/*		 
 * Copyright (C) 2002-2014 Sebastiano Vigna 
 *
 * 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 PACKAGE;

import java.util.Collection;

import it.unimi.dsi.fastutil.objects.ObjectArrays;


/** A class providing static methods and objects that do useful things with type-specific collections.
 *
 * @see java.util.Collections
 */

public class COLLECTIONS {

	private COLLECTIONS() {}

	/** An immutable class representing an empty type-specific collection.
	 *
	 * <P>This class may be useful to implement your own in case you subclass
	 * a type-specific collection.
	 */

	public abstract static class EmptyCollection KEY_GENERIC extends ABSTRACT_COLLECTION KEY_GENERIC {
		
		protected EmptyCollection() {}

		public boolean add( KEY_GENERIC_TYPE k ) { throw new UnsupportedOperationException(); }

		public boolean contains( KEY_TYPE k ) { return false; }
           
		public Object[] toArray() { return ObjectArrays.EMPTY_ARRAY; }

#if #keys(primitive)
		public KEY_TYPE[] TO_KEY_ARRAY( KEY_TYPE[] a ) { return a; }
		public KEY_TYPE[] TO_KEY_ARRAY() { return ARRAYS.EMPTY_ARRAY; }

		public boolean rem( KEY_TYPE k ) { throw new UnsupportedOperationException(); }
		public boolean addAll( COLLECTION c ) { throw new UnsupportedOperationException(); }
		public boolean removeAll( COLLECTION c ) { throw new UnsupportedOperationException(); }
		public boolean retainAll( COLLECTION c ) { throw new UnsupportedOperationException(); }
		public boolean containsAll( COLLECTION c ) { return c.isEmpty(); }
#else
		public boolean remove( final Object k ) { throw new UnsupportedOperationException(); }
		public <T> T[] toArray( T[] a ) { return a; }
#endif

		@SuppressWarnings("unchecked")
		public KEY_BIDI_ITERATOR KEY_GENERIC iterator() { return ITERATORS.EMPTY_ITERATOR; }

		public int size() { return 0; }
		public void clear() {}

		public int hashCode() { return 0; }
		public boolean equals( Object o ) { 
			if ( o == this ) return true;
			if ( ! ( o instanceof Collection ) ) return false;
			return ((Collection<?>)o).isEmpty();
		}
	}


	/** A synchronized wrapper class for collections. */

	public static class SynchronizedCollection KEY_GENERIC implements COLLECTION KEY_GENERIC, java.io.Serializable {

		private static final long serialVersionUID = -7046029254386353129L;

		protected final COLLECTION KEY_GENERIC collection;
		protected final Object sync;

		protected SynchronizedCollection( final COLLECTION KEY_GENERIC c, final Object sync ) {
			if ( c == null ) throw new NullPointerException();
			this.collection = c;
			this.sync = sync;
		}

		protected SynchronizedCollection( final COLLECTION KEY_GENERIC c ) {
			if ( c == null ) throw new NullPointerException();
			this.collection = c;
			this.sync = this;
		}

		public int size() { synchronized( sync ) { return collection.size(); } }
		public boolean isEmpty() { synchronized( sync ) { return collection.isEmpty(); } }
		public boolean contains( final KEY_TYPE o ) { synchronized( sync ) { return collection.contains( o ); } }

		public KEY_TYPE[] TO_KEY_ARRAY() { synchronized( sync ) { return collection.TO_KEY_ARRAY(); } }

