/*
 * Copyright (c) 2019 Pantheon Technologies, s.r.o.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.xpath.api;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.Beta;
import java.util.Optional;

/**
 * Type-safe shim to ensure concrete {@link YangXPathMathSupport} implementations get handed properly-typed
 * YangNumberExprs.
 *
 * @param <N> Type of YangNumberExpr
 * @author Robert Varga
 */
@Beta
public abstract class AbstractYangXPathMathSupport<N extends YangNumberExpr> implements YangXPathMathSupport {
    private static final long serialVersionUID = 1L;

    private final Class<N> numberClass;

    protected AbstractYangXPathMathSupport(final Class<N> numberClass) {
        this.numberClass = requireNonNull(numberClass);
    }

    @Override
    public final N negateNumber(final YangNumberExpr number) {
        checkArgument(numberClass.isInstance(requireNonNull(number)), "Expected %s have %s", numberClass, number);
        return doNegateNumber(numberClass.cast(number));
    }

    @Override
    public final Optional<YangExpr> tryEvaluate(final YangBinaryOperator operator, final YangNumberExpr left,
            final YangNumberExpr right) {
        if (!numberClass.isInstance(left) || !numberClass.isInstance(right)) {
            requireNonNull(operator);
            requireNonNull(left);
            requireNonNull(right);
            return Optional.empty();
        }

        return Optional.of(doEvaluate(requireNonNull(operator), numberClass.cast(left), numberClass.cast(right)));
    }

    /**
     * Create a {@link YangNumberExpr} representing the negated value of a number.
     *
     * @param number input number
     * @return negated number expression
     */
    protected abstract N doNegateNumber(N number);

    /**
     * Evaluate an  operator and its left- and right-handside.
     *
     * @param operator Operator to apply
     * @param left Left hand-side
     * @param right Right hand-side
     * @return Evaluation result
     */
    protected abstract YangExpr doEvaluate(YangBinaryOperator operator, N left, N right);

    protected abstract Object readResolve();
}