/*
    * 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.commons.lang3.function;
  
  import java.lang.invoke.MethodHandle;
  import java.lang.invoke.MethodHandleProxies;
  import java.lang.invoke.MethodHandles;
  import java.lang.reflect.Method;
  import java.util.Objects;
  import java.util.function.BiConsumer;
  import java.util.function.BiFunction;
  import java.util.function.Function;
  import java.util.function.Supplier;
  
  import org.apache.commons.lang3.exception.UncheckedIllegalAccessException;
  
  /**
   * Converts {@link Method} objects to lambdas.
   * <p>
   * More specifically, produces instances of single-method interfaces which redirect calls to methods; see
   * {@link #asInterfaceInstance(Class, Method)}.
   * </p>
   * <h2>Calling supplier methods with no arguments</h2>
   * <p>
   * If the interface's single-method defines no arguments, use {@link #asFunction(Method)} and then apply the function
   * passing in the object to receive the method call.
   * </p>
   * <p>
   * For example to invoke {@link String#length()}:
   * </p>
   *
   * <pre>
   * final Method method = String.class.getMethod("length");
   * final Function&lt;String, Integer&gt; function = MethodInvokers.asFunction(method);
   * assertEquals(3, function.apply("ABC"));
   * </pre>
   *
   * <h2>Calling function methods with one argument</h2>
   * <p>
   * If the interface's single-method defines one argument, use {@link #asBiFunction(Method)} and then apply the function
   * passing in the object to receive the method call. The second argument to the function is the only argument to the
   * method.
   * </p>
   * <p>
   * For example to invoke {@link String#charAt(int)}:
   * </p>
   *
   * <pre>
   * final Method method = String.class.getMethod("charAt", int.class);
   * final BiFunction&lt;String, Integer, Character&gt; function = MethodInvokers.asBiFunction(method);
   * assertEquals('C', function.apply("ABC", 2));
   * </pre>
   *
   * @since 3.13.0
   */
  public final class MethodInvokers {
  
      /**
       * Produces a {@link BiConsumer} for a given <em>consumer</em> Method. For example, a classic setter method (as opposed
       * to a fluent setter). You call the BiConsumer with two arguments: (1) the object receiving the method call, and (2)
       * the method argument.
       *
       * @param <T> the type of the first argument to the operation: The type containing the Method.
       * @param <U> the type of the second argument to the operation: The type of the method argument.
       * @param method the method to invoke.
       * @return a correctly-typed wrapper for the given target.
       */
      @SuppressWarnings("unchecked")
      public static <T, U> BiConsumer<T, U> asBiConsumer(final Method method) {
          return asInterfaceInstance(BiConsumer.class, method);
      }
  
      /**
       * Produces a {@link BiFunction} for a given a <em>function</em> Method. You call the BiFunction with two arguments: (1)
       * the object receiving the method call, and (2) the method argument. The BiFunction return type must match the method's
       * return type.
       * <p>
       * For example to invoke {@link String#charAt(int)}:
       * </p>
       *
       * <pre>
       * final Method method = String.class.getMethod("charAt", int.class);
       * final BiFunction&lt;String, Integer, Character&gt; function = MethodInvokers.asBiFunction(method);
       * assertEquals('C', function.apply("ABC", 2));
      * </pre>
      *
      * @param <T> the type of the first argument to the function: The type containing the method.
      * @param <U> the type of the second argument to the function: the method argument type.
      * @param <R> the type of the result of the function: The method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <T, U, R> BiFunction<T, U, R> asBiFunction(final Method method) {
         return asInterfaceInstance(BiFunction.class, method);
     }
 
     /**
      * Produces a {@link FailableBiConsumer} for a given <em>consumer</em> Method. For example, a classic setter method (as
      * opposed to a fluent setter). You call the FailableBiConsumer with two arguments: (1) the object receiving the method
      * call, and (2) the method argument.
      *
      * @param <T> the type of the first argument to the operation: The type containing the Method.
      * @param <U> the type of the second argument to the operation: The type of the method argument.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <T, U> FailableBiConsumer<T, U, Throwable> asFailableBiConsumer(final Method method) {
         return asInterfaceInstance(FailableBiConsumer.class, method);
     }
 
