/*
 * Copyright (c) 2015 Pantheon Technologies s.r.o. and others.  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.model.api.stmt;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.annotations.Beta;
import com.google.common.collect.Range;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.yangtools.concepts.Immutable;

@Beta
public abstract class UnresolvedNumber extends Number implements Immutable {
    private static final @NonNull UnresolvedNumber MAX = new UnresolvedNumber() {
        private static final long serialVersionUID = 1L;

        @Override
        public <T extends Number & Comparable<T>> T resolveLength(final Range<? extends T> span) {
            return resolve(span.upperEndpoint());
        }

        @Override
        public <T extends Number & Comparable<T>> T resolveRange(final Range<? extends T> span) {
            return resolve(span.upperEndpoint());
        }

        @Override
        public String toString() {
            return "max";
        }

        private Object readResolve() {
            return MAX;
        }
    };

    private static final @NonNull UnresolvedNumber MIN = new UnresolvedNumber() {
        private static final long serialVersionUID = 1L;

        @Override
        public <T extends Number & Comparable<T>> T resolveLength(final Range<? extends T> span) {
            return resolve(span.lowerEndpoint());
        }

        @Override
        public <T extends Number & Comparable<T>> T resolveRange(final Range<? extends T> span) {
            return resolve(span.lowerEndpoint());
        }

        @Override
        public String toString() {
            return "min";
        }

        private Object readResolve() {
            return MIN;
        }
    };

    private static final long serialVersionUID = 1L;

    UnresolvedNumber() {
        // Hidden on purpose
    }

    public static @NonNull UnresolvedNumber min() {
        return MIN;
    }

    public static @NonNull UnresolvedNumber max() {
        return MAX;
    }

    @Override
    public final int intValue() {
        throw new UnsupportedOperationException();
    }

    @Override
    public final long longValue() {
        throw new UnsupportedOperationException();
    }

    @Override
    public final float floatValue() {
        throw new UnsupportedOperationException();
    }

    @Override
    public final double doubleValue() {
        throw new UnsupportedOperationException();
    }

    private static <T extends Number> T resolve(final T number) {
        checkArgument(!(number instanceof UnresolvedNumber));
        return number;
    }

    public abstract <T extends Number & Comparable<T>> @NonNull T resolveLength(Range<? extends T> span);

    public abstract <T extends Number & Comparable<T>> @NonNull T resolveRange(Range<? extends T> span);

    @Override
    public abstract String toString();
}