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();

        }

}