/*
 * $Header: /home/cvs/jakarta-tomcat/src/share/org/apache/jasper/runtime/JspWriterImpl.java,v 1.10 2004/02/23 06:26:32 billbarker Exp $
 * $Revision: 1.10 $
 * $Date: 2004/02/23 06:26:32 $
 *
 *
 *  Copyright 1999-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.jasper.runtime;

import java.io.IOException;
import java.io.Writer;

import javax.servlet.ServletResponse;
import javax.servlet.jsp.JspWriter;

import org.apache.jasper.Constants;

/**
 * Write text to a character-output stream, buffering characters so as
 * to provide for the efficient writing of single characters, arrays,
 * and strings. 
 *
 * Provide support for discarding for the output that has been 
 * buffered. 
 * 
 * This needs revisiting when the buffering problems in the JSP spec
 * are fixed -akv 
 *
 * @author Anil K. Vijendran
 */
public class JspWriterImpl extends JspWriter {

    
    protected Writer out;

    protected ServletResponse response;
    
    protected char cb[];
    protected int nextChar;

    protected static int defaultCharBufferSize = Constants.DEFAULT_BUFFER_SIZE;

    protected boolean flushed = false;

    public JspWriterImpl() {
	super( defaultCharBufferSize, true );
    }

    /**
     * Create a buffered character-output stream that uses a default-sized
     * output buffer.
     *
     * @param  response  A Servlet Response
     */
    public JspWriterImpl(ServletResponse response) {
        this(response, defaultCharBufferSize, true);
    }

    /**
     * Create a new buffered character-output stream that uses an output
     * buffer of the given size.
     *
     * @param  response A Servlet Response
     * @param  sz   	Output-buffer size, a positive integer
     *
     * @exception  IllegalArgumentException  If sz is <= 0
     */
    public JspWriterImpl(ServletResponse response, int sz, 
                         boolean autoFlush) {
        super(sz, autoFlush);
        if (sz < 0)
            throw new IllegalArgumentException("Buffer size <= 0");
	this.response = response;
        cb = sz == 0 ? null : new char[sz];
	nextChar = 0;
    }

    void init( ServletResponse response, int sz, boolean autoFlush ) {
	this.response= response;
	if( sz > 0 && ( cb == null || sz > cb.length ) )
	    cb=new char[sz];
	nextChar = 0;
	this.autoFlush=autoFlush;
	this.bufferSize=sz;
    }

    /**
     * Flush the output buffer to the underlying character stream, without
     * flushing the stream itself.  This method is non-private only so that it
     * may be invoked by PrintStream.
     */
    public final void flushBuffer() throws IOException {
	synchronized (lock) {
            if (bufferSize == 0)
                return;
            flushed = true;
	    ensureOpen();
	    if (nextChar == 0)
		return;
            initOut();
            out.write(cb, 0, nextChar);
	    nextChar = 0;
	}
    }

    protected void initOut() throws IOException {
        if (out == null) {
            out = response.getWriter();
	    //System.out.println("JspWriterImpl: initOut: " + this + " " +out);
	}
    }
	

    /**
     * Discard the output buffer.
     */
    public final void clear() throws IOException {
	synchronized (lock) {
            if (bufferSize == 0)
                throw new IllegalStateException(Constants.getString("jsp.error.ise_on_clear"));
            if (flushed)
                throw new IOException(Constants.getString("jsp.error.attempt_to_clear_flushed_buffer"));
            ensureOpen();
	    nextChar = 0;
	}
    }

    public void clearBuffer() throws IOException {
	synchronized (lock) {
            if (bufferSize == 0)
                throw new IllegalStateException(Constants.getString("jsp.error.ise_on_clear"));
            ensureOpen();
	    nextChar = 0;
	}
    }

    private final void bufferOverflow() throws IOException {
        throw new IOException(Constants.getString("jsp.error.overflow"));
    }

    /**
     * Flush the stream.
     *
     */
    public void flush()  throws IOException {
        synchronized (lock) {
            flushBuffer();
            if (out != null) {
                out.flush();
		// Also flush the response buffer.
		response.flushBuffer();
	    }
        }
    }

    /**
     * Close the stream.
     *
     */
    public void close() throws IOException {
        synchronized (lock) {
            if (response == null)
                return;
            flush();
            if (out != null)
                out.close();
            out = null;
	    //            cb = null;
        }
    }

    /**
     * @return the number of bytes unused in the buffer
     */
    public int getRemaining() {
        return bufferSize - nextChar;
    }

    /** check to make sure that the stream has not been closed */
    protected void ensureOpen() throws IOException {
	if (response == null)
	    throw new IOException("Stream closed");
    }


