/*  Tiffany Chiu
    October 4, 2018
    3.2: Functions */
import java.util.Scanner;
import java.text.DecimalFormat;
class Main {
  public static void main(String[] args) {

    // new Scanner
    Scanner sc = new Scanner (System.in);
    Scanner ss = new Scanner (System.in);

    // new decimal format
    DecimalFormat d = new DecimalFormat (".##");

/* Question 1
noteToFreq: this program allows the user to input a note, and outputs the frequency. */



    System.out.println ("-------------------- \n \nQuestion 1 \n ");

      // Declare variables
    String note;
    double frequency;

      // User inputs a note
    System.out.print ("Enter a note: ");
    note = ss.nextLine ();
    note = note.toUpperCase();

      // The frequency is output
    frequency = noteToFreq(note);   // calls for the noteToFreq function

    if (frequency > 1) {
    System.out.println (note + " has a frequency of " + d.format(frequency) + " Hz.");
    }
    else {
      System.out.println ("Invalid input.");
    }

/*Question 2
freqToNote: this program allows the user to input a frequency, and outputs the note. */

    System.out.println ("-------------------- \n \nQuestion 2 \n ");

      // User inputs a frequency
    System.out.print ("Enter a frequency (Hz): ");
    frequency = sc.nextDouble();

      // The note is output
    note = freqToNote(frequency);   // calls for the freqToNote function

    if (frequency >= 260.63 && frequency <= 494.88) {
      System.out.println (note);
    }

/* Question 3
passChecker: this program takes a username and password from the user and outputs whether it was a
"successful login" (i.e. if the password matched the corresponding username). */

  System.out.println ("-------------------- \n \nQuestion 3 \n ");

    // Declare variables and arrays
  String user, pass;
  String userList[] = new String[] {"Tiffany", "325318301", "@tiffanyc_"};
  String passList[] = new String[] {"Chiu", "tdsb", "abcd123"};

    // User inputs username and password
  System.out.print ("Username: ");
  user = ss.nextLine();
  System.out.print ("Password: ");
  pass = ss.nextLine();

    // Output
  System.out.println (passChecker (user, pass, userList, passList));

/* Question 4
palindromeChecker(): this program checks whether a string is a palindrome. */

  System.out.println ("-------------------- \n \nQuestion 4 \n ");

    // Declare variables
  boolean palindrome;
  String phrase;

    // User input
  System.out.print ("Enter a word or phrase: ");
  phrase = ss.nextLine ();

  palindrome = palindromeChecker(phrase);

  System.out.println (palindrome);



  }


  // Question 1 noteToFreq
  public static double noteToFreq(String note) {  // This function reads a note and outputs its frequency

    // Declare variables
    double noteA, noteB, noteC, noteD, noteE, noteF, noteG, freq;
    int octave;

    /* Initialize; Assign frequency values for notes A - G in the first octave, because frequencies in higher octaves are
    power functions of the lowest frequency of each note. */
    noteC = 16.352;
    noteD = 18.354;
    noteE = 20.602;
    noteF = 21.827;
    noteG = 24.50;
    noteA = 27.50;
    noteB = 30.8675;

    if (note.length()==2) {   // does not run the following code unless the length of the string is 2

    note = note.toUpperCase ();
    freq = 0;

    octave = (Integer.parseInt((note.substring(1))));     // Separates the octave value from the note as an integer value

      if (octave<=8 && octave>=0) {     // does not run the following code if the value is not between 0 and 8

