/*
 * Copyright (C) 2010-2022 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.List;
import java.util.Spliterator;
import static it.unimi.dsi.fastutil.BigArrays.length;
import it.unimi.dsi.fastutil.BigArrays;
import it.unimi.dsi.fastutil.BigList;

#if ! KEYS_USE_REFERENCE_EQUALITY
/** A type-specific {@link BigList}; provides some additional methods that use polymorphism to avoid (un)boxing.
 *
 * <p>Additionally, this interface strengthens {@link #iterator()}, {@link #listIterator()},
 * {@link #listIterator(long)} and {@link #subList(long,long)}.
 *
 * <p>Besides polymorphic methods, this interfaces specifies methods to copy into an array or remove contiguous
 * sublists. Although the abstract implementation of this interface provides simple, one-by-one implementations
 * of these methods, it is expected that concrete implementation override them with optimized versions.
 *
 * @see List
 */
public interface BIG_LIST KEY_GENERIC extends BigList<KEY_GENERIC_CLASS>, COLLECTION KEY_GENERIC, Comparable<BigList<? extends KEY_GENERIC_CLASS>> {
#else
/** A type-specific {@link BigList}; provides some additional methods that use polymorphism to avoid (un)boxing.
 *
 * <p>Additionally, this interface strengthens {@link #iterator()}, {@link #listIterator()},
 * {@link #listIterator(long)} and {@link #subList(long,long)}.
 *
 * <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 BigList}s. For example, a
 * {@code aReferenceBigList.equals(aObjectBigList)} may return different a different result then
 * {@code aObjectBigList.equals(aReferenceBigList)}, in violation of {@link Object#equals equals}'s contract
 * requiring it being symmetric.
 *
 * <p>Besides polymorphic methods, this interfaces specifies methods to copy into an array or remove contiguous
 * sublists. Although the abstract implementation of this interface provides simple, one-by-one implementations
 * of these methods, it is expected that concrete implementation override them with optimized versions.
 *
 * @see List
 */
public interface BIG_LIST KEY_GENERIC extends BigList<KEY_GENERIC_CLASS>, COLLECTION KEY_GENERIC {
#endif

	/** Returns a type-specific iterator on the elements of this list.
	 *
	 * @apiNote This specification strengthens the one given in {@link java.util.Collection#iterator()}.
	 * @see java.util.Collection#iterator()
	 */
	@Override
	KEY_BIG_LIST_ITERATOR KEY_GENERIC iterator();


	/** Returns a type-specific big-list iterator on this type-specific big list.
	 *
	 * @apiNote This specification strengthens the one given in {@link BigList#listIterator()}.
	 * @see BigList#listIterator()
	 */
	@Override
	KEY_BIG_LIST_ITERATOR KEY_GENERIC listIterator();

	/** Returns a type-specific list iterator on this type-specific big list starting at a given index.
	 *
	 * @apiNote This specification strengthens the one given in {@link BigList#listIterator(long)}.
	 * @see BigList#listIterator(long)
	 */
	@Override
	KEY_BIG_LIST_ITERATOR KEY_GENERIC listIterator(long index);

	/** Returns a type-specific spliterator on the elements of this big-list.
	 *
	 * <p>BigList spliterators must report at least {@link Spliterator#SIZED} and {@link Spliterator#ORDERED}.
	 *
	 * <p>See {@link java.util.List#spliterator()} for more documentation on the requirements
	 * of the returned spliterator (despite {@code BigList} not being a {@code List}, most of the
	 * same requirements apply.
	 *
	 * @apiNote This is generally the only {@code spliterator} method subclasses should override.
	 *
	 * @implSpec The default implementation returns a late-binding spliterator (see
	 * {@link Spliterator} for documentation on what binding policies mean).
	 * <ul>
	 * <li>For {@link java.util.RandomAccess RandomAccess} lists, this will return a spliterator
	 * that calls the type-specific {@link #get(long)} method on the appropriate indexes.</li>
	 * <li>Otherwise, the spliterator returned will wrap this instance's type specific {@link #iterator}.</li>
	 * </ul>
	 * <p>In either case, the spliterator reports {@link Spliterator#SIZED},
	 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
	 *
	 * @implNote As the non-{@linkplain java.util.RandomAccess RandomAccess} case is based on 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 Spliterator#trySplit() trySplit()} will have linear runtime.
	 * <p>For {@link java.util.RandomAccess RandomAccess} lists, the parallel performance should
	 * be reasonable assuming {@link #get(long)} is truly constant time like {@link java.util.RandomAccess
	 * RandomAccess} suggests. 
	 *
	 * @return {@inheritDoc}
	 * @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(), size64(), SPLITERATORS.LIST_SPLITERATOR_CHARACTERISTICS);
	}
#endif