#if #keys(primitive)
		public Object[] toArray() { synchronized( sync ) { return collection.toArray(); } }
		public KEY_TYPE[] TO_KEY_ARRAY( final KEY_TYPE[] a ) { synchronized( sync ) { return collection.TO_KEY_ARRAY( a ); } }
		public KEY_TYPE[] toArray( final KEY_TYPE[] a ) { synchronized( sync ) { return collection.TO_KEY_ARRAY( a ); } }

		public boolean addAll( final COLLECTION c ) { synchronized( sync ) { return collection.addAll( c ); } }
		public boolean containsAll( final COLLECTION c ) { synchronized( sync ) { return collection.containsAll( c ); } }
		public boolean removeAll( final COLLECTION c ) { synchronized( sync ) { return collection.removeAll( c ); } }
		public boolean retainAll( final COLLECTION c ) { synchronized( sync ) { return collection.retainAll( c ); } }

		public boolean add( final KEY_GENERIC_CLASS k ) { synchronized( sync ) { return collection.add( k ); } }
		public boolean contains( final Object k ) { synchronized( sync ) { return collection.contains( k ); } }
#endif

		public <T> T[] toArray( final T[] a ) { synchronized( sync ) { return collection.toArray( a ); } }

		public KEY_ITERATOR KEY_GENERIC iterator() { return collection.iterator(); }

		@Deprecated
		public KEY_ITERATOR KEY_GENERIC KEY_ITERATOR_METHOD() { return iterator(); }

		public boolean add( final KEY_GENERIC_TYPE k ) { synchronized( sync ) { return collection.add( k ); } }
		public boolean rem( final KEY_TYPE k ) { synchronized( sync ) { return collection.REMOVE( k ); } }
		public boolean remove( final Object ok ) { synchronized( sync ) { return collection.remove( ok ); } }

		public boolean addAll( final Collection<? extends KEY_GENERIC_CLASS> c ) { synchronized( sync ) { return collection.addAll( c ); } }
		public boolean containsAll( final Collection<?> c ) { synchronized( sync ) { return collection.containsAll( c ); } }
		public boolean removeAll( final Collection<?> c ) { synchronized( sync ) { return collection.removeAll( c ); } }
		public boolean retainAll( final Collection<?> c ) { synchronized( sync ) { return collection.retainAll( c ); } }

		public void clear() { synchronized( sync ) { collection.clear(); } }
		public String toString() { synchronized( sync ) { return collection.toString(); } }
	}


	/** Returns a synchronized collection backed by the specified collection.
	 *
	 * @param c the collection to be wrapped in a synchronized collection.
	 * @return a synchronized view of the specified collection.
	 * @see java.util.Collections#synchronizedCollection(Collection)
	 */
	public static KEY_GENERIC COLLECTION KEY_GENERIC synchronize( final COLLECTION KEY_GENERIC c ) { return new SynchronizedCollection KEY_GENERIC( c ); }

	/** Returns a synchronized collection backed by the specified collection, using an assigned object to synchronize.
	 *
	 * @param c the collection to be wrapped in a synchronized collection.
	 * @param sync an object that will be used to synchronize the list access.
	 * @return a synchronized view of the specified collection.
	 * @see java.util.Collections#synchronizedCollection(Collection)
	 */

	public static KEY_GENERIC COLLECTION KEY_GENERIC synchronize( final COLLECTION KEY_GENERIC c, final Object sync ) { return new SynchronizedCollection KEY_GENERIC( c, sync ); }


	/** An unmodifiable wrapper class for collections. */

	public static class UnmodifiableCollection KEY_GENERIC implements COLLECTION KEY_GENERIC, java.io.Serializable {

		private static final long serialVersionUID = -7046029254386353129L;

		protected final COLLECTION KEY_GENERIC collection;

		protected UnmodifiableCollection( final COLLECTION KEY_GENERIC c ) {
			if ( c == null ) throw new NullPointerException();
			this.collection = c;
		}

		public int size() { return collection.size(); }
		public boolean isEmpty() { return collection.isEmpty(); }
		public boolean contains( final KEY_TYPE o ) { return collection.contains( o ); }

		public KEY_ITERATOR KEY_GENERIC iterator() { return ITERATORS.unmodifiable( collection.iterator() ); }