      if (note.substring (0,1).equals ("C")) {      // If the note is C (regardless of octave), the frequency is equal to the frequency of C0 times 2 to the power of the octave
        freq = ((noteC)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("D")) {   // If the note is D, the frequency is the frequency of D0 times 2 to the power of the octave
        freq = ((noteD)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("E")) {   // If the note is E, the frequency is the frequency of E0 times 2 to the power of the octave
        freq = ((noteE)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("F")) {   // If the note is F, the frequency is the frequency of F0 times 2 to the power of the octave
        freq = ((noteF)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("G")) {   // If the note is G, the frequency is the frequency of G0 times 2 to the power of the octave
        freq = ((noteG)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("A")) {   // If the note is A, the frequency is the frequency of A0 times 2 to the power of the octave
        freq = ((noteA)*Math.pow(2,octave));
      }
      else if (note.substring (0,1).equals ("B")) {   // If the note is B, the frequency is the frequency of B0 times 2 to the power of the octave
        freq = ((noteB)*Math.pow(2,octave));
      }
      else {
        System.out.println ("Invalid note");    // If all statements are false, the note is invalid
      } }

      return freq;
    }
    return -1;
  }

  // Question 2 freqToNote
  public static String freqToNote(double freq) {  // This function reads a frequency and outputs the note (with a tolerance of +/- 1.0 Hz)

    // Declare variables
    double noteA, noteB, noteC, noteD, noteE, noteF, noteG;
    String note;

    // Initialize
    noteC = 261.63;
    noteD = 293.66;
    noteE = 329.63;
    noteF = 349.23;
    noteG = 392.00;
    noteA = 440.00;
    noteB = 493.88;

    note = "";

    if (freq <= (noteC + 1.0) && freq >= (noteC - 1.0)) {   // If the frequency is within +/- 1 Hz of that of C4, the note is C4
      note = "C4";
    }
    else if (freq <= (noteD + 1.0) && freq >= (noteD - 1.0)) {    // If the frequency is within +/- 1 Hz of that of D4, the note is D4
      note = "D4";
    }
    else if (freq <= (noteE + 1.0) && freq >= (noteE - 1.0)) {    // If the frequency is within +/- 1 Hz of that of E4, the note is E4
      note = "E4";
    }
    else if (freq <= (noteF + 1.0) && freq >= (noteF - 1.0)) {    // If the frequency is within +/- 1 Hz of that of F4, the note is F4
      note = "F4";
    }
    else if (freq <= (noteG + 1.0) && freq >= (noteG - 1.0)) {    // If the frequency is within +/- 1 Hz of that of G4, the note is G4
      note = "G4";
    }
    else if (freq <= (noteA + 1.0) && freq >= (noteA - 1.0)) {    // If the frequency is within +/- 1 Hz of that of A4, the note is A4
      note = "A4";
    }
    else if (freq <= (noteB + 1.0) && freq >= (noteB - 1.0)) {    // If the frequency is within +/- 1 Hz of that of B4, the note is B4
      note = "B4";
    }
    else {          // If all statements are false, the note is not within the 5th octave
      System.out.println ("That frequency does not correspond to a known note.");
    }

    return note;

  }

  // Question 3 passChecker
  public static boolean passChecker(String user, String pass, String userList[], String passList[]) {

    // Declare variables
    boolean login = true;

    if (pass.equals ("")) {
      login = true;
    }
    else {

      for (int i = 0; i < userList.length; i++) {
          if (user.equals(userList[i]) && pass.equals(passList[i])) {
            login = true;
          }
          else {
            login = false;
          }
      }
    }
    return login;
  }

  // Question 4 palindromeChecker
  public static boolean palindromeChecker(String phrase) {

    // Declare variables
    String phraseBackwards;
    boolean palindrome;
    int phraseLength;
    char [] phraseLetters;

    phraseBackwards = "";
    phrase = phrase.toLowerCase();
    phrase = phrase.replaceAll ("\\W", "");
    System.out.print (phrase);
    phraseLetters = phrase.toCharArray ();
    phraseLength = phrase.length() - 1;

  for (int u = phraseLength; u >= 0; u--)
  {
    phraseBackwards += (phrase.charAt (u));
  }

   if (phraseBackwards.equals(phrase)) {
     palindrome = true;
   }
   else {
     palindrome = false;
   }
    return palindrome;
  }

}