import java.util.Scanner;
import java.io.*;

public class Main {
    public static Scanner scan = new Scanner(System.in);
    public final static String MISTAKE_NOT_FOUND_MESSAGE = "Error! A file" +
            "with the same name was not found. Try again.";
    public final static String MISTAKE_NOT_OPEN_MESSAGE = "Error! Unable to " +
            "open this file.Please check the file and try again.\n";
    public static final String THEME_MESSAGE = "This program implements Shell sorting algorithm";
    public static final String DOTTED_LINE = "------------------------------------------------";
    public static final String CHOOSE_INPUT = "If you want to fill the array from the keyboard, please, enter 'K'," +
            " if you want to use the file, please, enter 'F'";
    public static final String INPUT_ARRAY_LENGTH = "Please input the length of the array. (an integer value from 2 to 10)";
    public static final String SMT_WRONG = "Something wrong, please try again";
    public static final String NOT_INVALID_DATA = "The length does not match the elements of the array, please check the file for correctness";
    public static final String INPUT_FILE_NAME = "Please enter the name of the file from which to read data. \n" +
            "For example,\"C:\\Users\\Eugene\\Desktop\\Name.txt";
    public static final String OUTPUT_FILE_NAME = "Please enter the name of the file which you want to write the result. \n" +
            "For example,\"C:\\Users\\Eugene\\Desktop\\Name.txt";
    public static final String CHOOSE_OUTPUT = "\nWould you like to put the result in a file? ('Y' - save, 'N' - don't save)";
    public static final String NOT_CORRECT_INPUT = "Attention, an error occurred while Input. Please try again";

    public enum typeOfInput {
        CHOOSE_KEYBOARD, CHOOSE_FILE;
    }

    public enum typeOfOutput {
        YES, NO;
    }

    public static void main(String[] args) {

        System.out.println(THEME_MESSAGE + "\n" + DOTTED_LINE);
        int lengthArray;
        int[] arrayNumbers = new int[0];
        typeOfInput Input = chooseInput();
        switch (Input) {
            case CHOOSE_KEYBOARD:
                System.out.println(INPUT_ARRAY_LENGTH);
                lengthArray = checkInputNumbers(1, 20);
                arrayNumbers = new int[lengthArray];
                inputArrayFromKeyboard(arrayNumbers, lengthArray);
                break;
            case CHOOSE_FILE:
                arrayNumbers = inputArrayFromFile();
                System.out.println("Entered matrix:");
                outputInConsole(arrayNumbers);
                break;
        }
        sortingArray(arrayNumbers);
        outputInConsole(arrayNumbers);
        typeOfOutput Output = chooseOutput();
        switch (Output) {
            case YES:
                outputResultToFile(arrayNumbers);
                break;
            case NO:
                break;
        }
        System.out.println(DOTTED_LINE + "\nProgram completed.");
    }

    private static void sortingArray(int[] arr) {
        for (int inc = arr.length / 2; inc >= 1; inc = inc / 2)
            for (int step = 0; step < inc; step++)
                insertionSort(arr, step, inc);
    }

    private static void insertionSort(int[] arr, int start, int inc) {
        int temp;
        for (int i = start; i < arr.length - 1; i += inc)
            for (int j = Math.min(i + inc, arr.length - 1); j - inc >= 0; j = j - inc)
                if (arr[j - inc] > arr[j]) {
                    temp = arr[j];
                    arr[j] = arr[j - inc];
                    arr[j - inc] = temp;
                } else break;
    }

    public static void inputArrayFromKeyboard(int[] array, int arraylength) {
        System.out.println("Please enter the array elements in the range from -10_000 to 10_000");
        for (int i = 0; i < arraylength; i++) {
            System.out.print("Array[" + (i) + "]" + " = ");
            array[i] = checkInputNumbers(-10_000, 10_000);
        }
    }

    public static boolean checkInputParameters(int num, int min, int max) {
        return ((num > min) && (num < max));
    }

