// 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.actions;

import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.shell.TerminationStatus;
import com.google.devtools.build.lib.vfs.Path;
import com.google.protobuf.ByteString;
import java.io.InputStream;
import java.time.Duration;
import java.util.Locale;
import java.util.Optional;
import javax.annotation.Nullable;

/** The result of a {@link Spawn}'s execution. */
public interface SpawnResult {
  /** The status of the attempted Spawn execution. */
  enum Status {
    /** Subprocess executed successfully, and returned a zero exit code. */
    SUCCESS,

    /** Subprocess executed successfully, but returned a non-zero exit code. */
    NON_ZERO_EXIT(true),

    /** Subprocess execution timed out. */
    TIMEOUT(true),

    /**
     * The subprocess ran out of memory. On Linux systems, the kernel may kill processes in
     * low-memory situations, and this status is intended to report such a case back to Bazel.
     */
    OUT_OF_MEMORY(true),

    /**
     * Subprocess did not execute, it's not the user's fault, and the error is not catastrophic. If
     * keep_going is enabled then Bazel will try to continue the build, possibly will attempt to
     * rerun the same spawn, and possibly will attempt to run other actions.
     */
    EXECUTION_FAILED,

    /**
     * Subprocess did not execute, it's not the user's fault, and the error is catastrophic. Bazel
     * will not rerun this spawn. Bazel will attempt to not run other actions (regardless of whether
     * keep_going is enabled).
     */
    EXECUTION_FAILED_CATASTROPHICALLY,

    /**
     * Subprocess did not execute, and it may be the user's fault. The user may be able to fix it.
     * For example, a remote system may have denied the execution due to too many inputs or too
     * large inputs.
     */
    EXECUTION_DENIED(true),

    /** The remote execution system is overloaded and had to refuse execution for this Spawn. */
    REMOTE_EXECUTOR_OVERLOADED,

    /**
     * The result of the remotely executed Spawn could not be retrieved due to errors in the remote
     * caching layer.
     */
    REMOTE_CACHE_FAILED;

    private final boolean isUserError;

    Status(boolean isUserError) {
      this.isUserError = isUserError;
    }

    Status() {
      this(false);
    }

    public boolean isConsideredUserError() {
      return isUserError;
    }
  }

  /**
   * Returns whether the spawn was actually run, regardless of the exit code. I.e., returns
   * {@code true} if {@link #status} is any of {@link Status#SUCCESS}, {@link Status#NON_ZERO_EXIT},
   * {@link Status#TIMEOUT} or {@link Status#OUT_OF_MEMORY}.
   *
   * <p>Returns false if there were errors that prevented the spawn from being run, such as network
   * errors, missing local files, errors setting up sandboxing, etc.
   */
  boolean setupSuccess();

  /** Returns true if the status was {@link Status#EXECUTION_FAILED_CATASTROPHICALLY}. */
  boolean isCatastrophe();

  /** Returns the status of the attempted Spawn execution. */
  Status status();

  /**
   * Returns the exit code of the subprocess if the subprocess was executed.
   *
   * <p>Returns zero if {@link #status} returns {@link Status#SUCCESS}.
   *
   * <p>Returns non-zero if {@link #status} returns {@link Status#NON_ZERO_EXIT} or {@link
   * Status#OUT_OF_MEMORY}.
   *
   * <p>Returns 128 + 14 (corresponding to the Unix signal SIGALRM) if {@link #status} returns
   * {@link Status#TIMEOUT}.
   */
  int exitCode();

  /**
   * Returns the host name of the executor or {@code null}. This information is intended for
   * debugging purposes, especially for remote execution systems. Remote caches usually do not store
   * the original host name, so this is generally {@code null} for cache hits.
   */
  @Nullable
  String getExecutorHostName();

  /**
   * Returns the name of the SpawnRunner that executed the spawn. It should always be defined,
   * unless isCacheHit is true, in which case the spawn was not actually run.
   */
  String getRunnerName();

  /**
   * Returns the wall time taken by the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Duration> getWallTime();

  /**
   * Returns the user time taken by the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Duration> getUserTime();

  /**
   * Returns the system time taken by the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Duration> getSystemTime();

  /**
   * Returns the number of block output operations during the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Long> getNumBlockOutputOperations();

  /**
   * Returns the number of block input operations during the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Long> getNumBlockInputOperations();

  /**
   * Returns the number of involuntary context switches during the {@link Spawn}'s execution.
   *
   * @return the measurement, or empty in case of execution errors or when the measurement is not
   *     implemented for the current platform
   */
  Optional<Long> getNumInvoluntaryContextSwitches();

  SpawnMetrics getMetrics();

  /** Returns whether the spawn result was a cache hit. */
  boolean isCacheHit();

  /** Returns an optional custom failure message for the result. */
  default String getFailureMessage() {
    return "";
  }

