import java.util.ArrayList;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.Scanner;

public class Todo
{
    private static final int INT_FLAG = -5;
    private static final String STRING_FLAG = "";
    private static final int PROGRAM_WIDTH = 20;

    private static final int ADD_ITEM = 1;
    private static final int CHANGE_ITEM_STATUS = 2;
    private static final int REMOVE_ITEM = 3;
    private static final int EXIT_PROGRAM = 4;

    private static final String[] MENU_OPTIONS = {"Add item", "Change item status", "Remove item", "Exit"};
    private static ArrayList<TodoItem> tasks = new ArrayList<TodoItem>();


    public static void main(String[] args)
    {
        int userInput = INT_FLAG;

        while(userInput != EXIT_PROGRAM)
        {
            displayTasksWithStatus(tasks);
            displayMenu();

            userInput = intInput("Enter option's number: ");
            executeChoosenOption(userInput);
        }
    }

    private static void displayTasksWithStatus(ArrayList<TodoItem> tasks)
    /**
     * Displays all tasks enumerated, everyone in new line
     */
    {
        displayBar();
        if (tasks.isEmpty())
            System.out.println("Your tasks list is empty!");

        else
        {
            System.out.println("TASKS");
            System.out.println();

            for ( TodoItem element : tasks)
                {
                    System.out.print(tasks.indexOf(element) + 1);
                    System.out.print(". ");
                    element.showNameAndStatus();
                }
        }
        System.out.println();
        displayBar();
    }

    private static void displayBar()
    /**
     * Displays horizontal bar
     */
    {
        for (int i = PROGRAM_WIDTH; i>=0; i--)
        {
            System.out.print("_");
        }
        System.out.println();
    }

    private static void displayMenu()
    /**
     * Displays possible menu options in program
     */
    {
        ArrayList<String> options = new ArrayList<String>(Arrays.asList(MENU_OPTIONS));

        for ( String choice : options)
        {
            System.out.print(options.indexOf(choice) + 1);
            System.out.print(". ");
            System.out.println(choice);
        }

        displayBar();
    }

    private static void executeChoosenOption(int option)
    /**
     * Changes tasks list state depending on option choosen
     */
    {

        if (option == ADD_ITEM)
        {
            String taskName;
            taskName = strInput("Enter task name: ");
            TodoItem task = new TodoItem(taskName);
            tasks.add(task);
        }
        else if (option == REMOVE_ITEM)
        {
            int taskIndex;
            taskIndex = intInput("Enter task's number to remove: ");
            tasks.remove(taskIndex - 1);
        }
        else if (option == CHANGE_ITEM_STATUS)
        {
            int taskIndex;
            TodoItem task;
            taskIndex = intInput("Enter task's number to change status: ");

            task = tasks.get(taskIndex - 1);
            task.toggleDone();
        }
    }

    private static int intInput(String question)
    /**
     * Asks question to user and returns his answer in int
     */
    {
        Scanner in = new Scanner(System.in);
        int userInput = INT_FLAG;

        System.out.print(question);

        try
        {
            userInput = in.nextInt();
        }
        catch( InputMismatchException e)
        {
            System.out.println("Enter number!");
        }

        return userInput;
    }

    private static String strInput(String question)
    /**
     * Asks question to user and return his answer in String
     */
    {
        Scanner in = new Scanner(System.in);
        String userInput = STRING_FLAG;

        System.out.println(question);
        userInput = in.next();

        return userInput;
    }
}