/*******************************************************************************
 * Copyright (c) 2000, 2014 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jdt.internal.corext.refactoring.generics;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.eclipse.core.runtime.Assert;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.dom.CastExpression;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.IMethodBinding;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.IVariableBinding;
import org.eclipse.jdt.core.dom.Modifier;
import org.eclipse.jdt.core.dom.Type;

import org.eclipse.jdt.internal.core.manipulation.JavaManipulationPlugin;
import org.eclipse.jdt.internal.corext.dom.Bindings;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.CompilationUnitRange;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.ArrayType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.GenericType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.ParameterizedType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.TType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.TypeEnvironment;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.TypeVariable;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ArrayElementVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ArrayTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.CastVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.CollectionElementVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ConstraintVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ITypeConstraint2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ImmutableTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.IndependentTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ParameterTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ParameterizedTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.ReturnTypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.SubTypeConstraint2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.TypeEquivalenceSet;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.TypeVariable2;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.VariableVariable2;
import org.eclipse.jdt.internal.corext.refactoring.util.RefactoringASTParser;

public class InferTypeArgumentsTCModel {
	private static final String INDEXED_COLLECTION_ELEMENTS= "IndexedCollectionElements"; //$NON-NLS-1$
	private static final String ARRAY_ELEMENT= "ArrayElement"; //$NON-NLS-1$
	private static final String USED_IN= "UsedIn"; //$NON-NLS-1$
	private static final String METHOD_RECEIVER= "MethodReceiver"; //$NON-NLS-1$
	private static final Map<String, CollectionElementVariable2> EMPTY_COLLECTION_ELEMENT_VARIABLES_MAP= Collections.emptyMap();

	/**
	 * Map from a {@link ConstraintVariable2} to itself.
	 */
	private HashMap<ConstraintVariable2, ConstraintVariable2> fConstraintVariables;
	/**
	 * Map from a {@link ITypeConstraint2} to itself.
	 */
	private HashMap<ITypeConstraint2, ITypeConstraint2> fTypeConstraints;
	private Collection<CastVariable2> fCastVariables;

	private HashSet<ConstraintVariable2> fCuScopedConstraintVariables;

	private TypeEnvironment fTypeEnvironment;

	private static final int MAX_TTYPE_CACHE= 1024;
	private Map<String, TType> fTTypeCache= new LinkedHashMap<String, TType>(MAX_TTYPE_CACHE, 0.75f, true) {
		private static final long serialVersionUID= 1L;
		@Override
		protected boolean removeEldestEntry(Map.Entry<String, TType> eldest) {
			return size() > MAX_TTYPE_CACHE;
		}
	};


	public InferTypeArgumentsTCModel() {
		fTypeConstraints= new HashMap<>();
		fConstraintVariables= new LinkedHashMap<>(); // make iteration independent of hashCode() implementation
		fCastVariables= new ArrayList<>();

		fCuScopedConstraintVariables= new HashSet<>();

		fTypeEnvironment= new TypeEnvironment(true);
	}

	/**
	 * Allows for avoiding the creation of SimpleTypeConstraints based on properties of
	 * their constituent ConstraintVariables and ConstraintOperators. Can be used to e.g.
	 * avoid creation of constraints for assignments between built-in types.
	 *
	 * @param cv1
	 * @param cv2
	 * @return <code>true</code> iff the type constraint should really be created
	 */
	protected boolean keep(ConstraintVariable2 cv1, ConstraintVariable2 cv2) {
		if ((cv1 == null || cv2 == null))
			return false;

		if (cv1.equals(cv2)) {
			if (cv1 == cv2)
				return false;
			else
				Assert.isTrue(false);
		}

		if (cv1 instanceof CollectionElementVariable2 || cv2 instanceof CollectionElementVariable2)
			return true;

		if (cv1 instanceof IndependentTypeVariable2 || cv2 instanceof IndependentTypeVariable2)
			return true;

		if (isAGenericType(cv1.getType()))
			return true;

		if (isAGenericType(cv2.getType()))
			return true;

		return false;
	}

	/**
	 * @param cv
	 * @return a List of ITypeConstraint2s where cv is used
	 */
	@SuppressWarnings("unchecked")
	public List<ITypeConstraint2> getUsedIn(ConstraintVariable2 cv) {
		Object usedIn= cv.getData(USED_IN);
		if (usedIn == null)
			return Collections.emptyList();
		else if (usedIn instanceof ArrayList)
			return Collections.unmodifiableList((ArrayList<ITypeConstraint2>) usedIn);
		else
			return Collections.singletonList((ITypeConstraint2) usedIn);
	}

	public void newCu() {
		pruneUnusedCuScopedCvs();
		fCuScopedConstraintVariables.clear();
		fTTypeCache.clear();
	}

	private void pruneUnusedCuScopedCvs() {
		for (ConstraintVariable2 cv : fCuScopedConstraintVariables) {
			pruneCvIfUnused(cv);
		}
	}

	private boolean pruneCvIfUnused(ConstraintVariable2 cv) {
		if (!getUsedIn(cv).isEmpty())
			return false;

		if (cv.getTypeEquivalenceSet() != null) {
			if (cv.getTypeEquivalenceSet().getContributingVariables().length > 0)
				return false;
		}