  /**
   * Returns a {@link Spawn}'s output in-memory, if supported and available.
   *
   * <p>This behavior may be triggered with {@link
   * ExecutionRequirements#REMOTE_EXECUTION_INLINE_OUTPUTS}.
   */
  @Nullable
  default InputStream getInMemoryOutput(ActionInput output) {
    return null;
  }

  String getDetailMessage(
      String messagePrefix,
      String message,
      boolean verboseFailures,
      boolean catastrophe,
      boolean forciblyRunRemotely);

  /** Returns a file path to the action metadata log. */
  Optional<MetadataLog> getActionMetadataLog();

  /** Basic implementation of {@link SpawnResult}. */
  @Immutable
  @ThreadSafe
  final class SimpleSpawnResult implements SpawnResult {
    private final int exitCode;
    private final Status status;
    private final String executorHostName;
    private final String runnerName;
    private final SpawnMetrics spawnMetrics;
    private final Optional<Duration> wallTime;
    private final Optional<Duration> userTime;
    private final Optional<Duration> systemTime;
    private final Optional<Long> numBlockOutputOperations;
    private final Optional<Long> numBlockInputOperations;
    private final Optional<Long> numInvoluntaryContextSwitches;
    private final Optional<MetadataLog> actionMetadataLog;
    private final boolean cacheHit;
    private final String failureMessage;

    // Invariant: Either both have a value or both are null.
    @Nullable private final ActionInput inMemoryOutputFile;
    @Nullable private final ByteString inMemoryContents;

    SimpleSpawnResult(Builder builder) {
      this.exitCode = builder.exitCode;
      this.status = Preconditions.checkNotNull(builder.status);
      this.executorHostName = builder.executorHostName;
      this.runnerName = builder.runnerName;
      this.spawnMetrics = builder.spawnMetrics != null
          ? builder.spawnMetrics
          : SpawnMetrics.forLocalExecution(builder.wallTime.orElse(Duration.ZERO));
      this.wallTime = builder.wallTime;
      this.userTime = builder.userTime;
      this.systemTime = builder.systemTime;
      this.numBlockOutputOperations = builder.numBlockOutputOperations;
      this.numBlockInputOperations = builder.numBlockInputOperations;
      this.numInvoluntaryContextSwitches = builder.numInvoluntaryContextSwitches;
      this.cacheHit = builder.cacheHit;
      this.failureMessage = builder.failureMessage;
      this.inMemoryOutputFile = builder.inMemoryOutputFile;
      this.inMemoryContents = builder.inMemoryContents;
      this.actionMetadataLog = builder.actionMetadataLog;
    }

    @Override
    public boolean setupSuccess() {
      return status == Status.SUCCESS
          || status == Status.NON_ZERO_EXIT
          || status == Status.TIMEOUT
          || status == Status.OUT_OF_MEMORY;
    }

    @Override
    public boolean isCatastrophe() {
      return status == Status.EXECUTION_FAILED_CATASTROPHICALLY;
    }

    @Override
    public int exitCode() {
      return exitCode;
    }

    @Override
    public Status status() {
      return status;
    }

    @Override
    public String getExecutorHostName() {
      return executorHostName;
    }

    @Override
    public String getRunnerName() {
      return runnerName;
    }

    @Override
    public SpawnMetrics getMetrics() {
      return spawnMetrics;
    }

    @Override
    public Optional<Duration> getWallTime() {
      return wallTime;
    }

    @Override
    public Optional<Duration> getUserTime() {
      return userTime;
    }

    @Override
    public Optional<Duration> getSystemTime() {
      return systemTime;
    }

    @Override
    public Optional<Long> getNumBlockOutputOperations() {
      return numBlockOutputOperations;
    }

    @Override
    public Optional<Long> getNumBlockInputOperations() {
      return numBlockInputOperations;
    }

    @Override
    public Optional<Long> getNumInvoluntaryContextSwitches() {
      return numInvoluntaryContextSwitches;
    }

    @Override
    public boolean isCacheHit() {
      return cacheHit;
    }

    @Override
    public String getFailureMessage() {
      return failureMessage;
    }

    @Override
    public String getDetailMessage(
        String messagePrefix,
        String message,
        boolean verboseFailures,
        boolean catastrophe,
        boolean forciblyRunRemotely) {
      TerminationStatus status = new TerminationStatus(
          exitCode(), status() == Status.TIMEOUT);
      String reason = " (" + status.toShortString() + ")"; // e.g " (Exit 1)"
      // Include the command line as error message if --verbose_failures is enabled or
      // the command line didn't exit normally.
      String explanation = verboseFailures || !status.exited() ? ": " + message : "";

      if (!status().isConsideredUserError()) {
        String errorDetail = status().name().toLowerCase(Locale.US)
            .replace('_', ' ');
        explanation += ". Note: Remote connection/protocol failed with: " + errorDetail;
      }
      if (status() == Status.TIMEOUT) {
        if (getWallTime().isPresent()) {
          explanation +=
              String.format(
                  Locale.US,
                  " (failed due to timeout after %.2f seconds.)",
                  getWallTime().get().toMillis() / 1000.0);
        } else {
          explanation += " (failed due to timeout.)";
        }
      } else if (status() == Status.OUT_OF_MEMORY) {
        explanation += " (Remote action was terminated due to Out of Memory.)";
      }
      if (status() != Status.TIMEOUT && forciblyRunRemotely) {
        explanation += " Action tagged as local was forcibly run remotely and failed - it's "
            + "possible that the action simply doesn't work remotely";
      }
      if (!Strings.isNullOrEmpty(failureMessage)) {
        explanation += " " + failureMessage;
      }
      return messagePrefix + " failed" + reason + explanation;
    }

