// 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.runtime.commands;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.FilesToRunProvider;
import com.google.devtools.build.lib.analysis.RunfilesSupport;
import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
import com.google.devtools.build.lib.analysis.config.RunUnder;
import com.google.devtools.build.lib.buildtool.BuildRequest;
import com.google.devtools.build.lib.buildtool.BuildRequest.BuildRequestOptions;
import com.google.devtools.build.lib.buildtool.BuildResult;
import com.google.devtools.build.lib.buildtool.BuildTool;
import com.google.devtools.build.lib.buildtool.OutputDirectoryLinksUtils;
import com.google.devtools.build.lib.buildtool.TargetValidator;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.Reporter;
import com.google.devtools.build.lib.exec.SymlinkTreeHelper;
import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
import com.google.devtools.build.lib.packages.OutputFile;
import com.google.devtools.build.lib.packages.Rule;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.packages.TargetUtils;
import com.google.devtools.build.lib.pkgcache.LoadingFailedException;
import com.google.devtools.build.lib.runtime.BlazeCommand;
import com.google.devtools.build.lib.runtime.BlazeRuntime;
import com.google.devtools.build.lib.runtime.Command;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.shell.AbnormalTerminationException;
import com.google.devtools.build.lib.shell.BadExitStatusException;
import com.google.devtools.build.lib.shell.CommandException;
import com.google.devtools.build.lib.syntax.Type;
import com.google.devtools.build.lib.util.CommandBuilder;
import com.google.devtools.build.lib.util.CommandDescriptionForm;
import com.google.devtools.build.lib.util.CommandFailureUtils;
import com.google.devtools.build.lib.util.ExitCode;
import com.google.devtools.build.lib.util.FileType;
import com.google.devtools.build.lib.util.OptionsUtils;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.util.ShellEscaper;
import com.google.devtools.build.lib.util.io.OutErr;
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 com.google.devtools.common.options.Option;
import com.google.devtools.common.options.OptionsBase;
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsProvider;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * Builds and run a target with the given command line arguments.
 */
@Command(name = "run",
         builds = true,
         options = { RunCommand.RunOptions.class },
         inherits = { BuildCommand.class },
         shortDescription = "Runs the specified target.",
         help = "resource:run.txt",
         allowResidue = true,
         binaryStdOut = true,
         completion = "label-bin",
         binaryStdErr = true)
public class RunCommand implements BlazeCommand  {

  public static class RunOptions extends OptionsBase {
    @Option(name = "script_path",
        category = "run",
        defaultValue = "null",
        converter = OptionsUtils.PathFragmentConverter.class,
        help = "If set, write a shell script to the given file which invokes the "
            + "target. If this option is set, the target is not run from %{product}. "
            + "Use '%{product} run --script_path=foo //foo && foo' to invoke target '//foo' "
            + "This differs from '%{product} run //foo' in that the %{product} lock is released "
            + "and the executable is connected to the terminal's stdin.")
    public PathFragment scriptPath;
  }

  @VisibleForTesting
  public static final String SINGLE_TARGET_MESSAGE = "Blaze can only run a single target. "
      + "Do not use wildcards that match more than one target";
  @VisibleForTesting
  public static final String NO_TARGET_MESSAGE = "No targets found to run";

  private static final String PROCESS_WRAPPER = "process-wrapper";

  // Value of --run_under as of the most recent command invocation.
  private RunUnder currentRunUnder;

  private static final FileType RUNFILES_MANIFEST = FileType.of(".runfiles_manifest");

  @VisibleForTesting  // productionVisibility = Visibility.PRIVATE
  protected BuildResult processRequest(final CommandEnvironment env, BuildRequest request) {
    return new BuildTool(env).processRequest(request, new TargetValidator() {
      @Override
      public void validateTargets(Collection<Target> targets, boolean keepGoing)
          throws LoadingFailedException {
        RunCommand.this.validateTargets(env.getReporter(), targets, keepGoing);
      }
    });
  }

  @Override
  public void editOptions(CommandEnvironment env, OptionsParser optionsParser) { }

