/*
 * Copyright 2012-present Facebook, Inc.
 *
 * 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 com.facebook.buck.junit;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.containsString;
import static org.junit.Assert.assertEquals;

import com.facebook.buck.testutil.integration.ProjectWorkspace;
import com.facebook.buck.testutil.integration.ProjectWorkspace.ProcessResult;
import com.facebook.buck.testutil.integration.TestDataHelper;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterables;
import com.google.common.io.Files;

import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * Integration test to verify that timeouts are handled as expected by {@link JUnitRunner}.
 * <p>
 * Note that there is a quirk when running tests with threads and timeouts described at
 * https://github.com/junit-team/junit/issues/686. This test verifies that Buck honors this behavior
 * of JUnit with its custom {@link BuckBlockJUnit4ClassRunner}.
 * <p>
 * That said, this behavior of JUnit interacts badly with a default test timeout in
 * {@code .buckconfig} because it requires adding {@link org.junit.rules.Timeout} to the handful of
 * tests that exploit this behavior.
 */
public class TimeoutIntegrationTest {

  private static final String PATH_TO_TIMEOUT_BEHAVIOR_TEST = "TimeoutChangesBehaviorTest.java";

  @Rule
  public TemporaryFolder temporaryFolder = new TemporaryFolder();

  @Test
  public void testThatTimeoutsInTestsWorkAsExpected() throws IOException {
    ProjectWorkspace workspace = TestDataHelper.createProjectWorkspaceForScenario(
        this, "timeouts", temporaryFolder);
    workspace.setUp();

    // ExceedsAnnotationTimeoutTest should fail.
    ProcessResult exceedsAnnotationTimeoutTestResult = workspace.runBuckCommand(
        "test", "//:ExceedsAnnotationTimeoutTest");
    assertEquals("Test should fail due to timeout",
        1,
        exceedsAnnotationTimeoutTestResult.getExitCode());
    assertThat(exceedsAnnotationTimeoutTestResult.getStderr(),
        containsString(
            "FAILURE testShouldFailDueToExpiredTimeout: test timed out after 1000 milliseconds"));

    // TimeoutChangesBehaviorTest should pass.
    ProcessResult timeoutTestWithoutTimeout = workspace.runBuckCommand(
        "test", "//:TimeoutChangesBehaviorTest");
    assertEquals(0, timeoutTestWithoutTimeout.getExitCode());

    // TimeoutChangesBehaviorTest with @Test(timeout) specified should fail.
    // See https://github.com/junit-team/junit/issues/686 about why it fails.
    modifyTimeoutInTestAnnotation(PATH_TO_TIMEOUT_BEHAVIOR_TEST, /* addTimeout */ true);
    ProcessResult timeoutTestWithTimeoutOnAnnotation = workspace.runBuckCommand(
        "test", "//:TimeoutChangesBehaviorTest");
    assertEquals(1, timeoutTestWithTimeoutOnAnnotation.getExitCode());
    assertThat(timeoutTestWithTimeoutOnAnnotation.getStderr(),
        containsString(
            "FAILURE testTimeoutDictatesTheSuccessOfThisTest: " +
            "Database should have an open transaction due to setUp()."));

    // TimeoutChangesBehaviorTest with @Rule(Timeout) should pass.
    modifyTimeoutInTestAnnotation(PATH_TO_TIMEOUT_BEHAVIOR_TEST, /* addTimeout */ false);
    insertTimeoutRule(PATH_TO_TIMEOUT_BEHAVIOR_TEST);
    ProcessResult timeoutTestWithTimeoutRule = workspace.runBuckCommand(
        "test", "//:TimeoutChangesBehaviorTest");
    assertEquals(0, timeoutTestWithTimeoutRule.getExitCode());

    workspace.verify();
  }

  /**
   * Swaps all instances of {@code @Test} with {@code @Test(timeout = 10000)} in the specified Java
   * file, as determined by the value of {@code addTimeout}.
   */
  private void modifyTimeoutInTestAnnotation(String path, final boolean addTimeout)
      throws IOException {
    Function<String, String> transform = new Function<String, String>() {
      @Override public String apply(String line) {
        String original = addTimeout ? "@Test" : "@Test(timeout = 100000)";
        String replacement = addTimeout ? "@Test(timeout = 100000)" : "@Test";
        return line.replace(original, replacement) + '\n';
      }
    };
    rewriteFileWithTransform(path, transform);
  }

  /**
   * Inserts the following after the top-level class declaration:
   * <pre>
   *   @org.junit.Rule
   *   public org.junit.rules.Timeout timeoutForTests = new org.junit.rules.Timeout(10000);
   * </pre>
   */
  private void insertTimeoutRule(String path) throws IOException {
    Function<String, String> transform = new Function<String, String>() {
      @Override
      public String apply(String line) {
        if (line.startsWith("public class")) {
          return line + "\n\n" +
              "  @org.junit.Rule\n" +
              "  public org.junit.rules.Timeout timeoutForTests = " +
              "new org.junit.rules.Timeout(10000);\n";
        } else {
          return line + '\n';
        }
      }
    };
    rewriteFileWithTransform(path, transform);
  }

  /**
   * Finds the file at the specified path, transforms all of its lines using the specified
   * {@code transform} parameter, and writes the transformed lines back to the path.
   */
  private void rewriteFileWithTransform(String path, Function<String, String> transform)
      throws IOException {
    File javaFile = new File(temporaryFolder.getRoot(), path);
    List<String> lines = Files.readLines(javaFile, Charsets.UTF_8);
    String java = Joiner.on("").join(Iterables.transform(lines, transform));
    Files.write(java, javaFile, Charsets.UTF_8);
  }
}