/*
 * Copyright (C) 2010-2017 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;

#if KEYS_REFERENCE
import it.unimi.dsi.fastutil.Stack;
#endif

import java.util.Iterator;
import java.util.Collection;
import java.util.NoSuchElementException;

import it.unimi.dsi.fastutil.BigList;
import it.unimi.dsi.fastutil.BigListIterator;

/**  An abstract class providing basic methods for big lists implementing a type-specific big list interface. */

public abstract class ABSTRACT_BIG_LIST KEY_GENERIC extends ABSTRACT_COLLECTION KEY_GENERIC implements BIG_LIST KEY_GENERIC, STACK KEY_GENERIC {

	protected ABSTRACT_BIG_LIST() {}

	/** Ensures that the given index is nonnegative and not greater than this big-list size.
	 *
	 * @param index an index.
	 * @throws IndexOutOfBoundsException if the given index is negative or greater than this big-list size.
	 */
	protected void ensureIndex(final long index) {
		if (index < 0)  throw new IndexOutOfBoundsException("Index (" + index + ") is negative");
		if (index > size64()) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than list size (" + (size64()) + ")");
	}

	/** Ensures that the given index is nonnegative and smaller than this big-list size.
	 *
	 * @param index an index.
	 * @throws IndexOutOfBoundsException if the given index is negative or not smaller than this big-list size.
	 */
	protected void ensureRestrictedIndex(final long index) {
		if (index < 0)  throw new IndexOutOfBoundsException("Index (" + index + ") is negative");
		if (index >= size64()) throw new IndexOutOfBoundsException("Index (" + index + ") is greater than or equal to list size (" + (size64()) + ")");
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public void add(final long index, final KEY_GENERIC_TYPE k) {
		throw new UnsupportedOperationException();
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific version of {@link BigList#add(long, Object)}.
	 */
	@Override
	public boolean add(final KEY_GENERIC_TYPE k) {
		add(size64(), k);
		return true;
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public KEY_GENERIC_TYPE REMOVE_KEY(long i) {
		throw new UnsupportedOperationException();
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation always throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public KEY_GENERIC_TYPE set(final long index, final KEY_GENERIC_TYPE k) {
		throw new UnsupportedOperationException();
	}

	/** Adds all of the elements in the specified collection to this list (optional operation). */
	@Override
	public boolean addAll(long index, final Collection<? extends KEY_GENERIC_CLASS> c) {
		ensureIndex(index);
		final Iterator<? extends KEY_GENERIC_CLASS> i = c.iterator();
		final boolean retVal = i.hasNext();
		while(i.hasNext()) add(index++, i.next());
		return retVal;
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific version of {@link BigList#addAll(long, Collection)}.
	 */
	@Override
	public boolean addAll(final Collection<? extends KEY_GENERIC_CLASS> c) {
		return addAll(size64(), c);
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to {@link #listIterator()}.
	 */
	@Override
	public KEY_BIG_LIST_ITERATOR KEY_GENERIC iterator() {
		return listIterator();
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to {@link BigList#listIterator(long) listIterator(0)}.
	 */
	@Override
	public KEY_BIG_LIST_ITERATOR KEY_GENERIC listIterator() {
		return listIterator(0L);
	}

	/** {@inheritDoc}
	 * <p>This implementation is based on the random-access methods. */
	@Override
	public KEY_BIG_LIST_ITERATOR KEY_GENERIC listIterator(final long index) {
		ensureIndex(index);

		return new KEY_BIG_LIST_ITERATOR KEY_GENERIC() {
				long pos = index, last = -1;

				@Override
				public boolean hasNext() { return pos < ABSTRACT_BIG_LIST.this.size64(); }

				@Override
				public boolean hasPrevious() { return pos > 0; }

				@Override
				public KEY_GENERIC_TYPE NEXT_KEY() { if (! hasNext()) throw new NoSuchElementException(); return ABSTRACT_BIG_LIST.this.GET_KEY(last = pos++); }

				@Override
				public KEY_GENERIC_TYPE PREV_KEY() { if (! hasPrevious()) throw new NoSuchElementException(); return ABSTRACT_BIG_LIST.this.GET_KEY(last = --pos); }

