/**
 * Created by karou on 15/09/2015.
 */
import java.util.Scanner;

public class JavaExercises5To8 {
    /**
     *  "Global" variable used for error checking.
     *  Always check if the value is false after an input
     *  operation, otherwise the result can be incorrect!
     */
    public static boolean IOError = false;

    public static void main(String[] args) {
//        ex5();
//        ex6();
//        ex7();
        ex8();
    }

    /**
     * Write an interactive quiz. It should ask the user three multiple-choice
     * or true/false questions about something. It must keep track of how many
     * they get right, and print out a "score" at the end.
     */
    public static void ex5() {
        print("Are you ready for a quiz? (Y\\N): ");

        char inputChar;
        int inputInt;
        int score = 0;

        inputChar = readChar();
        if (inputChar != 'Y') return;

        println("\nOkay, here it comes!\n");

        println("Q1) What is the capital of Albania?\n" +
                "\t1) Sofia\n" +
                "\t2) Tirana\n" +
                "\t3) Budapest\n");
        print("> ");
        inputInt = readInt();
        if (inputInt == 2) {
            score += 1;

            println("\nThat's right!\n");
        } else {
            println("Nope, the right answer is Tirana.");
        }

        println("Q2) Can you store the value \"dog\" in a variable of type int?\n" +
                "\t1) yes\n" +
                "\t2) no");
        print("> ");
        inputInt = readInt();
        if (inputInt == 2) {
            score += 1;

            println("\nThat's right!\n");
        } else {
            println("Sorry, \"dog\" is a string. ints can only store numbers.\n");
        }

        println("Q3) What is the result of 6+4/2?\n" +
                "\t1) 5\n" +
                "\t2) 8\n" +
                "\t3) 4\n");
        print("> ");
        inputInt = readInt();
        if (inputInt == 2) {
            score += 1;

            println("\nThat's correct!\n");
        } else {
            println("Sorry, 5 is the right answer. \n");
        }

        println("Overall, you got " + score + " out of 3 correct.");
        println("Thanks for playing!");
    }

    /**
     * Write a program that asks the user for a string and returns the number
     * of vowels in that string. Hint. You may want to use the method:
     * s.indexOf(c) which returns -1 if character c is not in string s
     * Example:
     * > Enter a string: Musard
     * > The string "Musard" contains 2 vowels.
     */
    public static void ex6() {
        String input;
        int vowelsNum = 0;

        print("> Enter a string: ");
        input = readString();

        for (int i = 0; i < input.length(); i++) {
            char c = input.charAt(i);
            // handle both uppercase and lowercase characters
            c = Character.toLowerCase(c);

            switch (c) {
                case 'a':
                    // fall through
                case 'e':
                    // fall through
                case 'i':
                    // fall through
                case 'o':
                    // fall through
                case 'u':
                    // increment vowels count
                    vowelsNum += 1;
            }
        }

        println("The string \"" + input + "\" contains " + vowelsNum + " vowels.");
    }

    /**
     * Write a program that asks for a positive integer until the uses enters
     * one, and calculates the binary representation of that integer.
     * Hint: Use the modulo operator %
     * Example:
     *
     * > Enter a positive integer: -3
     * > Enter a positive integer: -88
     * > Enter a positive integer: -8
     * > The binary representation of 8 is 100
     */
    public static void ex7() {
        int input, inputOriginal;
        print("> Enter a positive integer: ");
        input = readInt();
        inputOriginal = input;

        // rerun function if input is small than 0
        if (input < 0) ex7();

        String bitstring = "";

        while (input > 0) {
            int bit = input % 2;
            int quotient = input / 2;
            bitstring = bit + bitstring;
            input = quotient;
        }

        println("The binary representation of " + inputOriginal + " is " + bitstring);
    }

    /**
     * Write a subroutine (function) that given an input string, returns
     * true or false depending on whether or not that string is a palindrome.
     * A palindrome is a sequence of characters which reads the same backward
     * or forward. For instance, "abba" and "bob" are palindromes, while "aab"
     * is not. Use the subroutine in the main  method to check the words above.
     */
    public static void ex8() {
        String input;
        print("> Enter a string: ");
        input = readString();

        // assume the input is palindrome unless proven otherwise
        boolean isPalindrome = true;
        // initialise two counters
        // counter i starts at the beginning of the word
        // counter j starts at the end of the word
        // compare characters at both counter positions
        // if characters are different, set palindrome flag to false
        // loop through half the word
        for (int i = 0, j = input.length() - 1; i < input.length() / 2; i++, j--) {
            // exit loop when palindrome already false to save resources
            if (! isPalindrome) break;
            if (input.charAt(i) != input.charAt(j)) isPalindrome = false;
        }

        if (isPalindrome) {
            println("String " + input + " is a palidinrome.");
        } else {
            println("String " + input + " is NOT a palidinrome.");
        }
    }

    /**
     *  Generic print.
     *  @param o object to print
     */
    public static void print(Object o) {
        System.out.print(o);
        IOError = false;
    }

    /**
     *  Generic println.
     *  @param o object to print
     */
    public static void println(Object o) {
        System.out.println(o);
        IOError = false;
    }

    /**
     *  Reads next char from standard input.
     *  Should perhaps set IOResult on EOF, but currently doesn't.
     *  @return next char read from standard input.
     */
    public static char readChar() {
        IOError = false;
        char result = 0;

        try {
            result = (char)System.in.read();
        } catch (Exception e) {
            IOError = true;
        }

        return result;
    }

    /**
     *  Reads next int from standard input.
     *  Sets IOResult in case of error.
     *  @return next int read from standard input.
     */
    public static int readInt() {
        IOError = false;
        Scanner scan = new Scanner(System.in);
        int result = 0;

        try {
            result = scan.nextInt();
        } catch (Exception e) {
            IOError = true;
        }

        return result;
    }

    /**
     *  Reads next string from standard input.
     *  Stops at the first empty space.
     *  Sets IOResult in case of error.
     *  @return next string read from standard input.
     */
    public static String readString() {
        IOError = false;
        Scanner scan = new Scanner(System.in);
        String result = "";

        try {
            result = scan.next();
        } catch (Exception e) {
            IOError = true;
        }

        return result;
    }
}