package org.warp.commonutils.type;

import it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.NoSuchElementException;
import org.warp.commonutils.error.IndexOutOfBoundsException;

/**
 * A stack but with the behavior of a Linked HashSet
 *
 * <p>A stack must provide the classical {@link #push(Object)} and
 * {@link #pop()} operations, but may be also <em>peekable</em> to some extent: it may provide just the {@link #top()}
 * function, or even a more powerful {@link #peek(int)} method that provides access to all elements on the stack
 * (indexed from the top, which has index 0).
 */

public interface StackSet<K> {


	/**
	 * Pushes the given object on the stack.
	 *
	 * @param o the object that will become the new top of the stack.
	 * @return true if added, false if already present
	 */
	boolean push(K o);

	/**
	 * Pop multiple times
	 * @param count the number of times to pop
	 * @return list of popped elements
	 */
	default List<K> pop(int count) {
		if (count < 0) {
			throw new IndexOutOfBoundsException(count);
		}
		var items = new ArrayList<K>(count);
		for (int i = 0; i < count; i++) {
			items.add(this.pop());
		}
		return items;
	}

	/**
	 * Pops the top off the stack.
	 *
	 * @return the top of the stack.
	 * @throws NoSuchElementException if the stack is empty.
	 */
	K pop();

	/**
	 * Checks whether the stack is empty.
	 *
	 * @return true if the stack is empty.
	 */
	boolean isEmpty();

	/**
	 * Peeks at the top of the stack (optional operation).
	 *
	 * <p>This default implementation returns {@link #peek(int) peek(0)}.
	 *
	 * @return the top of the stack.
	 * @throws NoSuchElementException if the stack is empty.
	 */
	default K top() {
		return peek(0);
	}

	/**
	 * Peeks at an element on the stack (optional operation).
	 *
	 * <p>This default implementation just throws an {@link UnsupportedOperationException}.
	 *
	 * @param i an index from the stop of the stack (0 represents the top).
	 * @return the {@code i}-th element on the stack.
	 * @throws IndexOutOfBoundsException if the designated element does not exist..
	 */
	default K peek(int i) {
		throw new UnsupportedOperationException();
	}

	static <T> StackSet<T> create() {
		return new HashStackSet<>();
	}

	static <T> StackSet<T> wrap(LinkedHashSet<T> linkedHashSet) {
		return new JavaStackSetWrapper<>(linkedHashSet);
	}

	static <T> StackSet<T> wrap(ObjectLinkedOpenHashSet<T> linkedHashSet) {
		return new FastUtilStackSetWrapper<>(linkedHashSet);
	}

	static <T> StackSet<T> wrap(ObjectLinkedOpenHashSet<T> linkedHashSet, AddStrategy addStrategy) {
		return new FastUtilStackSetWrapper<>(linkedHashSet, addStrategy);
	}

}