/*
 * Copyright (C) 2002-2024 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 static it.unimi.dsi.fastutil.Size64.sizeOf;
#if KEYS_BYTE_CHAR_SHORT_FLOAT
import WIDENED_PACKAGE.KEY_WIDENED_ITERATOR;
import WIDENED_PACKAGE.KEY_WIDENED_SPLITERATOR;
#endif

#if KEYS_USE_REFERENCE_EQUALITY
/** A type-specific {@link Collection}; provides some additional methods
 * that use polymorphism to avoid (un)boxing.
 *
 * <p>Additionally, this class defines strengthens (again) {@link #iterator()}.
 *
 * @see Collection
 */
#else
 /** A type-specific {@link Collection}; provides some additional methods
 * that use polymorphism to avoid (un)boxing.
 *
 * <p>Additionally, this class defines strengthens (again) {@link #iterator()}.
 *
 * <p>This interface specifies reference equality semantics (members will be compared equal with
 * {@code ==} instead of {@link Object#equals(Object) equals}), which may result in breaks in contract
 * if attempted to be used with non reference-equality semantics based {@link Collection}s. For example, a
 * {@code aReferenceCollection.equals(aObjectCollection)} may return different a different result then
 * {@code aObjectCollection.equals(aReferenceCollection)}, in violation of {@link Object#equals equals}'s
 * contract requiring it being symmetric.
 *
 * @see Collection
 */
#endif
public interface COLLECTION KEY_GENERIC extends Collection<KEY_GENERIC_CLASS>, KEY_ITERABLE KEY_GENERIC {

	/** Returns a type-specific iterator on the elements of this collection.
	 *
	 * @apiNote This specification strengthens the one given in
	 * {@link java.lang.Iterable#iterator()}, which was already
	 * strengthened in the corresponding type-specific class,
	 * but was weakened by the fact that this interface extends {@link Collection}.
	 *
	 * @return a type-specific iterator on the elements of this collection.
	 */
	@Override
	KEY_ITERATOR KEY_GENERIC iterator();

#if KEYS_PRIMITIVE && !KEY_CLASS_Boolean
#if KEYS_INT_LONG_DOUBLE
	/** Returns a primitive iterator on the elements of this collection.<p>
	 *
	 * <p>This method is identical to {@link #iterator()}, as the type-specific
	 * iterator is already compatible with the JDK's primitive iterators.
	 * It only exists for compatibility with the other primitive types' {@code Collection}s
	 * that have use for widened iterators.
	 *
	 * @return a primitive iterator on the elements of this collection.
	 * @since 8.5.0
	 */
	@Override
	default KEY_WIDENED_ITERATOR KEY_WIDENED_ITERATOR_METHOD() { return iterator(); }
#else
#if KEY_CLASS_Character
	/**
	 * Returns a widened primitive iterator on the elements of this collection.<p>
	 *
	 * <p>This method is provided for the purpose of APIs that expect only the JDK's
	 * primitive iterators, of which there are only {@code int}, {@code long}, and {@code double}.
	 *
	 * <p><b>WARNING</b>: This is <em>not</em> the same as converting the source to a sequence
	 * of code points. This returned instance literally performs {@code (int)(charValue)} casts.
	 * Surrogate pairs will be left as separate elements instead of combined into a single element
	 * with the code point it represents. See {@link Character} for more discussion on code points,
	 * char values, and surrogate pairs.
	 *
	 * @return a widened primitive iterator on the elements of this collection.
	 * @since 8.5.0
	 */
#else
	/**
	 * Returns a widened primitive iterator on the elements of this collection.<p>
	 *
	 * <p>This method is provided for the purpose of APIs that expect only the JDK's
	 * primitive iterators, of which there are only {@code int}, {@code long}, and {@code double}.
	 *
	 * @return a widened primitive iterator on the elements of this collection.
	 * @since 8.5.0
	 */
#endif
	@Override
	default KEY_WIDENED_ITERATOR KEY_WIDENED_ITERATOR_METHOD() {
		return KEY_ITERABLE.super.KEY_WIDENED_ITERATOR_METHOD();
	}
#endif
#endif

	// If you change these default spliterator methods, you will likely need to update Iterable, List, Set, and SortedSet too

