/*
    * 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
    *
    *      https://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 static org.apache.commons.lang3.LangAssertions.assertNullPointerException;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  import java.lang.reflect.Method;
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.function.Function;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  import org.apache.commons.lang3.exception.CustomUncheckedException;
  import org.junit.jupiter.api.Test;
  
  /**
   * Tests {@link MethodInvokers#asFunction(Method)}.
   */
  class MethodInvokersFunctionTest extends MethodFixtures {
  
      @Test
      void testApply0Arg() throws NoSuchMethodException, SecurityException {
          final Function<MethodFixtures, String> func = MethodInvokers.asFunction(getMethodForGetString());
          assertEquals(INSTANCE.getString(), func.apply(INSTANCE));
      }
  
      @Test
      void testApply0ArgThrowsUnchecked() throws NoSuchMethodException, SecurityException {
          final Function<MethodFixtures, String> func = MethodInvokers.asFunction(getMethodForGetStringThrowsUnchecked());
          assertThrows(CustomUncheckedException.class, () -> func.apply(INSTANCE));
      }
  
      @Test
      void testBuildVarArg() throws SecurityException, NoSuchMethodException {
          MethodInvokers.asFunction(getMethodForGetStringVarStringArgs());
      }
  
      @Test
      void testConstructorForNull() throws SecurityException {
          assertNullPointerException(() -> MethodInvokers.asFunction(null));
      }
  
      @Test
      void testFindAndInvoke() throws SecurityException {
          // Finding
          final List<Function<Object, Object>> invokers = Stream.of(MethodFixtures.class.getDeclaredMethods())
              .filter(m -> m.isAnnotationPresent(AnnotationTestFixture.class)).map(MethodInvokers::asFunction).collect(Collectors.toList());
          assertEquals(2, invokers.size());
          // ...
          // Invoking
          final Set<Object> set1 = invokers.stream().map(i -> i.apply(MethodFixtures.INSTANCE)).collect(Collectors.toSet());
          assertEquals(new HashSet<>(Arrays.asList(INSTANCE.getString(), INSTANCE.getString2())), set1);
          final Set<Object> set2 = Stream.of(INSTANCE).map(invokers.get(0)).collect(Collectors.toSet());
          final Set<Object> set3 = Stream.of(INSTANCE).map(invokers.get(1)).collect(Collectors.toSet());
          set2.addAll(set3);
          assertEquals(new HashSet<>(Arrays.asList(INSTANCE.getString(), INSTANCE.getString2())), set2);
      }
  
      @Test
      void testFullExample() throws SecurityException, ReflectiveOperationException {
          final Method method = String.class.getMethod("length");
          final Function<String, Integer> function = MethodInvokers.asFunction(method);
          assertEquals(3, function.apply("ABC"));
      }
  
      @Test
      void testMapComputeIfAbsent() throws NoSuchMethodException, SecurityException {
          final Map<MethodFixtures, String> map = new HashMap<>();
          map.computeIfAbsent(INSTANCE, MethodInvokers.asFunction(getMethodForGetString()));
          assertEquals(INSTANCE.getString(), map.get(INSTANCE));
      }
  
      @Test
      void testToString() throws SecurityException, ReflectiveOperationException {
          // Should not blow up and must return _something_
          assertFalse(MethodInvokers.asFunction(getMethodForGetString()).toString().isEmpty());
     }
 
 }