/*
 * 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 play.libs.reflect;

import java.lang.reflect.Array;
import java.util.HashMap;
import java.util.Map;

/** Imported from apache.commons.lang3 3.6 */
abstract class ClassUtils {

  public static int arrayGetLength(final Object array) {
    if (array == null) {
      return 0;
    }
    return Array.getLength(array);
  }

  /** An empty immutable {@code Class} array. */
  public static final Class<?>[] EMPTY_CLASS_ARRAY = new Class[0];

  /**
   * Checks if one {@code Class} can be assigned to a variable of another {@code Class}.
   *
   * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this method takes into
   * account widenings of primitive classes and {@code null}s.
   *
   * <p>Primitive widenings allow an int to be assigned to a long, float or double. This method
   * returns the correct result for these cases.
   *
   * <p>{@code Null} may be assigned to any reference type. This method will return {@code true} if
   * {@code null} is passed in and the toClass is non-primitive.
   *
   * <p>Specifically, this method tests whether the type represented by the specified {@code Class}
   * parameter can be converted to the type represented by this {@code Class} object via an identity
   * conversion widening primitive or widening reference conversion. See <em><a
   * href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, sections
   * 5.1.1, 5.1.2 and 5.1.4 for details.
   *
   * <p><strong>Since Lang 3.0,</strong> this method will default behavior for calculating
   * assignability between primitive and wrapper types <em>corresponding to the running Java
   * version</em>; i.e. autoboxing will be the default behavior in VMs running Java versions >= 1.5.
   *
   * @param cls the Class to check, may be null
   * @param toClass the Class to try to assign into, returns false if null
   * @return {@code true} if assignment possible
   */
  public static boolean isAssignable(Class<?> cls, Class<?> toClass) {
    return isAssignable(
        cls, toClass, /* actually play runs on VMs > 8 only so autoboxing is always true */ true);
  }

  /**
   * Checks if one {@code Class} can be assigned to a variable of another {@code Class}.
   *
   * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this method takes into
   * account widenings of primitive classes and {@code null}s.
   *
   * <p>Primitive widenings allow an int to be assigned to a long, float or double. This method
   * returns the correct result for these cases.
   *
   * <p>{@code Null} may be assigned to any reference type. This method will return {@code true} if
   * {@code null} is passed in and the toClass is non-primitive.
   *
   * <p>Specifically, this method tests whether the type represented by the specified {@code Class}
   * parameter can be converted to the type represented by this {@code Class} object via an identity
   * conversion widening primitive or widening reference conversion. See <em><a
   * href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, sections
   * 5.1.1, 5.1.2 and 5.1.4 for details.
   *
   * @param cls the Class to check, may be null
   * @param toClass the Class to try to assign into, returns false if null
   * @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers
   * @return {@code true} if assignment possible
   */
  public static boolean isAssignable(Class<?> cls, Class<?> toClass, boolean autoboxing) {
    if (toClass == null) {
      return false;
    }
    // have to check for null, as isAssignableFrom doesn't
    if (cls == null) {
      return !toClass.isPrimitive();
    }
    // autoboxing:
    if (autoboxing) {
      if (cls.isPrimitive() && !toClass.isPrimitive()) {
        cls = primitiveToWrapper(cls);
        if (cls == null) {
          return false;
        }
      }
      if (toClass.isPrimitive() && !cls.isPrimitive()) {
        cls = wrapperToPrimitive(cls);
        if (cls == null) {
          return false;
        }
      }
    }
    if (cls.equals(toClass)) {
      return true;
    }
    if (cls.isPrimitive()) {
      if (toClass.isPrimitive() == false) {
        return false;
      }
      if (Integer.TYPE.equals(cls)) {
        return Long.TYPE.equals(toClass)
            || Float.TYPE.equals(toClass)
            || Double.TYPE.equals(toClass);
      }
      if (Long.TYPE.equals(cls)) {
        return Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass);
      }
      if (Boolean.TYPE.equals(cls)) {
        return false;
      }
      if (Double.TYPE.equals(cls)) {
        return false;
      }
      if (Float.TYPE.equals(cls)) {
        return Double.TYPE.equals(toClass);
      }
      if (Character.TYPE.equals(cls)) {
        return Integer.TYPE.equals(toClass)
            || Long.TYPE.equals(toClass)
            || Float.TYPE.equals(toClass)
            || Double.TYPE.equals(toClass);
      }
      if (Short.TYPE.equals(cls)) {
        return Integer.TYPE.equals(toClass)
            || Long.TYPE.equals(toClass)
            || Float.TYPE.equals(toClass)
            || Double.TYPE.equals(toClass);
      }
      if (Byte.TYPE.equals(cls)) {
        return Short.TYPE.equals(toClass)
            || Integer.TYPE.equals(toClass)
            || Long.TYPE.equals(toClass)
            || Float.TYPE.equals(toClass)
            || Double.TYPE.equals(toClass);
      }
      // should never get here
      return false;
    }
    return toClass.isAssignableFrom(cls);
  }