		ArrayElementVariable2 arrayElementVariable= getArrayElementVariable(cv);
		if (arrayElementVariable != null && ! pruneCvIfUnused(arrayElementVariable))
			return false;

		Map<String, CollectionElementVariable2> elementVariables= getElementVariables(cv);
		for (CollectionElementVariable2 elementVariable : elementVariables.values()) {
			if (! pruneCvIfUnused(elementVariable))
				return false;
		}

		fConstraintVariables.remove(cv);
		return true;
	}

	public ConstraintVariable2[] getAllConstraintVariables() {
		ConstraintVariable2[] result= new ConstraintVariable2[fConstraintVariables.size()];
		int i= 0;
		for (Iterator<ConstraintVariable2> iter= fConstraintVariables.keySet().iterator(); iter.hasNext(); i++)
			result[i]= iter.next();
		return result;
	}

	public ITypeConstraint2[] getAllTypeConstraints() {
		Set<ITypeConstraint2> typeConstraints= fTypeConstraints.keySet();
		return typeConstraints.toArray(new ITypeConstraint2[typeConstraints.size()]);
	}

	public CastVariable2[] getCastVariables() {
		return fCastVariables.toArray(new CastVariable2[fCastVariables.size()]);
	}

	public void createSubtypeConstraint(ConstraintVariable2 cv1, ConstraintVariable2 cv2) {
		if (! keep(cv1, cv2))
			return;

		ConstraintVariable2 storedCv1= storedCv(cv1);
		ConstraintVariable2 storedCv2= storedCv(cv2);
		ITypeConstraint2 typeConstraint= new SubTypeConstraint2(storedCv1, storedCv2);

		Object storedTc= fTypeConstraints.get(typeConstraint);
		if (storedTc == null) {
			fTypeConstraints.put(typeConstraint, typeConstraint);
		} else {
			typeConstraint= (ITypeConstraint2) storedTc;
		}

		registerCvWithTc(storedCv1, typeConstraint);
		registerCvWithTc(storedCv2, typeConstraint);
	}

	private ConstraintVariable2 storedCv(ConstraintVariable2 cv) {
		Object stored= fConstraintVariables.get(cv);
		if (stored == null) {
			fConstraintVariables.put(cv, cv);
			return cv;
		} else {
			return (ConstraintVariable2) stored;
		}
	}

	private void registerCvWithTc(ConstraintVariable2 storedCv, ITypeConstraint2 typeConstraint) {
		Object usedIn= storedCv.getData(USED_IN);
		if (usedIn == null) {
			storedCv.setData(USED_IN, typeConstraint);
		} else if (usedIn instanceof ArrayList) {
			@SuppressWarnings("unchecked")
			ArrayList<ITypeConstraint2> usedInList= (ArrayList<ITypeConstraint2>) usedIn;
			usedInList.add(typeConstraint);
		} else {
			ArrayList<ITypeConstraint2> usedInList= new ArrayList<>(2);
			usedInList.add((ITypeConstraint2) usedIn);
			usedInList.add(typeConstraint);
			storedCv.setData(USED_IN, usedInList);
		}
	}

	public void createEqualsConstraint(ConstraintVariable2 leftElement, ConstraintVariable2 rightElement) {
		if (leftElement == null || rightElement == null)
			return;

