package org.warp.commonutils.type;

import java.util.LinkedHashSet;
import java.util.NoSuchElementException;
import org.warp.commonutils.error.IndexOutOfBoundsException;

public class JavaStackSetWrapper<T> implements StackSet<T> {

	private final LinkedHashSet<T> linkedHashSet;

	public JavaStackSetWrapper(LinkedHashSet<T> linkedHashSet) {
		this.linkedHashSet = linkedHashSet;
	}

	@Override
	public boolean push(T o) {
		return linkedHashSet.add(o);
	}

	@Override
	public T pop() {
		var it = linkedHashSet.iterator();
		if (!it.hasNext()) {
			throw new NoSuchElementException();
		}
		// Go to the last element
		T lastValue;
		do {
			lastValue = it.next();
		} while (it.hasNext());
		// Remove the last element
		it.remove();
		return lastValue;
	}

	@Override
	public boolean isEmpty() {
		return linkedHashSet.isEmpty();
	}

	@Override
	public T top() {
		if (linkedHashSet.isEmpty()) {
			throw new NoSuchElementException();
		}

		var it = linkedHashSet.iterator();
		T lastValue;
		do {
			lastValue = it.next();
		} while (it.hasNext());
		return lastValue;
	}

	@Override
	public T peek(int i) {
		var size = linkedHashSet.size();
		int positionFromBottom = size - 1 - i;

		if (positionFromBottom < 0 || positionFromBottom >= size) {
			throw new IndexOutOfBoundsException(positionFromBottom, 0, size);
		}

		var it = linkedHashSet.iterator();
		// Skip middle elements
		if (positionFromBottom > 0) {
			for (int j = 0; j < positionFromBottom; j++) {
				it.next();
			}
		}
		return it.next();
	}
}