	/** Returns a type-specific view of the portion of this type-specific big list from the index {@code from}, inclusive, to the index {@code to}, exclusive.
	 *
	 * @apiNote This specification strengthens the one given in {@link BigList#subList(long,long)}.
	 *
	 * @see BigList#subList(long,long)
	 */
	@Override
	BIG_LIST KEY_GENERIC subList(long from, long to);

	/** Copies (hopefully quickly) elements of this type-specific big list into the given big array.
	 *
	 * @param from the start index (inclusive).
	 * @param a the destination big array.
	 * @param offset the offset into the destination big array where to store the first element copied.
	 * @param length the number of elements to be copied.
	 */
	void getElements(long from, KEY_TYPE a[][], long offset, long length);

	/** Copies (hopefully quickly) elements of this type-specific big list into the given array.
	 *
	 * @param from the start index (inclusive).
	 * @param a the destination array.
	 * @param offset the offset into the destination array where to store the first element copied.
	 * @param length the number of elements to be copied.
	 */
	default void getElements(long from, KEY_TYPE a[], int offset, int length) {
#if KEYS_REFERENCE
		getElements(from, new KEY_TYPE[][]{a}, (long)offset, (long)length);
#else
		getElements(from, new KEY_TYPE[][]{a}, offset, length);
#endif
	}

	/** Removes (hopefully quickly) elements of this type-specific big list.
	 *
	 * @param from the start index (inclusive).
	 * @param to the end index (exclusive).
	 */
	void removeElements(long from, long to);

	/** Add (hopefully quickly) elements to this type-specific big list.
	 *
	 * @param index the index at which to add elements.
	 * @param a the big array containing the elements.
	 */
	void addElements(long index, KEY_GENERIC_TYPE a[][]);

	/** Add (hopefully quickly) elements to this type-specific big list.
	 *
	 * @param index the index at which to add elements.
	 * @param a the big array containing the elements.
	 * @param offset the offset of the first element to add.
	 * @param length the number of elements to add.
	 */
	void addElements(long index, KEY_GENERIC_TYPE a[][], long offset, long length);

	/** Set (hopefully quickly) elements to match the array given.
	 * @param a the big array containing the elements.
	 * @since 8.5.0
	 */
	default void setElements(KEY_GENERIC_TYPE a[][]) {
		setElements(0, a);
	}

	/** Set (hopefully quickly) elements to match the array given.
	 * @param index the index at which to start setting elements.
	 * @param a the big array containing the elements.
	 * @since 8.5.0
	 */
	default void setElements(long index, KEY_GENERIC_TYPE a[][]) {
		setElements(index, a, 0, length(a));
	}

	/** Set (hopefully quickly) elements to match the array given.
	 *
	 * Sets each in this list to the corresponding elements in the array, as if by
	 * <pre>
	 * ListIterator iter = listIterator(index);
	 * long i = 0;
	 * while (i &lt; length) {
	 *   iter.next();
	 *   iter.set(BigArrays.get(a, offset + i++);
	 * }
	 * </pre>
	 * However, the exact implementation may be more efficient, taking into account
	 * whether random access is faster or not, or at the discretion of subclasses,
	 * abuse internals.
	 *
	 * @param index the index at which to start setting elements.
	 * @param a the big array containing the elements.
	 * @param offset the offset of the first element to add.
	 * @param length the number of elements to add.
	 * @since 8.5.0
	 */
	default void setElements(long index, KEY_GENERIC_TYPE a[][], long offset, long length) {
		// We can't use AbstractList#ensureIndex, sadly.
		if (index < 0)  throw new IndexOutOfBoundsException("Index (" + index + ") is negative");
		if (index > size64()) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than list size (" + (size64()) + ")");
		BigArrays.ensureOffsetLength(a, offset, length);
		if (index + length > size64()) throw new IndexOutOfBoundsException("End index (" + (index + length) + ") is greater than list size (" + size64() + ")");
		KEY_BIG_LIST_ITERATOR KEY_GENERIC iter = listIterator(index);
		long i = 0;
		while (i < length) {
			iter.NEXT_KEY();
			iter.set(BigArrays.get(a, offset + i++));
		}
	}