		TypeEquivalenceSet leftSet= leftElement.getTypeEquivalenceSet();
		TypeEquivalenceSet rightSet= rightElement.getTypeEquivalenceSet();
		if (leftSet == null) {
			if (rightSet == null) {
				TypeEquivalenceSet set= new TypeEquivalenceSet(leftElement, rightElement);
				leftElement.setTypeEquivalenceSet(set);
				rightElement.setTypeEquivalenceSet(set);
			} else {
				rightSet.add(leftElement);
				leftElement.setTypeEquivalenceSet(rightSet);
			}
		} else {
			if (rightSet == null) {
				leftSet.add(rightElement);
				rightElement.setTypeEquivalenceSet(leftSet);
			} else if (leftSet == rightSet) {
				return;
			} else {
				ConstraintVariable2[] cvs= rightSet.getContributingVariables();
				leftSet.addAll(cvs);
				for (ConstraintVariable2 cv : cvs) {
					cv.setTypeEquivalenceSet(leftSet);
				}
			}
		}
	}

	public TType createTType(ITypeBinding typeBinding) {
		String key= typeBinding.getKey();
		TType cached= fTTypeCache.get(key);
		if (cached != null)
			return cached;
		TType type= fTypeEnvironment.create(typeBinding);
		fTTypeCache.put(key, type);
		return type;
	}

	private TType getBoxedType(ITypeBinding typeBinding, Expression expression) {
		if (typeBinding == null)
			return null;

		if (! typeBinding.isPrimitive())
			return createTType(typeBinding);

		if (expression == null || ! expression.resolveBoxing())
			return null;

		ITypeBinding boxed= Bindings.getBoxedTypeBinding(typeBinding, expression.getAST());
		return createTType(boxed);
	}

	public VariableVariable2 makeVariableVariable(IVariableBinding variableBinding) {
		if (variableBinding == null)
			return null;
		TType type= getBoxedType(variableBinding.getType(), /*no boxing*/null);
		if (type == null)
			return null;
		VariableVariable2 cv= new VariableVariable2(type, variableBinding);
		VariableVariable2 storedCv= (VariableVariable2) storedCv(cv);
		if (storedCv == cv) {
			if (! variableBinding.isField() || Modifier.isPrivate(variableBinding.getModifiers()))
				fCuScopedConstraintVariables.add(storedCv);
			makeElementVariables(storedCv, type);
			makeArrayElementVariable(storedCv);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, '[' + variableBinding.getName() + ']');
		}
		return storedCv;
	}

	public VariableVariable2 makeDeclaredVariableVariable(IVariableBinding variableBinding, ICompilationUnit cu) {
		VariableVariable2 cv= makeVariableVariable(variableBinding);
		if (cv == null)
			return null;
		cv.setCompilationUnit(cu);
		return cv;
	}

	public TypeVariable2 makeTypeVariable(Type type) {
		ICompilationUnit cu= RefactoringASTParser.getCompilationUnit(type);
		TType ttype= getBoxedType(type.resolveBinding(), /*no boxing*/null);
		if (ttype == null)
			return null;

		CompilationUnitRange range= new CompilationUnitRange(cu, type);
		TypeVariable2 typeVariable= new TypeVariable2(ttype, range);
		TypeVariable2 storedCv= (TypeVariable2) storedCv(typeVariable);
		if (storedCv == typeVariable) {
			fCuScopedConstraintVariables.add(storedCv);
			if (isAGenericType(ttype))
				makeElementVariables(storedCv, ttype);
			makeArrayElementVariable(storedCv);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, type.toString());
		}
		return storedCv;
	}

	public IndependentTypeVariable2 makeIndependentTypeVariable(TypeVariable type) {
		IndependentTypeVariable2 cv= new IndependentTypeVariable2(type);
		IndependentTypeVariable2 storedCv= (IndependentTypeVariable2) storedCv(cv);
		if (cv == storedCv) {
			fCuScopedConstraintVariables.add(storedCv);
//			if (isAGenericType(typeBinding)) // would lead to infinite recursion!
//				makeElementVariables(storedCv, typeBinding);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, "IndependentType(" + type.getPrettySignature() + ")"); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return storedCv;
	}

	public ParameterizedTypeVariable2 makeParameterizedTypeVariable(ITypeBinding typeBinding) {
		if (typeBinding == null)
			return null;
		TType type= createTType(typeBinding);
		return makeParameterizedTypeVariable(type);
	}

	private ParameterizedTypeVariable2 makeParameterizedTypeVariable(TType type) {
		Assert.isTrue(isAGenericType(type));

