package stdlib;
/* ***********************************************************************
 *  Compilation:  javac In.java
 *  Execution:    java In   (basic test --- see source for required files)
 *
 *  Reads in data of various types from standard input, files, and URLs.
 *
 *************************************************************************/

import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.Scanner;
import java.util.regex.Pattern;

/**
 *  <i>Input</i>. This class provides methods for reading strings
 *  and numbers from standard input, file input, URLs, and sockets.
 *  <p>
 *  The Locale used is: language = English, country = US. This is consistent
 *  with the formatting conventions with Java floating-point literals,
 *  command-line arguments (via {@link Double#parseDouble(String)})
 *  and standard output.
 *  <p>
 *  For additional documentation, see
 *  <a href="http://introcs.cs.princeton.edu/31datatype">Section 3.1</a> of
 *  <i>Introduction to Programming in Java: An Interdisciplinary Approach</i>
 *  by Robert Sedgewick and Kevin Wayne.
 *  <p>
 *  Like {@link Scanner}, reading a token also consumes preceding Java
 *  whitespace, reading a full line consumes
 *  the following end-of-line delimeter, while reading a character consumes
 *  nothing extra.
 *  <p>
 *  Whitespace is defined in {@link Character#isWhitespace(char)}. Newlines
 *  consist of \n, \r, \r\n, and Unicode hex code points 0x2028, 0x2029, 0x0085;
 *  see <a href="http://www.docjar.com/html/api/java/util/Scanner.java.html">
 *  {@code Scanner.java}</a> (NB: Java 6u23 and earlier uses only \r, \r, \r\n).
 */
public final class In {

        private 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 */

        /**
         * Create an input stream from standard input.
         */
        public In() {
                scanner = new Scanner(new BufferedInputStream(System.in), charsetName);
                scanner.useLocale(usLocale);
        }

        /**
         * Create an input stream from a socket.
         */
        public In(java.net.Socket socket) {
                try {
                        InputStream is = socket.getInputStream();
                        scanner = new Scanner(new BufferedInputStream(is), charsetName);
                        scanner.useLocale(usLocale);
                }
                catch (IOException ioe) {
                        System.err.println("Could not open " + socket);
                }
        }

        /**
         * Create an input stream from a URL.
         */
        public In(URL url) {
                try {
                        URLConnection site = url.openConnection();
                        InputStream is     = site.getInputStream();
                        scanner            = new Scanner(new BufferedInputStream(is), charsetName);
                        scanner.useLocale(usLocale);
                }
                catch (IOException ioe) {
                        System.err.println("Could not open " + url);
                }
        }

        /**
         * Create an input stream from a file.
         */
        public In(File file) {
                try {
                        scanner = new Scanner(file, charsetName);
                        scanner.useLocale(usLocale);
                }
                catch (IOException ioe) {
                        System.err.println("Could not open " + file);
                }
        }


        /**
         * Create an input stream from a filename or web page name.
         */
        public In(String s) {
                try {
                        // first try to read file from local file system
                        File file = new File(s);
                        if (file.exists()) {
                                scanner = new Scanner(file, charsetName);
                                scanner.useLocale(usLocale);
                                return;
                        }

                        // next try for files included in jar
                        URL url = getClass().getResource(s);

                        // or URL from web
                        if (url == null) { url = new URL(s); }

                        URLConnection site = url.openConnection();
                        InputStream is     = site.getInputStream();
                        scanner            = new Scanner(new BufferedInputStream(is), charsetName);
                        scanner.useLocale(usLocale);
                }
                catch (IOException ioe) {
                        System.err.println("Could not open " + s);
                }
        }

        /**
         * Create an input stream from a given Scanner source; use with
         * {@code new Scanner(String)} to read from a string.
         * <p>
         * Note that this does not create a defensive copy, so the
         * scanner will be mutated as you read on.
         */
        public In(Scanner scanner) {
                this.scanner = scanner;
        }

        /**
         * Does the input stream exist?
         */
        public boolean exists()  {
                return scanner != null;
        }

        /* * 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 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 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 boolean hasNextChar() {
                scanner.useDelimiter(EMPTY_PATTERN);
                boolean result = scanner.hasNext();
                scanner.useDelimiter(WHITESPACE_PATTERN);
                return result;
        }


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

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

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

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

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

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

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

        /**
         * Read and return the next byte.
         */
        public 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 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 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 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 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 */

        /**
         * Close the input stream.
         */
        public void close() {
                scanner.close();
        }

