/*
 * 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.internal.sql.engine.util;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;

/**
 * Primitives.
 * TODO Documentation https://issues.apache.org/jira/browse/IGNITE-15859
 */
public final class Primitives {
    private Primitives() {
    }

    /** A map from primitive types to their corresponding wrapper types. */
    private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE;

    /** A map from wrapper types to their corresponding primitive types. */
    private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE;

    static {
        Map<Class<?>, Class<?>> primToWrap = new LinkedHashMap<>(16);
        Map<Class<?>, Class<?>> wrapToPrim = new LinkedHashMap<>(16);

        add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
        add(primToWrap, wrapToPrim, byte.class, Byte.class);
        add(primToWrap, wrapToPrim, char.class, Character.class);
        add(primToWrap, wrapToPrim, double.class, Double.class);
        add(primToWrap, wrapToPrim, float.class, Float.class);
        add(primToWrap, wrapToPrim, int.class, Integer.class);
        add(primToWrap, wrapToPrim, long.class, Long.class);
        add(primToWrap, wrapToPrim, short.class, Short.class);
        add(primToWrap, wrapToPrim, void.class, Void.class);

        PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap);
        WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim);
    }

    private static void add(
            Map<Class<?>, Class<?>> forward,
            Map<Class<?>, Class<?>> backward,
            Class<?> key,
            Class<?> value) {
        forward.put(key, value);
        backward.put(value, key);
    }

    /**
     * Returns {@code true} if {@code type} is one of the nine primitive-wrapper types, such as {@link Integer}.
     *
     * @see Class#isPrimitive
     */
    public static boolean isWrapperType(Class<?> type) {
        return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(Objects.requireNonNull(type));
    }

    /**
     * Returns the corresponding wrapper type of {@code type} if it is a primitive type; otherwise returns {@code type}
     * itself.
     *
     * <pre>
     *     wrap(int.class) == Integer.class
     *     wrap(Integer.class) == Integer.class
     *     wrap(String.class) == String.class
     * </pre>
     */
    public static <T> Class<T> wrap(Class<T> type) {
        Objects.requireNonNull(type);

        Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(type);
        return (wrapped == null) ? type : wrapped;
    }

    /**
     * Returns the corresponding primitive type of {@code type} if it is a wrapper type; otherwise  returns {@code type}
     * itself.
     *
     * <pre>
     *     unwrap(Integer.class) == int.class
     *     unwrap(int.class) == int.class
     *     unwrap(String.class) == String.class
     * </pre>
     */
    public static <T> Class<T> unwrap(Class<T> type) {
        Objects.requireNonNull(type);

        Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(type);

        return (unwrapped == null) ? type : unwrapped;
    }
}
