import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * The TextReader class provides methods for reading data expressed in human-readable
 * character format.  A TextReader can be used as a wrapper for any Reader or
 * InputStream to enable easy character-based input.
 * 
 * Note that all of the input methods in this class throw errors of type
 * IOException.  An IOException can occur when an attempt is made to read
 * data from the input source.  An error can occur if an attempt is made to
 * read past the end of the input source; the exception in this case is of
 * type TextReader.EndOfStreamError, which is a subclass of IOException.
 * An error can also occur if an attempt is made to read data of a particular
 * type from the input and the next item in input is not of the correct type;
 * in this case, the error is of type TextReader.BadDataException, which is
 * another subclass of IOException.
 * 
 * Once an input stream has been wrapped in a TextReader, data should only be
 * read from the stream using the wrapper.  This is because the TextReader reads
 * and buffers some data internally, and any data that has been buffered is not
 * available for reading except through the TextReader.
 */
public class TextReader implements AutoCloseable{

    // "implments AutoCloseable" was added in July 2014 to make it possible to use
    // TextReader as a resource in try..catch.  This did not require any
    // other change to the class.

    /**
     * The value returned by the peek() method when the input is at end-of-stream.
     * (The value of this constant is (char)0xFFFF.)
     */
    public final char EOF = (char)0xFFFF; 

    /**
     * The value returned by the peek() method when the input is at end-of-line.
     * The value of this constant is the character '\n'.
     */
    public final char EOLN = '\n'; 

    /**
     * Represents the error of trying to read past the end of the input source
     * of the TextReader.  Users of the class could catch this exception to
     * detect end-of-stream.  This is a subclass of IOException, so catching
     * IOException will also catch end-of-stream errors.
     */
    public static class EndOfStreamException extends IOException {
        public EndOfStreamException() {
            super("Attempt to read past end-of-stream.");
        }
    }

    /**
     * Represents the error that occurs when an attempt is made to read some type
     * of data, and the next item in the stream is not of the correct type.  
     * This is a subclass of IOException, so catching
     * IOException will also catch BadDataException.
     */
    public static class BadDataException extends IOException {
        public BadDataException(String errorMessage) {
            super(errorMessage);
        }
    }



    // ***************************** Constructors and closing *********************


    /**
     * Create a TextReader that will take its input from a specified Reader.
     * @s the non-null Reader from which the TextReader will read.
     * @throws NullPointerException if s is null.
     */
    public TextReader(Reader s) {
        if ( s == null )
            throw new NullPointerException("Can't create a TextReader for a null stream.");
        if (s instanceof BufferedReader)
            in = (BufferedReader)s;
        else
            in = new BufferedReader(s);
    }


    /**
     * Create a TextReader that will take its input from a specified InputStream.
     * (Internally, the InputStream is wrapped in a Reader of type InputStreamReader.)
     * @s the non-null InputStream from which the TextReader will read.
     * @throws NullPointerException if s is null.
     */
    public TextReader(InputStream s) {
        this( new InputStreamReader(s) );
    }


    /**
     * Closes the stream that is the input source for this TextReader by
     * calling its close() method.  Does not throw any exceptions; if
     * an exception occurs when the input source is closed, that exception
     * is ignored.
     */
    public void close()  {
        try {    
            in.close();
        }
        catch (IOException e) {
        }
    }


    // *************************** Input Methods *********************************

    /**
     * Test whether the next character in the input source is an end-of-line.  Note that
     * this method does NOT skip whitespace before testing for end-of-line -- if you want to do
     * that, call skipBlanks() first.
     */
    public boolean eoln() throws IOException { 
        return peek() == '\n'; 
    }

    /**
     * Test whether the next character in the input source is an end-of-file.  Note that
     * this method does NOT skip whitespace before testing for end-of-line -- if you want to do
     * that, call skipBlanks() or skipWhitespace() first.
     */
    public boolean eof() throws IOException  { 
        return peek() == EOF; 
    }