    /**
     * Write a single character.
     *
     */
    public void write(int c) throws IOException {
        synchronized (lock) {
            ensureOpen();
            if (bufferSize == 0) {
                initOut();
                out.write(c);
            }
            else {
                if (nextChar >= bufferSize)
                    if (autoFlush)
                        flushBuffer();
                    else
                        bufferOverflow();
                cb[nextChar++] = (char) c;
            }
        }
    }

    /**
     * Our own little min method, to avoid loading java.lang.Math if we've run
     * out of file descriptors and we're trying to print a stack trace.
     */
    private int min(int a, int b) {
	if (a < b) return a;
	return b;
    }

    /**
     * Write a portion of an array of characters.
     *
     * 
 Ordinarily this method stores characters from the given array into
     * this stream's buffer, flushing the buffer to the underlying stream as
     * needed.  If the requested length is at least as large as the buffer,
     * however, then this method will flush the buffer and write the characters
     * directly to the underlying stream.  Thus redundant
     * DiscardableBufferedWriters will not copy data unnecessarily.
     *
     * @param  cbuf  A character array
     * @param  off   Offset from which to start reading characters
     * @param  len   Number of characters to write
     *
     */
    public void write(char cbuf[], int off, int len) 
        throws IOException 
    {
        synchronized (lock) {
            ensureOpen();

            if (bufferSize == 0) {
                initOut();
                out.write(cbuf, off, len);
                return;
            }

            if ((off < 0) || (off > cbuf.length) || (len < 0) ||
                ((off + len) > cbuf.length) || ((off + len) < 0)) {
                throw new IndexOutOfBoundsException();
            } else if (len == 0) {
                return;
            } 

            if (len >= bufferSize) {
                /* If the request length exceeds the size of the output buffer,
                   flush the buffer and then write the data directly.  In this
                   way buffered streams will cascade harmlessly. */
                if (autoFlush)
                    flushBuffer();
                else
                    bufferOverflow();
		initOut();
                out.write(cbuf, off, len);
                return;
            }

            int b = off, t = off + len;
            while (b < t) {
                int d = min(bufferSize - nextChar, t - b);
                System.arraycopy(cbuf, b, cb, nextChar, d);
                b += d;
                nextChar += d;
                if (nextChar >= bufferSize) 
                    if (autoFlush)
                        flushBuffer();
                    else
                        bufferOverflow();
            }
        }
    }

    /**
     * Write an array of characters.  This method cannot be inherited from the
     * Writer class because it must suppress I/O exceptions.
     */
    public void write(char buf[]) throws IOException {
	write(buf, 0, buf.length);
    }

    /**
     * Write a portion of a String.
     *
     * @param  s     String to be written
     * @param  off   Offset from which to start reading characters
     * @param  len   Number of characters to be written
     *
     */
    public void write(String s, int off, int len) throws IOException {
        synchronized (lock) {
            ensureOpen();
            if (bufferSize == 0) {
                initOut();
                out.write(s, off, len);
                return;
            }
            int b = off, t = off + len;
            while (b < t) {
                int d = min(bufferSize - nextChar, t - b);
                s.getChars(b, b + d, cb, nextChar);
                b += d;
                nextChar += d;
                if (nextChar >= bufferSize) 
                    if (autoFlush)
                        flushBuffer();
                    else
                        bufferOverflow();
            }
        }
    }

    /**
     * Write a string.  This method cannot be inherited from the Writer class
     * because it must suppress I/O exceptions.
     */
    public void write(String s) throws IOException {
	write(s, 0, s.length());
    }

    static String lineSeparator;
    static {
	try {
	    lineSeparator =  System.getProperty("line.separator");
	} catch( RuntimeException ex ) {
	    lineSeparator="\r\n";
	}
    }

    /**
     * Write a line separator.  The line separator string is defined by the
     * system property line.separator, and is not necessarily a single
     * newline ('\n') character.
     *
     * @exception  IOException  If an I/O error occurs
     */
    
    public void newLine() throws IOException {
	synchronized (lock) {
	    write(lineSeparator);
	}
    }


    /* Methods that do not terminate lines */

    /**
     * Print a boolean value.  The string produced by {@link
     * java.lang.String#valueOf(boolean)} is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link
     * #write(int)} method.
     *
     * @param      b   The boolean to be printed
     */
    public void print(boolean b) throws IOException {
	write(b ? "true" : "false");
    }

    /**
     * Print a character.  The character is translated into one or more bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link
     * #write(int)} method.
     *
     * @param      c   The char to be printed
     */
    public void print(char c) throws IOException {
	write(String.valueOf(c));
    }

