/*******************************************************************************
 * Copyright (c) 2000, 2011 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:
 *   Robert M. Fuhrer (rfuhrer@watson.ibm.com), IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.corext.refactoring.typeconstraints.typesets;

import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;

import org.eclipse.core.runtime.Assert;

import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.ArrayType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints.types.TType;
import org.eclipse.jdt.internal.corext.refactoring.typeconstraints2.TTypes;

/**
 * A type-safe wrapper for {@code Set<TType>} that also adds {@code TType}-specific
 * functionality, e.g. subTypes() and superTypes().
 */
public class EnumeratedTypeSet extends TypeSet {
	static private int sCount= 0;

	static public int getCount() {
		return sCount;
	}

	static public void resetCount() {
		sCount= 0;
	}

	/**
	 * Set containing the TTypes in this EnumeratedTypeSet.
	 */
	Set<TType> fMembers= new LinkedHashSet<>();

	/**
	 * Constructs a new EnumeratedTypeSet with the members of Set s in it.
	 * All elements of s must be TTypes.
	 *
	 * @param types the types
	 * @param typeSetEnvironment the environment
	 */
	public EnumeratedTypeSet(Iterator<TType> types, TypeSetEnvironment typeSetEnvironment) {
		super(typeSetEnvironment);
		while (types.hasNext()) {
			fMembers.add(types.next());
		}
		sCount++;
	}

	/**
	 * Constructs an empty EnumeratedTypeSet.
	 *
	 * @param typeSetEnvironment the environment
	 */
	public EnumeratedTypeSet(TypeSetEnvironment typeSetEnvironment) {
		super(typeSetEnvironment);
		sCount++;
	}

	/**
	 * Constructs a new EnumeratedTypeSet with the given single TType in it.
	 *
	 * @param t the type
	 * @param typeSetEnvironment the environment
	 */
	public EnumeratedTypeSet(TType t, TypeSetEnvironment typeSetEnvironment) {
		super(typeSetEnvironment);
		Assert.isNotNull(t);
		fMembers.add(t);
		sCount++;
	}

	/**
	 * @return <code>true</code> iff this set represents the universe of TTypes
	 */
	@Override
	public boolean isUniverse() {
		return false;
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) return true;
		if (o instanceof EnumeratedTypeSet) {
			EnumeratedTypeSet other= (EnumeratedTypeSet) o;

			return fMembers.equals(other.fMembers);
		} else if (o instanceof SingletonTypeSet) {
			SingletonTypeSet other= (SingletonTypeSet) o;

			return (fMembers.size() == 1) && fMembers.contains(other.anyMember());
		} else if (o instanceof TypeSet) {
			TypeSet other= (TypeSet) o;

			for(Iterator<TType> otherIter= other.iterator(); otherIter.hasNext(); ) {
				if (!fMembers.contains(otherIter.next()))
					return false;
			}
			for(Iterator<TType> myIter= fMembers.iterator(); myIter.hasNext(); ) {
				if (!other.contains(myIter.next()))
					return false;
			}
			return true;
		} else
			return false;
	}

	@Override
	public int hashCode() {
		return 37 + fMembers.hashCode();
	}

	/**
	 * Computes and returns a <em>new</em> EnumeratedTypeSet representing the intersection of the
	 * receiver with s2. Does not modify the receiver.
	 * @param s2 the other type set
	 */
	@Override
	protected TypeSet specialCasesIntersectedWith(TypeSet s2) {
		if (s2 instanceof EnumeratedTypeSet) {
			EnumeratedTypeSet result= new EnumeratedTypeSet(getTypeSetEnvironment());

			result.addAll(this); // copy first since retainAll() modifies in-place
			result.retainAll(s2);
			if (result.size() > 0)
				return result;
			else
				return getTypeSetEnvironment().getEmptyTypeSet();
		}
		return null;
	}

	/**
	 * Modifies this EnumeratedTypeSet to represent the intersection of the receiver with s2.
	 * @param s2 the other type set
	 */
	public void intersectWith(TypeSet s2) {
		if (isUniverse()) {
			if (s2.isUniverse())
				return;
			// More than an optimization: the universe never contains array types, so
			// if s2 has array types, the following will retain them, as it should.
			EnumeratedTypeSet ets2= (EnumeratedTypeSet) s2;
			fMembers= new LinkedHashSet<>();
			fMembers.addAll(ets2.fMembers);
		} else
			retainAll(s2);
	}