  @Override
  public ExitCode exec(CommandEnvironment env, OptionsProvider options) {
    BlazeRuntime runtime = env.getRuntime();
    RunOptions runOptions = options.getOptions(RunOptions.class);
    // This list should look like: ["//executable:target", "arg1", "arg2"]
    List<String> targetAndArgs = options.getResidue();

    // The user must at the least specify an executable target.
    if (targetAndArgs.isEmpty()) {
      env.getReporter().handle(Event.error("Must specify a target to run"));
      return ExitCode.COMMAND_LINE_ERROR;
    }
    String targetString = targetAndArgs.get(0);
    List<String> runTargetArgs = targetAndArgs.subList(1, targetAndArgs.size());
    RunUnder runUnder = options.getOptions(BuildConfiguration.Options.class).runUnder;

    OutErr outErr = env.getReporter().getOutErr();
    List<String> targets = (runUnder != null) && (runUnder.getLabel() != null)
        ? ImmutableList.of(targetString, runUnder.getLabel().toString())
        : ImmutableList.of(targetString);
    BuildRequest request = BuildRequest.create(
        this.getClass().getAnnotation(Command.class).name(), options,
        runtime.getStartupOptionsProvider(), targets, outErr,
        env.getCommandId(), env.getCommandStartTime());

    currentRunUnder = runUnder;
    BuildResult result;
    try {
      result = processRequest(env, request);
    } finally {
      currentRunUnder = null;
    }

    if (!result.getSuccess()) {
      env.getReporter().handle(Event.error("Build failed. Not running target"));
      return result.getExitCondition();
    }

    // Make sure that we have exactly 1 built target (excluding --run_under),
    // and that it is executable.
    // These checks should only fail if keepGoing is true, because we already did
    // validation before the build began.  See {@link #validateTargets()}.
    Collection<ConfiguredTarget> targetsBuilt = result.getSuccessfulTargets();
    ConfiguredTarget targetToRun = null;
    ConfiguredTarget runUnderTarget = null;

    if (targetsBuilt != null) {
      int maxTargets = runUnder != null && runUnder.getLabel() != null ? 2 : 1;
      if (targetsBuilt.size() > maxTargets) {
        env.getReporter().handle(Event.error(SINGLE_TARGET_MESSAGE));
        return ExitCode.COMMAND_LINE_ERROR;
      }
      for (ConfiguredTarget target : targetsBuilt) {
        ExitCode targetValidation = fullyValidateTarget(env, target);
        if (targetValidation != ExitCode.SUCCESS) {
          return targetValidation;
        }
        if (runUnder != null && target.getLabel().equals(runUnder.getLabel())) {
          if (runUnderTarget != null) {
            env.getReporter().handle(Event.error(
                null, "Can't identify the run_under target from multiple options?"));
            return ExitCode.COMMAND_LINE_ERROR;
          }
          runUnderTarget = target;
        } else if (targetToRun == null) {
          targetToRun = target;
        } else {
          env.getReporter().handle(Event.error(SINGLE_TARGET_MESSAGE));
          return ExitCode.COMMAND_LINE_ERROR;
        }
      }
    }
    // Handle target & run_under referring to the same target.
    if ((targetToRun == null) && (runUnderTarget != null)) {
      targetToRun = runUnderTarget;
    }
    if (targetToRun == null) {
      env.getReporter().handle(Event.error(NO_TARGET_MESSAGE));
      return ExitCode.COMMAND_LINE_ERROR;
    }

    Path executablePath = Preconditions.checkNotNull(
        targetToRun.getProvider(FilesToRunProvider.class).getExecutable().getPath());
    BuildConfiguration configuration = targetToRun.getConfiguration();
    if (configuration == null) {
      // The target may be an input file, which doesn't have a configuration. In that case, we
      // choose any target configuration.
      configuration = result.getBuildConfigurationCollection().getTargetConfigurations().get(0);
    }
    Path workingDir;
    try {
      workingDir = ensureRunfilesBuilt(env, targetToRun);
    } catch (CommandException e) {
      env.getReporter().handle(Event.error("Error creating runfiles: " + e.getMessage()));
      return ExitCode.LOCAL_ENVIRONMENTAL_ERROR;
    }