    /**
     * Print an integer.  The string produced by {@link
     * java.lang.String#valueOf(int)} is translated into bytes according
     * to the platform's default character encoding, and these bytes are
     * written in exactly the manner of the {@link #write(int)}
     * method.
     *
     * @param      i   The int to be printed
     * @see        java.lang.Integer#toString(int)
     */
    public void print(int i) throws IOException {
	write(String.valueOf(i));
    }

    /**
     * Print a long integer.  The string produced by {@link
     * java.lang.String#valueOf(long)} is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link #write(int)}
     * method.
     *
     * @param      l   The long to be printed
     * @see        java.lang.Long#toString(long)
     */
    public void print(long l) throws IOException {
	write(String.valueOf(l));
    }

    /**
     * Print a floating-point number.  The string produced by {@link
     * java.lang.String#valueOf(float)} is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link #write(int)}
     * method.
     *
     * @param      f   The float to be printed
     * @see        java.lang.Float#toString(float)
     */
    public void print(float f) throws IOException {
	write(String.valueOf(f));
    }

    /**
     * Print a double-precision floating-point number.  The string produced by
     * {@link java.lang.String#valueOf(double)} is translated into
     * bytes according to the platform's default character encoding, and these
     * bytes are written in exactly the manner of the {@link
     * #write(int)} method.
     *
     * @param      d   The double to be printed
     * @see        java.lang.Double#toString(double)
     */
    public void print(double d) throws IOException {
	write(String.valueOf(d));
    }

    /**
     * Print an array of characters.  The characters are converted into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link #write(int)}
     * method.
     *
     * @param      s   The array of chars to be printed
     *
     * @throws  NullPointerException  If s is null
     */
    public void print(char s[]) throws IOException {
	write(s);
    }

    /**
     * Print a string.  If the argument is null then the string
     * "null" is printed.  Otherwise, the string's characters are
     * converted into bytes according to the platform's default character
     * encoding, and these bytes are written in exactly the manner of the
     * {@link #write(int)} method.
     *
     * @param      s   The String to be printed
     */
    public void print(String s) throws IOException {
	if (s == null) {
	    s = "null";
	}
	write(s);
    }

    /**
     * Print an object.  The string produced by the {@link
     * java.lang.String#valueOf(Object)} method is translated into bytes
     * according to the platform's default character encoding, and these bytes
     * are written in exactly the manner of the {@link #write(int)}
     * method.
     *
     * @param      obj   The Object to be printed
     * @see        java.lang.Object#toString()
     */
    public void print(Object obj) throws IOException {
	write(String.valueOf(obj));
    }

    /* Methods that do terminate lines */

    /**
     * Terminate the current line by writing the line separator string.  The
     * line separator string is defined by the system property
     * line.separator, and is not necessarily a single newline
     * character ('\n').
     *
     * Need to change this from PrintWriter because the default
     * println() writes  to the sink directly instead of through the
     * write method...  
     */
    public void println() throws IOException {
	newLine();
    }

    /**
     * Print a boolean value and then terminate the line.  This method behaves
     * as though it invokes {@link #print(boolean)} and then
     * {@link #println()}.
     */
    public void println(boolean x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print a character and then terminate the line.  This method behaves as
     * though it invokes {@link #print(char)} and then {@link
     * #println()}.
     */
    public void println(char x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print an integer and then terminate the line.  This method behaves as
     * though it invokes {@link #print(int)} and then {@link
     * #println()}.
     */
    public void println(int x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print a long integer and then terminate the line.  This method behaves
     * as though it invokes {@link #print(long)} and then
     * {@link #println()}.
     */
    public void println(long x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print a floating-point number and then terminate the line.  This method
     * behaves as though it invokes {@link #print(float)} and then
     * {@link #println()}.
     */
    public void println(float x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print a double-precision floating-point number and then terminate the
     * line.  This method behaves as though it invokes {@link
     * #print(double)} and then {@link #println()}.
     */
    public void println(double x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print an array of characters and then terminate the line.  This method
     * behaves as though it invokes {@link #print(char[])} and then
     * {@link #println()}.
     */
    public void println(char x[]) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print a String and then terminate the line.  This method behaves as
     * though it invokes {@link #print(String)} and then
     * {@link #println()}.
     */
    public void println(String x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /**
     * Print an Object and then terminate the line.  This method behaves as
     * though it invokes {@link #print(Object)} and then
     * {@link #println()}.
     */
    public void println(Object x) throws IOException {
	synchronized (lock) {
	    print(x);
	    println();
	}
    }

    /** Package-level access
     */
    void recycle() {
	flushed = false;
	nextChar = 0;
    }
}