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();

	}

}