		ParameterizedTypeVariable2 cv= new ParameterizedTypeVariable2(type);
		ParameterizedTypeVariable2 storedCv= (ParameterizedTypeVariable2) storedCv(cv);
		if (cv == storedCv) {
			fCuScopedConstraintVariables.add(storedCv);
			makeElementVariables(storedCv, type);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, "ParameterizedType(" + type.getPrettySignature() + ")"); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return storedCv;
	}

	public ArrayTypeVariable2 makeArrayTypeVariable(ITypeBinding typeBinding) {
		if (typeBinding == null)
			return null;
		TType type= createTType(typeBinding);
		return makeArrayTypeVariable((ArrayType) type);
	}

	private ArrayTypeVariable2 makeArrayTypeVariable(ArrayType type) {
		ArrayTypeVariable2 cv= new ArrayTypeVariable2(type);
		ArrayTypeVariable2 storedCv= (ArrayTypeVariable2) storedCv(cv);
		if (cv == storedCv) {
			fCuScopedConstraintVariables.add(storedCv);
			makeArrayElementVariable(storedCv);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, "ArrayType(" + type.getPrettySignature() + ")"); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return storedCv;
	}

	public ParameterTypeVariable2 makeParameterTypeVariable(IMethodBinding methodBinding, int parameterIndex) {
		if (methodBinding == null)
			return null;
		TType type= getBoxedType(methodBinding.getParameterTypes() [parameterIndex], /*no boxing*/null);
		if (type == null)
			return null;

		ParameterTypeVariable2 cv= new ParameterTypeVariable2(type, parameterIndex, methodBinding);
		ParameterTypeVariable2 storedCv= (ParameterTypeVariable2) storedCv(cv);
		if (storedCv == cv) {
			if (methodBinding.getDeclaringClass().isLocal() || Modifier.isPrivate(methodBinding.getModifiers()))
				fCuScopedConstraintVariables.add(cv);
			makeElementVariables(storedCv, type);
			makeArrayElementVariable(storedCv);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, "[Parameter(" + parameterIndex + "," + Bindings.asString(methodBinding) + ")]"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
		}
		return storedCv;
	}

	/**
	 * Make a ParameterTypeVariable2 from a method declaration.
	 * The constraint variable is always stored if it passes the type filter.
	 * @param methodBinding
	 * @param parameterIndex
	 * @param cu
	 * @return the ParameterTypeVariable2, or <code>null</code>
	 */
	public ParameterTypeVariable2 makeDeclaredParameterTypeVariable(IMethodBinding methodBinding, int parameterIndex, ICompilationUnit cu) {
		if (methodBinding == null)
			return null;
		ParameterTypeVariable2 cv= makeParameterTypeVariable(methodBinding, parameterIndex);
		if (cv == null)
			return null;
		cv.setCompilationUnit(cu);
		return cv;
	}

	public ReturnTypeVariable2 makeReturnTypeVariable(IMethodBinding methodBinding) {
		if (methodBinding == null)
			return null;
		TType returnType= getBoxedType(methodBinding.getReturnType(), /*no boxing*/null);
		if (returnType == null)
			return null;

		ReturnTypeVariable2 cv= new ReturnTypeVariable2(returnType, methodBinding);
		ReturnTypeVariable2 storedCv= (ReturnTypeVariable2) storedCv(cv);
		if (cv == storedCv) {
			makeElementVariables(storedCv, returnType);
			makeArrayElementVariable(storedCv);
			if (JavaManipulationPlugin.DEBUG_TYPE_CONSTRAINTS)
				storedCv.setData(ConstraintVariable2.TO_STRING, "[ReturnType(" + Bindings.asString(methodBinding) + ")]"); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return storedCv;
	}

	public ReturnTypeVariable2 makeDeclaredReturnTypeVariable(IMethodBinding methodBinding, ICompilationUnit cu) {
		if (methodBinding == null)
			return null;
		ReturnTypeVariable2 cv= makeReturnTypeVariable(methodBinding);
		if (cv == null)
			return null;

		cv.setCompilationUnit(cu);
		if (methodBinding.getDeclaringClass().isLocal())
			fCuScopedConstraintVariables.add(cv);
		return cv;
	}

	public ImmutableTypeVariable2 makeImmutableTypeVariable(ITypeBinding typeBinding, Expression expression) {
//		Assert.isTrue(! typeBinding.isGenericType()); // see JDT/Core bug 80472
		TType type= getBoxedType(typeBinding, expression);
		if (type == null)
			return null;
		return makeImmutableTypeVariable(type);
	}

	public ImmutableTypeVariable2 makeImmutableTypeVariable(TType type) {
		ImmutableTypeVariable2 cv= new ImmutableTypeVariable2(type);
		ImmutableTypeVariable2 storedCv= (ImmutableTypeVariable2) storedCv(cv);
		if (cv == storedCv) {
			makeFixedElementVariables(storedCv, type);
			makeArrayElementVariable(storedCv);
		}
		return storedCv;
	}

	public static boolean isAGenericType(TType type) {
		return type.isGenericType()
				|| type.isParameterizedType()
				|| (type.isRawType() && type.getTypeDeclaration().isGenericType());
	}