	/**
	 * @return a new TypeSet representing the set of all sub-types of the
	 * types in the receiver
	 */
	@Override
	public TypeSet subTypes() {
		if (isUniverse())
			return makeClone(); // subtypes(universe) = universe

		if (fMembers.contains(getJavaLangObject()))
			return getTypeSetEnvironment().getUniverseTypeSet();

		return getTypeSetEnvironment().createSubTypesSet(this);
	}

	public static EnumeratedTypeSet makeArrayTypesForElements(Iterator<TType> elemTypes, TypeSetEnvironment typeSetEnvironment) {
		EnumeratedTypeSet result= new EnumeratedTypeSet(typeSetEnvironment);

		while (elemTypes.hasNext()) {
			TType t= elemTypes.next();
			result.add(TTypes.createArrayType(t, 1));
		}
//		result.initComplete();
		return result;
	}

	/**
	 * @return a new TypeSet representing the set of all super-types of the
	 * types in the receiver
	 */
	@Override
	public TypeSet superTypes() {
		if (isUniverse())
			return makeClone(); // The supertypes of the universe is the universe

		return getTypeSetEnvironment().createSuperTypesSet(this);
	}

	@Override
	public TypeSet makeClone() {
		EnumeratedTypeSet result= new EnumeratedTypeSet(getTypeSetEnvironment());

		result.fMembers.addAll(fMembers);
		result.initComplete();
		return result;
	}

	public int size() {
		return fMembers.size();
	}

	public void clear() {
		if (isUniverse())
			fMembers= new LinkedHashSet<>();
		else
			fMembers.clear();
	}

	@Override
	public boolean isEmpty() {
		return fMembers.isEmpty();
	}

	public TType[] toArray() {
		return fMembers.toArray(new TType[fMembers.size()]);
	}

	public boolean add(TType t) {
		// Doesn't make sense to do here what other methods do (copy-and-modify)
		Assert.isTrue(!isUniverse(), "Someone's trying to expand the universe!"); //$NON-NLS-1$
		return fMembers.add(t);
	}

	@Override
	public boolean contains(TType t) {
		if (isUniverse())
			return true;
		return fMembers.contains(t);
	}

	public boolean remove(TType t) {
		if (isUniverse())
			fMembers= cloneSet(fMembers);
		return fMembers.remove(t);
	}

	private Set<TType> cloneSet(Set<TType> members) {
		Set<TType> result= new LinkedHashSet<>();
		result.addAll(members);
		return result;
	}

	public boolean addAll(TypeSet s) {
		if (s instanceof EnumeratedTypeSet) {
			EnumeratedTypeSet ets= (EnumeratedTypeSet) s;

			return fMembers.addAll(ets.fMembers);
		} else {
			EnumeratedTypeSet ets= s.enumerate();

			return fMembers.addAll(ets.fMembers);
		}
	}

	@Override
	public TypeSet addedTo(TypeSet that) {
		EnumeratedTypeSet result= new EnumeratedTypeSet(getTypeSetEnvironment());

		result.addAll(this);
		result.addAll(that);
		result.initComplete();
		return result;
	}

	@Override
	public boolean containsAll(TypeSet s) {
		if (isUniverse())
			return true;
		if (s.isUniverse())
			return false;
		EnumeratedTypeSet ets= s.enumerate();

		return fMembers.containsAll(ets.fMembers);
	}

	public boolean removeAll(EnumeratedTypeSet s) {
		if (isUniverse())
			fMembers= cloneSet(fMembers);
		return fMembers.removeAll(s.fMembers);
	}

	public boolean retainAll(TypeSet s) {
		if (s.isUniverse()) return false;

		EnumeratedTypeSet ets= (EnumeratedTypeSet) s;

		if (isUniverse()) {
			fMembers= cloneSet(ets.fMembers);
			return true;
		} else
			return fMembers.retainAll(ets.fMembers);
	}

	@Override
	public boolean isSingleton() {
		return fMembers.size() == 1;
	}

	@Override
	public TType anyMember() {
		return fMembers.iterator().next();
	}

	@Override
	public TypeSet upperBound() {
		if (fMembers.size() == 1)
			return new SingletonTypeSet(fMembers.iterator().next(), getTypeSetEnvironment());
		if (fMembers.contains(getJavaLangObject()))
			return new SingletonTypeSet(getJavaLangObject(), getTypeSetEnvironment());

