package stdlib;
/* ***********************************************************************
 *  Compilation:  javac StdIn.java
 *  Execution:    java StdIn   (interactive test of basic functionality)
 *
 *  Reads in data of various types from standard input.
 *
 *************************************************************************/

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.regex.Pattern;

/**
 *  <i>Standard input</i>. This class provides methods for reading strings
 *  and numbers from standard input. See
 *  <a href="http://introcs.cs.princeton.edu/15inout">Section 1.5</a> of
 *  <i>Introduction to Programming in Java: An Interdisciplinary Approach</i>
 *  by Robert Sedgewick and Kevin Wayne.
 *  <p>
 *  See the technical information in the documentation of the {@link In}
 *  class, which applies to this class as well.
 */
public final class StdIn {

  // it doesn't make sense to instantiate this class
  private StdIn() {}

  private static Scanner scanner;

  /* * begin: section (1 of 2) of code duplicated from In to StdIn */

  // assume Unicode UTF-8 encoding
  private static final String charsetName = "UTF-8";

  // assume language = English, country = US for consistency with System.out.
  private static final java.util.Locale usLocale =
      new java.util.Locale("en", "US");

  // the default token separator; we maintain the invariant that this value
  // is held by the scanner's delimiter between calls
  private static final Pattern WHITESPACE_PATTERN
  = Pattern.compile("\\p{javaWhitespace}+");

  // makes whitespace characters significant
  private static final Pattern EMPTY_PATTERN
  = Pattern.compile("");

  // used to read the entire input. source:
  // http://weblogs.java.net/blog/pat/archive/2004/10/stupid_scanner_1.html
  private static final Pattern EVERYTHING_PATTERN
  = Pattern.compile("\\A");

  /* * end: section (1 of 2) of code duplicated from In to StdIn */

  /* * begin: section (2 of 2) of code duplicated from In to StdIn,
   *  with all methods changed from "public" to "public static" ***/

  /**
   * Is the input empty (except possibly for whitespace)? Use this
   * to know whether the next call to {@link #readString()},
   * {@link #readDouble()}, etc will succeed.
   */
  public static boolean isEmpty() {
    return !scanner.hasNext();
  }

  /**
   * Does the input have a next line? Use this to know whether the
   * next call to {@link #readLine()} will succeed. <p> Functionally
   * equivalent to {@link #hasNextChar()}.
   */
  public static boolean hasNextLine() {
    return scanner.hasNextLine();
  }

  /**
   * Is the input empty (including whitespace)? Use this to know
   * whether the next call to {@link #readChar()} will succeed. <p> Functionally
   * equivalent to {@link #hasNextLine()}.
   */
  public static boolean hasNextChar() {
    scanner.useDelimiter(EMPTY_PATTERN);
    boolean result = scanner.hasNext();
    scanner.useDelimiter(WHITESPACE_PATTERN);
    return result;
  }


  /**
   * Read and return the next line.
   */
  public static String readLine() {
    String line;
    try                 { line = scanner.nextLine(); }
    catch (Exception e) { line = null;               }
    return line;
  }

  /**
   * Read and return the next character.
   */
  public static char readChar() {
    scanner.useDelimiter(EMPTY_PATTERN);
    String ch = scanner.next();
    assert (ch.length() == 1) : "Internal (Std)In.readChar() error!"
    + " Please contact the authors.";
    scanner.useDelimiter(WHITESPACE_PATTERN);
    return ch.charAt(0);
  }


  /**
   * Read and return the remainder of the input as a string.
   */
  public static String readAll() {
    if (!scanner.hasNextLine())
      return "";

    String result = scanner.useDelimiter(EVERYTHING_PATTERN).next();
    // not that important to reset delimeter, since now scanner is empty
    scanner.useDelimiter(WHITESPACE_PATTERN); // but let's do it anyway
    return result;
  }


  /**
   * Read and return the next string.
   */
  public static String readString() {
    return scanner.next();
  }

  /**
   * Read and return the next int.
   */
  public static int readInt() {
    return scanner.nextInt();
  }

  /**
   * Read and return the next double.
   */
  public static double readDouble() {
    return scanner.nextDouble();
  }

  /**
   * Read and return the next float.
   */
  public static float readFloat() {
    return scanner.nextFloat();
  }

  /**
   * Read and return the next long.
   */
  public static long readLong() {
    return scanner.nextLong();
  }