    /**
     * Reads the next character from the input source.  The character can be a whitespace
     * character; compare this to the getChar() method, which skips over whitespace and returns the
     * next non-whitespace character.  An end-of-line is always returned as the character '\n', even
     * when the actual end-of-line in the input source is something else, such as '\r' or "\r\n".
     */
    public char getAnyChar() throws IOException { 
        return readChar(); 
    }

    /**
     * Returns the next character in the input source, without actually removing that
     * character from the input.  The character can be a whitespace character and can be the
     * end-of-file character (specified by the constant TextIO.EOF). An end-of-line is always returned 
     * as the character '\n', even when the actual end-of-line in the input source is something else, 
     * such as '\r' or "\r\n". 
     */
    public char peek() throws IOException { 
        return lookChar();
    }

    /**
     * Skips over any whitespace characters, except for end-of-lines.  After this method is called,
     * the next input character is either an end-of-line, an end-of-file, or a non-whitespace character.
     */
    public void skipBlanks() throws IOException { 
        char ch=lookChar();
        while (ch != EOF && ch != '\n' && Character.isWhitespace(ch)) {
            readChar();
            ch = lookChar();
        }
    }

    /**
     * Skips over any whitespace characters, including for end-of-lines.  After this method is called,
     * the next input character is either an end-of-file or a non-whitespace character.
     */
    private void skipWhitespace()  throws IOException{
        char ch=lookChar();
        while (ch != EOF && Character.isWhitespace(ch)) {
            readChar();
            ch = lookChar();
        }
    }

    /**
     * Skips whitespace characters and then reads a value of type byte from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public byte getlnByte()  throws IOException{ 
        byte x=getByte(); 
        emptyBuffer(); 
        return x; 
    }

    /**
     * Skips whitespace characters and then reads a value of type short from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public short getlnShort() throws IOException {
        short x=getShort();
        emptyBuffer(); 
        return x; 
    }

    /**
     * Skips whitespace characters and then reads a value of type int from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public int getlnInt() throws IOException { 
        int x=getInt(); 
        emptyBuffer(); 
        return x; 
    }

    /**
     * Skips whitespace characters and then reads a value of type long from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public long getlnLong() throws IOException {
        long x=getLong(); 
        emptyBuffer(); 
        return x;
    }

    /**
     * Skips whitespace characters and then reads a value of type float from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public float getlnFloat() throws IOException {
        float x=getFloat(); 
        emptyBuffer(); 
        return x;
    }

    /**
     * Skips whitespace characters and then reads a value of type double from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public double getlnDouble() throws IOException { 
        double x=getDouble(); 
        emptyBuffer(); 
        return x; 
    }

    /**
     * Skips whitespace characters and then reads a value of type char from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source.
     */
    public char getlnChar() throws IOException {
        char x=getChar(); 
        emptyBuffer(); 
        return x;
    }

    /**
     * Skips whitespace characters and then reads a value of type double from input, 
     * discarding the rest of the current line of input (including the next end-of-line 
     * character, if any).  An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input. 
     * <p>Legal inputs for a boolean input are: true, t, yes, y, 1, false, f, no, n, 
     * and 0; letters can be either upper case or lower case. One "word" of input is read, 
     * using the getWord() method, and it must be one of these; note that the "word" 
     * must be terminated by a whitespace character (or end-of-file).
     */
    public boolean getlnBoolean() throws IOException { 
        boolean x=getBoolean(); 
        emptyBuffer();
        return x; 
    }

    /**
     * Skips whitespace characters and then reads one "word" from input, discarding the rest of 
     * the current line of input (including the next end-of-line character, if any).  A word is 
     * defined as a sequence of non-whitespace characters (not just letters!).  An error occurs 
     * if an attempt is made to read past end-of-file or if an IOException is thrown when an 
     * attempt is made to read data from the input source.
     */
    public String getlnWord() throws IOException {
        String x=getWord(); 
        emptyBuffer(); 
        return x; 
    }

    /**
     * This is identical to getln().
     */
    public String getlnString() throws IOException {
        return getln();
    } 

