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package com.sun.tools.internal.xjc.reader.xmlschema.ct;

import java.util.HashMap;

import java.util.Iterator;

import java.util.Map;

import com.sun.tools.internal.xjc.reader.xmlschema.WildcardNameClassBuilder;

import com.sun.xml.internal.xsom.XSAttributeUse;

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

import com.sun.xml.internal.xsom.XSContentType;

import com.sun.xml.internal.xsom.XSDeclaration;

import com.sun.xml.internal.xsom.XSElementDecl;

import com.sun.xml.internal.xsom.XSModelGroup;

import com.sun.xml.internal.xsom.XSModelGroupDecl;

import com.sun.xml.internal.xsom.XSParticle;

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

import com.sun.xml.internal.xsom.XSWildcard;

import com.sun.xml.internal.xsom.visitor.XSTermFunction;

import javax.xml.namespace.QName;

import com.sun.xml.internal.rngom.nc.ChoiceNameClass;

import com.sun.xml.internal.rngom.nc.NameClass;

import com.sun.xml.internal.rngom.nc.SimpleNameClass;

/**

 * Binds a complex type derived from another complex type by extension.

 *

 * @author

 *     Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)

 */

abstract class AbstractExtendedComplexTypeBuilder extends CTBuilder {

    /**

     * Map from {@link XSComplexType} to {@link NameClass}[2] that

     * represents the names used in its child elements [0] and

     * attributes [1].

     */

    protected final Map<XSComplexType, NameClass[]> characteristicNameClasses = new HashMap<XSComplexType, NameClass[]>();

    /**

     * Computes a name class that represents everything in a given content model.

     */

    protected final XSTermFunction<NameClass> contentModelNameClassBuilder = new XSTermFunction<NameClass>() {

        @Override

        public NameClass wildcard(XSWildcard wc) {

            return WildcardNameClassBuilder.build(wc);

        }

        @Override

        public NameClass modelGroupDecl(XSModelGroupDecl decl) {

            return modelGroup(decl.getModelGroup());

        }

        @Override

        public NameClass modelGroup(XSModelGroup group) {

            NameClass nc = NameClass.NULL;

            for( int i=0; i<group.getSize(); i++ )

                nc = new ChoiceNameClass(nc, group.getChild(i).getTerm().apply(this));

            return nc;

        }

        public NameClass elementDecl(XSElementDecl decl) {

            return getNameClass(decl);

        }

    };

    /**

     * Checks if the particles/attributes defined in the type parameter

     * collides with the name classes of anc/enc.

     *

     * @return true if there's a collision.

     */

    protected boolean checkCollision(NameClass anc, NameClass enc, XSComplexType type) {

        NameClass[] chnc = characteristicNameClasses.get(type);

        if (chnc == null) {

            chnc = new NameClass[2];

            chnc[0] = getNameClass(type.getContentType());

            // build attribute name classes

            NameClass nc = NameClass.NULL;

            Iterator itr = type.iterateAttributeUses();

            while( itr.hasNext() )

                anc = new ChoiceNameClass(anc, getNameClass(((XSAttributeUse) itr.next()).getDecl()));

            XSWildcard wc = type.getAttributeWildcard();

            if(wc!=null)

                nc = new ChoiceNameClass(nc, WildcardNameClassBuilder.build(wc));

            chnc[1] = nc;

            characteristicNameClasses.put(type, chnc);

        }

        return chnc[0].hasOverlapWith(enc) || chnc[1].hasOverlapWith(anc);

    }

    /**

     * Looks for the derivation chain t_1 > t_2 > ... > t

     * and find t_i such that t_i derives by restriction but

     * for every j>i, t_j derives by extension.

     *

     * @return null

     *      If there's no such t_i or if t_i is any type.

     */

    protected XSComplexType getLastRestrictedType(XSComplexType t) {

        if (t.getBaseType() == schemas.getAnyType()) {

            return null;   // we don't count the restriction from anyType

        }

        if (t.getDerivationMethod() == XSType.RESTRICTION) {

            return t;

        }

        XSComplexType baseType = t.getBaseType().asComplexType();

        if (baseType != null) {

            return getLastRestrictedType(baseType);

        } else {

            return null;

        }

    }

    /**

     * Checks if this new extension is safe.

     *

     * UGLY.

     * <p>

     * If you have ctA extending ctB and ctB restricting ctC, our

     * Java classes will look like CtAImpl extending CtBImpl

     * extending CtCImpl.

     *

     * <p>

     * Since a derived class unmarshaller uses the base class unmarshaller,

     * this could potentially result in incorrect unmarshalling.

     * We used to just reject such a case, but then we found that

     * there are schemas that are using it.

     *

     * <p>

     * One generalized observation that we reached is that if the extension

     * is only adding new elements/attributes which has never been used

     * in any of its base class (IOW, if none of the particle / attribute use /

     * attribute wildcard can match the name of newly added elements/attributes)

     * then it is safe to add them.

     *

     * <p>

     * This function checks if the derivation chain to this type is

     * not using restriction, and if it is, then checks if it is safe

     * according to the above condition.

     *

     * @return false

     *      If this complex type needs to be rejected.

     */

    protected boolean checkIfExtensionSafe(XSComplexType baseType, XSComplexType thisType) {

        XSComplexType lastType = getLastRestrictedType(baseType);

        if (lastType == null) {

            return true;    // no restriction in derivation chain

        }

        NameClass anc = NameClass.NULL;

        // build name class for attributes in new complex type

        Iterator itr = thisType.iterateDeclaredAttributeUses();

        while (itr.hasNext()) {

            anc = new ChoiceNameClass(anc, getNameClass(((XSAttributeUse) itr.next()).getDecl()));

        }

        // TODO: attribute wildcard

        NameClass enc = getNameClass(thisType.getExplicitContent());

        // check against every base type ... except the root anyType

        while (lastType != lastType.getBaseType()) {

            if (checkCollision(anc, enc, lastType)) {

                return false;

            }

            if (lastType.getBaseType().isSimpleType()) // if the base type is a simple type, there won't be

            // any further name collision.

            {

                return true;

            }

            lastType = lastType.getBaseType().asComplexType();

        }

        return true;    // OK

    }

    /**

     * Gets a {@link NameClass} that represents all the terms in the given content type.

     * If t is not a particle, just return an empty name class.

     */

    private NameClass getNameClass(XSContentType t) {

        if(t==null) return NameClass.NULL;

        XSParticle p = t.asParticle();

        if(p==null) return NameClass.NULL;

        else        return p.getTerm().apply(contentModelNameClassBuilder);

    }

    /**

     * Gets a {@link SimpleNameClass} from the name of a {@link XSDeclaration}.

     */

    private NameClass getNameClass(XSDeclaration decl) {

        return new SimpleNameClass(new QName(decl.getTargetNamespace(), decl.getName()));

    }

}