/*******************************************************************************
 * Copyright (c) 2005 Oracle Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Ian Trimble - initial API and implementation
 *******************************************************************************/ 
package org.eclipse.jst.pagedesigner.dtmanager.converter.operations;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jst.pagedesigner.dtmanager.converter.ITagConverterContext;
import org.eclipse.jst.pagedesigner.dtmanager.converter.ITransformOperation;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Abstract ITransformOperation implementation. Maintains ITagConverterContext
 * instance and collection of child ITransformOperation instances.
 * 
 * @author Ian Trimble - Oracle
 */
public abstract class AbstractTransformOperation implements ITransformOperation {

	/**
	 * ITagConverterContext instance.
	 */
	protected ITagConverterContext tagConverterContext;

	/**
	 * Collection of child ITransformOperation instances.
	 */
	protected List childOperations;

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.dtmanager.converter.ITransformOperation#transform(org.w3c.dom.Element, org.w3c.dom.Element)
	 */
	public abstract Element transform(Element srcElement, Element curElement);

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.dtmanager.converter.ITransformOperation#setTagConverterContext(org.eclipse.jst.pagedesigner.dtmanager.converter.internal.provisional.ITagConverterContext)
	 */
	public void setTagConverterContext(ITagConverterContext tagConverterContext) {
        // API: this should really be set on construction since other methods
        // cannot be called until it is set.
		this.tagConverterContext = tagConverterContext;
	}

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.dtmanager.converter.ITransformOperation#appendChildOperation(org.eclipse.jst.pagedesigner.dtmanager.converter.internal.provisional.ITransformOperation)
	 */
	public void appendChildOperation(ITransformOperation operation) {
		if (operation != null) {
			if (childOperations == null) {
				childOperations = new ArrayList();
			}
			operation.setTagConverterContext(tagConverterContext);
			childOperations.add(operation);
		}
	}

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.dtmanager.converter.ITransformOperation#getChildOperations()
	 */
	public List getChildOperations() {
		return childOperations;
	}

	/**
	 * Convenience method to execute child ITransformOperation instances.
	 * 
	 * @param srcElement Source Element instance.
	 * @param curElement Current Element instance (that is being transformed).
	 * @return New current Element instance.
	 */
	protected Element executeChildOperations(Element srcElement, Element curElement) {
		Element retElement = curElement;
		if (childOperations != null && childOperations.size() > 0) {
			Iterator itChildOperations = childOperations.iterator();
			while (itChildOperations.hasNext()) {
				ITransformOperation childOperation = (ITransformOperation)itChildOperations.next();
				retElement = childOperation.transform(srcElement, retElement);
			}
		}
		return retElement;
	}

	/**
	 * Creates a new Element.
	 * 
	 * @param tagName Name of Element to be created.
	 * @return New Element instance.
	 */
	protected Element createElement(String tagName) {
		ITransformOperation operation =
			TransformOperationFactory.getInstance().getTransformOperation(
					TransformOperationFactory.OP_CreateElementOperation,
					new String[]{tagName});
		operation.setTagConverterContext(tagConverterContext);
		return operation.transform(null, null);
	}

	/**
	 * Creates and appends a new child Element.
	 * 
	 * @param tagName Name of child Element to be created.
	 * @param parentElement Element instance to which to append the new
	 * Element.
	 * @return New Element instance.
	 */
	protected Element appendChildElement(String tagName, Element parentElement) {
		ITransformOperation operation =
			TransformOperationFactory.getInstance().getTransformOperation(
					TransformOperationFactory.OP_AppendChildElementOperation,
					new String[]{tagName});
		operation.setTagConverterContext(tagConverterContext);
		return operation.transform(null, parentElement);
	}

	/**
	 * Creates and appends a new child Text.
	 * 
	 * @param content Content of new child Text.
	 * @param parentElement Element instance to which to append the new Text.
	 */
	protected void appendChildText(String content, Element parentElement) {
		ITransformOperation operation =
			TransformOperationFactory.getInstance().getTransformOperation(
					TransformOperationFactory.OP_AppendChildTextOperation,
					new String[]{content});
		operation.setTagConverterContext(tagConverterContext);
		operation.transform(null, parentElement);
	}

	/**
	 * Gets collection of child Element instances who's local name matches
	 * specified tag name.
	 * 
	 * @param srcNode Source Node instance.
	 * @param tagName Tag local name.
	 * @return Collection of child Element instances who's local name matches
	 * specified tag name.
	 */
	protected List getChildElements(Node srcNode, String tagName) {
		List childElements = new ArrayList();
		NodeList childNodes = srcNode.getChildNodes();
		for (int i = 0; i < childNodes.getLength(); i++) {
			Node curNode = childNodes.item(i);
			if (curNode.getNodeType() == Node.ELEMENT_NODE) {
				String curNodeName = curNode.getLocalName();
				if (curNode != null && curNodeName.equals(tagName)) {
					childElements.add(curNode);
				}
			}
		}
		return childElements;
	}

}