  /**
   * Checks if an array of Classes can be assigned to another array of Classes.
   *
   * <p>This method calls {@link #isAssignable(Class, Class) isAssignable} for each Class pair in
   * the input arrays. It can be used to check if a set of arguments (the first parameter) are
   * suitably compatible with a set of method parameter types (the second parameter).
   *
   * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this method takes into
   * account widenings of primitive classes and {@code null}s.
   *
   * <p>Primitive widenings allow an int to be assigned to a {@code long}, {@code float} or {@code
   * double}. This method returns the correct result for these cases.
   *
   * <p>{@code Null} may be assigned to any reference type. This method will return {@code true} if
   * {@code null} is passed in and the toClass is non-primitive.
   *
   * <p>Specifically, this method tests whether the type represented by the specified {@code Class}
   * parameter can be converted to the type represented by this {@code Class} object via an identity
   * conversion widening primitive or widening reference conversion. See <em><a
   * href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, sections
   * 5.1.1, 5.1.2 and 5.1.4 for details.
   *
   * @param classArray the array of Classes to check, may be {@code null}
   * @param toClassArray the array of Classes to try to assign into, may be {@code null}
   * @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers
   * @return {@code true} if assignment possible
   */
  public static boolean isAssignable(
      Class<?>[] classArray, Class<?>[] toClassArray, boolean autoboxing) {
    if (arrayGetLength(classArray) != arrayGetLength(toClassArray)) {
      return false;
    }
    if (classArray == null) {
      classArray = EMPTY_CLASS_ARRAY;
    }
    if (toClassArray == null) {
      toClassArray = EMPTY_CLASS_ARRAY;
    }
    for (int i = 0; i < classArray.length; i++) {
      if (isAssignable(classArray[i], toClassArray[i], autoboxing) == false) {
        return false;
      }
    }
    return true;
  }

  /** Maps primitive {@code Class}es to their corresponding wrapper {@code Class}. */
  private static final Map<Class<?>, Class<?>> primitiveWrapperMap = new HashMap<>();

  static {
    primitiveWrapperMap.put(Boolean.TYPE, Boolean.class);
    primitiveWrapperMap.put(Byte.TYPE, Byte.class);
    primitiveWrapperMap.put(Character.TYPE, Character.class);
    primitiveWrapperMap.put(Short.TYPE, Short.class);
    primitiveWrapperMap.put(Integer.TYPE, Integer.class);
    primitiveWrapperMap.put(Long.TYPE, Long.class);
    primitiveWrapperMap.put(Double.TYPE, Double.class);
    primitiveWrapperMap.put(Float.TYPE, Float.class);
    primitiveWrapperMap.put(Void.TYPE, Void.TYPE);
  }

  /** Maps wrapper {@code Class}es to their corresponding primitive types. */
  private static final Map<Class<?>, Class<?>> wrapperPrimitiveMap = new HashMap<>();

  static {
    for (Class<?> primitiveClass : primitiveWrapperMap.keySet()) {
      Class<?> wrapperClass = primitiveWrapperMap.get(primitiveClass);
      if (!primitiveClass.equals(wrapperClass)) {
        wrapperPrimitiveMap.put(wrapperClass, primitiveClass);
      }
    }
  }

  /**
   * Converts the specified primitive Class object to its corresponding wrapper Class object.
   *
   * <p>NOTE: From v2.2, this method handles {@code Void.TYPE}, returning {@code Void.TYPE}.
   *
   * @param cls the class to convert, may be null
   * @return the wrapper class for {@code cls} or {@code cls} if {@code cls} is not a primitive.
   *     {@code null} if null input.
   * @since 2.1
   */
  static Class<?> primitiveToWrapper(final Class<?> cls) {
    Class<?> convertedClass = cls;
    if (cls != null && cls.isPrimitive()) {
      convertedClass = primitiveWrapperMap.get(cls);
    }
    return convertedClass;
  }

  /**
   * Converts the specified wrapper class to its corresponding primitive class.
   *
   * <p>This method is the counter part of {@code primitiveToWrapper()}. If the passed in class is a
   * wrapper class for a primitive type, this primitive type will be returned (e.g. {@code
   * Integer.TYPE} for {@code Integer.class}). For other classes, or if the parameter is
   * <b>null</b>, the return value is <b>null</b>.
   *
   * @param cls the class to convert, may be <b>null</b>
   * @return the corresponding primitive type if {@code cls} is a wrapper class, <b>null</b>
   *     otherwise
   * @see #primitiveToWrapper(Class)
   * @since 2.4
   */
  public static Class<?> wrapperToPrimitive(Class<?> cls) {
    return wrapperPrimitiveMap.get(cls);
  }
}