	public static boolean isAGenericType(ITypeBinding type) {
		return type.isGenericType()
				|| type.isParameterizedType()
				|| (type.isRawType() && type.getTypeDeclaration().isGenericType());
	}

	public CastVariable2 makeCastVariable(CastExpression castExpression, ConstraintVariable2 expressionCv) {
		ITypeBinding typeBinding= castExpression.resolveTypeBinding();
		ICompilationUnit cu= RefactoringASTParser.getCompilationUnit(castExpression);
		CompilationUnitRange range= new CompilationUnitRange(cu, castExpression);
		CastVariable2 castCv= new CastVariable2(createTType(typeBinding), range, expressionCv);
		fCastVariables.add(castCv);
		return castCv;
	}

	public TypeEnvironment getTypeEnvironment() {
		return fTypeEnvironment;
	}

	public CollectionElementVariable2 getElementVariable(ConstraintVariable2 constraintVariable, ITypeBinding typeVariable) {
		Assert.isTrue(typeVariable.isTypeVariable()); // includes null check
		HashMap<String, CollectionElementVariable2> typeVarToElementVars= getIndexedCollectionElements(constraintVariable);
		if (typeVarToElementVars == null)
			return null;
		return typeVarToElementVars.get(typeVariable.getKey());
	}

	public Map<String, CollectionElementVariable2> getElementVariables(ConstraintVariable2 constraintVariable) {
		Map<String, CollectionElementVariable2> elementVariables= getIndexedCollectionElements(constraintVariable);
		if (elementVariables == null)
			return EMPTY_COLLECTION_ELEMENT_VARIABLES_MAP;
		else
			return elementVariables;
	}

	public ArrayElementVariable2 getArrayElementVariable(ConstraintVariable2 constraintVariable) {
		return (ArrayElementVariable2) constraintVariable.getData(ARRAY_ELEMENT);
	}

	private void setArrayElementVariable(ConstraintVariable2 constraintVariable, ArrayElementVariable2 arrayElementVariable) {
		constraintVariable.setData(ARRAY_ELEMENT, arrayElementVariable);
	}

	public void makeArrayElementVariable(ConstraintVariable2 constraintVariable2) {
		if (constraintVariable2.getType() == null || ! constraintVariable2.getType().isArrayType())
			return;

		ArrayElementVariable2 storedArrayElementVariable= getArrayElementVariable(constraintVariable2);
		if (storedArrayElementVariable != null)
			return;

		ArrayElementVariable2 arrayElementCv= new ArrayElementVariable2(constraintVariable2);
		arrayElementCv= (ArrayElementVariable2) storedCv(arrayElementCv);
		setArrayElementVariable(constraintVariable2, arrayElementCv);

		makeArrayElementVariable(arrayElementCv); //recursive
	}

	public void makeElementVariables(ConstraintVariable2 expressionCv, TType type) {
		if (isAGenericType(type)) {
			GenericType genericType= (GenericType) type.getTypeDeclaration();
			TType[] typeParameters= genericType.getTypeParameters();
			for (int i= 0; i < typeParameters.length; i++) {
				TypeVariable typeVariable= (TypeVariable) typeParameters[i];
				makeElementVariable(expressionCv, typeVariable, i);
				if (typeVariable.getBounds().length != 0) {
					//TODO: create subtype constraints for bounds
				}
			}
		}
		makeElementVariablesFromSupertypes(expressionCv, type.getTypeDeclaration());
	}

	private void makeElementVariablesFromSupertypes(ConstraintVariable2 expressionCv, TType type) {
		TType superclass= type.getSuperclass();
		if (superclass != null) {
			makeSupertypeElementVariables(expressionCv, superclass);
		}

		for (TType intf : type.getInterfaces()) {
			makeSupertypeElementVariables(expressionCv, intf);
		}

	}

	private void makeSupertypeElementVariables(ConstraintVariable2 expressionCv, TType supertype) {
		if (supertype.isParameterizedType() || supertype.isRawType()) {
			TType[] typeArguments= null;
			if (supertype.isParameterizedType()) {
				typeArguments= ((ParameterizedType) supertype).getTypeArguments();
			}
			TypeVariable[] typeParameters= ((GenericType) supertype.getTypeDeclaration()).getTypeParameters();
			for (int i= 0; i < typeParameters.length; i++) {
				TypeVariable typeParameter= typeParameters[i];
				TType referenceTypeArgument;
				if (typeArguments == null) { // raw type
					referenceTypeArgument= typeParameter.getErasure();
				} else {
					referenceTypeArgument= typeArguments[i];
				}
				if (referenceTypeArgument.isTypeVariable()) {
					CollectionElementVariable2 referenceTypeArgumentCv= getElementVariable(expressionCv, (TypeVariable) referenceTypeArgument);
					if (referenceTypeArgumentCv != null) {
						setElementVariable(expressionCv, referenceTypeArgumentCv, typeParameter);
						continue;
					}
				}
				makeElementVariable(expressionCv, typeParameter, CollectionElementVariable2.NOT_DECLARED_TYPE_VARIABLE_INDEX);
			}
		}
		makeElementVariablesFromSupertypes(expressionCv, supertype);
	}

