(boolean required, int eliminationIndex, int from, int to) {
        String[] partValues = new String[to - from];
        for (int i = from; i < to; i++) {
            partValues[i - from] = Integer.toString(i);
        }
        return addPart(required, eliminationIndex, partValues);
    }

    public StringDataGenerator addPart(boolean required, int eliminationIndex, String... partValues) {
        if (partValuesList.isEmpty()) {
            partValuesLength = partValues.length;
        } else {
            if (partValues.length != partValuesLength) {
                throw new IllegalStateException("The partValues length (" + partValues.length
                        + ") is not the same as the partValuesLength ("
                        + partValuesLength + ") of the others.");
            }
        }
        if (required) {
            requiredSize++;
        }
        partValuesList.add(partValues);
        eliminationIndexMap.add(eliminationIndex);
        indexLimit = (int) Math.pow(partValuesLength, partValuesList.size());
        filteredPartValuesList = partValuesList;
        return this;
    }

    public void reset() {
        filteredPartValuesList = partValuesList;
        index = 0;
    }

    public void predictMaximumSizeAndReset(int maximumSize) {
        indexLimit = (int) Math.pow(partValuesLength, partValuesList.size());
        filteredPartValuesList = partValuesList;
        for (int i = 1; i < partValuesList.size(); i++) {
            int proposedIndexLimit = (int) Math.pow(partValuesLength, i);
            if (maximumSize <= proposedIndexLimit) {
                filteredPartValuesList = new ArrayList<>(partValuesList);
                while (i < filteredPartValuesList.size() && filteredPartValuesList.size() > requiredSize) {
                    int eliminationIndex = eliminationIndexMap.get(filteredPartValuesList.size() - 1);
                    filteredPartValuesList.remove(eliminationIndex);
                }
                indexLimit = proposedIndexLimit;
                break;
            }
        }
        index = 0;
    }

    public String generateNextValue() {
        if (index >= indexLimit) {
            throw new IllegalStateException("No more elements: the index (" + index
                    + ") is higher than the indexLimit (" + indexLimit + ").\n"
                    + "Maybe predictMaximumSizeAndReset()"
                    + " was called with a too low maximumSize.");
        }
        int listSize = filteredPartValuesList.size();
        StringBuilder result = new StringBuilder(listSize * 80);
        // Make sure we have a unique combination
        if (listSize >= HALF_SEQUENCE_MAP.length) {
            throw new IllegalStateException("A listSize (" + listSize + ") is not yet supported.");
        }
        int[] halfSequence = HALF_SEQUENCE_MAP[listSize];
        int[] chosens = new int[listSize];
        int previousChosen = 0;
        for (int i = 0; i < listSize; i++) {
            int chosen = (previousChosen
                    + (index % (int) Math.pow(partValuesLength, halfSequence[i] + 1.0)
                            / (int) Math.pow(partValuesLength, halfSequence[i])))
                    % partValuesLength;
            chosens[i] = chosen;
            previousChosen = chosen;
        }
        for (int i = 0; i < listSize; i++) {
            if (i > 0) {
                result.append(delimiter);
            }
            String[] partValues = filteredPartValuesList.get(i);
            result.append(partValues[chosens[i]]);
        }
        index++;
        if (capitalizeFirstLetter) {
            result.setCharAt(0, Character.toUpperCase(result.charAt(0)));
        }
        return result.toString();
    }

}
