// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.lib.exec;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.devtools.build.lib.actions.Action;
import com.google.devtools.build.lib.rules.test.TestRunnerAction;

/**
 * Class implements --check_???_up_to_date execution filter predicate
 * that prevents certain actions from being executed (thus aborting
 * the build if action is not up-to-date).
 */
public final class CheckUpToDateFilter implements Predicate<Action> {

  /**
   * Determines an execution filter based on the --check_up_to_date and
   * --check_tests_up_to_date options. Returns a singleton if possible.
   */
  public static Predicate<Action> fromOptions(ExecutionOptions options) {
    if (!options.testCheckUpToDate && !options.checkUpToDate) {
      return Predicates.alwaysTrue();
    }
    return new CheckUpToDateFilter(options);
  }

  private final boolean allowBuildActionExecution;
  private final boolean allowTestActionExecution;

  /**
   * Creates new execution filter based on --check_up_to_date and
   * --check_tests_up_to_date options.
   */
  private CheckUpToDateFilter(ExecutionOptions options) {
    // If we want to check whether test is up-to-date, we should disallow
    // test execution.
    this.allowTestActionExecution = !options.testCheckUpToDate;

    // Build action execution should be prohibited in two cases - if we are
    // checking whether build is up-to-date or if we are checking that tests
    // are up-to-date (and test execution is not allowed).
    this.allowBuildActionExecution = allowTestActionExecution && !options.checkUpToDate;
  }

  /**
   * @return true if actions' execution is allowed, false - otherwise
   */
  @Override
  public boolean apply(Action action) {
    if (action instanceof AlwaysOutOfDateAction) {
      // Always allow fileset manifest action to execute because it identifies files included
      // in the fileset during execution time.
      return true;
    } else if (action instanceof TestRunnerAction) {
      return allowTestActionExecution;
    } else {
      return allowBuildActionExecution;
    }
  }

}