	public void makeFixedElementVariables(ConstraintVariable2 expressionCv, TType type) {
		if (isAGenericType(type)) {
			GenericType genericType= (GenericType) type.getTypeDeclaration();
			TType[] typeParameters= genericType.getTypeParameters();
			TType[] typeArguments= null;
			if (type.isParameterizedType())
				typeArguments= ((ParameterizedType) type).getTypeArguments();

			for (int i= 0; i < typeParameters.length; i++) {
				TypeVariable typeVariable= (TypeVariable) typeParameters[i];
				CollectionElementVariable2 elementCv= makeElementVariable(expressionCv, typeVariable, i);
				TType referenceTypeArgument;
				if (typeArguments == null) { // raw type
					continue; // do not consider
				} else {
					referenceTypeArgument= typeArguments[i];
				}
				createEqualsConstraint(elementCv, makeImmutableTypeVariable(referenceTypeArgument));
//				if (typeVariable.getBounds().length != 0) {
//					//TODO: create subtype constraints for bounds
//				}
			}
		}
		makeFixedElementVariablesFromSupertypes(expressionCv, type.getTypeDeclaration());
	}

	private void makeFixedElementVariablesFromSupertypes(ConstraintVariable2 expressionCv, TType type) {
		TType superclass= type.getSuperclass();
		if (superclass != null)
			makeFixedSupertypeElementVariables(expressionCv, superclass);

		for (TType intf : type.getInterfaces()) {
			makeFixedSupertypeElementVariables(expressionCv, intf);
		}
	}

	private void makeFixedSupertypeElementVariables(ConstraintVariable2 expressionCv, TType supertype) {
		if (supertype.isParameterizedType() || supertype.isRawType()) {
			TType[] typeArguments= null;
			if (supertype.isParameterizedType())
				typeArguments= ((ParameterizedType) supertype).getTypeArguments();

			TypeVariable[] typeParameters= ((GenericType) supertype.getTypeDeclaration()).getTypeParameters();
			for (int i= 0; i < typeParameters.length; i++) {
				TypeVariable typeParameter= typeParameters[i];
				TType referenceTypeArgument;
				if (typeArguments == null) { // raw type
					continue; // do not consider
				} else {
					referenceTypeArgument= typeArguments[i];
				}
				if (referenceTypeArgument.isTypeVariable()) {
					CollectionElementVariable2 referenceTypeArgumentCv= getElementVariable(expressionCv, (TypeVariable) referenceTypeArgument);
					setElementVariable(expressionCv, referenceTypeArgumentCv, typeParameter);
				} else {
					CollectionElementVariable2 elementCv= makeElementVariable(expressionCv, typeParameter, CollectionElementVariable2.NOT_DECLARED_TYPE_VARIABLE_INDEX);
					createEqualsConstraint(elementCv, makeImmutableTypeVariable(referenceTypeArgument));
				}
			}
		}
		makeFixedElementVariablesFromSupertypes(expressionCv, supertype);
	}

