package speiger.src.collections.PACKAGE.collections;

import java.util.Iterator;
import java.util.Objects;
#if !TYPE_OBJECT
import java.util.function.Consumer;

import speiger.src.collections.PACKAGE.functions.CONSUMER;

#endif
import speiger.src.collections.PACKAGE.functions.consumer.BI_OBJECT_CONSUMER;

/**
 * A Type-Specific {@link Iterator} that reduces (un)boxing
 * @Type(T)
 */
public interface ITERATOR KEY_GENERIC_TYPE extends Iterator<CLASS_TYPE>
{
#if !TYPE_OBJECT
	/**
 	* Returns the next element in the iteration.
 	*
 	* @return the next element in the iteration
 	* @throws java.util.NoSuchElementException if the iteration has no more elements
 	* @see Iterator#next()
 	*/
	public KEY_TYPE NEXT();
	
	/** {@inheritDoc}
	* <p>This default implementation delegates to the corresponding type-specific function.
	* @deprecated Please use the corresponding type-specific function instead. 
	*/
	@Override
	@Deprecated
	public default CLASS_TYPE next() { return KEY_TO_OBJ(NEXT()); }
	
    /**
     * Performs the given action for each remaining element until all elements
     * have been processed or the action throws an exception.  Actions are
     * performed in the order of iteration, if that order is specified.
     * Exceptions thrown by the action are relayed to the caller.
     *
     * @implSpec
     * <p>The default implementation behaves as if:
     * <pre>{@code
     *     while (hasNext()) action.accept(NEXT());
     * }</pre>
     *
     * @param action The action to be performed for each element
     * @throws java.lang.NullPointerException if the specified action is null
     * @see Iterator#forEachRemaining(Consumer)
     */
	public default void forEachRemaining(CONSUMER action) {
        Objects.requireNonNull(action);
        while(hasNext()) { action.accept(NEXT()); }
	}
	
	/** {@inheritDoc}
 	* <p>This default implementation delegates to the corresponding type-specific function.
 	* @deprecated Please use the corresponding type-specific function instead. 
 	*/
	@Deprecated
	@Override
	default void forEachRemaining(Consumer<? super CLASS_TYPE> action) {
        Objects.requireNonNull(action);
        forEachRemaining(action::accept);
	}
	
#endif
	/**
	 * Helper function to reduce Lambda usage and allow for more method references, since these are faster/cleaner.
	 * @param input the object that should be included
     * @param action The action to be performed for each element
     * @param <E> the generic type of the Object
     * @throws java.lang.NullPointerException if the specified action is null
	 */
	default <E> void forEachRemaining(E input, BI_OBJECT_CONSUMER KEY_VALUE_SPECIAL_GENERIC_TYPE action) {
    	Objects.requireNonNull(action);
    	while(hasNext()) { action.accept(NEXT(), input); }
	}
	
	/**
	 * Skips the Given amount of elements if possible. A Optimization function to skip elements faster if the implementation allows it.
	 * @param amount the amount of elements that should be skipped
	 * @return the amount of elements that were skipped
	 */
	default int skip(int amount) {
		if(amount < 0) throw new IllegalStateException("Negative Numbers are not allowed");
		int i = 0;
		for(;i<amount && hasNext();NEXT(), i++);
		return i;
	}
}