	/** Returns a type-specific spliterator on the elements of this collection.
	 *
	 * <p>See {@link java.util.Collection#spliterator()} for more documentation on the requirements
	 * of the returned spliterator.
	 *
	 * @apiNote This specification strengthens the one given in
	 * {@link java.util.Collection#spliterator()}.
	 * <p>Also, this is generally the only {@code spliterator} method subclasses should override.
	 *
	 * @implSpec The default implementation returns a late-binding spliterator (see
	 * {@link java.util.Spliterator Spliterator} for documentation on what binding policies mean)
	 * that wraps this instance's type specific {@link #iterator}.
	 * <p>Additionally, it reports {@link java.util.Spliterator#SIZED Spliterator.SIZED}
	 *
	 * @implNote As this default implementation wraps the iterator, and {@link java.util.Iterator}
	 * is an inherently linear API, the returned spliterator will yield limited performance gains
	 * when run in parallel contexts, as the returned spliterator's
	 * {@link java.util.Spliterator#trySplit() trySplit()} will have linear runtime.
	 *
	 * @return a type-specific spliterator on the elements of this collection.
	 * @since 8.5.0
	 */
	@Override
#if SPLITERATOR_ASSURE_OVERRIDE
	abstract KEY_SPLITERATOR KEY_GENERIC spliterator();
#else
	default KEY_SPLITERATOR KEY_GENERIC spliterator() {
		return SPLITERATORS.asSpliterator(
				iterator(), sizeOf(this), SPLITERATORS.COLLECTION_SPLITERATOR_CHARACTERISTICS);
	}
#endif

#if KEYS_PRIMITIVE && !KEY_CLASS_Boolean
#if KEYS_INT_LONG_DOUBLE
	/** Returns a primitive spliterator on the elements of this collection.<p>
	 *
	 * <p>This method is identical to {@link #spliterator()}, as the type-specific
	 * spliterator is already compatible with the JDK's primitive spliterators.
	 * It only exists for compatibility with the other primitive types' {@code Collection}s
	 * that have use for widened spliterators.
	 *
	 * @return a primitive spliterator on the elements of this collection.
	 * @since 8.5.0
	 */
	@Override
	default KEY_WIDENED_SPLITERATOR KEY_WIDENED_SPLITERATOR_METHOD() { return spliterator(); }
#else
#if KEY_CLASS_Character
	/** Returns widened primitive spliterator on the elements of this collection.<p>
	 *
	 * <p>This method is provided for the purpose of APIs that expect only the JDK's
	 * primitive spliterators, of which there are only {@code int}, {@code long}, and {@code double}.
	 *
	 * <p><b>WARNING</b>: This is <em>not</em> the same as converting the source to a sequence
	 * of code points. This returned instance literally performs {@code (int)(charValue)} casts.
	 * Surrogate pairs will be left as separate elements instead of combined into a single element
	 * with the code point it represents. See {@link Character} for more discussion on code points,
	 * char values, and surrogate pairs.
	 *
	 * @return a widened primitive spliterator on the elements of this collection.
	 * @since 8.5.0
	 */
#else
	/** Returns widened primitive spliterator on the elements of this collection.<p>
	 *
	 * <p>This method is provided for the purpose of APIs that expect only the JDK's
	 * primitive spliterators, of which there are only {@code int}, {@code long}, and {@code double}.
	 *
	 * @return a widened primitive spliterator on the elements of this collection.
	 * @since 8.5.0
	 */
#endif
	@Override
	default KEY_WIDENED_SPLITERATOR KEY_WIDENED_SPLITERATOR_METHOD() {
		return KEY_ITERABLE.super.KEY_WIDENED_SPLITERATOR_METHOD();
	}
#endif
#endif

#if KEYS_PRIMITIVE

	/** Ensures that this collection contains the specified element (optional operation).
	 * @see Collection#add(Object)
	 */
	boolean add(KEY_TYPE key);

	/** Returns {@code true} if this collection contains the specified element.
	 * @see Collection#contains(Object)
	 */
	boolean contains(KEY_TYPE key);

	/** Removes a single instance of the specified element from this
	 * collection, if it is present (optional operation).
	 *
	 * <p>Note that this method should be called {@link java.util.Collection#remove(Object) remove()}, but the clash
	 * with the similarly named index-based method in the {@link java.util.List} interface
	 * forces us to use a distinguished name. For simplicity, the set interfaces reinstates
	 * {@code remove()}.
	 *
	 * @see Collection#remove(Object)
	 */
	boolean rem(KEY_TYPE key);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	default boolean add(final KEY_GENERIC_CLASS key) {
		return add(KEY_CLASS2TYPE(key));
	}