  /**
   * Read and return the next short.
   */
  public static short readShort() {
    return scanner.nextShort();
  }

  /**
   * Read and return the next byte.
   */
  public static byte readByte() {
    return scanner.nextByte();
  }

  /**
   * Read and return the next boolean, allowing case-insensitive
   * "true" or "1" for true, and "false" or "0" for false.
   */
  public static boolean readBoolean() {
    String s = readString();
    if (s.equalsIgnoreCase("true"))  return true;
    if (s.equalsIgnoreCase("false")) return false;
    if (s.equals("1"))               return true;
    if (s.equals("0"))               return false;
    throw new java.util.InputMismatchException();
  }

  /**
   * Read all strings until the end of input is reached, and return them.
   */
  public static String[] readAllStrings() {
    // we could use readAll.trim().split(), but that's not consistent
    // since trim() uses characters 0x00..0x20 as whitespace
    String[] tokens = WHITESPACE_PATTERN.split(readAll());
    if (tokens.length == 0 || tokens[0].length() > 0)
      return tokens;
    String[] decapitokens = new String[tokens.length-1];
    for (int i=0; i < tokens.length-1; i++)
      decapitokens[i] = tokens[i+1];
    return decapitokens;
  }

  /**
   * Read all ints until the end of input is reached, and return them.
   */
  public static int[] readAllInts() {
    String[] fields = readAllStrings();
    int[] vals = new int[fields.length];
    for (int i = 0; i < fields.length; i++)
      vals[i] = Integer.parseInt(fields[i]);
    return vals;
  }

  /**
   * Read all doubles until the end of input is reached, and return them.
   */
  public static double[] readAllDoubles() {
    String[] fields = readAllStrings();
    double[] vals = new double[fields.length];
    for (int i = 0; i < fields.length; i++)
      vals[i] = Double.parseDouble(fields[i]);
    return vals;
  }

  /* * end: section (2 of 2) of code duplicated from In to StdIn */


  /**
   * If StdIn changes, use this to reinitialize the scanner.
   */
  private static void resync() {
    setScanner(new Scanner(new java.io.BufferedInputStream(System.in),
        charsetName));
  }

  private static void setScanner(Scanner scanner) {
    StdIn.scanner = scanner;
    StdIn.scanner.useLocale(usLocale);
  }

  // do this once when StdIn is initialized
  static {
    resync();
  }

  /**
   * Reads all ints from stdin.
   * @deprecated For more consistency, use {@link #readAllInts()}
   */
  @Deprecated public static int[] readInts() {
    return readAllInts();
  }

  /**
   * Reads all doubles from stdin.
   * @deprecated For more consistency, use {@link #readAllDoubles()}
   */
  @Deprecated public static double[] readDoubles() {
    return readAllDoubles();
  }

  /**
   * Reads all Strings from stdin.
   * @deprecated For more consistency, use {@link #readAllStrings()}
   */
  @Deprecated public static String[] readStrings() {
    return readAllStrings();
  }

  /**
   * Redirect to a file.  This is a hack to get programs to work easily in eclipse.
   * (Added by James Riely 2012/01/12.)
   */
  public static void fromFile(String filename) {
    try {
      StdIn.scanner = new Scanner(new BufferedInputStream(new FileInputStream (filename)), StdIn.charsetName);
    } catch (FileNotFoundException e) {
      throw new Error (e.getMessage ());
    }
    StdIn.scanner.useLocale(StdIn.usLocale);
  }

  /**
   * Redirect to a string.  This is a hack to get programs to work easily in eclipse.
   * (Added by James Riely 2012/01/12.)
   */
  public static void fromString(String s) {
    StdIn.scanner = new Scanner(s);
    StdIn.scanner.useLocale(StdIn.usLocale);
  }

  /**
   * Interactive test of basic functionality.
   */
  public static void main(String[] args) {

    System.out.println("Type a string: ");
    String s = StdIn.readString();
    System.out.println("Your string was: " + s);
    System.out.println();

    System.out.println("Type an int: ");
    int a = StdIn.readInt();
    System.out.println("Your int was: " + a);
    System.out.println();

    System.out.println("Type a boolean: ");
    boolean b = StdIn.readBoolean();
    System.out.println("Your boolean was: " + b);
    System.out.println();

    System.out.println("Type a double: ");
    double c = StdIn.readDouble();
    System.out.println("Your double was: " + c);
    System.out.println();

  }

}