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/*
 * Copyright 2011-Present Author or Authors.
 *
 * 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 org.cp.elements.lang.reflect;

import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import org.cp.elements.lang.annotation.NullSafe;
import org.cp.elements.lang.annotation.Nullable;

/**
 * Abstract utility class for determining the language modifiers on a {@link Class} or a {@link Member}.
 *
 * A {@link Member} may be a {@link Field} or a {@link Method}.
 *
 * @author John Blum
 * @see java.lang.Object
 * @see java.lang.Class
 * @see java.lang.reflect.Field
 * @see java.lang.reflect.Member
 * @see java.lang.reflect.Method
 * @see java.lang.reflect.Modifier
 * @since 1.0.0
 */
@SuppressWarnings("unused")
public abstract class ModifierUtils {

  public static final int[] JAVA_MODIFIERS = {
    Modifier.ABSTRACT,
    Modifier.FINAL,
    Modifier.INTERFACE,
    Modifier.NATIVE,
    Modifier.PRIVATE,
    Modifier.PROTECTED,
    Modifier.PUBLIC,
    Modifier.STATIC,
    Modifier.STRICT,
    Modifier.SYNCHRONIZED,
    Modifier.TRANSIENT,
    Modifier.VOLATILE,
  };

  /**
   * Determines whether the given object is {@literal abstract}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal abstract}.
   * @see java.lang.reflect.Modifier#isAbstract(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isAbstract(@Nullable Object obj) {
    return Modifier.isAbstract(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal final}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal final}.
   * @see java.lang.reflect.Modifier#isFinal(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isFinal(@Nullable Object obj) {
    return Modifier.isFinal(getModifiers(obj));
  }

  /**
   * Determines whether the given object is an {@link Class interface}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class interface}.
   * @return a boolean value indicating whether the given object is an {@link Class interface}.
   * @see java.lang.reflect.Modifier#isInterface(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isInterface(@Nullable Object obj) {
    return Modifier.isInterface(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal native}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Method}.
   * @return a boolean value indicating whether the given object is {@literal native}.
   * @see java.lang.reflect.Modifier#isNative(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isNative(@Nullable Object obj) {
    return Modifier.isNative(getModifiers(obj));
  }

  /**
   * Determines whether the given object has {@literal package-private} access.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object has {@literal package-private} access.
   * @see #isPrivate(Object)
   * @see #isProtected(Object)
   * @see #isPublic(Object)
   */
  @NullSafe
  public static boolean isPackagePrivate(@Nullable Object obj) {
    return !(isPrivate(obj) || isProtected(obj) || isPublic(obj));
  }

  /**
   * Determines whether the given object has {@literal private} access.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal private}.
   * @see java.lang.reflect.Modifier#isPrivate(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isPrivate(@Nullable Object obj) {
    return Modifier.isPrivate(getModifiers(obj));
  }

  /**
   * Determines whether the given object has {@literal protected} access.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal protected}.
   * @see java.lang.reflect.Modifier#isProtected(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isProtected(@Nullable Object obj) {
    return Modifier.isProtected(getModifiers(obj));
  }

  /**
   * Determines whether the given object has {@literal public} access.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal public}.
   * @see java.lang.reflect.Modifier#isPublic(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isPublic(@Nullable Object obj) {
    return Modifier.isPublic(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal static}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal static}.
   * @see java.lang.reflect.Modifier#isStatic(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isStatic(@Nullable Object obj) {
    return Modifier.isStatic(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal strict}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * @return a boolean value indicating whether the given object is {@literal strict}.
   * @see java.lang.reflect.Modifier#isStrict(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isStrict(@Nullable Object obj) {
    return Modifier.isStrict(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal synchronized}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Method}.
   * @return a boolean value indicating whether the given object is {@literal synchronized}.
   * @see java.lang.reflect.Modifier#isSynchronized(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isSynchronized(@Nullable Object obj) {
    return Modifier.isSynchronized(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal transient}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Field}.
   * @return a boolean value indicating whether the given object is {@literal transient}.
   * @see java.lang.reflect.Modifier#isTransient(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isTransient(@Nullable Object obj) {
    return Modifier.isTransient(getModifiers(obj));
  }

  /**
   * Determines whether the given object is {@literal volatile}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Field}.
   * @return a boolean value indicating whether the given object is {@literal volatile}.
   * @see java.lang.reflect.Modifier#isVolatile(int)
   * @see #getModifiers(Object)
   */
  @NullSafe
  public static boolean isVolatile(@Nullable Object obj) {
    return Modifier.isVolatile(getModifiers(obj));
  }

  /**
   * Determines the {@link Modifier modifiers} for a given {@link Class} or {@link Member}
   * from the given {@link Object}.
   *
   * @param obj {@link Object} to evaluate. The {@link Object} must be a {@link Class} or a {@link Member}.
   * If the {@link Object} is a POJO, then the {@link Object Object's} {@link Class} {@link Modifier Modifiers}
   * are returned.
   * @return the {@link Modifier modifiers} for the given {@link Class} or {@link Member}.
   * Returns {@literal 0} if the {@link Object} has no modifiers.
   * @see java.lang.reflect.Member#getModifiers()
   * @see java.lang.Class#getModifiers()
   */
  @NullSafe
  static int getModifiers(@Nullable Object obj) {

    return obj instanceof Class ? ((Class) obj).getModifiers()
      : obj instanceof Member ? ((Member) obj).getModifiers()
      : obj != null ? obj.getClass().getModifiers()
      : 0;
  }
}