/*
 * 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.CharArrayReader;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;

import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyContent;

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. 
 *
 * @author Rajiv Mordani
 * @author Jan Luehe
 */
public class BodyContentImpl extends BodyContent {

    private static final String LINE_SEPARATOR = System.getProperty(
                                                    "line.separator");

    private char[] cb;
    private int nextChar;
    private boolean closed;

    // Enclosed writer to which any output is written
    private Writer writer;

    // See comment in setWriter()
    private int bufferSizeSave;

    /**
     * Constructor.
     */
    public BodyContentImpl(JspWriter enclosingWriter) {
        super(enclosingWriter);
	bufferSize = Constants.DEFAULT_TAG_BUFFER_SIZE;
	cb = new char[bufferSize];
	nextChar = 0;
	closed = false;
    }

    /**
     * Write a single character.
     */
    public void write(int c) throws IOException {
	if (writer != null) {
	    writer.write(c);
	} else {
	    ensureOpen();
	    if (nextChar >= bufferSize) {
		reAllocBuff (1);
	    }
	    cb[nextChar++] = (char) c;
	}
    }

    /**
     * Write a portion of an array of characters.
     *
     * <p> 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
     * <code>DiscardableBufferedWriter</code>s 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 {
	if (writer != null) {
	    writer.write(cbuf, off, len);
	} else {
	    ensureOpen();

	    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 - nextChar)
		reAllocBuff (len);
	    
	    System.arraycopy(cbuf, off, cb, nextChar, len);
	    nextChar+=len;
	}
    }

    /**
     * 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 {
	if (writer != null) {
	    writer.write(buf);
	} else {
	    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 {
	if (writer != null) {
	    writer.write(s, off, len);
	} else {
	    ensureOpen();
	    if (len >= bufferSize - nextChar)
		reAllocBuff(len);

	    s.getChars(off, off + len, cb, nextChar);
	    nextChar += len;
	}
    }

    /**
     * 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 {
	if (writer != null) {
	    writer.write(s);
	} else {
	    write(s, 0, s.length());
	}
    }

    /**
     * Write a line separator.  The line separator string is defined by the
     * system property <tt>line.separator</tt>, and is not necessarily a single
     * newline ('\n') character.
     *
     * @throws IOException If an I/O error occurs
     */
    public void newLine() throws IOException {
	if (writer != null) {
	    writer.write(LINE_SEPARATOR);
	} else {
	    write(LINE_SEPARATOR);
	}
    }

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

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

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

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

    /**
     * Print a double-precision floating-point number.  The string produced by
     * <code>{@link java.lang.String#valueOf(double)}</code> is translated into
     * bytes according to the platform's default character encoding, and these
     * bytes are written in exactly the manner of the <code>{@link
     * #write(int)}</code> method.
     *
     * @param d The <code>double</code> to be printed
     * @throws IOException
     */
    public void print(double d) throws IOException {
	if (writer != null) {
	    writer.write(String.valueOf(d));
	} else {
	    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
     * <code>{@link #write(int)}</code> method.
     *
     * @param s The array of chars to be printed
     *
     * @throws NullPointerException If <code>s</code> is <code>null</code>
     * @throws IOException
     */
    public void print(char[] s) throws IOException {
	if (writer != null) {
	    writer.write(s);
	} else {
	    write(s);
	}
    }

    /**
     * Print a string.  If the argument is <code>null</code> then the string
     * <code>"null"</code> 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
     * <code>{@link #write(int)}</code> method.
     *
     * @param s The <code>String</code> to be printed
     * @throws IOException
     */
    public void print(String s) throws IOException {
	if (s == null) s = "null";
	if (writer != null) {
	    writer.write(s);
	} else {
	    write(s);
	}
    }

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

    /**
     * Terminate the current line by writing the line separator string.  The
     * line separator string is defined by the system property
     * <code>line.separator</code>, and is not necessarily a single newline
     * character (<code>'\n'</code>).
     *
     * @throws IOException
     */
    public void println() throws IOException {
	newLine();
    }