#if KEYS_PRIMITIVE

	/** Inserts the specified element at the specified position in this type-specific big list (optional operation).
	 * @see BigList#add(long,Object)
	 */
	void add(long index, KEY_TYPE key);

	/** Inserts all of the elements in the specified type-specific collection into this type-specific big list at the specified position (optional operation).
	 * @see List#addAll(int,java.util.Collection)
	 */
	boolean addAll(long index, COLLECTION c);

	/** Returns the element at the specified position.
	 * @see BigList#get(long)
	 */
	KEY_TYPE GET_KEY(long index);

	/** Removes the element at the specified position.
	 * @see BigList#remove(long) */
	KEY_TYPE REMOVE_KEY(long index);

	/** Replaces the element at the specified position in this big list with the specified element (optional operation).
	 * @see BigList#set(long,Object)
	 */
	KEY_TYPE set(long index, KEY_TYPE k);

	/** Returns the index of the first occurrence of the specified element in this type-specific big list, or -1 if this big list does not contain the element.
	 * @see BigList#indexOf(Object)
	 */
	long indexOf(KEY_TYPE k);

	/** Returns the index of the last occurrence of the specified element in this type-specific big list, or -1 if this big list does not contain the element.
	 * @see BigList#lastIndexOf(Object)
	 */
	long lastIndexOf(KEY_TYPE k);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	void add(long index, KEY_CLASS key);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	KEY_GENERIC_CLASS get(long index);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	long indexOf(Object o);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	long lastIndexOf(Object o);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	KEY_GENERIC_CLASS remove(long index);

	/** {@inheritDoc}
	 * @deprecated Please use the corresponding type-specific method instead. */
	@Deprecated
	@Override
	KEY_GENERIC_CLASS set(long index, KEY_GENERIC_CLASS k);
#endif

	/** Inserts all of the elements in the specified type-specific big list into this type-specific big list at the specified position (optional operation).
	 * @apiNote This method exists only for the sake of efficiency: override are expected to use {@link #getElements}/{@link #addElements}.
	 * @implSpec This method delegates to the one accepting a collection, but it might be implemented more efficiently.
	 * @see BigList#addAll(long,Collection)
	 */
	default boolean addAll(final long index, final BIG_LIST KEY_EXTENDS_GENERIC l) { return addAll(index, (COLLECTION KEY_EXTENDS_GENERIC) l); }

	/** Appends all of the elements in the specified type-specific big list to the end of this type-specific big list (optional operation).
	 * @implSpec This method delegates to the index-based version, passing {@link #size()} as first argument.
	 * @see BigList#addAll(Collection)
	 */
	default boolean addAll(final BIG_LIST KEY_EXTENDS_GENERIC l) { return addAll(size64(), l); }


	/** Inserts all of the elements in the specified type-specific list into this type-specific big list at the specified position (optional operation).
	 * @apiNote This method exists only for the sake of efficiency: override are expected to use {@link #getElements}/{@link #addElements}.
	 * @implSpec This method delegates to the one accepting a collection, but it might be implemented more efficiently.
	 * @see BigList#addAll(long,Collection)
	 */
	default boolean addAll(final long index, final LIST KEY_EXTENDS_GENERIC l) { return addAll(index, (COLLECTION KEY_EXTENDS_GENERIC) l); }

	/** Appends all of the elements in the specified type-specific list to the end of this type-specific big list (optional operation).
	 * @implSpec This method delegates to the index-based version, passing {@link #size()} as first argument.
	 * @see BigList#addAll(Collection)
	 */
	default boolean addAll(final LIST KEY_EXTENDS_GENERIC l) { return addAll(size64(), l); }

	// Without any toBigArray methods, there is no sensible default sort methods we can have.
}