		@Deprecated
		public KEY_ITERATOR KEY_GENERIC KEY_ITERATOR_METHOD() { return iterator(); }

		public boolean add( final KEY_GENERIC_TYPE k ) { throw new UnsupportedOperationException(); }
		public boolean remove( final Object ok ) { throw new UnsupportedOperationException(); }

		public boolean addAll( final Collection<? extends KEY_GENERIC_CLASS> c ) { throw new UnsupportedOperationException(); }
		public boolean containsAll( final Collection<?> c ) { return collection.containsAll( c ); }
		public boolean removeAll( final Collection<?> c ) { throw new UnsupportedOperationException(); }
		public boolean retainAll( final Collection<?> c ) { throw new UnsupportedOperationException(); }

		public void clear() { throw new UnsupportedOperationException(); }
		public String toString() { return collection.toString(); }

		public <T> T[] toArray( final T[] a ) { return collection.toArray( a ); }

		public Object[] toArray() { return collection.toArray(); }

#if #keys(primitive)
		public KEY_TYPE[] TO_KEY_ARRAY() { return collection.TO_KEY_ARRAY(); }
		public KEY_TYPE[] TO_KEY_ARRAY( final KEY_TYPE[] a ) { return collection.TO_KEY_ARRAY( a ); }
		public KEY_TYPE[] toArray( final KEY_TYPE[] a ) { return collection.toArray( a ); }
		public boolean rem( final KEY_TYPE k ) { throw new UnsupportedOperationException(); }

		public boolean addAll( final COLLECTION c ) { throw new UnsupportedOperationException(); }
		public boolean containsAll( final COLLECTION c ) { return collection.containsAll( c ); }
		public boolean removeAll( final COLLECTION c ) { throw new UnsupportedOperationException(); }
		public boolean retainAll( final COLLECTION c ) { throw new UnsupportedOperationException(); }

		public boolean add( final KEY_GENERIC_CLASS k ) { throw new UnsupportedOperationException(); }
		public boolean contains( final Object k ) { return collection.contains( k ); }
#endif
	}


	/** Returns an unmodifiable collection backed by the specified collection.
	 *
	 * @param c the collection to be wrapped in an unmodifiable collection.
	 * @return an unmodifiable view of the specified collection.
	 * @see java.util.Collections#unmodifiableCollection(Collection)
	 */
	public static KEY_GENERIC COLLECTION KEY_GENERIC unmodifiable( final COLLECTION KEY_GENERIC c ) { return new UnmodifiableCollection KEY_GENERIC( c ); }

	/** A collection wrapper class for iterables. */

	public static class IterableCollection KEY_GENERIC extends ABSTRACT_COLLECTION KEY_GENERIC implements java.io.Serializable {

		private static final long serialVersionUID = -7046029254386353129L;

		protected final KEY_ITERABLE KEY_GENERIC iterable;

		protected IterableCollection( final KEY_ITERABLE KEY_GENERIC iterable ) {
			if ( iterable == null ) throw new NullPointerException();
			this.iterable = iterable;
		}

		public int size() { 
			int c = 0;
			final KEY_ITERATOR KEY_GENERIC iterator = iterator();
			while( iterator.hasNext() ) {
				iterator.next();
				c++;
			}
			
			return c;
		}
		
		public boolean isEmpty() { return iterable.iterator().hasNext(); }
		public KEY_ITERATOR KEY_GENERIC iterator() { return iterable.iterator(); }

		@Deprecated
		public KEY_ITERATOR KEY_GENERIC KEY_ITERATOR_METHOD() { return iterator(); }
	}


	/** Returns an unmodifiable collection backed by the specified iterable.
	 *
	 * @param iterable the iterable object to be wrapped in an unmodifiable collection.
	 * @return an unmodifiable collection view of the specified iterable.
	 */
	@SuppressWarnings("unchecked")
	public static KEY_GENERIC COLLECTION KEY_GENERIC asCollection( final KEY_ITERABLE KEY_GENERIC iterable ) { 
		if ( iterable instanceof COLLECTION ) return (COLLECTION KEY_GENERIC)iterable;
		return new IterableCollection KEY_GENERIC( iterable );
	}

}