    List<String> args = runTargetArgs;

    FilesToRunProvider provider = targetToRun.getProvider(FilesToRunProvider.class);
    RunfilesSupport runfilesSupport = provider == null ? null : provider.getRunfilesSupport();
    if (runfilesSupport != null && runfilesSupport.getArgs() != null) {
      List<String> targetArgs = runfilesSupport.getArgs();
      if (!targetArgs.isEmpty()) {
        args = Lists.newArrayListWithCapacity(targetArgs.size() + runTargetArgs.size());
        args.addAll(targetArgs);
        args.addAll(runTargetArgs);
      }
    }

    //
    // We now have a unique executable ready to be run.
    //
    // We build up two different versions of the command to run: one with an absolute path, which
    // we'll actually run, and a prettier one with the long absolute path to the executable
    // replaced with a shorter relative path that uses the symlinks in the workspace.
    PathFragment prettyExecutablePath =
        OutputDirectoryLinksUtils.getPrettyPath(executablePath,
            runtime.getWorkspaceName(), runtime.getWorkspace(),
            options.getOptions(BuildRequestOptions.class).getSymlinkPrefix());
    List<String> cmdLine = new ArrayList<>();
    if (runOptions.scriptPath == null) {
      PathFragment processWrapperPath = runtime.getBinTools().getExecPath(PROCESS_WRAPPER);
      Preconditions.checkNotNull(
          processWrapperPath, PROCESS_WRAPPER + " not found in embedded tools");
      cmdLine.add(runtime.getDirectories().getExecRoot()
          .getRelative(processWrapperPath).getPathString());
      cmdLine.add("-1");
      cmdLine.add("15");
      cmdLine.add("-");
      cmdLine.add("-");
    }
    List<String> prettyCmdLine = new ArrayList<>();
    // Insert the command prefix specified by the "--run_under=<command-prefix>" option
    // at the start of the command line.
    if (runUnder != null) {
      String runUnderValue = runUnder.getValue();
      if (runUnderTarget != null) {
        // --run_under specifies a target. Get the corresponding executable.
        // This must be an absolute path, because the run_under target is only
        // in the runfiles of test targets.
        runUnderValue = runUnderTarget
            .getProvider(FilesToRunProvider.class).getExecutable().getPath().getPathString();
        // If the run_under command contains any options, make sure to add them
        // to the command line as well.
        List<String> opts = runUnder.getOptions();
        if (!opts.isEmpty()) {
          runUnderValue += " " + ShellEscaper.escapeJoinAll(opts);
        }
      }
      cmdLine.add(configuration.getShExecutable().getPathString());
      cmdLine.add("-c");
      cmdLine.add(runUnderValue + " " + executablePath.getPathString() + " " +
          ShellEscaper.escapeJoinAll(args));
      prettyCmdLine.add(configuration.getShExecutable().getPathString());
      prettyCmdLine.add("-c");
      prettyCmdLine.add(runUnderValue + " " + prettyExecutablePath.getPathString() + " " +
          ShellEscaper.escapeJoinAll(args));
    } else {
      cmdLine.add(executablePath.getPathString());
      cmdLine.addAll(args);
      prettyCmdLine.add(prettyExecutablePath.getPathString());
      prettyCmdLine.addAll(args);
    }

    // Add a newline between the blaze output and the binary's output.
    outErr.printErrLn("");

    if (runOptions.scriptPath != null) {
      String unisolatedCommand = CommandFailureUtils.describeCommand(
          CommandDescriptionForm.COMPLETE_UNISOLATED,
          cmdLine, null, workingDir.getPathString());
      if (writeScript(env, runOptions.scriptPath, unisolatedCommand)) {
        return ExitCode.SUCCESS;
      } else {
        return ExitCode.RUN_FAILURE;
      }
    }

    env.getReporter().handle(Event.info(
        null, "Running command line: " + ShellEscaper.escapeJoinAll(prettyCmdLine)));

    com.google.devtools.build.lib.shell.Command command = new CommandBuilder()
        .addArgs(cmdLine).setEnv(env.getClientEnv()).setWorkingDir(workingDir).build();

    try {
      // Restore a raw EventHandler if it is registered. This allows for blaze run to produce the
      // actual output of the command being run even if --color=no is specified.
      env.getReporter().switchToAnsiAllowingHandler();

