// 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.util;

import com.google.common.annotations.VisibleForTesting;
import com.google.devtools.build.lib.shell.AbnormalTerminationException;
import com.google.devtools.build.lib.shell.Command;
import com.google.devtools.build.lib.shell.CommandException;
import com.google.devtools.build.lib.shell.CommandResult;
import javax.annotation.Nullable;

/** Utility methods relating to the {@link Command} class. */
public class CommandUtils {

  private CommandUtils() {} // Prevent instantiation.

  @VisibleForTesting
  @Nullable
  static String cwd(Command command) {
    return command.getWorkingDirectory() == null ? null : command.getWorkingDirectory().getPath();
  }

  /**
   * Construct an error message that describes a failed command invocation.
   * Currently this returns a message of the form "foo failed: error executing
   * command /dir/foo bar baz: exception message", with the
   * command's stdout and stderr output appended if available.
   */
  public static String describeCommandFailure(boolean verbose, CommandException exception) {
    Command command = exception.getCommand();
    String message =
        CommandFailureUtils.describeCommandFailure(verbose, cwd(command), command)
            + ": "
            + exception.getMessage();
    if (exception instanceof AbnormalTerminationException) {
      CommandResult result = ((AbnormalTerminationException) exception).getResult();
      try {
        return message + "\n"
            + new String(result.getStdout())
            + new String(result.getStderr());
      } catch (IllegalStateException e) {
        // This can happen if the command didn't save stdout/stderr,
        // so ignore this exception and fall through to the ordinary case.
      }
    }
    return message;
  }

}