/*
 * 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.
 */

package org.apache.xerces.dom;

import org.w3c.dom.DOMException;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;



/**
 * The DOMImplementation class is description of a particular
 * implementation of the Document Object Model. As such its data is
 * static, shared by all instances of this implementation.
 * <P>
 * The DOM API requires that it be a real object rather than static
 * methods. However, there's nothing that says it can't be a singleton,
 * so that's how I've implemented it.
 * 
 * @xerces.internal
 *
 * @version $Id: DOMImplementationImpl.java 516291 2007-03-09 04:26:22Z mrglavas $
 * @since  PR-DOM-Level-1-19980818.
 */
public class DOMImplementationImpl extends CoreDOMImplementationImpl
    implements DOMImplementation {

    //
    // Data
    //

    // static

    /** Dom implementation singleton. */
    static DOMImplementationImpl singleton = new DOMImplementationImpl();


    //
    // Public methods
    //

    /** NON-DOM: Obtain and return the single shared object */
    public static DOMImplementation getDOMImplementation() {
        return singleton;
    }

    //
    // DOMImplementation methods
    //

    /**
     * Test if the DOM implementation supports a specific "feature" --
     * currently meaning language and level thereof.
     *
     * @param feature      The package name of the feature to test.
     * In Level 1, supported values are "HTML" and "XML" (case-insensitive).
     * At this writing, org.apache.xerces.dom supports only XML.
     *
     * @param version      The version number of the feature being tested.
     * This is interpreted as "Version of the DOM API supported for the
     * specified Feature", and in Level 1 should be "1.0"
     *
     * @return    true iff this implementation is compatable with the
     * specified feature and version.
     */
    public boolean hasFeature(String feature, String version) {

        boolean result = super.hasFeature(feature, version);
        if (!result) {
            boolean anyVersion = version == null || version.length() == 0;
            if (feature.startsWith("+")) {
                feature = feature.substring(1);
            }
            return (
                (feature.equalsIgnoreCase("Events")
                    && (anyVersion || version.equals("2.0")))
                    || (feature.equalsIgnoreCase("MutationEvents")
                        && (anyVersion || version.equals("2.0")))
                    || (feature.equalsIgnoreCase("Traversal")
                        && (anyVersion || version.equals("2.0")))
                    || (feature.equalsIgnoreCase("Range")
                        && (anyVersion || version.equals("2.0")))
                    || (feature.equalsIgnoreCase("MutationEvents")
                        && (anyVersion || version.equals("2.0"))));
        }
        return result;
    } // hasFeature(String,String):boolean



    /**
     * Introduced in DOM Level 2. <p>
     *
     * Creates an XML Document object of the specified type with its document
     * element.
     *
     * @param namespaceURI     The namespace URI of the document
     *                         element to create, or null.
     * @param qualifiedName    The qualified name of the document
     *                         element to create.
     * @param doctype          The type of document to be created or null.<p>
     *
     *                         When doctype is not null, its
     *                         Node.ownerDocument attribute is set to
     *                         the document being created.
     * @return Document        A new Document object.
     * @throws DOMException    WRONG_DOCUMENT_ERR: Raised if doctype has
     *                         already been used with a different document.
     * @since WD-DOM-Level-2-19990923
     */
    public Document           createDocument(String namespaceURI,
                                             String qualifiedName,
                                             DocumentType doctype)
                                             throws DOMException
    {
        if (doctype != null && doctype.getOwnerDocument() != null) {
            String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "WRONG_DOCUMENT_ERR", null);
            throw new DOMException(DOMException.WRONG_DOCUMENT_ERR, msg);
        }
        DocumentImpl doc = new DocumentImpl(doctype);
        // If namespaceURI and qualifiedName are null return a Document with no document element.
        if (qualifiedName != null || namespaceURI != null) {
            Element e = doc.createElementNS(namespaceURI, qualifiedName);
            doc.appendChild(e);
        }
        return doc;
    }


} // class DOMImplementationImpl