package speiger.src.collections.PACKAGE.queues;

#if TYPE_OBJECT
import java.util.Arrays;
import java.util.Comparator;
import java.util.function.Consumer;
#endif
import java.util.Objects;
import java.util.NoSuchElementException;

import speiger.src.collections.PACKAGE.collections.ITERATOR;
#if !TYPE_OBJECT
import speiger.src.collections.PACKAGE.functions.COMPARATOR;
import speiger.src.collections.PACKAGE.functions.CONSUMER;
#endif
import speiger.src.collections.PACKAGE.functions.consumer.BI_OBJECT_CONSUMER;
import speiger.src.collections.PACKAGE.functions.function.PREDICATE;
import speiger.src.collections.utils.ITrimmable;

/**
 * A Simple First In First Out Priority Queue that is a Good Replacement for a linked list (or ArrayDequeue)
 * Its specific implementation uses a backing array that grows and shrinks as it is needed.
 * @Type(T)
 */
public class ARRAY_FIFO_QUEUE KEY_GENERIC_TYPE implements PRIORITY_DEQUEUE KEY_GENERIC_TYPE, ITrimmable
{
	/** Max Possible ArraySize without the JVM Crashing */
    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
    /** The Minimum Capacity that is allowed */
	public static final int MIN_CAPACITY = 4;
	/** The Backing array */
	protected transient KEY_TYPE[] array;
	/** The First Index pointer */
	protected int first;
	/** The Last Index pointer */
	protected int last;
	
	/**
	 * Constructor using a initial array
	 * @param values the Array that should be used
	 */
	public ARRAY_FIFO_QUEUE(KEY_TYPE[] values) {
		this(values, 0, values.length);
	}
	
	/**
	 * Constructor using a initial array
	 * @param values the Array that should be used
	 * @param size the amount of elements that are in the initial array
	 * @throws IllegalStateException if values is smaller then size
	 */
	public ARRAY_FIFO_QUEUE(KEY_TYPE[] values, int size) {
		this(values, 0, size);
	}
	
	/**
	 * Constructor using a initial array
	 * @param values the Array that should be used
	 * @param offset where to begin in the initial array
	 * @param size the amount of elements that are in the initial array
	 * @throws IllegalStateException if values is smaller then size
	 */
	public ARRAY_FIFO_QUEUE(KEY_TYPE[] values, int offset, int size) {
		if (values.length < size) throw new IllegalArgumentException("Initial array (" + values.length + ") is smaller then the expected size (" + size + ")");
		if(values.length <= 0) values = NEW_KEY_ARRAY(1);
		array = values;
		first = offset;
		last = (offset + size) % array.length;
		if(array.length == size) expand();
	}
	
	/**
	 * Constructor with a Min Capacity
	 * @param capacity the initial capacity of the backing array
	 * @throws IllegalStateException if the initial size is smaller 0
	 */
	public ARRAY_FIFO_QUEUE(int capacity) {
		if (capacity < 0) throw new IllegalArgumentException("Initial capacity (" + capacity + ") is negative");
		array = NEW_KEY_ARRAY(Math.max(1, capacity));
	}
	
	/**
	 * Default Construtor
	 */
	public ARRAY_FIFO_QUEUE() {
		this(MIN_CAPACITY);
	}
	
	@Override
	public ITERATOR KEY_GENERIC_TYPE iterator() {
		return new Iter();
	}
	
	@Override
	public int size() {
		final int apparentLength = last - first;
		return apparentLength >= 0 ? apparentLength : array.length + apparentLength;
	}
	
	@Override
	public void clear() {
#if TYPE_OBJECT
		Arrays.fill(array, null);
#endif
		first = last = 0;
	}
	
	@Override
	public void enqueue(KEY_TYPE e) {
		array[last] = e;
		last = ++last % array.length;
		if(last == first) expand();
	}
	
	@Override
	public void enqueueFirst(KEY_TYPE e) {
		if(first == 0) first = array.length;
		array[--first] = e;
		if(first == last) expand();
	}
	
	@Override
	public KEY_TYPE dequeue() {
		if(first == last) throw new NoSuchElementException();
		KEY_TYPE data = array[first];
#if TYPE_OBJECT
		array[first] = null;
#endif
		first = ++first % array.length;
		reduce();
		return data;
	}
	
	@Override
	public KEY_TYPE dequeueLast() {
		if(first == last) throw new NoSuchElementException();
		if(last == 0) last = array.length;
		KEY_TYPE data = array[--last];
#if TYPE_OBJECT
		array[last] = null;
#endif
		reduce();
		return data;
	}
	
	@Override
	public KEY_TYPE peek(int index) {
		if(first == last || index < 0 || index > size()) throw new NoSuchElementException();
		return array[(first + index) % array.length];
	}
	
	@Override
	public boolean removeFirst(KEY_TYPE e) {
		if(first == last) return false;
		for(int i = 0,m=size();i<m;i++) {
			int index = (first + i) % array.length;
			if(e == array[index])
				return removeIndex(index);
		}
		return false;
	}
	