     /**
      * Produces a {@link FailableBiFunction} for a given a <em>function</em> Method. You call the FailableBiFunction with
      * two arguments: (1) the object receiving the method call, and (2) the method argument. The BiFunction return type must
      * match the method's return type.
      *
      * @param <T> the type of the first argument to the function: The type containing the method.
      * @param <U> the type of the second argument to the function: the method argument type.
      * @param <R> the type of the result of the function: The method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <T, U, R> FailableBiFunction<T, U, R, Throwable> asFailableBiFunction(final Method method) {
         return asInterfaceInstance(FailableBiFunction.class, method);
     }
 
     /**
      * Produces a {@link FailableFunction} for a given a <em>supplier</em> Method. You call the Function with one argument:
      * the object receiving the method call. The FailableFunction return type must match the method's return type.
      *
      * @param <T> the type of the first argument to the function: The type containing the method.
      * @param <R> the type of the result of the function: The method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <T, R> FailableFunction<T, R, Throwable> asFailableFunction(final Method method) {
         return asInterfaceInstance(FailableFunction.class, method);
     }
 
     /**
      * Produces a {@link FailableSupplier} for a given a <em>supplier</em> Method. The FailableSupplier return type must
      * match the method's return type.
      * <p>
      * Only works with static methods.
      * </p>
      *
      * @param <R> The Method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <R> FailableSupplier<R, Throwable> asFailableSupplier(final Method method) {
         return asInterfaceInstance(FailableSupplier.class, method);
     }
 
     /**
      * Produces a {@link Function} for a given a <em>supplier</em> Method. You call the Function with one argument: the
      * object receiving the method call. The Function return type must match the method's return type.
      * <p>
      * For example to invoke {@link String#length()}:
      * </p>
      *
      * <pre>
      * final Method method = String.class.getMethod("length");
      * final Function&lt;String, Integer&gt; function = MethodInvokers.asFunction(method);
      * assertEquals(3, function.apply("ABC"));
      * </pre>
      *
      * @param <T> the type of the first argument to the function: The type containing the method.
      * @param <R> the type of the result of the function: The method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <T, R> Function<T, R> asFunction(final Method method) {
         return asInterfaceInstance(Function.class, method);
     }
 
     /**
      * Produces an instance of the given single-method interface which redirects its calls to the given method.
      * <p>
      * For the definition of "single-method", see {@linkplain MethodHandleProxies#asInterfaceInstance(Class, MethodHandle)}.
      * </p>
      *
      * @param <T> The interface type.
      * @param interfaceClass a class object representing {@code T}.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      * @see MethodHandleProxies#asInterfaceInstance(Class, MethodHandle)
      */
     public static <T> T asInterfaceInstance(final Class<T> interfaceClass, final Method method) {
         return MethodHandleProxies.asInterfaceInstance(Objects.requireNonNull(interfaceClass, "interfaceClass"), unreflectUnchecked(method));
     }
 
     /**
      * Produces a {@link Supplier} for a given a <em>supplier</em> Method. The Supplier return type must match the method's
      * return type.
      * <p>
      * Only works with static methods.
      * </p>
      *
      * @param <R> The Method return type.
      * @param method the method to invoke.
      * @return a correctly-typed wrapper for the given target.
      */
     @SuppressWarnings("unchecked")
     public static <R> Supplier<R> asSupplier(final Method method) {
         return asInterfaceInstance(Supplier.class, method);
     }
 
     /**
      * Throws NullPointerException if {@code method} is {@code null}.
      *
      * @param method The method to test.
      * @return The given method.
      * @throws NullPointerException if {@code method} is {@code null}.
      */
     private static Method requireMethod(final Method method) {
         return Objects.requireNonNull(method, "method");
     }
 
     private static MethodHandle unreflect(final Method method) throws IllegalAccessException {
         return MethodHandles.lookup().unreflect(requireMethod(method));
     }
 
     private static MethodHandle unreflectUnchecked(final Method method) {
         try {
             return unreflect(method);
         } catch (final IllegalAccessException e) {
             throw new UncheckedIllegalAccessException(e);
         }
     }
 
     /**
      * No need to create instances.
      */
     private MethodInvokers() {
         // noop
     }
 
 }