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

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

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

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

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

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

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

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

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

    /**
     * Clear the contents of the buffer. If the buffer has been already
     * been flushed then the clear operation shall throw an IOException
     * to signal the fact that some data has already been irrevocably 
     * written to the client response stream.
     *
     * @throws IOException If an I/O error occurs
     */
    public void clear() throws IOException {
	if (writer != null) {
	    throw new IOException();
	} else {
	    nextChar = 0;
	}
    }

    /**
     * Clears the current contents of the buffer. Unlike clear(), this
     * mehtod will not throw an IOException if the buffer has already been
     * flushed. It merely clears the current content of the buffer and
     * returns.
     *
     * @throws IOException If an I/O error occurs
     */
    public void clearBuffer() throws IOException {
        if (writer == null) {
	    this.clear();
	}
    }

    /**
     * Close the stream, flushing it first.  Once a stream has been closed,
     * further write() or flush() invocations will cause an IOException to be
     * thrown.  Closing a previously-closed stream, however, has no effect.
     *
     * @throws IOException If an I/O error occurs
     */
    public void close() throws IOException {
	if (writer != null) {
	    writer.close();
	} else {
	    cb = null;	
	    closed = true;
	}
    }

    /**
     * @return the number of bytes unused in the buffer
     */
    public int getRemaining() {
	return (writer == null) ? bufferSize-nextChar : 0;
    }

    /**
     * Return the value of this BodyJspWriter as a Reader.
     * Note: this is after evaluation!!  There are no scriptlets,
     * etc in this stream.
     *
     * @return the value of this BodyJspWriter as a Reader
     */
    public Reader getReader() {
	return (writer == null) ? new CharArrayReader (cb, 0, nextChar) : null;
    }

    /**
     * Return the value of the BodyJspWriter as a String.
     * Note: this is after evaluation!!  There are no scriptlets,
     * etc in this stream.
     *
     * @return the value of the BodyJspWriter as a String
     */
    public String getString() {
	return (writer == null) ? new String(cb, 0, nextChar) : null;
    }
	
    /**
     * Write the contents of this BodyJspWriter into a Writer.
     * Subclasses are likely to do interesting things with the
     * implementation so some things are extra efficient.
     *
     * @param out The writer into which to place the contents of this body
     * evaluation
     */
    public void writeOut(Writer out) throws IOException {
	if (writer == null) {
	    out.write(cb, 0, nextChar);
	    // Flush not called as the writer passed could be a BodyContent and
	    // it doesn't allow to flush.
	}
    }

    /**
     * Sets the writer to which all output is written.
     */
    void setWriter(Writer writer) {
	this.writer = writer;
	if (writer != null) {
	    // According to the spec, the JspWriter returned by 
	    // JspContext.pushBody(java.io.Writer writer) must behave as
	    // though it were unbuffered. This means that its getBufferSize()
	    // must always return 0. The implementation of
	    // JspWriter.getBufferSize() returns the value of JspWriter's
	    // 'bufferSize' field, which is inherited by this class. 
	    // Therefore, we simply save the current 'bufferSize' (so we can 
	    // later restore it should this BodyContentImpl ever be reused by
	    // a call to PageContext.pushBody()) before setting it to 0.
	    if (bufferSize != 0) {
		bufferSizeSave = bufferSize;
		bufferSize = 0;
	    }
	} else {
	    bufferSize = bufferSizeSave;
	    clearBody();
	}
    }

    private void ensureOpen() throws IOException {
	if (closed) throw new IOException("Stream closed");
    }

    /**
     * Reallocates buffer since the spec requires it to be unbounded.
     */
    private void reAllocBuff(int len) {

        if (bufferSize + len <= cb.length) {
            bufferSize = cb.length;
            return;
        }

        if (len < cb.length) {
            len = cb.length;
        }

        bufferSize = cb.length + len;
        char[] tmp = new char[bufferSize];

	System.arraycopy(cb, 0, tmp, 0, cb.length);
	cb = tmp;
	tmp = null;

    }


}