/**
 * Copyright 2004-2006 DFKI GmbH.
 * All Rights Reserved.  Use is subject to license terms.
 *
 * This file is part of MARY TTS.
 *
 * MARY TTS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package marytts.util.data;

import java.util.Arrays;
import java.util.List;

/**
 * Create one DoubleDataSource from a parallel stream of DoubleDataSources. The length of the resulting stream is the length of
 * the longest stream.
 * 
 * @author Marc Schröder
 */
public class MixerDoubleDataSource extends BaseDoubleDataSource {
	protected DoubleDataSource[] sources;
	protected boolean hasMoreData = true;

	/**
	 * 
	 * @param inputSources
	 *            input sources
	 */
	public MixerDoubleDataSource(DoubleDataSource[] inputSources) {
		super();
		sources = new DoubleDataSource[inputSources.length];
		// The length of the mixed data is the length of the longest input
		dataLength = 0;
		for (int i = 0; i < inputSources.length; i++) {
			if (dataLength != DoubleDataSource.NOT_SPECIFIED) {
				long dl = inputSources[i].getDataLength();
				if (dl == DoubleDataSource.NOT_SPECIFIED)
					dataLength = DoubleDataSource.NOT_SPECIFIED;
				else if (dl > dataLength)
					dataLength = dl;
			}
			if (inputSources[i] instanceof BlockwiseDoubleDataSource) {
				sources[i] = new BufferedDoubleDataSource(inputSources[i]);
			} else {
				sources[i] = inputSources[i];
			}
		}
	}

	/**
	 * 
	 * @param inputSources
	 *            a list of DoubleDataSource objects.
	 */
	public MixerDoubleDataSource(List inputSources) {
		this((DoubleDataSource[]) inputSources.toArray(new DoubleDataSource[0]));
	}

	public boolean hasMoreData() {
		if (!hasMoreData)
			return false;
		// else, we may have more data. Check:
		boolean foundOneWithData = false;
		for (int i = 0; i < sources.length; i++)
			if (sources[i].hasMoreData()) {
				foundOneWithData = true;
				break;
			}
		if (foundOneWithData) {
			return true;
		} else {
			hasMoreData = false;
			return false;
		}
	}

	/**
	 * The number of doubles that can currently be read from this double data source without blocking. This number can change over
	 * time.
	 * 
	 * @return the number of doubles that can currently be read without blocking
	 */
	public int available() {
		// Return the value for the longest source
		int available = 0;
		for (int i = 0; i < sources.length; i++) {
			int a = sources[i].available();
			if (a > available)
				available = a;
		}
		return available;

	}

	public int getData(double[] target, int targetPos, int length) {
		if (target.length - targetPos < length) {
			throw new IllegalArgumentException("Target array cannot hold enough data (" + (target.length - targetPos)
					+ " left, but " + length + " requested)");
		}
		double[] buf = new double[length];
		int maxCopied = 0;

		for (int i = 0; i < sources.length; i++) {
			int copied = sources[i].getData(buf);
			if (copied > maxCopied) {
				// only initialise to 0 those sections that are actually written to:
				Arrays.fill(target, targetPos + maxCopied, targetPos + copied, 0.);
				maxCopied = copied;
			}
			for (int j = 0; j < copied; j++) {
				target[targetPos + j] += buf[j];
			}
		}
		return maxCopied;
	}

}