/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.ignite.ml.math.impls.matrix;

import java.util.Arrays;
import java.util.List;
import java.util.function.Function;
import org.apache.ignite.ml.math.Matrix;
import org.junit.Test;

import static org.junit.Assert.assertEquals;

/**
 * Attribute tests for matrices.
 */
public class MatrixAttributeTest {
    /** */
    private final List<MatrixAttributeTest.AttrCfg> attrCfgs = Arrays.asList(
        new AttrCfg("isDense", Matrix::isDense,
            DenseLocalOnHeapMatrix.class, DenseLocalOffHeapMatrix.class, RandomMatrix.class, DiagonalMatrix.class),
        new AttrCfg("isArrayBased", Matrix::isArrayBased, DenseLocalOnHeapMatrix.class),
        new AttrCfg("isDistributed", Matrix::isDistributed),
        new AttrCfg("isRandomAccess", Matrix::isRandomAccess, DenseLocalOnHeapMatrix.class, DenseLocalOffHeapMatrix.class, RandomMatrix.class, DiagonalMatrix.class, SparseLocalOnHeapMatrix.class),
        new AttrCfg("isSequentialAccess", Matrix::isSequentialAccess, DiagonalMatrix.class)
    );

    /** */
    private final List<MatrixAttributeTest.Specification> specFixture = Arrays.asList(
        new Specification(new DenseLocalOnHeapMatrix(1, 1)),
        new Specification(new DenseLocalOffHeapMatrix(1, 1)),
        new Specification(new RandomMatrix(1, 1)),
        new Specification(new DiagonalMatrix(new double[] {1.0})),
        new Specification(new FunctionMatrix(1, 1, (x, y) -> 1.0)),
        new Specification(new SparseLocalOnHeapMatrix(1, 1))
    );

    /** */
    @Test
    public void isDenseTest() {
        assertAttribute("isDense");
    }

    /** */
    @Test
    public void isArrayBasedTest() {
        assertAttribute("isArrayBased");
    }

    /** */
    @Test
    public void isSequentialAccessTest() {
        assertAttribute("isSequentialAccess");
    }

    /** */
    @Test
    public void isRandomAccessTest() {
        assertAttribute("isRandomAccess");
    }

    /** */
    @Test
    public void isDistributedTest() {
        assertAttribute("isDistributed");
    }

    /** */
    private void assertAttribute(String name) {
        final MatrixAttributeTest.AttrCfg attr = attrCfg(name);

        for (MatrixAttributeTest.Specification spec : specFixture)
            spec.verify(attr);
    }

    /** */
    private MatrixAttributeTest.AttrCfg attrCfg(String name) {
        for (MatrixAttributeTest.AttrCfg attr : attrCfgs)
            if (attr.name.equals(name))
                return attr;

        throw new IllegalArgumentException("Undefined attribute " + name);
    }

    /** See http://en.wikipedia.org/wiki/Specification_pattern */
    private static class Specification {
        /** */
        private final Matrix m;
        /** */
        private final Class<? extends Matrix> underlyingType;
        /** */
        private final List<String> attrsFromUnderlying;
        /** */
        final String desc;

        /** */
        Specification(Matrix m, Class<? extends Matrix> underlyingType, String... attrsFromUnderlying) {
            this.m = m;
            this.underlyingType = underlyingType;
            this.attrsFromUnderlying = Arrays.asList(attrsFromUnderlying);
            final Class<? extends Matrix> clazz = m.getClass();
            desc = clazz.getSimpleName() + (clazz.equals(underlyingType)
                ? "" : " (underlying type " + underlyingType.getSimpleName() + ")");
        }

        /** */
        Specification(Matrix m) {
            this(m, m.getClass());
        }

        /** */
        void verify(MatrixAttributeTest.AttrCfg attr) {
            final boolean obtained = attr.obtain.apply(m);

            final Class<? extends Matrix> typeToCheck
                = attrsFromUnderlying.contains(attr.name) ? underlyingType : m.getClass();

            final boolean exp = attr.trueInTypes.contains(typeToCheck);

            assertEquals("Unexpected " + attr.name + " value for " + desc, exp, obtained);
        }
    }

    /** */
    private static class AttrCfg {
        /** */
        final String name;
        /** */
        final Function<Matrix, Boolean> obtain;
        /** */
        final List<Class> trueInTypes;

        /** */
        AttrCfg(String name, Function<Matrix, Boolean> obtain, Class... trueInTypes) {
            this.name = name;
            this.obtain = obtain;
            this.trueInTypes = Arrays.asList(trueInTypes);
        }
    }
}
