/*
 * JBoss, Home of Professional Open Source
 * Copyright 2014, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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 org.jboss.weld.util.collections;

import java.util.AbstractSet;
import java.util.Collection;
import java.util.Set;
import java.util.Spliterator;
import java.util.Spliterators;

/**
 * Common implementation for all immutable set implementations.
 *
 * @author Jozef Hartinger
 * @see WELD-1753
 *
 * @param <T> the element type
 */
abstract class AbstractImmutableSet<T> extends AbstractSet<T> implements Set<T> {

    @Override
    public boolean add(T e) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean remove(Object o) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean addAll(Collection<? extends T> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void clear() {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean isEmpty() {
        return false;
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        for (Object item : c) {
            if (!contains(item)) {
                return false;
            }
        }
        return true;
    }

    @SuppressWarnings("checkstyle:equalshashcode")
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof Set<?>) {
            return equalsSet((Set<?>) obj);
        }
        return false;
    }

    boolean equalsSet(Set<?> that) {
        return this.size() == that.size() && that.containsAll(this);
    }

    @Override
    public Spliterator<T> spliterator() {
        return Spliterators.spliterator(this, Spliterator.DISTINCT | Spliterator.IMMUTABLE | Spliterator.NONNULL);
    }
}