        /**
         * Reads all ints from a file
         * @deprecated Clearer to use
         * {@code new In(filename)}.{@link #readAllInts()}
         */
        @Deprecated public static int[] readInts(String filename) {
                return new In(filename).readAllInts();
        }

        /**
         * Reads all doubles from a file
         * @deprecated Clearer to use
         * {@code new In(filename)}.{@link #readAllDoubles()}
         */
        @Deprecated public static double[] readDoubles(String filename) {
                return new In(filename).readAllDoubles();
        }

        /**
         * Reads all strings from a file
         * @deprecated Clearer to use
         * {@code new In(filename)}.{@link #readAllStrings()}
         */
        @Deprecated public static String[] readStrings(String filename) {
                return new In(filename).readAllStrings();
        }

        /**
         * Reads all ints from stdin
         * @deprecated Clearer to use {@link StdIn#readAllInts()}
         */
        @Deprecated public static int[] readInts() {
                return new In().readAllInts();
        }

        /**
         * Reads all doubles from stdin
         * @deprecated Clearer to use {@link StdIn#readAllDoubles()}
         */
        @Deprecated public static double[] readDoubles() {
                return new In().readAllDoubles();
        }

        /**
         * Reads all strings from stdin
         * @deprecated Clearer to use {@link StdIn#readAllStrings()}
         */
        @Deprecated public static String[] readStrings() {
                return new In().readAllStrings();
        }

        /**
         * Return true if the next value from the input stream can be interpreted as an int
         */
        public boolean hasNextInt() {
                return scanner.hasNextInt();
        }

        /**
         * Return true if the next value from the input stream can be interpreted as an double
         */
        public boolean hasNextDouble() {
                return scanner.hasNextDouble();
        }

        /**
         * Return true if the next value from the input stream can be interpreted as an float
         */
        public boolean hasNextFloat() {
                return scanner.hasNextFloat();
        }

        /**
         * Return true if the next value from the input stream can be interpreted as a long
         */
        public boolean hasNextLong() {
                return scanner.hasNextLong();
        }

        /**
         * Return true if the next value from the input stream can be interpreted as a byte
         */
        public boolean hasNextByte() {
                return scanner.hasNextByte();
        }

        /**
         * Test client.
         */
        public static void main(String[] args) {
                In in;
                String urlName = "http://introcs.cs.princeton.edu/stdlib/InTest.txt";

                // read from a URL
                System.out.println("readAll() from URL " + urlName);
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In(urlName);
                        System.out.println(in.readAll());
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();

                // read one line at a time from URL
                System.out.println("readLine() from URL " + urlName);
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In(urlName);
                        while (!in.isEmpty()) {
                                String s = in.readLine();
                                System.out.println(s);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();

                // read one string at a time from URL
                System.out.println("readString() from URL " + urlName);
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In(urlName);
                        while (!in.isEmpty()) {
                                String s = in.readString();
                                System.out.println(s);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();


                // read one line at a time from file in current directory
                System.out.println("readLine() from current directory");
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In("./InTest.txt");
                        while (!in.isEmpty()) {
                                String s = in.readLine();
                                System.out.println(s);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();


                // read one line at a time from file using relative path
                System.out.println("readLine() from relative path");
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In("../stdlib/InTest.txt");
                        while (!in.isEmpty()) {
                                String s = in.readLine();
                                System.out.println(s);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();

                // read one char at a time
                System.out.println("readChar() from file");
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In("InTest.txt");
                        while (!in.isEmpty()) {
                                char c = in.readChar();
                                System.out.print(c);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();
                System.out.println();

                // read one line at a time from absolute OS X / Linux path
                System.out.println("readLine() from absolute OS X / Linux path");
                System.out.println("---------------------------------------------------------------------------");
                in = new In("/n/fs/introcs/www/java/stdlib/InTest.txt");
                try {
                        while (!in.isEmpty()) {
                                String s = in.readLine();
                                System.out.println(s);
                        }
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();


                // read one line at a time from absolute Windows path
                System.out.println("readLine() from absolute Windows path");
                System.out.println("---------------------------------------------------------------------------");
                try {
                        in = new In("G:\\www\\introcs\\stdlib\\InTest.txt");
                        while (!in.isEmpty()) {
                                String s = in.readLine();
                                System.out.println(s);
                        }
                        System.out.println();
                }
                catch (Exception e) { System.out.println(e); }
                System.out.println();

        }

}