/*
 * Copyright 2000-2002,2004 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.xerces.impl.dtd;

import org.apache.xerces.xni.grammars.XMLGrammarDescription;
import org.apache.xerces.xni.XMLResourceIdentifier;
import org.apache.xerces.xni.parser.XMLInputSource;

import org.apache.xerces.util.XMLResourceIdentifierImpl;
import java.util.Vector;

/**
 * All information specific to DTD grammars.  
 * 
 * @xerces.internal
 * 
 * @author Neil Graham, IBM
 * @version $Id: XMLDTDDescription.java 320090 2004-10-04 22:00:42Z mrglavas $
 */
public class XMLDTDDescription extends XMLResourceIdentifierImpl
        implements org.apache.xerces.xni.grammars.XMLDTDDescription {

    // Data

    // pieces of information needed to make this usable as a Grammar key
    // if we know the root of this grammar, here's its name:
    protected String fRootName = null;

    // if we don't know the root name, this stores all elements that
    // could serve; fPossibleRoots and fRootName cannot both be non-null
    protected Vector fPossibleRoots = null;

    // Constructors:
    public XMLDTDDescription(XMLResourceIdentifier id, String rootName) {
        this.setValues(id.getPublicId(), id.getLiteralSystemId(),
                id.getBaseSystemId(), id.getExpandedSystemId());
        this.fRootName = rootName;
        this.fPossibleRoots = null;
    } // init(XMLResourceIdentifier, String)

    public XMLDTDDescription(String publicId, String literalId,
                String baseId, String expandedId, String rootName) {
        this.setValues(publicId, literalId, baseId, expandedId);
        this.fRootName = rootName;
        this.fPossibleRoots = null;
    } // init(String, String, String, String, String)

    public XMLDTDDescription(XMLInputSource source) {
        this.setValues(source.getPublicId(), null,
                source.getBaseSystemId(), source.getSystemId());
        this.fRootName = null;
        this.fPossibleRoots = null;
    } // init(XMLInputSource)

    // XMLGrammarDescription methods

    public String getGrammarType () {
        return XMLGrammarDescription.XML_DTD;
    } // getGrammarType():  String

    /** 
     * @return the root name of this DTD or null if root name is unknown
     */
    public String getRootName() {
        return fRootName;
    } // getRootName():  String

    /** Set the root name **/
    public void setRootName(String rootName) {
        fRootName = rootName;
        fPossibleRoots = null;
    }

    /** Set possible roots **/
    public void setPossibleRoots(Vector possibleRoots) {
        fPossibleRoots = possibleRoots;
    } 

    /**
     * Compares this grammar with the given grammar. Currently, we compare 
     * as follows:
     * - if grammar type not equal return false immediately
     * - try and find a common root name:
     *    - if both have roots, use them
     *    - else if one has a root, examine other's possible root's for a match;
     *    - else try all combinations
     *  - test fExpandedSystemId and fPublicId as above
     * 
     * @param desc The description of the grammar to be compared with
     * @return     True if they are equal, else false
     */
    public boolean equals(Object desc) {
        if(!(desc instanceof XMLGrammarDescription)) return false;
    	if (!getGrammarType().equals(((XMLGrammarDescription)desc).getGrammarType())) {
    	    return false;
    	}
        // assume it's a DTDDescription
        XMLDTDDescription dtdDesc = (XMLDTDDescription)desc;
        if(fRootName != null) {
            if((dtdDesc.fRootName) != null && !dtdDesc.fRootName.equals(fRootName)) {
                return false;
            } else if(dtdDesc.fPossibleRoots != null && !dtdDesc.fPossibleRoots.contains(fRootName)) {
                return false;
            }
        } else if(fPossibleRoots != null) {
            if(dtdDesc.fRootName != null) {
                if(!fPossibleRoots.contains(dtdDesc.fRootName)) { 
                    return false;
                }
            } else if(dtdDesc.fPossibleRoots == null) {
                return false;
            } else {
                boolean found = false;
                for(int i = 0; i<fPossibleRoots.size(); i++) {
                    String root = (String)fPossibleRoots.elementAt(i);
                    found = dtdDesc.fPossibleRoots.contains(root);
                    if(found) break;
                }
                if(!found) return false;
            }
        }
        // if we got this far we've got a root match... try other two fields,
        // since so many different DTD's have roots in common:
        if(fExpandedSystemId != null) {
            if(!fExpandedSystemId.equals(dtdDesc.fExpandedSystemId)) 
                return false;
        } 
        else if(dtdDesc.fExpandedSystemId != null)
            return false;
        if(fPublicId != null) {
            if(!fPublicId.equals(dtdDesc.fPublicId)) 
                return false;
        } 
        else if(dtdDesc.fPublicId != null)
            return false;
    	return true;
    }
    
    /**
     * Returns the hash code of this grammar
     * Because our .equals method is so complex, we just return a very
     * simple hash that might avoid calls to the equals method a bit...
     * @return The hash code
     */
    public int hashCode() {
        if(fExpandedSystemId != null)
            return fExpandedSystemId.hashCode();
        if(fPublicId != null)
            return fPublicId.hashCode();
        // give up; hope .equals can handle it:
        return 0;
    }
} // class XMLDTDDescription