    public static int checkInputNumbers(int min, int max) {
        boolean isCorrect = true;
        int number = 0;
        Scanner scan = new Scanner(System.in);
        do {
            try {
                number = scan.nextInt();
                if (checkInputParameters(number, min - 1, max + 1)) {
                    isCorrect = false;
                } else {
                    System.out.println("Error! Enter a number. The number " +
                            "must be between " + min + " and max " + "!");
                }
            } catch (Exception e) {
                System.out.println("Error! Enter a number: ");
                scan.next();
            }
        } while (isCorrect);
        return number;
    }

    public static void outputInConsole(int arr[]) {
        System.out.println("\nResult sorting array:");
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + "\t");
        }
    }

    public static boolean checkSymbol(char symbol, char firstSymbol, char secondSymbol){
        return ((symbol != firstSymbol) & (symbol != secondSymbol));
    }

    public static typeOfInput chooseInput() {
        typeOfInput answer = null;
        boolean isNotCorrect;
        do {
            System.out.println(CHOOSE_INPUT);
            char symbol = scan.next().charAt(0);
            symbol = Character.toUpperCase(symbol);
            isNotCorrect = (checkSymbol(symbol, 'K', 'F'));
            if (symbol == 'K') {
                answer = typeOfInput.CHOOSE_KEYBOARD;
            } else if (symbol == 'F') {
                answer = typeOfInput.CHOOSE_FILE;
            }
        }
        while (isNotCorrect);
        return answer;
    }

    public static int[] inputArrayFromFile() {
        boolean isInvalidInput;
        int[] arrayNumbers = new int[0];
        scan.nextLine();
        do {
            System.out.println(INPUT_FILE_NAME);
            String fileName = scan.nextLine();
            try {
                BufferedReader input = new BufferedReader(new FileReader(fileName));
                String text = input.readLine();
                int lengthOfMatrix = Integer.parseInt(text);
                isInvalidInput = checkInputParameters(lengthOfMatrix, 2, 10);
                arrayNumbers = new int[lengthOfMatrix];
                text = input.readLine();
                String[] arrFilling = text.split(" ");
                for (int i = 0; i < lengthOfMatrix; i++) {
                    arrayNumbers[i] = Integer.parseInt(arrFilling[i]);
                }
                input.close();
            } catch (ArrayIndexOutOfBoundsException e) {
                System.out.println(NOT_INVALID_DATA);
                isInvalidInput = true;
            } catch (FileNotFoundException e) {
                System.out.println(MISTAKE_NOT_FOUND_MESSAGE);
                isInvalidInput = true;
            } catch (IOException e) {
                System.out.println(MISTAKE_NOT_OPEN_MESSAGE);
                isInvalidInput = true;
            } catch (NumberFormatException e) {
                System.out.println("Error! The file contains invalid data. " +
                        "Please check the file and try again.");
                isInvalidInput = true;
            } catch (Exception e) {
                System.out.println(SMT_WRONG);
                isInvalidInput = true;
            }
        } while (isInvalidInput);
        return arrayNumbers;
    }

    public static typeOfOutput chooseOutput() {
        typeOfOutput answer;
        boolean isNotCorrect;
        do {
            System.out.println(CHOOSE_OUTPUT);
            char symbol = scan.next().charAt(0);
            symbol = Character.toUpperCase(symbol);
            isNotCorrect = (checkSymbol(symbol, 'Y', 'N'));
            if (symbol == 'Y') {
                answer = typeOfOutput.YES;
            } else {
                answer = typeOfOutput.NO;
            }
        }
        while (isNotCorrect);
        return answer;
    }

    public static void outputResultToFile(int[] arrayNumbers) {
        boolean isInvalidOutput;
        scan.nextLine();
        do {
            isInvalidOutput = false;
            System.out.println(OUTPUT_FILE_NAME);
            String FileName = scan.nextLine();
            try {
                BufferedWriter output = new BufferedWriter(new FileWriter(FileName));
                output.write("Result sorting array: \n");
                for (int i : arrayNumbers) {
                    output.write(arrayNumbers[i] + "    ");
                }
                output.close();
            } catch (FileNotFoundException e) {
                System.out.println(MISTAKE_NOT_FOUND_MESSAGE);
                isInvalidOutput = true;
            } catch (IOException e) {
                System.out.println(MISTAKE_NOT_OPEN_MESSAGE);
                isInvalidOutput = true;
            }
        }
        while (isInvalidOutput);
        System.out.println("Data recording completed successfully.");
    }
}