      // The command API is a little strange in that the following statement
      // will return normally only if the program exits with exit code 0.
      // If it ends with any other code, we have to catch BadExitStatusException.
      command.execute(com.google.devtools.build.lib.shell.Command.NO_INPUT,
          com.google.devtools.build.lib.shell.Command.NO_OBSERVER,
          outErr.getOutputStream(),
          outErr.getErrorStream(),
          true /* interruptible */).getTerminationStatus().getExitCode();
      return ExitCode.SUCCESS;
    } catch (BadExitStatusException e) {
      String message = "Non-zero return code '"
                       + e.getResult().getTerminationStatus().getExitCode()
                       + "' from command: " + e.getMessage();
      env.getReporter().handle(Event.error(message));
      return ExitCode.RUN_FAILURE;
    } catch (AbnormalTerminationException e) {
      // The process was likely terminated by a signal in this case.
      return ExitCode.INTERRUPTED;
    } catch (CommandException e) {
      env.getReporter().handle(Event.error("Error running program: " + e.getMessage()));
      return ExitCode.RUN_FAILURE;
    }
  }

  /**
   * Ensures that runfiles are built for the specified target. If they already
   * are, does nothing, otherwise builds them.
   *
   * @param target the target to build runfiles for.
   * @return the path of the runfiles directory.
   * @throws CommandException
   */
  private Path ensureRunfilesBuilt(CommandEnvironment env, ConfiguredTarget target)
      throws CommandException {
    FilesToRunProvider provider = target.getProvider(FilesToRunProvider.class);
    RunfilesSupport runfilesSupport = provider == null ? null : provider.getRunfilesSupport();
    if (runfilesSupport == null) {
      return env.getWorkingDirectory();
    }

    Artifact manifest = runfilesSupport.getRunfilesManifest();
    PathFragment runfilesDir = runfilesSupport.getRunfilesDirectoryExecPath();
    Path workingDir = env.getRuntime().getExecRoot()
        .getRelative(runfilesDir)
        .getRelative(runfilesSupport.getRunfiles().getSuffix());

    // When runfiles are not generated, getManifest() returns the
    // .runfiles_manifest file, otherwise it returns the MANIFEST file. This is
    // a handy way to check whether runfiles were built or not.
    if (!RUNFILES_MANIFEST.matches(manifest.getFilename())) {
      // Runfiles already built, nothing to do.
      return workingDir;
    }

    SymlinkTreeHelper helper = new SymlinkTreeHelper(
        manifest.getExecPath(),
        runfilesDir,
        false);
    helper.createSymlinksUsingCommand(env.getRuntime().getExecRoot(), target.getConfiguration(),
        env.getRuntime().getBinTools());
    return workingDir;
  }

  private boolean writeScript(CommandEnvironment env, PathFragment scriptPathFrag, String cmd) {
    final String SH_SHEBANG = "#!/bin/sh";
    Path scriptPath = env.getWorkingDirectory().getRelative(scriptPathFrag);
    try {
      FileSystemUtils.writeContent(scriptPath, StandardCharsets.ISO_8859_1,
          SH_SHEBANG + "\n" + cmd + " \"$@\"");
      scriptPath.setExecutable(true);
    } catch (IOException e) {
      env.getReporter().handle(Event.error("Error writing run script:" + e.getMessage()));
      return false;
    }
    return true;
  }