				@Override
				public long nextIndex() { return pos; }

				@Override
				public long previousIndex() { return pos - 1; }

				@Override
				public void add(KEY_GENERIC_TYPE k) {
					ABSTRACT_BIG_LIST.this.add(pos++, k);
					last = -1;
				}

				@Override
				public void set(KEY_GENERIC_TYPE k) {
					if (last == -1) throw new IllegalStateException();
					ABSTRACT_BIG_LIST.this.set(last, k);
				}

				@Override
				public void remove() {
					if (last == -1) throw new IllegalStateException();
					ABSTRACT_BIG_LIST.this.REMOVE_KEY(last);
					/* If the last operation was a next(), we are removing an element *before* us, and we must decrease pos correspondingly. */
					if (last < pos) pos--;
					last = -1;
				}
			};
	}


	/** Returns true if this list contains the specified element.
	 * <p>This implementation delegates to {@code indexOf()}.
	 * @see BigList#contains(Object)
	 */
	@Override
	public boolean contains(final KEY_TYPE k) { return indexOf(k) >= 0; }

	@Override
	public long indexOf(final KEY_TYPE k) {
		final KEY_BIG_LIST_ITERATOR KEY_GENERIC i = listIterator();
		KEY_GENERIC_TYPE e;
		while(i.hasNext()) {
			e = i.NEXT_KEY();
			if (KEY_EQUALS(k, e)) return i.previousIndex();
		}
		return -1;
	}

	@Override
	public long lastIndexOf(final KEY_TYPE k) {
		KEY_BIG_LIST_ITERATOR KEY_GENERIC i = listIterator(size64());
		KEY_GENERIC_TYPE e;
		while(i.hasPrevious()) {
			e = i.PREV_KEY();
			if (KEY_EQUALS(k, e)) return i.nextIndex();
		}
		return -1;
	}

	@Override
	public void size(final long size) {
		long i = size64();
		if (size > i) while(i++ < size) add(KEY_NULL);
		else while(i-- != size) remove(i);
	}

	@Override
	public BIG_LIST KEY_GENERIC subList(final long from, final long to) {
		ensureIndex(from);
		ensureIndex(to);
		if (from > to) throw new IndexOutOfBoundsException("Start index (" + from + ") is greater than end index (" + to + ")");

		return new SUBLIST KEY_GENERIC_DIAMOND(this, from, to);
	}

	/** {@inheritDoc}
	 *
	 * <p>This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void removeElements(final long from, final long to) {
		ensureIndex(to);
		KEY_BIG_LIST_ITERATOR KEY_GENERIC i = listIterator(from);
		long n = to - from;
		if (n < 0) throw new IllegalArgumentException("Start index (" + from + ") is greater than end index (" + to + ")");
		while(n-- != 0) {
			i.NEXT_KEY();
			i.remove();
		}
	}

	/** {@inheritDoc}
	 *
	 * <p>This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void addElements(long index, final KEY_GENERIC_TYPE a[][], long offset, long length) {
		ensureIndex(index);
		BIG_ARRAYS.ensureOffsetLength(a, offset, length);
		while(length-- != 0) add(index++, BIG_ARRAYS.get(a, offset++));
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the analogous method for big-array fragments.
	 */
	@Override
	public void addElements(final long index, final KEY_GENERIC_TYPE a[][]) {
		addElements(index, a, 0, BIG_ARRAYS.length(a));
	}

	/** {@inheritDoc}
	 *
	 * <p>This is a trivial iterator-based implementation. It is expected that
	 * implementations will override this method with a more optimized version.
	 */
	@Override
	public void getElements(final long from, final KEY_TYPE a[][], long offset, long length) {
		KEY_BIG_LIST_ITERATOR KEY_GENERIC i = listIterator(from);
		BIG_ARRAYS.ensureOffsetLength(a, offset, length);
		if (from + length > size64()) throw new IndexOutOfBoundsException("End index (" + (from + length) + ") is greater than list size (" + size64() + ")");
		while(length-- != 0) BIG_ARRAYS.set(a, offset++, i.NEXT_KEY());
	}