		EnumeratedTypeSet result= new EnumeratedTypeSet(getTypeSetEnvironment());

		// Add to result each element of fMembers that has no proper supertype in fMembers
		result.fMembers.addAll(fMembers);
		for(Iterator<TType> iter= fMembers.iterator(); iter.hasNext(); ) {
			TType t= iter.next();

			if (t.isArrayType()) {
				ArrayType at= (ArrayType) t;
				int numDims= at.getDimensions();
				for(Iterator<TType> subIter=TTypes.getAllSubTypesIterator(at.getElementType()); subIter.hasNext(); ) {
					result.fMembers.remove(TTypes.createArrayType(subIter.next(), numDims));
				}
			} else {
				for (Iterator<TType> iterator= TTypes.getAllSubTypesIterator(t); iterator.hasNext();) {
					result.fMembers.remove(iterator.next());
				}
			}
		}
		result.initComplete();
		return result;
	}

	@Override
	public TypeSet lowerBound() {
		if (fMembers.size() == 1)
			return new SingletonTypeSet(fMembers.iterator().next(), getTypeSetEnvironment());

		EnumeratedTypeSet result= new EnumeratedTypeSet(getTypeSetEnvironment());

		// Add to result each element of fMembers that has no proper subtype in fMembers
		result.fMembers.addAll(fMembers);

		for(Iterator<TType> iter= fMembers.iterator(); iter.hasNext(); ) {
			TType t= iter.next();

			// java.lang.Object is only in the lower bound if fMembers consists
			// of only java.lang.Object, but that case is handled above.
			if (t.equals(getJavaLangObject())) {
				result.fMembers.remove(t);
				continue;
			}

			if (t instanceof ArrayType) {
				ArrayType at= (ArrayType) t;
				int numDims= at.getDimensions();
				for(Iterator<TType> superIter=TTypes.getAllSuperTypesIterator(at.getElementType()); superIter.hasNext(); ) {
					result.fMembers.remove(TTypes.createArrayType(superIter.next(), numDims));
				}
			} else {
				for (Iterator<TType> iterator= TTypes.getAllSuperTypesIterator(t); iterator.hasNext();) {
					result.fMembers.remove(iterator.next());
				}
			}
		}
		if (result.size() > 0)
			return result;
		else
			return getTypeSetEnvironment().getEmptyTypeSet();
	}

	@Override
	public boolean hasUniqueLowerBound() {
		return fMembers.size() == 1;
	}

	@Override
	public boolean hasUniqueUpperBound() {
		return fMembers.size() == 1;
	}

	@Override
	public TType uniqueLowerBound() {
		if (fMembers.size() == 1)
			return fMembers.iterator().next();
		return null;
	}

	@Override
	public TType uniqueUpperBound() {
		if (fMembers.size() == 1)
			return fMembers.iterator().next();
		return null;
	}

	@Override
	public Iterator<TType> iterator() {
		return fMembers.iterator();
	}

	/**
	 * Limits the display of set elements to the first sMaxElements.
	 */
	private static final int sMaxElements= 10; // Integer.MAX_VALUE;

	@Override
	public String toString() {
		StringBuilder b= new StringBuilder();
		b.append("{" + fID+ ":"); //$NON-NLS-1$ //$NON-NLS-2$
		if (isUniverse())
			b.append(" <universe>"); //$NON-NLS-1$
		else {
			int count=0;
			Iterator<TType> iter;
			for(iter= iterator(); iter.hasNext() && count < sMaxElements; count++) {
				TType type= iter.next();
				b.append(' ')
				 .append(type.getPrettySignature());
				if (iter.hasNext())
					b.append(',');
			}
			if (iter.hasNext())
				b.append(" ..."); //$NON-NLS-1$
		}
		b.append(" }"); //$NON-NLS-1$
		return b.toString();
	}

	@Override
	public EnumeratedTypeSet enumerate() {
		return this; // (EnumeratedTypeSet) makeClone();
	}

	public void initComplete() {
		Assert.isTrue(! fMembers.isEmpty());
	}

}