    @Nullable
    @Override
    public InputStream getInMemoryOutput(ActionInput output) {
      if (inMemoryOutputFile != null && inMemoryOutputFile.equals(output)) {
        return inMemoryContents.newInput();
      }
      return null;
    }

    @Override
    public Optional<MetadataLog> getActionMetadataLog() {
      return actionMetadataLog;
    }
  }

  /** Builder class for {@link SpawnResult}. */
  final class Builder {
    private int exitCode;
    private Status status;
    private String executorHostName;
    private String runnerName = "";
    private SpawnMetrics spawnMetrics;
    private Optional<Duration> wallTime = Optional.empty();
    private Optional<Duration> userTime = Optional.empty();
    private Optional<Duration> systemTime = Optional.empty();
    private Optional<Long> numBlockOutputOperations = Optional.empty();
    private Optional<Long> numBlockInputOperations = Optional.empty();
    private Optional<Long> numInvoluntaryContextSwitches = Optional.empty();
    private Optional<MetadataLog> actionMetadataLog = Optional.empty();
    private boolean cacheHit;
    private String failureMessage = "";

    // Invariant: Either both have a value or both are null.
    @Nullable private ActionInput inMemoryOutputFile;
    @Nullable private ByteString inMemoryContents;

    public SpawnResult build() {
      Preconditions.checkArgument(!runnerName.isEmpty());
      if (status == Status.SUCCESS) {
        Preconditions.checkArgument(exitCode == 0);
      }
      if (status == Status.NON_ZERO_EXIT
          || status == Status.TIMEOUT
          || status == Status.OUT_OF_MEMORY) {
        Preconditions.checkArgument(exitCode != 0);
      }
      return new SimpleSpawnResult(this);
    }

    public Builder setExitCode(int exitCode) {
      this.exitCode = exitCode;
      return this;
    }

    public Builder setStatus(Status status) {
      this.status = status;
      return this;
    }

    public Builder setExecutorHostname(String executorHostName) {
      this.executorHostName = executorHostName;
      return this;
    }

    public Builder setRunnerName(String runnerName) {
      this.runnerName = runnerName;
      return this;
    }

    public Builder setSpawnMetrics(SpawnMetrics spawnMetrics) {
      this.spawnMetrics = spawnMetrics;
      return this;
    }

    public Builder setWallTime(Duration wallTime) {
      this.wallTime = Optional.of(wallTime);
      return this;
    }

    public Builder setUserTime(Duration userTime) {
      this.userTime = Optional.of(userTime);
      return this;
    }

    public Builder setSystemTime(Duration systemTime) {
      this.systemTime = Optional.of(systemTime);
      return this;
    }

    public Builder setNumBlockOutputOperations(long numBlockOutputOperations) {
      this.numBlockOutputOperations = Optional.of(numBlockOutputOperations);
      return this;
    }

    public Builder setNumBlockInputOperations(long numBlockInputOperations) {
      this.numBlockInputOperations = Optional.of(numBlockInputOperations);
      return this;
    }

    public Builder setNumInvoluntaryContextSwitches(long numInvoluntaryContextSwitches) {
      this.numInvoluntaryContextSwitches = Optional.of(numInvoluntaryContextSwitches);
      return this;
    }

    public Builder setCacheHit(boolean cacheHit) {
      this.cacheHit = cacheHit;
      return this;
    }

    public Builder setFailureMessage(String failureMessage) {
      this.failureMessage = failureMessage;
      return this;
    }

    public Builder setInMemoryOutput(ActionInput outputFile, ByteString contents) {
      this.inMemoryOutputFile = Preconditions.checkNotNull(outputFile);
      this.inMemoryContents = Preconditions.checkNotNull(contents);
      return this;
    }

    Builder setActionMetadataLog(MetadataLog actionMetadataLog) {
      this.actionMetadataLog = Optional.of(actionMetadataLog);
      return this;
    }
  }

  /** A {@link Spawn}'s metadata name and {@link Path}. */
  final class MetadataLog {
    private final String name;
    private final Path filePath;

    public MetadataLog(String name, Path filePath) {
      this.name = name;
      this.filePath = filePath;
    }

    public String getName() {
      return this.name;
    }

    public Path getFilePath() {
      return this.filePath;
    }
  }
}