    /**
     * Reads all the characters from the input source, up to the next end-of-line.  The end-of-line
     * is read but is not included in the return value.  Any other whitespace characters on the line 
     * are retained, even if they occur at the start of input.  The return value will be an empty 
     * string if there are no characters before the end-of-line.  An error occurs if an attempt is 
     * made to read past end-of-file or if an IOException is thrown when an attempt is made to 
     * read data from the input source.
     */
    public String getln() throws IOException {
        StringBuffer s = new StringBuffer(100);
        char ch = readChar();
        while (ch != '\n') {
            s.append(ch);
            ch = readChar();
        }
        return s.toString();
    }

    /**
     * Skips whitespace characters and then reads a value of type byte from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public byte getByte() throws IOException   { 
        return (byte)readInteger(-128L,127L); 
    }

    /**
     * Skips whitespace characters and then reads a value of type short from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public short getShort()  throws IOException{ 
        return (short)readInteger(-32768L,32767L);
    }   

    /**
     * Skips whitespace characters and then reads a value of type int from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public int getInt()   throws IOException   { 
        return (int)readInteger(Integer.MIN_VALUE, Integer.MAX_VALUE);
    }

    /**
     * Skips whitespace characters and then reads a value of type long from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public long getLong()  throws IOException  { 
        return readInteger(Long.MIN_VALUE, Long.MAX_VALUE); 
    }

    /**
     * Skips whitespace characters and then reads a value of type char from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public char getChar() throws IOException { 
        skipWhitespace();
        return readChar();
    }

    /**
     * Skips whitespace characters and then reads a value of type float from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public float getFloat() throws IOException {
        float x = 0.0F;
        while (true) {
            String str = readRealString();
            if (str == null) {
                errorMessage("Floating point number not found.",
                        "Real number in the range " + (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
            }
            else {
                try { 
                    x = Float.parseFloat(str); 
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal floating point input, " + str + ".",
                            "Real number in the range " +  (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
                    continue;
                }
                if (Float.isInfinite(x)) {
                    errorMessage("Floating point input outside of legal range, " + str + ".",
                            "Real number in the range " +  (-Float.MAX_VALUE) + " to " + Float.MAX_VALUE);
                    continue;
                }
                break;
            }
        }
        return x;
    }

    /**
     * Skips whitespace characters and then reads a value of type double from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     */
    public double getDouble() throws IOException {
        double x = 0.0;
        while (true) {
            String str = readRealString();
            if (str == null) {
                errorMessage("Floating point number not found.",
                        "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
            }
            else {
                try { 
                    x = Double.parseDouble(str); 
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal floating point input, " + str + ".",
                            "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
                    continue;
                }
                if (Double.isInfinite(x)) {
                    errorMessage("Floating point input outside of legal range, " + str + ".",
                            "Real number in the range " + (-Double.MAX_VALUE) + " to " + Double.MAX_VALUE);
                    continue;
                }
                break;
            }
        }
        return x;
    }

    /**
     * Skips whitespace characters and then reads one "word" from input.  Any characters that
     * remain on the line are saved for subsequent input operations.  A word is 
     * defined as a sequence of non-whitespace characters (not just letters!).  An error occurs 
     * if an attempt is made to read past end-of-file or if an IOException is thrown when an 
     * attempt is made to read data from the input source.
     */
    public String getWord() throws IOException {
        skipWhitespace();
        StringBuffer str = new StringBuffer(50);
        char ch = lookChar();
        while (ch == EOF || !Character.isWhitespace(ch)) {
            str.append(readChar());
            ch = lookChar();
        }
        return str.toString();
    }