	@Override
	public boolean removeLast(KEY_TYPE e) {
		if(first == last) return false;
		for(int i = size()-1;i>=0;i--) {
			int index = (first + i) % array.length;
			if(e == array[index])
				return removeIndex(index);
		}
		return false;
	}
	
	protected boolean removeIndex(int index) {
		if(first >= last ? index < first && index > last : index < first || index > last) return false;
		if(index == first) {
#if TYPE_OBJECT
			array[first] = null;
#endif
			first++;
		}
		else if(index == last) {
			last--;
#if TYPE_OBJECT
			array[last] = null;
#endif
		}
		else if(index > last) {
			System.arraycopy(array, first, array, first+1, (index - first));
#if TYPE_OBJECT
			array[first] = null;
#endif
			first = ++first % array.length;
		}
		else if(index < first) {
			System.arraycopy(array, index+1, array, index, (last - index) - 1);
#if TYPE_OBJECT
			array[last] = null;
#endif
			if(--last < 0) last += array.length;
		}
		else {
			if(index - first < last - index) {
				System.arraycopy(array, first, array, first+1, (index - first));
#if TYPE_OBJECT
				array[first] = null;
#endif
				first = ++first % array.length;
			}
			else {
				System.arraycopy(array, index+1, array, index, (last - index) - 1);
#if TYPE_OBJECT
				array[last] = null;
#endif
				if(--last < 0) last += array.length;
			}
		}
		reduce();
		return true;
	}
	
	@Override
	public void onChanged() {}
	
	@Override
	public COMPARATOR KEY_SUPER_GENERIC_TYPE comparator() { return null; }
	
	@Override
	public void forEach(CONSUMER KEY_SUPER_GENERIC_TYPE action) {
		Objects.requireNonNull(action);
		if(first == last) return;
		for(int i = 0,m=size();i<m;i++)
			action.accept(array[(first + i) % array.length]);
		clearAndTrim(0);
	}
	
	@Override
	public <E> void forEach(E input, BI_OBJECT_CONSUMER KEY_VALUE_SPECIAL_GENERIC_TYPE action) {
		Objects.requireNonNull(action);
		if(first == last) return;
		for(int i = 0,m=size();i<m;i++)
			action.accept(array[(first + i) % array.length], input);
		clearAndTrim(0);	
	}
	
	@Override
	public boolean matchesAny(PREDICATE KEY_GENERIC_TYPE filter) {
		Objects.requireNonNull(filter);
		for(int i = 0,m=size();i<m;i++) {
			if(filter.TEST_VALUE(array[(first + i) % array.length])) return true;
		}
		return false;
	}
	
	@Override
	public boolean matchesNone(PREDICATE KEY_GENERIC_TYPE filter) {
		Objects.requireNonNull(filter);
		for(int i = 0,m=size();i<m;i++) {
			if(filter.TEST_VALUE(array[(first + i) % array.length])) return false;
		}
		return true;
	}
	
	@Override
	public boolean matchesAll(PREDICATE KEY_GENERIC_TYPE filter) {
		Objects.requireNonNull(filter);
		for(int i = 0,m=size();i<m;i++) {
			if(!filter.TEST_VALUE(array[(first + i) % array.length])) return false;
		}
		return true;
	}
	
	@Override
	public KEY_TYPE findFirst(PREDICATE KEY_GENERIC_TYPE filter) {
		Objects.requireNonNull(filter);
		for(int i = 0,m=size();i<m;i++) {
			int index = (first + i) % array.length;
			if(filter.TEST_VALUE(array[index])) {
				KEY_TYPE data = array[index];
				removeIndex(index);
				return data;
			}
		}
		return EMPTY_VALUE;
	}
	
	@Override
	public boolean trim(int size) {
		int newSize = Math.max(size, size());
		if(newSize >= array.length) return false;
		KEY_TYPE[] newArray = NEW_KEY_ARRAY(newSize);
		if(first <= last) System.arraycopy(array, first, newArray, 0, last - first);
		else {
			System.arraycopy(array, first, newArray, 0, array.length - first);
			System.arraycopy(array, 0, newArray, array.length - first, last);
		}
		first = 0;
		last = size();
		array = newArray;
		return true;
	}
	
	/**
	 * Trims the collection down to the requested size and clears all elements while doing so
	 * @param size the amount of elements that should be allowed
	 * @note this will enforce minimum size of the collection itself
	 */
	@Override
	public void clearAndTrim(int size) {
		int newSize = Math.max(MIN_CAPACITY, size);
		if(array.length <= newSize) {
			clear();
			return;
		}
		first = last = 0;
		array = NEW_KEY_ARRAY(newSize);
	}
	
	@Override
	public KEY_GENERIC_SPECIAL_TYPE KEY_SPECIAL_TYPE[] TO_ARRAY(KEY_SPECIAL_TYPE[] input) {
		if(input == null || input.length < size()) input = NEW_SPECIAL_KEY_ARRAY(size());
		if (first <= last) System.arraycopy(array, first, input, 0, last - first);
		else {
			System.arraycopy(array, first, input, 0, array.length - first);
			System.arraycopy(array, 0, input, array.length - first, last);
		}
		return input;
	}
	
	protected void reduce() {
		final int size = size();
		if (array.length > MIN_CAPACITY && size <= array.length / 4) resize(size, array.length / 2);
	}
	
	protected void expand() {
		resize(array.length, (int)Math.min(MAX_ARRAY_SIZE, 2L * array.length));
	}
	
	protected final void resize(int oldSize, int newSize) {
		KEY_TYPE[] newArray = NEW_KEY_ARRAY(newSize);
		if(first >= last) {
			if(oldSize != 0)
			{
				System.arraycopy(array, first, newArray, 0, array.length - first);
				System.arraycopy(array, 0, newArray, array.length - first, last);
			}
		}
		else System.arraycopy(array, first, newArray, 0, last-first);
		first = 0;
		last = oldSize;
		array = newArray;
	}
	
	private class Iter implements ITERATOR KEY_GENERIC_TYPE
	{
		int index = first;
		@Override
		public boolean hasNext()
		{
			return index != last;
		}

		@Override
		public KEY_TYPE NEXT() {
			KEY_TYPE value = array[index];
			removeIndex(index);
			index = ++index % array.length;
			return value;
		}
	}
}