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/*
 * Copyright 2017 ~ 2025 the original author or authors. James Wong 
 *
 * Licensed 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 com.wl4g.infra.common.lang;

/**
 * Java versions.
 */
public enum JavaVersion {

    /**
     * Java 1.9.
     */
    NINE(9, "1.9", "java.security.cert.URICertStoreParameters"),

    /**
     * Java 1.8.
     */
    EIGHT(8, "1.8", "java.util.function.Function"),

    /**
     * Java 1.7.
     */
    SEVEN(7, "1.7", "java.nio.file.Files"),

    /**
     * Java 1.6.
     */
    SIX(6, "1.6", "java.util.ServiceLoader");

    private final int value;

    private final String name;

    private final boolean available;

    private JavaVersion(int value, String name, String className) {
        this.value = value;
        this.name = name;
        this.available = isPresent(className, getClass().getClassLoader());
    }

    public int getValue() {
        return value;
    }

    @Override
    public String toString() {
        return this.name;
    }

    /**
     * Returns the {@link JavaVersion} of the current runtime.
     * 
     * @return the {@link JavaVersion}
     */
    public static JavaVersion runtimeJavaVersion() {
        for (JavaVersion candidate : JavaVersion.values()) {
            if (candidate.available) {
                return candidate;
            }
        }
        return SIX;
    }

    /**
     * Determine whether the {@link Class} identified by the supplied name is
     * present and can be loaded. Will return {@code false} if either the class
     * or one of its dependencies is not present or cannot be loaded.
     * 
     * @param className
     *            the name of the class to check
     * @param classLoader
     *            the class loader to use (may be {@code null} which indicates
     *            the default class loader)
     * @return whether the specified class is present
     */
    private static boolean isPresent(String className, ClassLoader classLoader) {
        try {
            Class.forName(className, false, classLoader);
            return true;
        } catch (Throwable ex) {
            // Class or one of its dependencies is not present...
            return false;
        }
    }

}