/*
 *  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.compiler;

import java.util.Stack;
import java.util.Hashtable;

import javax.servlet.jsp.tagext.VariableInfo;

/**
 * Common stuff for use with TagBegin and TagEndGenerators.
 *
 * @author Anil K. Vijendran
 * @author Hans Bergsten [hans@gefionsoftware.com] (changed all statics to
 *         regular instance vars and methods to avoid corrupt state and
 *         multi-threading issues)
 */
abstract class TagGeneratorBase extends GeneratorBase {
    private Stack tagHandlerStack;
    private Hashtable tagVarNumbers;

    class TagVariableData {
        String tagHandlerInstanceName;
        String tagEvalVarName;
        String tagExceptionCheckName;
        TagVariableData(String tagHandlerInstanceName, String tagEvalVarName) {
            this.tagHandlerInstanceName = tagHandlerInstanceName;
            this.tagEvalVarName = tagEvalVarName;
            this.tagExceptionCheckName = tagHandlerInstanceName + "_exceptionCheck";
        }
    }

    /**
     * Sets the tag handler nesting stack for the current page.
     * Called when an instance is created.
     */
    protected void setTagHandlerStack(Stack tagHandlerStack) {
        this.tagHandlerStack = tagHandlerStack;
    }

    /**
     * Sets the tag variable number repository for the current page.
     * Called when an instance is created.
     */
    protected void setTagVarNumbers(Hashtable tagVarNumbers) {
        this.tagVarNumbers = tagVarNumbers;
    }

    protected void tagBegin(TagVariableData tvd) {
	tagHandlerStack.push(tvd);
    }

    protected TagVariableData tagEnd() {
	return (TagVariableData) tagHandlerStack.pop();
    }

    protected TagVariableData topTag() {
	if (tagHandlerStack.empty())
	    return null;
	return (TagVariableData) tagHandlerStack.peek();
    }

    private String substitute(String name, char from, String to) {
        StringBuffer s = new StringBuffer();
        int begin = 0;
        int last = name.length();
        int end;
        while (true) {
            end = name.indexOf(from, begin);
            if (end < 0)
                end = last;
            s.append(name.substring(begin, end));
            if (end == last)
                break;
            s.append(to);
            begin = end + 1;
        }
        return (s.toString());
    }

    protected String getTagVarName(String prefix, String shortTagName) {
	if (prefix.indexOf('-') >= 0)
	    prefix = substitute(prefix, '-', "$1");
	if (prefix.indexOf('.') >= 0)
	    prefix = substitute(prefix, '.', "$2");

        if (shortTagName.indexOf('-') >= 0)
            shortTagName = substitute(shortTagName, '-', "$1");
        if (shortTagName.indexOf('.') >= 0)
            shortTagName = substitute(shortTagName, '.', "$2");
        if (shortTagName.indexOf(':') >= 0)
            shortTagName = substitute(shortTagName, ':', "$3");
	// Fix: Can probably remove the synchronization now when no vars or method is static
	synchronized (tagVarNumbers) {
	    String tag = prefix+":"+shortTagName;
	    String varName = prefix+"_"+shortTagName+"_";
	    if (tagVarNumbers.get(tag) != null) {
		Integer i = (Integer) tagVarNumbers.get(tag);
		varName = varName + i.intValue();
		tagVarNumbers.put(tag, new Integer(i.intValue()+1));
		return varName;
	    } else {
		tagVarNumbers.put(tag, new Integer(1));
		return varName+"0";
	    }
	}
    }

    protected void declareVariables(ServletWriter writer, VariableInfo[] vi,
                                           boolean declare, boolean update, int scope)
    {
        if (vi != null)
            for(int i = 0; i < vi.length; i++)
                if (vi[i].getScope() == scope) {
                    if (vi[i].getDeclare() == true && declare == true)
                        writer.println(vi[i].getClassName()+" "+vi[i].getVarName()+" = null;");
                    if (update == true)
                        writer.println(vi[i].getVarName()+" = ("+
                                       vi[i].getClassName()+") pageContext.findAttribute("
                                       +writer.quoteString(vi[i].getVarName())+");");
                }
    }
}