	/**
	 * Create equality constraints between generic type variables of expressionCv and referenceCv.
	 * For example, the generic interface <code>java.lang.Iterable&lt;E&gt;</code> defines a method
	 * <code>Iterator&lt;E&gt; iterator()</code>. Given
	 * <ul>
	 *   <li>an expressionCv of a subtype of <code>Iterable</code>,</li>
	 *   <li>a referenceCv of a subtype of <code>Iterator</code>, and</li>
	 *   <li>a reference binding of the Iterable#iterator()'s return type (the parameterized type <code>Iterator&lt;E&gt;</code>),</li>
	 * </ul>
	 * this method creates an equality constraint between the type variable E in expressionCV and
	 * the type variable E in referenceCV.
	 *
	 * @param expressionCv the type constraint variable of an expression
	 * @param methodTypeVariables
	 * @param referenceCv the type constraint variable of a type reference
	 * @param reference the declared type reference
	 */
	public void createTypeVariablesEqualityConstraints(ConstraintVariable2 expressionCv, Map<String, IndependentTypeVariable2> methodTypeVariables, ConstraintVariable2 referenceCv, TType reference) {
		if (reference.isParameterizedType() || reference.isRawType()) {
			TType[] referenceTypeArguments= null;
			if (reference.isParameterizedType()) {
				referenceTypeArguments= ((ParameterizedType) reference).getTypeArguments();
			}
			TType[] referenceTypeParameters= ((GenericType) reference.getTypeDeclaration()).getTypeParameters();
			for (int i= 0; i < referenceTypeParameters.length; i++) {
				TypeVariable referenceTypeParameter= (TypeVariable) referenceTypeParameters[i];
				TType referenceTypeArgument;
				if (referenceTypeArguments == null)
					referenceTypeArgument= referenceTypeParameter.getErasure();
				else
					referenceTypeArgument= referenceTypeArguments[i];
				if (referenceTypeArgument.isTypeVariable()) {
					ConstraintVariable2 referenceTypeArgumentCv= getElementTypeCv(referenceTypeArgument, expressionCv, methodTypeVariables);
					CollectionElementVariable2 referenceTypeParametersCv= getElementVariable(referenceCv, referenceTypeParameter);
					createEqualsConstraint(referenceTypeArgumentCv, referenceTypeParametersCv);
				} else if (referenceTypeArgument.isWildcardType()) {
					ConstraintVariable2 referenceTypeArgumentCv= makeImmutableTypeVariable(fTypeEnvironment.VOID); //block it for now (bug 106174)
					CollectionElementVariable2 referenceTypeParametersCv= getElementVariable(referenceCv, referenceTypeParameter);
					createEqualsConstraint(referenceTypeArgumentCv, referenceTypeParametersCv);

//					WildcardType wildcardType= (WildcardType) referenceTypeArgument;
//					if (wildcardType.isUnboundWildcardType()) {
//						ConstraintVariable2 referenceTypeArgumentCv= makeImmutableTypeVariable(wildcardType);
//						CollectionElementVariable2 referenceTypeParametersCv= getElementVariable(referenceCv, referenceTypeParameter);
//						createEqualsConstraint(referenceTypeArgumentCv, referenceTypeParametersCv);
//					} else if (wildcardType.isSuperWildcardType() && wildcardType.getBound().isTypeVariable()) {
//						ConstraintVariable2 referenceTypeArgumentBoundCv= getElementTypeCv(wildcardType.getBound(), expressionCv, methodTypeVariables);
//						CollectionElementVariable2 referenceTypeParametersCv= getElementVariable(referenceCv, referenceTypeParameter);
//						//TODO: need *strict* subtype constraint?
//						createSubtypeConstraint(referenceTypeParametersCv, referenceTypeArgumentBoundCv);
//					}
					// else: TODO

//				} else if (referenceTypeArgument.isParameterizedType()) {
//					//TODO: nested containers
//					ParameterizedType parameterizedType= (ParameterizedType) referenceTypeArgument;
//					ParameterizedTypeVariable2 parameterizedTypeCv= makeParameterizedTypeVariable(parameterizedType.getTypeDeclaration());
//					CollectionElementVariable2 referenceTypeParametersCv= getElementVariable(referenceCv, referenceTypeParameter);
//					createEqualsConstraint(parameterizedTypeCv, referenceTypeParametersCv);
//					createElementEqualsConstraints(parameterizedTypeCv, referenceTypeParametersCv);
				} else {
					//TODO
				}
			}

		} else if (reference.isArrayType()) {
			TType elementType= ((ArrayType) reference).getElementType();
			if (elementType.isRawType())
				elementType= elementType.getErasure();
			ConstraintVariable2 elementTypeCv= getElementTypeCv(elementType, expressionCv, methodTypeVariables);
			ArrayElementVariable2 arrayElementTypeCv= getArrayElementVariable(referenceCv);
			createEqualsConstraint(elementTypeCv, arrayElementTypeCv);
		}
	}

	private ConstraintVariable2 getElementTypeCv(TType elementType, ConstraintVariable2 expressionCv, Map<String, IndependentTypeVariable2> methodTypeVariables) {
		if (elementType.isTypeVariable()) {
			ConstraintVariable2 elementTypeCv= methodTypeVariables.get(elementType.getBindingKey());
			if (elementTypeCv != null)
				return elementTypeCv;
			if (expressionCv != null)
				return getElementVariable(expressionCv, (TypeVariable) elementType);
		}
		return null;
	}

	private CollectionElementVariable2 makeElementVariable(ConstraintVariable2 expressionCv, TypeVariable typeVariable, int declarationTypeVariableIndex) {
		if (expressionCv == null)
			return null;

