/*
 * @(#)$Id$
 *
 * Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 *
 */

package com.sun.xslt.compiler;

import java.util.Vector;
import com.sun.xml.tree.ElementEx;
import com.sun.xslt.compiler.util.Type;
import com.sun.xslt.compiler.util.ReferenceType;
import de.fub.bytecode.generic.Instruction;
import de.fub.bytecode.generic.*;
import de.fub.bytecode.classfile.Field;
import com.sun.xslt.compiler.util.*;

final class Param extends TopLevelElement {
    private QName      _name;
    private boolean    _isLocal;	// true if the param is local
    private Expression _select;
    private Type       _type;
    // a JavaClass construct to refer to a JVM var
    private LocalVariableGen _local;
    // cached JavaClass instruction to push the contents of this var
    private Instruction _loadInstruction;
    // references to this variable (when local)
    private Vector     _refs = new Vector(2);
    // to make sure parameter field is not added twice
    private boolean    _compiled = false;

    public void display(int indent) {
	indent(indent);
	System.out.println("param " + _name);
	if (_select != null) {
	    indent(indent + IndentIncrement);
	    System.out.println("select " + _select.toString());
	}
	displayContents(indent + IndentIncrement);
    }

    public void addReference(ParameterRef pref) {
System.out.println("GTM> In  Param.addReference, param ref = " + pref);
	_refs.addElement(pref);
    }

    public void removeReference(ParameterRef pref) {
	_refs.remove(pref);
    }
    
    public void removeReference(ParameterRef pref, MethodGenerator methodGen) {
System.out.println("GTM> In Param.removeReference, param ref = " + pref);
System.out.println("GTM> In Param.removeReference, _refs = " + _refs);
	_refs.remove(pref);
	if (_refs.isEmpty()) {
	    _local.setEnd(methodGen.getInstructionList().getEnd());
	    methodGen.removeLocalVariable(_local);
	    _refs = null;
	    _local = null;
	}
    }

    public Instruction loadInstruction() {
	final Instruction instr = _loadInstruction;
	return instr != null
	    ? instr : (_loadInstruction = _type.LOAD(_local.getIndex()));
    }
    
    public Type getType() {
	return _type;
    }

    public boolean isLocal() {
	return _isLocal;
    }

    public QName getName() {
	return _name;
    }

    public void parseContents(ElementEx element, Parser parser) {
	// Parse attributes name and select (if present)
	final String name = element.getAttribute("name");

	if (name.length() > 0) {
	    _name = parser.getQName(name);
	}
        else {
	    reportError(element, parser, ErrorMsg.NREQATTR_ERR, "name");
        }

	// check whether variable/param of the same name is already in scope
	if (parser.lookupVariable(_name) != null) {
	    ErrorMsg error = new ErrorMsg(ErrorMsg.VARREDEF_ERR, _name, this);
	    parser.addError(error);
	}
	
	final String select = element.getAttribute("select");
	if (select.length() > 0) {
	    _select = parser.parseExpression(this, element, "select");
	}

	// Children must be parsed first -> static scoping
	parseChildren(element, parser);

	// Add a ref to this param to its enclosing construct
	final SyntaxTreeNode parent = getParent();
	if (parent instanceof Stylesheet) {
	    _isLocal = false;
	    ((Stylesheet)parent).addParam(this);
	    //!! check for redef
	    parser.getSymbolTable().addParam(this);
	}
	else {
	    _isLocal = true;
	    parent.addParam(this);
	}
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	if (_select != null) {
	    final Type tselect = _select.typeCheck(stable); 
	    if (tselect instanceof ReferenceType == false) {
		_select = new CastExpr(_select, Type.Reference);
	    }
	}
	else {
	    typeCheckContents(stable);
	}
	_type = Type.Reference;
	return Type.Void;
    }

    public void compileResultTree(ClassGenerator classGen,
				  MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	// Save the current handler base on the stack
	il.append(methodGen.loadHandler());

	// Create new instance of DOM class (with 64 nodes)
	final int init = cpg.addMethodref(DOM_IMPL, "<init>", "(I)V");
	il.append(new NEW(cpg.addClass(DOM_IMPL)));
	il.append(DUP);
	il.append(DUP);
	il.append(new PUSH(cpg, 64));
	il.append(new INVOKESPECIAL(init));

	// Overwrite old handler with DOM handler
	final int getOutputDomBuilder =
	    cpg.addMethodref(DOM_IMPL,
			     "getOutputDomBuilder",
			     "()" + TRANSLET_OUTPUT_SIG);
	il.append(new INVOKEVIRTUAL(getOutputDomBuilder));
	il.append(DUP);
	il.append(methodGen.storeHandler());

	// Call startDocument on the new handler
	il.append(methodGen.startDocument());

	// Instantiate result tree fragment
	translateContents(classGen, methodGen);

	// Call endDocument on the new handler
	il.append(methodGen.loadHandler());
	il.append(methodGen.endDocument());

	// Restore old handler base from stack
	il.append(SWAP);
	il.append(methodGen.storeHandler());
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();
	final String name = _name.getLocalPart(); // TODO: namespace ?

	if (_compiled) return;
	_compiled = true;

	if (isLocal()) {
	    il.append(classGen.loadTranslet());
	    il.append(new PUSH(cpg, name));
	    if (_select == null) {
		if (hasContents()) {
		    compileResultTree(classGen, methodGen);	
		}
		else {
		    // If no select and no contents push the empty string
		    il.append(new PUSH(cpg, ""));
		}
	    }
	    else {
		_select.translate(classGen, methodGen);
		_select.startResetIterator(classGen, methodGen);
	    }

	    // Call addParameter() from this class
	    final int addParameter = cpg.addMethodref(TRANSLET_CLASS,
						      ADD_PARAMETER,
						      ADD_PARAMETER_SIG);
	    il.append(new INVOKEVIRTUAL(addParameter));

	    if (_refs.isEmpty()) { // nobody uses the value
		il.append(_type.POP());
		_local = null;
	    }
	    else {		// normal case
		_local = methodGen.addLocalVariable2(name, _type.toJCType(),
						     il.getEnd());
		// Cache the result of addParameter() in a local variable
		il.append(_type.STORE(_local.getIndex()));
	    }
	}
	else {
	    String signature = _type.toSignature();
	    if (signature.equals(DOM_IMPL_SIG))
		signature = classGen.getDOMClassSig();
	    classGen.addField(new Field(ACC_PUBLIC, cpg.addUtf8(name),
					cpg.addUtf8(signature),
					null, cpg.getConstantPool()));
	    il.append(classGen.loadTranslet());
	    il.append(DUP);
	    il.append(new PUSH(cpg, name));

	    if (_select == null) {
		if (hasContents()) {
		    compileResultTree(classGen, methodGen);	
		}
		else {
		    // If no select and no contents push the empty string
		    il.append(new PUSH(cpg, ""));
		}
	    }
	    else {
		_select.translate(classGen, methodGen);
		_select.startResetIterator(classGen, methodGen);
	    }

	    // Call addParameter() from this class
	    il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
							 ADD_PARAMETER,
							 ADD_PARAMETER_SIG)));
	    // Cache the result of addParameter() in a field
	    il.append(new PUTFIELD(cpg.addFieldref(classGen.getClassName(),
						   name, signature)));
	}
    }
}