/*
 * Redberry: symbolic tensor computations.
 *
 * Copyright (c) 2010-2015:
 *   Stanislav Poslavsky   
 *   Bolotin Dmitriy       
 *
 * This file is part of Redberry.
 *
 * Redberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Redberry 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Redberry. If not, see .
 */
package cc.redberry.core.solver.frobenius;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

/**
 *
 * @author Dmitry Bolotin
 * @author Stanislav Poslavsky
 */
public final class FbUtils {
    public static final Comparator SOLUTION_COMPARATOR = new Comparator() {
        @Override
        public int compare(int[] o1, int[] o2) {
            if (o1.length != o2.length)
                throw new IllegalArgumentException();
            int c = 0;
            for (int i = 0; i < o1.length; ++i) {
                c = Integer.compare(o1[i], o2[i]);
                if (c != 0)
                    return c;
            }
            return c;
        }
    };

    public static List getAllSolutions(final int[]... equations) {
        List solutions = new ArrayList<>();
        FrobeniusSolver fbSolver = new FrobeniusSolver(equations);
        int[] solution;
        while ((solution = fbSolver.take()) != null)
            solutions.add(solution);
        return solutions;
    }

    public static Iterator iterator(int[][] equations) {
        return new SolutionsIterator(equations);
    }
    
    public static Iterable iterable(int[][] equations) {
        return new SolutionsIterator(equations);
    }

    private static class SolutionsIterator implements Iterator, Iterable {
        private final FrobeniusSolver fbSolver;
        private int[] solution;

        SolutionsIterator(int[][] equations) {
            this.fbSolver = new FrobeniusSolver(equations);
        }

        @Override
        public boolean hasNext() {
            return (solution = fbSolver.take()) != null;
        }

        @Override
        public int[] next() {
            return solution;
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException("Not supported.");
        }

        @Override
        public Iterator iterator() {
            return this;
        }
    }
}