// Copyright 2017 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.sandbox;

import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.actions.ActionExecutionContext;
import com.google.devtools.build.lib.actions.ActionStatusMessage;
import com.google.devtools.build.lib.actions.ExecException;
import com.google.devtools.build.lib.actions.ExecutionStrategy;
import com.google.devtools.build.lib.actions.Executor;
import com.google.devtools.build.lib.actions.Spawn;
import com.google.devtools.build.lib.actions.SpawnActionContext;
import com.google.devtools.build.lib.actions.UserExecException;
import com.google.devtools.build.lib.analysis.BlazeDirectories;
import com.google.devtools.build.lib.buildtool.BuildRequest;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

/** Strategy that uses sandboxing to execute a process. */
@ExecutionStrategy(
  name = {"sandboxed"},
  contextType = SpawnActionContext.class
)
public class ProcessWrapperSandboxedStrategy extends SandboxStrategy {
  public static boolean isSupported(CommandEnvironment env) {
    return ProcessWrapperRunner.isSupported(env);
  }

  private final SandboxOptions sandboxOptions;
  private final BlazeDirectories blazeDirs;
  private final Path execRoot;
  private final boolean verboseFailures;
  private final String productName;

  private final UUID uuid = UUID.randomUUID();
  private final AtomicInteger execCounter = new AtomicInteger();

  ProcessWrapperSandboxedStrategy(
      BuildRequest buildRequest,
      BlazeDirectories blazeDirs,
      boolean verboseFailures,
      String productName) {
    super(buildRequest, blazeDirs, verboseFailures, buildRequest.getOptions(SandboxOptions.class));
    this.sandboxOptions = buildRequest.getOptions(SandboxOptions.class);
    this.blazeDirs = blazeDirs;
    this.execRoot = blazeDirs.getExecRoot();
    this.verboseFailures = verboseFailures;
    this.productName = productName;
  }

  @Override
  protected void actuallyExec(
      Spawn spawn,
      ActionExecutionContext actionExecutionContext,
      AtomicReference<Class<? extends SpawnActionContext>> writeOutputFiles)
      throws ExecException, InterruptedException {
    Executor executor = actionExecutionContext.getExecutor();
    executor
        .getEventBus()
        .post(
            ActionStatusMessage.runningStrategy(
                spawn.getResourceOwner(), "processwrapper-sandbox"));
    SandboxHelpers.reportSubcommand(executor, spawn);

    // Each invocation of "exec" gets its own sandbox.
    Path sandboxPath = SandboxHelpers.getSandboxRoot(blazeDirs, productName, uuid, execCounter);
    Path sandboxExecRoot = sandboxPath.getRelative("execroot").getRelative(execRoot.getBaseName());

    Set<Path> writableDirs;
    SymlinkedExecRoot symlinkedExecRoot = new SymlinkedExecRoot(sandboxExecRoot);
    ImmutableSet<PathFragment> outputs = SandboxHelpers.getOutputFiles(spawn);
    try {
      writableDirs = getWritableDirs(sandboxExecRoot, spawn.getEnvironment());
      symlinkedExecRoot.createFileSystem(
          getMounts(spawn, actionExecutionContext), outputs, writableDirs);
    } catch (IOException e) {
      throw new UserExecException("I/O error during sandboxed execution", e);
    }

    SandboxRunner runner = new ProcessWrapperRunner(execRoot, sandboxExecRoot, verboseFailures);
    try {
      runSpawn(
          spawn,
          actionExecutionContext,
          spawn.getEnvironment(),
          symlinkedExecRoot,
          outputs,
          runner,
          writeOutputFiles);
    } finally {
      if (!sandboxOptions.sandboxDebug) {
        try {
          FileSystemUtils.deleteTree(sandboxPath);
        } catch (IOException e) {
          executor
              .getEventHandler()
              .handle(
                  Event.warn(
                      String.format(
                          "Cannot delete sandbox directory after action execution: %s (%s)",
                          sandboxPath.getPathString(), e)));
        }
      }
    }
  }
}