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	default boolean contains(final Object key) {
		if (key == null) return false;
		return contains(KEY_OBJ2TYPE(key));
	}

	/** {@inheritDoc}
	 * @deprecated Please use (and implement) the {@code rem()} method instead.
	 */
	@Deprecated
	@Override
	default boolean remove(final Object key) {
		if (key == null) return false;
		return rem(KEY_OBJ2TYPE(key));
	}

	/** Returns a primitive type array containing the items of this collection.
	 * @return a primitive type array containing the items of this collection.
	 * @see Collection#toArray()
	 */
	KEY_TYPE[] TO_KEY_ARRAY();

	/** Returns a primitive type array containing the items of this collection.
	 *
	 * <p>Note that, contrarily to {@link Collection#toArray(Object[])}, this
	 * methods just writes all elements of this collection: no special
	 * value will be added after the last one.
	 *
	 * @param a if this array is big enough, it will be used to store this collection.
	 * @return a primitive type array containing the items of this collection.
	 * @see Collection#toArray(Object[])
	 * @deprecated Please use {@code toArray()} instead&mdash;this method is redundant and will be removed in the future.
	 */
	@Deprecated
	default KEY_TYPE[] TO_KEY_ARRAY(KEY_TYPE a[]) {
		return toArray(a);
	}

	/** Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
	 *
	 * <p>Note that, contrarily to {@link Collection#toArray(Object[])}, this
	 * methods just writes all elements of this collection: no special
	 * value will be added after the last one.
	 *
	 * @param a if this array is big enough, it will be used to store this collection.
	 * @return a primitive type array containing the items of this collection.
	 * @see Collection#toArray(Object[])
	 */
	KEY_TYPE[] toArray(KEY_TYPE a[]);

	/** Adds all elements of the given type-specific collection to this collection.
	 *
	 * @param c a type-specific collection.
	 * @see Collection#addAll(Collection)
	 * @return {@code true} if this collection changed as a result of the call.
	 */
	boolean addAll(COLLECTION c);

	/** Checks whether this collection contains all elements from the given type-specific collection.
	 *
	 * @param c a type-specific collection.
	 * @see Collection#containsAll(Collection)
	 * @return {@code true} if this collection contains all elements of the argument.
	 */
	boolean containsAll(COLLECTION c);

	/** Remove from this collection all elements in the given type-specific collection.
	 *
	 * @param c a type-specific collection.
	 * @see Collection#removeAll(Collection)
	 * @return {@code true} if this collection changed as a result of the call.
	 */
	boolean removeAll(COLLECTION c);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	default boolean removeIf(final java.util.function.Predicate<? super KEY_GENERIC_CLASS> filter) {
		return removeIf(
			filter instanceof METHOD_ARG_PREDICATE ?
				((METHOD_ARG_PREDICATE) filter) :
				(METHOD_ARG_PREDICATE) key -> filter.test(KEY2OBJ(KEY_NARROWING(key))));
	}

	/** Remove from this collection all elements which satisfy the given predicate.
	 *
	 * @param filter a predicate which returns {@code true} for elements to be
	 *        removed.
	 * @see Collection#removeIf(java.util.function.Predicate)
	 * @return {@code true} if any elements were removed.
	 * @apiNote Implementing classes should generally override this method, and take the default
	 *   implementation of the other overloads which will delegate to this method (after proper
	 *   conversions).
	 */
	default boolean removeIf(final METHOD_ARG_PREDICATE filter) {
		java.util.Objects.requireNonNull(filter);
		boolean removed = false;
		final KEY_ITERATOR each = iterator();
		while (each.hasNext()) {
			if (filter.test(each.NEXT_KEY())) {
				each.remove();
				removed = true;
			}
		}
		return removed;
	}

#if KEYS_INT_LONG_DOUBLE
	// Because our primitive Predicate interface extends both the JDK's primitive
	// and object Predicate interfaces, calling this method with it would be ambiguous.
	// This overload exists to pass it to the proper primitive overload.

