/*******************************************************************************
*   Copyright 2013 Analog Devices, Inc.
*
*   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 com.analog.lyric.options;

import java.io.Serializable;

import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;

import com.analog.lyric.collect.ReleasableIterator;

/**
 * Provides default implementation of some {@link IOptionHolder} methods.
 * <p>
 * @see LocalOptionHolder
 * @see StatelessOptionHolder
 * @since 0.07
 * @author Christopher Barber
 */
public abstract class AbstractOptionHolder implements IOptionHolder
{
	@Override
	public ReleasableIterator<? extends IOptionHolder> getOptionDelegates()
	{
		return OptionParentIterator.create(this);
	}
	
	@Override
	public @Nullable IOptionHolder getOptionParent()
	{
		return null;
	}

	@NonNull // FIXME - workaround for Eclipse JDT bug (467610?)
	@Override
	public <T extends Serializable> T getOptionOrDefault(IOptionKey<T> key)
	{
		final T value = getOptionAndSource(key, null);
		return value != null ? value : key.defaultValue();
	}

	@Override
	@Nullable
	public <T extends Serializable> T getOption(IOptionKey<T> key)
	{
		return getOptionAndSource(key, null);
	}

	/*------------------------------
	 * AbstractOptionHolder methods
	 */
	
	/**
	 * Returns value and source of option with given key if set, else null.
	 * <p>
	 * @param key is a non-null option key.
	 * @param source if non-null with length at least one, the first element will
	 * be set to the object whose {@linkplain #getLocalOption(IOptionKey) local option}
	 * setting produced the return value. Nothing will be written if this method returns null.
	 * @see #getOption
	 * @since 0.07
	 */
	@Override
	@Nullable
	public <T extends Serializable> T getOptionAndSource(IOptionKey<T> key, @Nullable IOptionHolder[] source)
	{
		T result = getLocalOption(key);
		IOptionHolder delegate = this;

		if (result == null && !key.local())
		{
			final ReleasableIterator<? extends IOptionHolder> delegates = getOptionDelegates();

			delegates.next(); // skip first delegate, which is this option holder.
			while (delegates.hasNext())
			{
				delegate = delegates.next();

				result = delegate.getLocalOption(key);
				if (result != null && key.validForDelegator(result, this))
				{
					break;
				}
			}

			delegates.release();
		}
		
		if (result != null && source != null && source.length > 0)
		{
			source[0] = delegate;
		}

		return result;
	}

    /**
     * Returns value and source of option with up to specified depth in delegation chain.
     * <p>
     * @param key is a non-null option key.
     * @param maxDepth is the maximum number of {@linkplain #getOptionDelegates option delegates} to examine.
     * If zero, then only the current object will be examined. This will be implicitly set to zero if
     * {@code key} is {@linkplain IOptionKey#local local}.
     * @param depthReference is a non-empty array whose first entry will be set to the depth of the option
     * setting in the delegation chain or else set to Integer.MAX_VALUE if no option setting was found.
     * @return option value set for given {@code key}. Will be null if option is not set within the first
     * 1 + {@code maxDepth} delegates.
     * @since 0.07
     */
    @Nullable
    public <T extends Serializable> T getOptionUptoDepth(IOptionKey<T> key, int maxDepth, int[] depthReference)
    {
        T result = null;
        final ReleasableIterator<? extends IOptionHolder> delegates = getOptionDelegates();
        
        if (key.local())
        {
        	maxDepth = 0;
        }
        
        int depth = 0;
        for (; depth < maxDepth && delegates.hasNext(); ++depth)
        {
            final IOptionHolder delegate = delegates.next();
        
            result = delegate.getLocalOption(key);
            if (result != null && key.validForDelegator(result,  this))
            {
                break;
            }
        }
        
        delegates.release();

        depthReference[0] = result != null ? depth : Integer.MAX_VALUE;
        
        return result;
    }
}