	/** {@inheritDoc}
	 * <p>This implementation delegates to {@link #removeElements(long, long)}.*/
	@Override
	public void clear() {
		removeElements(0, size64());
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to {@link #size64()}.
	 * @deprecated Please use {@link #size64()} instead. */
	@Override
	@Deprecated
	public int size() {
		return (int)Math.min(Integer.MAX_VALUE, size64());
	}

#if ! KEY_CLASS_Reference
	private boolean valEquals(final Object a, final Object b) { return a == null ? b == null : a.equals(b); }
#endif

	/** Returns the hash code for this big list, which is identical to {@link java.util.List#hashCode()}.
	 *
	 * @return the hash code for this big list.
	 */
	@Override
	public int hashCode() {
		KEY_ITERATOR KEY_GENERIC i = iterator();
		int h = 1;
		long s = size64();
		while (s-- != 0) {
			KEY_GENERIC_TYPE k = i.NEXT_KEY();
			h = 31 * h + KEY2JAVAHASH(k);
		}
		return h;
	}

	@Override
	public boolean equals(final Object o) {
		if (o == this) return true;
		if (! (o instanceof BigList)) return false;
		final BigList<?> l = (BigList<?>)o;
		long s = size64();
		if (s != l.size64()) return false;

#if KEYS_PRIMITIVE
		if (l instanceof BIG_LIST) {
			final KEY_BIG_LIST_ITERATOR KEY_GENERIC i1 = listIterator(), i2 = ((BIG_LIST KEY_GENERIC)l).listIterator();
			while(s-- != 0) if (i1.NEXT_KEY() != i2.NEXT_KEY()) return false;
			return true;
		}
#endif

		final BigListIterator<?> i1 = listIterator(), i2 = l.listIterator();

#if KEY_CLASS_Reference
		while(s-- !=  0) if (i1.next() != i2.next()) return false;
#else
		while(s-- !=  0) if (! valEquals(i1.next(), i2.next())) return false;
#endif
		return true;
	}

#if ! KEY_CLASS_Reference
	/** Compares this big list to another object. If the
	 * argument is a {@link BigList}, this method performs a lexicographical comparison; otherwise,
	 * it throws a {@code ClassCastException}.
	 *
	 * @param l a big list.
	 * @return if the argument is a {@link BigList}, a negative integer,
	 * zero, or a positive integer as this list is lexicographically less than, equal
	 * to, or greater than the argument.
	 * @throws ClassCastException if the argument is not a big list.
	 */

	SUPPRESS_WARNINGS_KEY_UNCHECKED
	@Override
	public int compareTo(final BigList<? extends KEY_GENERIC_CLASS> l) {
		if (l == this) return 0;

		if (l instanceof BIG_LIST) {

			final KEY_BIG_LIST_ITERATOR KEY_GENERIC i1 = listIterator(), i2 = ((BIG_LIST KEY_GENERIC)l).listIterator();
			int r;
			KEY_GENERIC_TYPE e1, e2;

			while(i1.hasNext() && i2.hasNext()) {
				e1 = i1.NEXT_KEY();
				e2 = i2.NEXT_KEY();
				if ((r = KEY_CMP(e1, e2)) != 0) return r;
			}
			return i2.hasNext() ? -1 : (i1.hasNext() ? 1 : 0);
		}

		BigListIterator<? extends KEY_GENERIC_CLASS> i1 = listIterator(), i2 = l.listIterator();
		int r;

		while(i1.hasNext() && i2.hasNext()) {
			if ((r = ((Comparable<? super KEY_GENERIC_CLASS>)i1.next()).compareTo(i2.next())) != 0) return r;
		}
		return i2.hasNext() ? -1 : (i1.hasNext() ? 1 : 0);
	}
#endif

	@Override
	public void push(KEY_GENERIC_TYPE o) {
		add(o);
	}

	@Override
	public KEY_GENERIC_TYPE POP() {
		if (isEmpty()) throw new NoSuchElementException();
		return REMOVE_KEY(size64() - 1);
	}

	@Override
	public KEY_GENERIC_TYPE TOP() {
		if (isEmpty()) throw new NoSuchElementException();
		return GET_KEY(size64() - 1);
	}