    /**
     * Skips whitespace characters and then reads a value of type boolean from input.
     * Any characters that remain on the line are saved for subsequent input operations.
     * An error occurs if an attempt is made to read past end-of-file,
     * or if an IOException is thrown when an attempt is made to read data from the
     * input source, or if a value of the correct type is not found in the input.
     * <p>Legal inputs for a boolean input are: true, t, yes, y, 1, false, f, no, n, 
     * and 0; letters can be either upper case or lower case. One "word" of input is 
     * read, using the getWord() method, and it must be one of these; note that the "word"  
     * must be terminated by a whitespace character (or end-of-file).
     */
    public boolean getBoolean() throws IOException {
        boolean ans = false;
        while (true) {
            String s = getWord();
            if ( s.equalsIgnoreCase("true") || s.equalsIgnoreCase("t") ||
                    s.equalsIgnoreCase("yes")  || s.equalsIgnoreCase("y") ||
                    s.equals("1") ) {
                ans = true;
                break;
            }
            else if ( s.equalsIgnoreCase("false") || s.equalsIgnoreCase("f") ||
                    s.equalsIgnoreCase("no")  || s.equalsIgnoreCase("n") ||
                    s.equals("0") ) {
                ans = false;
                break;
            }
            else
                errorMessage("Illegal boolean input value.",
                        "one of:  true, false, t, f, yes, no, y, n, 0, or 1");
        }
        return ans;
    }

    // ***************** Everything beyond this point is private implementation detail *******************

    private BufferedReader in;  // The actual source of the input.

    private Matcher integerMatcher;  // Used for reading integer numbers; created from the integer Regex Pattern.
    private Matcher floatMatcher;   // Used for reading floating point numbers; created from the floatRegex Pattern.
    private final Pattern integerRegex = Pattern.compile("(\\+|-)?[0-9]+");
    private final Pattern floatRegex = Pattern.compile("(\\+|-)?(([0-9]+(\\.[0-9]*)?)|(\\.[0-9]+))((e|E)(\\+|-)?[0-9]+)?");

    private String buffer = null;  // One line read from input.
    private int pos = 0;           // Position of next char in input line that has not yet been processed.

    private String readRealString() throws IOException {   // read chars from input following syntax of real numbers
        skipWhitespace();
        if (lookChar() == EOF)
            return null;
        if (floatMatcher == null)
            floatMatcher = floatRegex.matcher(buffer);
        floatMatcher.region(pos,buffer.length());
        if (floatMatcher.lookingAt()) {
            String str = floatMatcher.group();
            pos = floatMatcher.end();
            return str;
        }
        else 
            return null;
    }

    private String readIntegerString() throws IOException {  // read chars from input following syntax of integers
        skipWhitespace();
        if (lookChar() == EOF)
            return null;
        if (integerMatcher == null)
            integerMatcher = integerRegex.matcher(buffer);
        integerMatcher.region(pos,buffer.length());
        if (integerMatcher.lookingAt()) {
            String str = integerMatcher.group();
            pos = integerMatcher.end();
            return str;
        }
        else 
            return null;
    }

    private long readInteger(long min, long max) throws IOException {  // read long integer, limited to specified range
        long x=0;
        while (true) {
            String s = readIntegerString();
            if (s == null){
                errorMessage("Integer value not found in input.",
                        "Integer in the range " + min + " to " + max);
            }
            else {
                String str = s.toString();
                try { 
                    x = Long.parseLong(str);
                }
                catch (NumberFormatException e) {
                    errorMessage("Illegal integer input, " + str + ".",
                            "Integer in the range " + min + " to " + max);
                    continue;
                }
                if (x < min || x > max) {
                    errorMessage("Integer input outside of legal range, " + str + ".",
                            "Integer in the range " + min + " to " + max);
                    continue;
                }
                break;
            }
        }
        return x;
    }


    private void errorMessage(String message, String expecting) throws IOException {  // Report error on input.
        throw new BadDataException("Error in input:  " + message + 
                "; Expecting " + expecting);
    }

    private char lookChar() throws IOException {  // return next character from input
        if (buffer == null || pos > buffer.length())
            fillBuffer();
        if (buffer == null)
            return EOF;
        else if (pos == buffer.length())
            return '\n';
        else 
            return buffer.charAt(pos);
    }

    private char readChar() throws IOException {  // return and discard next character from input
        char ch = lookChar();
        if (buffer == null) {
            throw new EndOfStreamException();
        }
        pos++;
        return ch;
    }

    private void fillBuffer() throws IOException {    // Wait for user to type a line and press return,
        buffer = in.readLine();
        pos = 0;
        floatMatcher = null;
        integerMatcher = null;
    }

    private void emptyBuffer() {   // discard the rest of the current line of input
        buffer = null;
    }



} // end of class TextReader