/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * 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 androidx.test.ext.junit.runners;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
import org.junit.runner.Description;
import org.junit.runner.Runner;
import org.junit.runner.manipulation.Filter;
import org.junit.runner.manipulation.Filterable;
import org.junit.runner.manipulation.NoTestsRemainException;
import org.junit.runner.manipulation.Sortable;
import org.junit.runner.manipulation.Sorter;
import org.junit.runner.notification.RunNotifier;
import org.junit.runners.model.InitializationError;

/**
 * A JUnit4 runner for Android tests.
 *
 * <p>This runner offers several features on top of the standard JUnit4 runner,
 *
 * <ul>
 *   <li>Supports running on Robolectric. This implementation will delegate to RobolectricTestRunner
 *       if test is running in Robolectric enviroment. A custom runner can be provided by specifying
 *       the full class name in a 'android.junit.runner' system property.
 *   <li>Supports a per-test timeout - specfied via a 'timeout_msec' {@link
 *       androidx.test.runner.AndroidJUnitRunner} argument.
 *   <li>Supports running tests on the application's UI Thread, for tests annotated with {@link
 *       androidx.test.annotation.UiThreadTest}.
 * </ul>
 *
 * <p>Usage {@code @RunWith(AndroidJUnit4.class)}
 */
public final class AndroidJUnit4 extends Runner implements Filterable, Sortable {

  private static final String TAG = "AndroidJUnit4";

  private final Runner delegate;

  public AndroidJUnit4(Class<?> klass) throws InitializationError {
    delegate = loadRunner(klass);
  }

  private static String getRunnerClassName() {
    String runnerClassName = System.getProperty("android.junit.runner", null);
    if (runnerClassName == null) {
      if (!System.getProperty("java.runtime.name").toLowerCase().contains("android")
          && hasClass("org.robolectric.RobolectricTestRunner")) {
        return "org.robolectric.RobolectricTestRunner";
      } else {
        return "androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner";
      }
    }
    return runnerClassName;
  }

  private static boolean hasClass(String className) {
    try {
      return Class.forName(className) != null;
    } catch (ClassNotFoundException e) {
      return false;
    }
  }

  private static Runner loadRunner(Class<?> testClass) throws InitializationError {
    String runnerClassName = getRunnerClassName();
    return loadRunner(testClass, runnerClassName);
  }

  @SuppressWarnings("unchecked")
  private static Runner loadRunner(Class<?> testClass, String runnerClassName)
      throws InitializationError {

    Class<? extends Runner> runnerClass = null;
    try {
      runnerClass = (Class<? extends Runner>) Class.forName(runnerClassName);
    } catch (ClassNotFoundException e) {
      throwInitializationError(
          String.format(
              "Delegate runner %s for AndroidJUnit4 could not be found.\n", runnerClassName),
          e);
    }

    Constructor<? extends Runner> constructor = null;
    try {
      constructor = runnerClass.getConstructor(Class.class);
    } catch (NoSuchMethodException e) {
      throwInitializationError(
          String.format(
              "Delegate runner %s for AndroidJUnit4 requires a public constructor that takes a"
                  + " Class<?>.\n",
              runnerClassName),
          e);
    }

    try {
      return constructor.newInstance(testClass);
    } catch (IllegalAccessException e) {
      throwInitializationError(
          String.format("Illegal constructor access for test runner %s\n", runnerClassName), e);
    } catch (InstantiationException e) {
      throwInitializationError(
          String.format("Failed to instantiate test runner %s\n", runnerClassName), e);
    } catch (InvocationTargetException e) {
      String details = getInitializationErrorDetails(e, testClass);
      throwInitializationError(
          String.format("Failed to instantiate test runner %s\n%s\n", runnerClass, details), e);
    }
    throw new IllegalStateException("Should never reach here");
  }

  private static void throwInitializationError(String details, Throwable cause)
      throws InitializationError {
    throw new InitializationError(new RuntimeException(details, cause));
  }

  private static String getInitializationErrorDetails(Throwable throwable, Class<?> testClass) {
    StringBuilder innerCause = new StringBuilder();
    final Throwable cause = throwable.getCause();

    if (cause == null) {
      return "";
    }

    final Class<? extends Throwable> causeClass = cause.getClass();
    if (causeClass == InitializationError.class) {
      final InitializationError initializationError = (InitializationError) cause;
      final List<Throwable> testClassProblemList = initializationError.getCauses();
      innerCause.append(
          String.format(
              "Test class %s is malformed. (%s problems):\n",
              testClass, testClassProblemList.size()));
      for (Throwable testClassProblem : testClassProblemList) {
        innerCause.append(testClassProblem).append("\n");
      }
    }
    return innerCause.toString();
  }

  @Override
  public Description getDescription() {
    return delegate.getDescription();
  }

  @Override
  public void run(RunNotifier runNotifier) {
    delegate.run(runNotifier);
  }

  @Override
  public void filter(Filter filter) throws NoTestsRemainException {
    ((Filterable) delegate).filter(filter);
  }

  @Override
  public void sort(Sorter sorter) {
    ((Sortable) delegate).sort(sorter);
  }
}