	/** Remove from this collection all elements which satisfy the given predicate.
	 *
	 * <p><b>WARNING</b>: Overriding this method is almost always a mistake, as this
	 * overload only exists to disambiguate. Instead, override the {@code removeIf()} overload
	 * that uses the JDK's primitive predicate type (e.g. {@link java.util.function.IntPredicate}).
	 *
	 * <p>If Java supported final default methods, this would be one, but sadly it does not.
	 *
	 * <p>If you checked and are overriding the version with {@code java.util.function.XPredicate}, and
	 * still see this warning, then your IDE is incorrectly conflating this method with the proper
	 * method to override, and you can safely ignore this message.
	 *
	 * @param filter a predicate which returns {@code true} for elements to be
	 *        removed.
	 * @see Collection#removeIf(java.util.function.Predicate)
	 * @return {@code true} if any elements were removed.
	 */
	default boolean removeIf(final KEY_PREDICATE filter) {
		return removeIf((JDK_PRIMITIVE_PREDICATE) filter);
	}
#elif KEYS_BYTE_CHAR_SHORT_FLOAT
	/** Remove from this collection all elements which satisfy the given predicate.
	 *
	 * @param filter a predicate which returns {@code true} for elements to be
	 *        removed.
	 * @see Collection#removeIf(java.util.function.Predicate)
	 * @return {@code true} if any elements were removed.
	 * @implNote Unless the argument is type-specific, this method will introduce an intermediary
	 *   lambda to perform widening casts. Please use the type-specific overload to avoid this overhead. 
	 */
	@SuppressWarnings("overloads")
	default boolean removeIf(final JDK_PRIMITIVE_PREDICATE filter) {
		return removeIf(filter instanceof KEY_PREDICATE ? (KEY_PREDICATE) filter : (KEY_PREDICATE) filter::test);
	}
#endif

	/** Retains in this collection only elements from the given type-specific collection.
	 *
	 * @param c a type-specific collection.
	 * @see Collection#retainAll(Collection)
	 * @return {@code true} if this collection changed as a result of the call.
	 */
	boolean retainAll(COLLECTION c);

#if !KEY_CLASS_Boolean
	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	default java.util.stream.Stream<KEY_GENERIC_CLASS> stream() { return Collection.super.stream(); }

#if KEY_CLASS_Character
	/** Return a primitive stream over the elements, performing widening casts if needed.
	 *
	 * <p><b>WARNING</b>: This is <em>not</em> the same as converting the source to a sequence
	 * of code points. This returned instance literally performs {@code (int)(charValue)} casts.
	 * Surrogate pairs will be left as separate elements instead of combined into a single element
	 * with the code point it represents. See {@link Character} for more discussion on code points,
	 * char values, and surrogate pairs.
	 *
	 * @return a primitive stream over the elements.
	 * @see Collection#stream()
	 * @see java.util.stream.IntStream
	 */
#else
	/** Return a primitive stream over the elements, performing widening casts if needed.
	 * @return a primitive stream over the elements.
	 * @see Collection#stream()
	 * @see java.util.stream.IntStream
	 */
#endif
	default JDK_PRIMITIVE_STREAM KEY_WIDENED_STREAM_METHOD() {
		return java.util.stream.StreamSupport.KEY_WIDENED_STREAM_METHOD(KEY_WIDENED_SPLITERATOR_METHOD(), false);
	}

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	default java.util.stream.Stream<KEY_GENERIC_CLASS> parallelStream() { return Collection.super.parallelStream(); }

#if KEY_CLASS_Character
	/** Return a parallel primitive stream over the elements, performing widening casts if needed.
	 *
	 * <p><b>WARNING</b>: This is <em>not</em> the same as converting the source to a sequence
	 * of code points. This returned instance literally performs {@code (int)(charValue)} casts.
	 * Surrogate pairs will be left as separate elements instead of combined into a single element
	 * with the code point it represents. See {@link Character} for more discussion on code points,
	 * char values, and surrogate pairs.
	 *
	 * @return a parallel primitive stream over the elements.
	 * @see Collection#parallelStream()
	 * @see java.util.stream.IntStream
	 */
#else
	/** Return a parallel primitive stream over the elements, performing widening casts if needed.
	 * @return a parallel primitive stream over the elements.
	 * @see Collection#parallelStream()
	 * @see java.util.stream.IntStream
	 */
#endif
	default JDK_PRIMITIVE_STREAM KEY_WIDENED_PARALLEL_STREAM_METHOD() {
		return java.util.stream.StreamSupport.KEY_WIDENED_STREAM_METHOD(KEY_WIDENED_SPLITERATOR_METHOD(), true);
	}
#endif

#endif
}