		CollectionElementVariable2 storedElementVariable= getElementVariable(expressionCv, typeVariable);
		if (storedElementVariable != null)
			return storedElementVariable;

		CollectionElementVariable2 cv= new CollectionElementVariable2(expressionCv, typeVariable, declarationTypeVariableIndex);
		cv= (CollectionElementVariable2) storedCv(cv);
		setElementVariable(expressionCv, cv, typeVariable);
		return cv;
	}

	@SuppressWarnings("unchecked")
	private static HashMap<String, CollectionElementVariable2> getIndexedCollectionElements(ConstraintVariable2 constraintVariable) {
		return constraintVariable == null ? null : (HashMap<String, CollectionElementVariable2>) constraintVariable.getData(INDEXED_COLLECTION_ELEMENTS);
	}

	private static void setElementVariable(ConstraintVariable2 typeConstraintVariable, CollectionElementVariable2 elementVariable, TypeVariable typeVariable) {
		HashMap<String, CollectionElementVariable2> keyToElementVar= getIndexedCollectionElements(typeConstraintVariable);
		String key= typeVariable.getBindingKey();
		if (keyToElementVar == null) {
			keyToElementVar= new HashMap<>();
			typeConstraintVariable.setData(INDEXED_COLLECTION_ELEMENTS, keyToElementVar);
		} else {
			Object existingElementVar= keyToElementVar.get(key);
			if (existingElementVar != null) {
				Assert.isTrue(existingElementVar == elementVariable);
			}
		}
		keyToElementVar.put(key, elementVariable);
	}

	public CollectionElementVariable2 getElementVariable(ConstraintVariable2 constraintVariable, TypeVariable typeVariable) {
		Assert.isTrue(typeVariable.isTypeVariable()); // includes null check
		HashMap<String, CollectionElementVariable2> typeVarToElementVars= getIndexedCollectionElements(constraintVariable);
		if (typeVarToElementVars == null)
			return null;
		return typeVarToElementVars.get(typeVariable.getBindingKey());
	}

	public void createElementEqualsConstraints(ConstraintVariable2 cv, ConstraintVariable2 initializerCv) {
		internalCreateElementEqualsConstraints(cv, initializerCv, false);
	}

	public void createAssignmentElementConstraints(ConstraintVariable2 cv, ConstraintVariable2 initializerCv) {
		internalCreateElementEqualsConstraints(cv, initializerCv, true);
	}

	private void internalCreateElementEqualsConstraints(ConstraintVariable2 cv, ConstraintVariable2 initializerCv, boolean isAssignment) {
		if (cv == null || initializerCv == null)
			return;

		Map<String, CollectionElementVariable2> leftElements= getElementVariables(cv);
		Map<String, CollectionElementVariable2> rightElements= getElementVariables(initializerCv);
		for (Entry<String, CollectionElementVariable2> leftEntry : leftElements.entrySet()) {
			String leftTypeVariableKey= leftEntry.getKey();
			CollectionElementVariable2 rightElementVariable= rightElements.get(leftTypeVariableKey);
			if (rightElementVariable != null) {
				CollectionElementVariable2 leftElementVariable= leftEntry.getValue();
				createEqualsConstraint(leftElementVariable, rightElementVariable);
				internalCreateElementEqualsConstraints(leftElementVariable, rightElementVariable, false); // recursive
			}
		}

		ArrayElementVariable2 leftArrayElement= getArrayElementVariable(cv);
		ArrayElementVariable2 rightArrayElement= getArrayElementVariable(initializerCv);
		if (leftArrayElement != null && rightArrayElement != null) {
			if (isAssignment)
				createSubtypeConstraint(rightArrayElement, leftArrayElement);
			else
				createEqualsConstraint(leftArrayElement, rightArrayElement);
			internalCreateElementEqualsConstraints(leftArrayElement, rightArrayElement, false); // recursive
		}
	}

	/**
	 * @return the receiver of the method invocation this expressionVariable
	 *         depends on, or null iff no receiver is available. If the receiver
	 *         stayed raw, then the method return type cannot be substituted.
	 */
	public ConstraintVariable2 getMethodReceiverCv(ConstraintVariable2 expressionVariable) {
		return (ConstraintVariable2) expressionVariable.getData(METHOD_RECEIVER);
	}

	public void setMethodReceiverCV(ConstraintVariable2 expressionVariable, ConstraintVariable2 methodReceiverCV) {
		expressionVariable.setData(METHOD_RECEIVER, methodReceiverCV);
	}

}