	@Override
	public KEY_GENERIC_TYPE PEEK(int i) {
		return GET_KEY(size64() - 1 - i);
	}


#if KEYS_PRIMITIVE
	/** Removes a single instance of the specified element from this collection, if it is present (optional operation).
	 * <p>This implementation delegates to {@code indexOf()}.
	 * @see BigList#remove(Object)
	 */
	@Override
	public boolean rem(KEY_TYPE k) {
		long index = indexOf(k);
		if (index == -1) return false;
		REMOVE_KEY(index);
		return true;
	}

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific version of {@link #addAll(long, Collection)}.
	 */
	@Override
	public boolean addAll(final long index, final COLLECTION c) { return addAll(index, (Collection<? extends KEY_CLASS>)c); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific version of {@link #addAll(long, Collection)}.
	 */
	@Override
	public boolean addAll(final long index, final BIG_LIST l) { return addAll(index, (COLLECTION)l); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific version of {@link #addAll(long, Collection)}.
	 */
	@Override
	public boolean addAll(final COLLECTION c) { return addAll(size64(), c); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the type-specific list version of {@link #addAll(long, Collection)}.
	 */
	@Override
	public boolean addAll(final BIG_LIST l) { return addAll(size64(), l); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public void add(final long index, final KEY_CLASS ok) { add(index, ok.KEY_VALUE()); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS set(final long index, final KEY_CLASS ok) { return KEY2OBJ(set(index, ok.KEY_VALUE())); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS get(final long index) { return KEY2OBJ(GET_KEY(index)); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public long indexOf(final Object ok) { return indexOf(KEY_OBJ2TYPE(ok)); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public long lastIndexOf(final Object ok) { return lastIndexOf(KEY_OBJ2TYPE(ok)); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS remove(final long index) { return KEY2OBJ(REMOVE_KEY(index)); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public void push(KEY_CLASS o) { push(o.KEY_VALUE()); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS pop() { return KEY_CLASS.valueOf(POP()); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS top() { return KEY_CLASS.valueOf(TOP()); }

	/** {@inheritDoc}
	 *
	 * <p>This implementation delegates to the corresponding type-specific method.
	 * @deprecated Please use the corresponding type-specific method instead.
	 */
	@Deprecated
	@Override
	public KEY_CLASS peek(int i) { return KEY_CLASS.valueOf(PEEK(i)); }

#endif

	@Override
	public String toString() {
		final StringBuilder s = new StringBuilder();
		final KEY_ITERATOR KEY_GENERIC i = iterator();
		long n = size64();
		KEY_GENERIC_TYPE k;
		boolean first = true;

		s.append("[");

		while(n-- != 0) {
			if (first) first = false;
			else s.append(", ");
			k = i.NEXT_KEY();
#if KEYS_REFERENCE
			if (this == k) s.append("(this big list)"); else
#endif
				s.append(String.valueOf(k));
		}

		s.append("]");
		return s.toString();
	}


	/** A class implementing a sublist view. */
	public static class SUBLIST KEY_GENERIC extends ABSTRACT_BIG_LIST KEY_GENERIC implements java.io.Serializable {
		private static final long serialVersionUID = -7046029254386353129L;
		/** The list this sublist restricts. */
		protected final BIG_LIST KEY_GENERIC l;
		/** Initial (inclusive) index of this sublist. */
		protected final long from;
		/** Final (exclusive) index of this sublist. */
		protected long to;

		public SUBLIST(final BIG_LIST KEY_GENERIC l, final long from, final long to) {
			this.l = l;
			this.from = from;
			this.to = to;
		}

		private boolean assertRange() {
			assert from <= l.size64();
			assert to <= l.size64();
			assert to >= from;
			return true;
		}

		@Override
		public boolean add(final KEY_GENERIC_TYPE k) {
			l.add(to, k);
			to++;
			assert assertRange();
			return true;
		}

		@Override
		public void add(final long index, final KEY_GENERIC_TYPE k) {
			ensureIndex(index);
			l.add(from + index, k);
			to++;
			assert assertRange();
		}

