/*
    * 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.configuration2.reloading;
  
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.mockito.ArgumentMatchers.any;
  import static org.mockito.ArgumentMatchers.eq;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.verify;
  import static org.mockito.Mockito.verifyNoMoreInteractions;
  import static org.mockito.Mockito.when;
  
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.ScheduledFuture;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.lang3.mutable.MutableObject;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  import org.mockito.stubbing.OngoingStubbing;
  
  /**
   * Test class for {@code PeriodicReloadingTrigger}.
   */
  public class TestPeriodicReloadingTrigger {
      /** Constant for a parameter to be passed to the controller. */
      private static final Object CTRL_PARAM = "Test controller parameter";
  
      /** Constant for the period. */
      private static final long PERIOD = 60;
  
      /** Constant for the period's time unit. */
      private static final TimeUnit UNIT = TimeUnit.SECONDS;
  
      /**
       * Creates a mock object for a scheduled future.
       *
       * @return the mock
       */
      @SuppressWarnings("unchecked")
      private static ScheduledFuture<Void> createFutureMock() {
          return mock(ScheduledFuture.class);
      }
  
      /** A mock for the executor service. */
      private ScheduledExecutorService executor;
  
      /** A mock for the reloading controller. */
      private ReloadingController controller;
  
      /**
       * Creates a test instance with default parameters.
       *
       * @return the test instance
       */
      private PeriodicReloadingTrigger createTrigger() {
          return new PeriodicReloadingTrigger(controller, CTRL_PARAM, PERIOD, UNIT, executor);
      }
  
      @BeforeEach
      public void setUp() throws Exception {
          executor = mock(ScheduledExecutorService.class);
          controller = mock(ReloadingController.class);
      }
  
      /**
       * Tests whether a default executor service is created if necessary.
       */
      @Test
      public void testDefaultExecutor() {
          final PeriodicReloadingTrigger trigger = new PeriodicReloadingTrigger(controller, CTRL_PARAM, PERIOD, UNIT);
          assertNotNull(trigger.getExecutorService());
      }
  
      /**
       * Tries to create an instance without a controller.
       */
      @Test
      public void testInitNoController() {
          assertThrows(IllegalArgumentException.class, () -> new PeriodicReloadingTrigger(null, CTRL_PARAM, PERIOD, UNIT));
      }
  
     /**
      * Tests that a newly created trigger is not running.
      */
     @Test
     public void testIsRunningAfterInit() {
         assertFalse(createTrigger().isRunning());
     }
 
     /**
      * Tests a shutdown operation.
      */
     @Test
     public void testShutdown() {
         final ScheduledFuture<Void> future = createFutureMock();
 
         whenScheduled().thenReturn(future);
         when(future.cancel(false)).thenReturn(Boolean.TRUE);
 
         final PeriodicReloadingTrigger trigger = createTrigger();
         trigger.start();
         trigger.shutdown();
 
         verifyScheduled();
         verify(future).cancel(false);
         verify(executor).shutdown();
         verifyNoMoreInteractions(future, controller, executor);
     }
 
     /**
      * Tests a shutdown operation which excludes the executor service.
      */
     @Test
     public void testShutdownNoExecutor() {
         createTrigger().shutdown(false);
     }
 
     /**
      * Tests whether the trigger can be started.
      */
     @Test
     public void testStart() {
         final ScheduledFuture<Void> future = createFutureMock();
         final MutableObject<Runnable> refTask = new MutableObject<>();
 
         whenScheduled().thenAnswer(invocation -> {
             refTask.setValue(invocation.getArgument(0, Runnable.class));
             return future;
         });
         when(controller.checkForReloading(CTRL_PARAM)).thenReturn(Boolean.FALSE);
 
         final PeriodicReloadingTrigger trigger = createTrigger();
         trigger.start();
         assertTrue(trigger.isRunning());
         refTask.getValue().run();
 
         verifyScheduled();
         verify(controller).checkForReloading(CTRL_PARAM);
         verifyNoMoreInteractions(future, controller, executor);
     }
 
     /**
      * Tests whether start() is a noop if the trigger is already running.
      */
     @Test
     public void testStartTwice() {
         final ScheduledFuture<Void> future = createFutureMock();
 
         whenScheduled().thenReturn(future);
 
         final PeriodicReloadingTrigger trigger = createTrigger();
         trigger.start();
         trigger.start();
 
         verifyScheduled();
         verifyNoMoreInteractions(future, controller, executor);
     }
 
     /**
      * Tests whether a running trigger can be stopped.
      */
     @Test
     public void testStop() {
         final ScheduledFuture<Void> future = createFutureMock();
 
         whenScheduled().thenReturn(future);
         when(future.cancel(false)).thenReturn(Boolean.TRUE);
 
         final PeriodicReloadingTrigger trigger = createTrigger();
         trigger.start();
         trigger.stop();
         assertFalse(trigger.isRunning());
 
         verifyScheduled();
         verify(future).cancel(false);
         verifyNoMoreInteractions(future, controller, executor);
     }
 
     /**
      * Tests stop() if the trigger is not running.
      */
     @Test
     public void testStopNotRunning() {
         createTrigger().stop();
     }
 
     /**
      * Verifies that an invocation has occurred on the executor mock which schedules the trigger task.
      */
     private void verifyScheduled() {
         verify(executor).scheduleAtFixedRate(any(), eq(PERIOD), eq(PERIOD), eq(UNIT));
     }
 
     /**
      * Prepares the executor mock to for any invocation which schedules the trigger task.
      * This method should be used to call one of the {@code thenReturn}, {@code thenAnswer} or {@code thenThrow} methods.
      *
      * @return An ongoing stubbing for the future
      */
     private OngoingStubbing<ScheduledFuture<?>> whenScheduled() {
         return when(executor.scheduleAtFixedRate(any(), eq(PERIOD), eq(PERIOD), eq(UNIT)));
     }
 }