/*
 * 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.impl.xs.models;

import org.apache.xerces.xni.QName;
import org.apache.xerces.impl.xs.XSElementDecl;
import org.apache.xerces.impl.xs.SubstitutionGroupHandler;
import org.apache.xerces.impl.xs.XMLSchemaException;
import org.apache.xerces.impl.xs.XSConstraints;

import java.util.Vector;

/**
 * XSAllCM implements XSCMValidator and handles &lt;all&gt;.
 *
 * @xerces.internal 
 *
 * @author Pavani Mukthipudi, Sun Microsystems Inc.
 * @version $Id: XSAllCM.java 449424 2006-09-24 16:22:30Z mrglavas $
 */
public class XSAllCM implements XSCMValidator {

    //
    // Constants
    //

    // start the content model: did not see any children
    private static final short STATE_START = 0;
    private static final short STATE_VALID = 1;
    private static final short STATE_CHILD = 1;


    //
    // Data
    //

    private XSElementDecl fAllElements[];
    private boolean fIsOptionalElement[];
    private boolean fHasOptionalContent = false;
    private int fNumElements = 0;

    //
    // Constructors
    //

    public XSAllCM (boolean hasOptionalContent, int size) {
        fHasOptionalContent = hasOptionalContent;
        fAllElements = new XSElementDecl[size];
        fIsOptionalElement = new boolean[size];
    }

    public void addElement (XSElementDecl element, boolean isOptional) {
        fAllElements[fNumElements] = element;
        fIsOptionalElement[fNumElements] = isOptional;
        fNumElements++;
    }


    //
    // XSCMValidator methods
    //

    /**
     * This methods to be called on entering a first element whose type
     * has this content model. It will return the initial state of the
     * content model
     *
     * @return Start state of the content model
     */
    public int[] startContentModel() {

        int[] state = new int[fNumElements + 1];

        for (int i = 0; i <= fNumElements; i++) {
            state[i] = STATE_START;
        }
        return state;
    }

    // convinient method: when error occurs, to find a matching decl
    // from the candidate elements.
    Object findMatchingDecl(QName elementName, SubstitutionGroupHandler subGroupHandler) {
        Object matchingDecl = null;
        for (int i = 0; i < fNumElements; i++) {
            matchingDecl = subGroupHandler.getMatchingElemDecl(elementName, fAllElements[i]);
            if (matchingDecl != null)
                break;
        }
        return matchingDecl;
    }

    /**
     * The method corresponds to one transition in the content model.
     *
     * @param elementName
     * @param currentState  Current state
     * @return an element decl object
     */
    public Object oneTransition (QName elementName, int[] currentState, SubstitutionGroupHandler subGroupHandler) {

        // error state
        if (currentState[0] < 0) {
            currentState[0] = XSCMValidator.SUBSEQUENT_ERROR;
            return findMatchingDecl(elementName, subGroupHandler);
        }

        // seen child
        currentState[0] = STATE_CHILD;
        
        Object matchingDecl = null;

        for (int i = 0; i < fNumElements; i++) {
            // we only try to look for a matching decl if we have not seen
            // this element yet.
            if (currentState[i+1] != STATE_START)
                continue;
            matchingDecl = subGroupHandler.getMatchingElemDecl(elementName, fAllElements[i]);
            if (matchingDecl != null) {
                // found the decl, mark this element as "seen".
                currentState[i+1] = STATE_VALID;
                return matchingDecl;
            }
        }

        // couldn't find the decl, change to error state.
        currentState[0] = XSCMValidator.FIRST_ERROR;
        return findMatchingDecl(elementName, subGroupHandler);
    }


    /**
     * The method indicates the end of list of children
     *
     * @param currentState  Current state of the content model
     * @return true if the last state was a valid final state
     */
    public boolean endContentModel (int[] currentState) {

        int state = currentState[0];

        if (state == XSCMValidator.FIRST_ERROR || state == XSCMValidator.SUBSEQUENT_ERROR) {
            return false;
        }

        // If <all> has minOccurs of zero and there are
        // no children to validate, it is trivially valid
        if (fHasOptionalContent && state == STATE_START) {
            return true;
        }

        for (int i = 0; i < fNumElements; i++) {
            // if one element is required, but not present, then error
            if (!fIsOptionalElement[i] && currentState[i+1] == STATE_START)
                return false;
        }

        return true;
    }

    /**
     * check whether this content violates UPA constraint.
     *
     * @param subGroupHandler the substitution group handler
     * @return true if this content model contains other or list wildcard
     */
    public boolean checkUniqueParticleAttribution(SubstitutionGroupHandler subGroupHandler) throws XMLSchemaException {
        // check whether there is conflict between any two leaves
        for (int i = 0; i < fNumElements; i++) {
            for (int j = i+1; j < fNumElements; j++) {
                if (XSConstraints.overlapUPA(fAllElements[i], fAllElements[j], subGroupHandler)) {
                    // REVISIT: do we want to report all errors? or just one?
                    throw new XMLSchemaException("cos-nonambig", new Object[]{fAllElements[i].toString(),
                                                                              fAllElements[j].toString()});
                }
            }
        }

        return false;
    }

    /**
     * Check which elements are valid to appear at this point. This method also
     * works if the state is in error, in which case it returns what should
     * have been seen.
     * 
     * @param state  the current state
     * @return       a Vector whose entries are instances of
     *               either XSWildcardDecl or XSElementDecl.
     */
    public Vector whatCanGoHere(int[] state) {
        Vector ret = new Vector();
        for (int i = 0; i < fNumElements; i++) {
            // we only try to look for a matching decl if we have not seen
            // this element yet.
            if (state[i+1] == STATE_START)
                ret.addElement(fAllElements[i]);
        }
        return ret;
    }

} // class XSAllCM

