/*-
 * ~~~~~~licensing~~~~~~
 * xsom
 * ==========
 * Copyright (C) 2020 - 2024 EmDev LLC
 * ==========
 * You may not use this file except in accordance with the License Terms of the Copyright
 * Holder located at: https://entaxy.ru/eula . All copyrights, all intellectual property
 * rights to the Software and any copies are the property of the Copyright Holder. Unless
 * it is explicitly allowed the Copyright Holder, the User is prohibited from using the
 * Software for commercial purposes to provide services to third parties.
 * 
 * The Copyright Holder hereby declares that the Software is provided on an "AS IS".
 * Under no circumstances does the Copyright Holder guarantee or promise that the
 * Software provided by him will be suitable or not suitable for the specific purposes
 * of the User, that the Software will meet all commercial and personal subjective
 * expectations of the User, that the Software will work properly, without technical
 * errors, quickly and uninterruptedly.
 * 
 * Under no circumstances shall the Copyright Holder or its Affiliates is not liable
 * to the User for any direct or indirect losses of the User, his expenses or actual
 * damage, including, downtime; loss of bussines; lost profit; lost earnings; loss
 * or damage to data, property, etc.
 * ~~~~~~/licensing~~~~~~
 */
/*
 * Copyright (C) 2017 Oracle
 *
 * 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 com.sun.xml.xsom.impl;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import com.sun.xml.xsom.XSComplexType;
import com.sun.xml.xsom.XSType;

/**
 * 
 * 
 * @author
 *     Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)
 */
class Util {
    private static XSType[] listDirectSubstitutables( XSType _this ) {
        ArrayList r = new ArrayList();
        
        // TODO: handle @block
        Iterator itr = ((SchemaImpl)_this.getOwnerSchema()).parent.iterateTypes();
        while( itr.hasNext() ) {
            XSType t = (XSType)itr.next();
            if( t.getBaseType()==_this )
                r.add(t);
        }
        return (XSType[]) r.toArray(new XSType[r.size()]);
    }

    public static XSType[] listSubstitutables( XSType _this ) {
        Set substitables = new HashSet();
        buildSubstitutables( _this, substitables );
        return (XSType[]) substitables.toArray(new XSType[substitables.size()]);
    }
    
    public static void buildSubstitutables( XSType _this, Set substitutables ) {
        if( _this.isLocal() )    return;
        buildSubstitutables( _this, _this, substitutables );
    }
    
    private static void buildSubstitutables( XSType head, XSType _this, Set substitutables ) {
        if(!isSubstitutable(head,_this))
            return;    // no derived type of _this can substitute head.
        
        if(substitutables.add(_this)) {
            XSType[] child = listDirectSubstitutables(_this);
            for( int i=0; i<child.length; i++ )
                buildSubstitutables( head, child[i], substitutables );
        }
    }
    
    /**
     * Implements
     * <code>Validation Rule: Schema-Validity Assessment (Element) 1.2.1.2.4</code> 
     */
    private static boolean isSubstitutable( XSType _base, XSType derived ) {
        // too ugly to the point that it's almost unbearable.
        // I mean, it's not even transitive. Thus we end up calling this method
        // for each candidate
        if( _base.isComplexType() ) {
            XSComplexType base = _base.asComplexType();
            
            for( ; base!=derived; derived=derived.getBaseType() ) {
                if( base.isSubstitutionProhibited( derived.getDerivationMethod() ) )
                    return false;    // Type Derivation OK (Complex)-1
            }
            return true;
        } else {
            // simple type don't have any @block
            return true;
        }
    }

}
