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/*
 * Zorbage: an algebraic data hierarchy for use in numeric processing.
 *
 * Copyright (c) 2016-2021 Barry DeZonia All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution.
 * 
 * Neither the name of the  nor the names of its contributors may
 * be used to endorse or promote products derived from this software without specific
 * prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL  BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */
package nom.bdezonia.zorbage.algorithm;

import nom.bdezonia.zorbage.sampling.IntegerIndex;
import nom.bdezonia.zorbage.algebra.Algebra;
import nom.bdezonia.zorbage.type.universal.PrimitiveConversion;
import nom.bdezonia.zorbage.type.universal.PrimitiveConverter;
import nom.bdezonia.zorbage.datasource.IndexedDataSource;
import nom.bdezonia.zorbage.datasource.TrimmedDataSource;

/**
 * 
 * @author Barry DeZonia
 *
 */
public class DataConvert {

	// do not instantiate
	
	private DataConvert() {}

	/**
	 * Convert a list of data of one type into a list of data of a different type.
	 * The types use their support of {@link PrimitiveConversion} to do translations
	 * with the minimum amount of data loss. The algorithm also uses primitive values
	 * during conversion eliminating many thousands of objec allocations.
	 * 
	 * @param fromAlgebra
	 * @param toAlgebra
	 * @param fromList
	 * @param toList
	 */
	public static ,
					U extends PrimitiveConversion,
					V extends Algebra,
					W extends PrimitiveConversion>
		void compute(T fromAlgebra, V toAlgebra, IndexedDataSource fromList, IndexedDataSource toList)
	{
		long fromSize = fromList.size();
		long toSize = toList.size();
		if (fromSize > toSize)
			throw new IllegalArgumentException("mismatched list sizes");
		int maxPieces = Runtime.getRuntime().availableProcessors();
		if (maxPieces > fromSize)
			maxPieces = 1;
		long start = 0;
		long count = fromSize / maxPieces;
		Thread[] threads = new Thread[maxPieces];
		for (int i = 0; i < maxPieces; i++) {
			if (i == maxPieces - 1) {
				count = fromSize - start;
			}
			Computer computer =
					new Computer<>(fromAlgebra, toAlgebra, start, count, fromList, toList);
			threads[i] = new Thread(computer);
			start += count;
		}
		
		for (int i = 0; i < threads.length; i++) {
			threads[i].start();
		}
		
		try {
			for (int i = 0; i < threads.length; i++) {
				threads[i].join();
			}
		} catch (InterruptedException e) {
			throw new IllegalArgumentException("ouch");
		}
	}

	private static class Computer,
									U extends PrimitiveConversion,
									V extends Algebra,
									W extends PrimitiveConversion>
		implements Runnable
	{
		private final T algU;
		private final V algW;
		private final IndexedDataSource src;
		private final IndexedDataSource dst;
		
		public Computer(T algU, V algW, long start, long count, IndexedDataSource src, IndexedDataSource dst) {
			this.algU = algU;
			this.algW = algW;
			this.src = new TrimmedDataSource<>(src, start, count);
			this.dst = new TrimmedDataSource<>(dst, start, count);
		}
		
		@Override
		public void run() {
			U from = algU.construct();
			W to = algW.construct();
			int numD = Math.max(from.numDimensions(), to.numDimensions());
			IntegerIndex tmp1 = new IntegerIndex(numD);
			IntegerIndex tmp2 = new IntegerIndex(numD);
			IntegerIndex tmp3 = new IntegerIndex(numD);
			long fromSize = src.size();
			for (long i = 0; i < fromSize; i++) {
				src.get(i, from);
				PrimitiveConverter.convert(tmp1, tmp2, tmp3, from, to);
				dst.set(i, to);
			}
		}
		
	}
}