/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */
/*
 * $Id$
 */

package org.apache.xalan.xsltc.compiler;

import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.GETSTATIC;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.PUSH;
import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
import org.apache.xalan.xsltc.compiler.util.Util;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class Text extends Instruction {

    private String _text;
    private boolean _escaping = true;
    private boolean _ignore = false;
    private boolean _textElement = false;

    /**
     * Create a blank Text syntax tree node.
     */
    public Text() {
	_textElement = true;
    }

    /**
     * Create text syntax tree node.
     * @param text is the text to put in the node.
     */
    public Text(String text) {
	_text = text;
    }

    /**
     * Returns the text wrapped inside this node
     * @return The text wrapped inside this node
     */
    protected String getText() {
	return _text;
    }

    /**
     * Set the text for this node. Appends the given text to any already
     * existing text (using string concatenation, so use only when needed).
     * @param text is the text to wrap inside this node.
     */
    protected void setText(String text) {
	if (_text == null)
	    _text = text;
	else
	    _text = _text + text;
    }

    public void display(int indent) {
	indent(indent);
	Util.println("Text");
	indent(indent + IndentIncrement);
	Util.println(_text);
    }
		
    public void parseContents(Parser parser) {
        final String str = getAttribute("disable-output-escaping");
	if ((str != null) && (str.equals("yes"))) _escaping = false;

	parseChildren(parser);

	if (_text == null) {
	    if (_textElement) {
		_text = EMPTYSTRING;
	    }
	    else {
		_ignore = true;
	    }
	}
	else if (_textElement) {
	    if (_text.length() == 0) _ignore = true;
	}
	else if (getParent() instanceof LiteralElement) {
	    LiteralElement element = (LiteralElement)getParent();
	    String space = element.getAttribute("xml:space");
	    if ((space == null) || (!space.equals("preserve")))
        {
            int i;
            final int textLength = _text.length();
            for (i = 0; i < textLength; i++) {
                char c = _text.charAt(i);
                if (!isWhitespace(c))
                    break;
            }
            if (i == textLength)
                _ignore = true;
        }
	}
	else {
        int i;
        final int textLength = _text.length();
        for (i = 0; i < textLength; i++) 
        {
            char c = _text.charAt(i);
            if (!isWhitespace(c))
                break;
        }
        if (i == textLength)
            _ignore = true;
	}
    }

    public void ignore() {
	_ignore = true;
    }

    public boolean isIgnore() {
    	return _ignore;
    }
    
    public boolean isTextElement() {
	return _textElement;
    }

    protected boolean contextDependent() {
	return false;
    }
 
    private static boolean isWhitespace(char c)
    {
    	return (c == 0x20 || c == 0x09 || c == 0x0A || c == 0x0D);
    }
 
    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	if (!_ignore) {
	    // Turn off character escaping if so is wanted.
	    final int esc = cpg.addInterfaceMethodref(OUTPUT_HANDLER,
						      "setEscaping", "(Z)Z");
	    if (!_escaping) {
		il.append(methodGen.loadHandler());
		il.append(new PUSH(cpg, false));
		il.append(new INVOKEINTERFACE(esc, 2));
	    }

            il.append(methodGen.loadHandler());

            // Call characters(String) or characters(char[],int,int), as
            // appropriate.
            if (!canLoadAsArrayOffsetLength()) {
                final int characters = cpg.addInterfaceMethodref(OUTPUT_HANDLER,
                                                           "characters",
                                                           "("+STRING_SIG+")V");
                il.append(new PUSH(cpg, _text));
                il.append(new INVOKEINTERFACE(characters, 2));
            } else {
                final int characters = cpg.addInterfaceMethodref(OUTPUT_HANDLER,
                                                                 "characters",
                                                                 "([CII)V");
                loadAsArrayOffsetLength(classGen, methodGen);
	        il.append(new INVOKEINTERFACE(characters, 4));
            }

	    // Restore character escaping setting to whatever it was.
	    // Note: setEscaping(bool) returns the original (old) value
	    if (!_escaping) {
		il.append(methodGen.loadHandler());
		il.append(SWAP);
		il.append(new INVOKEINTERFACE(esc, 2));
		il.append(POP);
	    }
	}
	translateContents(classGen, methodGen);
    }

    /**
     * Check whether this Text node can be stored in a char[] in the translet.
     * Calling this is precondition to calling loadAsArrayOffsetLength.
     * @see #loadAsArrayOffsetLength(ClassGenerator,MethodGenerator)
     * @return true if this Text node can be
     */
    public boolean canLoadAsArrayOffsetLength() {
        // Magic number!  21845*3 == 65535.  BCEL uses a DataOutputStream to
        // serialize class files.  The Java run-time places a limit on the size
        // of String data written using a DataOutputStream - it cannot require
        // more than 64KB when represented as UTF-8.  The number of bytes
        // required to represent a Java string as UTF-8 cannot be greater
        // than three times the number of char's in the string, hence the
        // check for 21845.

        return (_text.length() <= 21845);
    }

    /**
     * Generates code that loads the array that will contain the character
     * data represented by this Text node, followed by the offset of the
     * data from the start of the array, and then the length of the data.
     *
     * The pre-condition to calling this method is that
     * canLoadAsArrayOffsetLength() returns true.
     * @see #canLoadArrayOffsetLength()
     */
    public void loadAsArrayOffsetLength(ClassGenerator classGen,
                                        MethodGenerator methodGen) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();
        final XSLTC xsltc = classGen.getParser().getXSLTC();

        // The XSLTC object keeps track of character data
        // that is to be stored in char arrays.
        final int offset = xsltc.addCharacterData(_text);
        final int length = _text.length();
        String charDataFieldName =
            STATIC_CHAR_DATA_FIELD + (xsltc.getCharacterDataCount()-1);

        il.append(new GETSTATIC(cpg.addFieldref(xsltc.getClassName(),
                                       charDataFieldName,
                                       STATIC_CHAR_DATA_FIELD_SIG)));
        il.append(new PUSH(cpg, offset));
        il.append(new PUSH(cpg, _text.length()));
    }
}