  // Make sure we are building exactly 1 binary target.
  // If keepGoing, we'll build all the targets even if they are non-binary.
  private void validateTargets(Reporter reporter, Collection<Target> targets, boolean keepGoing)
      throws LoadingFailedException {
    Target targetToRun = null;
    Target runUnderTarget = null;

    boolean singleTargetWarningWasOutput = false;
    int maxTargets = currentRunUnder != null && currentRunUnder.getLabel() != null ? 2 : 1;
    if (targets.size() > maxTargets) {
      warningOrException(reporter, SINGLE_TARGET_MESSAGE, keepGoing);
      singleTargetWarningWasOutput = true;
    }
    for (Target target : targets) {
      String targetError = validateTarget(target);
      if (targetError != null) {
        warningOrException(reporter, targetError, keepGoing);
      }

      if (currentRunUnder != null && target.getLabel().equals(currentRunUnder.getLabel())) {
        // It's impossible to have two targets with the same label.
        Preconditions.checkState(runUnderTarget == null);
        runUnderTarget = target;
      } else if (targetToRun == null) {
        targetToRun = target;
      } else {
        if (!singleTargetWarningWasOutput) {
          warningOrException(reporter, SINGLE_TARGET_MESSAGE, keepGoing);
        }
        return;
      }
    }
    // Handle target & run_under referring to the same target.
    if ((targetToRun == null) && (runUnderTarget != null)) {
      targetToRun = runUnderTarget;
    }
    if (targetToRun == null) {
      warningOrException(reporter, NO_TARGET_MESSAGE, keepGoing);
    }
  }

  // If keepGoing, print a warning and return the given collection.
  // Otherwise, throw InvalidTargetException.
  private void warningOrException(Reporter reporter, String message,
      boolean keepGoing) throws LoadingFailedException {
    if (keepGoing) {
      reporter.handle(Event.warn(message + ". Will continue anyway"));
    } else {
      throw new LoadingFailedException(message);
    }
  }

  private static String notExecutableError(Target target) {
    return "Cannot run target " + target.getLabel() + ": Not executable";
  }

  /** Returns null if the target is a runnable rule, or an appropriate error message otherwise. */
  private static String validateTarget(Target target) {
    return isExecutable(target)
        ? null
        : notExecutableError(target);
  }

  /**
   * Performs all available validation checks on an individual target.
   *
   * @param target ConfiguredTarget to validate
   * @return ExitCode.SUCCESS if all checks succeeded, otherwise a different error code.
   */
  private ExitCode fullyValidateTarget(CommandEnvironment env, ConfiguredTarget target) {
    String targetError = validateTarget(target.getTarget());

    if (targetError != null) {
      env.getReporter().handle(Event.error(targetError));
      return ExitCode.COMMAND_LINE_ERROR;
    }

    Artifact executable = target.getProvider(FilesToRunProvider.class).getExecutable();
    if (executable == null) {
      env.getReporter().handle(Event.error(notExecutableError(target.getTarget())));
      return ExitCode.COMMAND_LINE_ERROR;
    }

    // Shouldn't happen: We just validated the target.
    Preconditions.checkState(executable != null,
        "Could not find executable for target %s", target);
    Path executablePath = executable.getPath();
    try {
      if (!executablePath.exists() || !executablePath.isExecutable()) {
        env.getReporter().handle(Event.error(
            null, "Non-existent or non-executable " + executablePath));
        return ExitCode.BLAZE_INTERNAL_ERROR;
      }
    } catch (IOException e) {
      env.getReporter().handle(Event.error(
          "Error checking " + executablePath.getPathString() + ": " + e.getMessage()));
      return ExitCode.LOCAL_ENVIRONMENTAL_ERROR;
    }

    return ExitCode.SUCCESS;
  }

  /**
   * Return true iff {@code target} is a rule that has an executable file. This includes
   * *_test rules, *_binary rules, and generated outputs.
   */
  private static boolean isExecutable(Target target) {
    return isOutputFile(target) || isExecutableNonTestRule(target)
        || TargetUtils.isTestRule(target);
  }

  /**
   * Return true iff {@code target} is a rule that generates an executable file and is user-executed
   * code.
   */
  private static boolean isExecutableNonTestRule(Target target) {
    if (!(target instanceof Rule)) {
      return false;
    }
    Rule rule = ((Rule) target);
    if (rule.getRuleClassObject().hasAttr("$is_executable", Type.BOOLEAN)) {
      return NonconfigurableAttributeMapper.of(rule).get("$is_executable", Type.BOOLEAN);
    }
    return false;
  }

  private static boolean isOutputFile(Target target) {
    return (target instanceof OutputFile);
  }
}