		@Override
		public boolean addAll(final long index, final Collection<? extends KEY_GENERIC_CLASS> c) {
			ensureIndex(index);
			to += c.size();
			return l.addAll(from + index, c);
		}

		@Override
		public KEY_GENERIC_TYPE GET_KEY(long index) {
			ensureRestrictedIndex(index);
			return l.GET_KEY(from + index);
		}

		@Override
		public KEY_GENERIC_TYPE REMOVE_KEY(long index) {
			ensureRestrictedIndex(index);
			to--;
			return l.REMOVE_KEY(from + index);
		}

		@Override
		public KEY_GENERIC_TYPE set(long index, KEY_GENERIC_TYPE k) {
			ensureRestrictedIndex(index);
			return l.set(from + index, k);
		}

		@Override
		public long size64() { return to - from; }

		@Override
		public void getElements(final long from, final KEY_TYPE[][] a, final long offset, final long length) {
			ensureIndex(from);
			if (from + length > size64())  throw new IndexOutOfBoundsException("End index (" + from + length + ") is greater than list size (" + size64() + ")");
			l.getElements(this.from + from, a, offset, length);
		}

		@Override
		public void removeElements(final long from, final long to) {
			ensureIndex(from);
			ensureIndex(to);
			l.removeElements(this.from + from, this.from + to);
			this.to -= (to - from);
			assert assertRange();
		}

		@Override
		public void addElements(final long index, final KEY_GENERIC_TYPE a[][], long offset, long length) {
			ensureIndex(index);
			l.addElements(this.from + index, a, offset, length);
			this.to += length;
			assert assertRange();
		}

		@Override
		public KEY_BIG_LIST_ITERATOR KEY_GENERIC listIterator(final long index) {
			ensureIndex(index);

			return new KEY_BIG_LIST_ITERATOR KEY_GENERIC() {
				long pos = index, last = -1;

				@Override
				public boolean hasNext() { return pos < size64(); }
				@Override
				public boolean hasPrevious() { return pos > 0; }
				@Override
				public KEY_GENERIC_TYPE NEXT_KEY() { if (! hasNext()) throw new NoSuchElementException(); return l.GET_KEY(from + (last = pos++)); }
				@Override
				public KEY_GENERIC_TYPE PREV_KEY() { if (! hasPrevious()) throw new NoSuchElementException(); return l.GET_KEY(from + (last = --pos)); }
				@Override
				public long nextIndex() { return pos; }
				@Override
				public long previousIndex() { return pos - 1; }
				@Override
				public void add(KEY_GENERIC_TYPE k) {
					if (last == -1) throw new IllegalStateException();
					SUBLIST.this.add(pos++, k);
					last = -1;
					assert assertRange();
				}
				@Override
				public void set(KEY_GENERIC_TYPE k) {
					if (last == -1) throw new IllegalStateException();
					SUBLIST.this.set(last, k);
				}
				@Override
				public void remove() {
					if (last == -1) throw new IllegalStateException();
					SUBLIST.this.REMOVE_KEY(last);
					/* If the last operation was a next(), we are removing an element *before* us, and we must decrease pos correspondingly. */
					if (last < pos) pos--;
					last = -1;
					assert assertRange();
				}
			};
		}

		@Override
		public BIG_LIST KEY_GENERIC subList(final long from, final long to) {
			ensureIndex(from);
			ensureIndex(to);
			if (from > to) throw new IllegalArgumentException("Start index (" + from + ") is greater than end index (" + to + ")");

			return new SUBLIST KEY_GENERIC_DIAMOND(this, from, to);
		}

#if KEYS_PRIMITIVE
		@Override
		public boolean rem(KEY_TYPE k) {
			long index = indexOf(k);
			if (index == -1) return false;
			to--;
			l.REMOVE_KEY(from + index);
			assert assertRange();
			return true;
		}

		@Override
		public boolean addAll(final long index, final COLLECTION c) {
			ensureIndex(index);
			return super.addAll(index, c);
		}

		@Override
		public boolean addAll(final long index, final BIG_LIST l) {
			ensureIndex(index);
			return super.addAll(index, l);
		}
#endif
	}
}
