/*
 * Copyright 2016 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.idea.blaze.base.async.process;

import com.google.common.base.Joiner;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Maps;
import com.google.common.io.ByteStreams;
import com.google.idea.blaze.base.command.BlazeCommand;
import com.google.idea.blaze.base.model.primitives.WorkspaceRoot;
import com.google.idea.blaze.base.scope.BlazeContext;
import com.google.idea.blaze.base.scope.BlazeScope;
import com.google.idea.blaze.base.scope.Scope;
import com.google.idea.blaze.base.scope.output.IssueOutput;
import com.google.idea.blaze.base.scope.output.PrintOutput;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.progress.ProcessCanceledException;
import com.intellij.util.SystemProperties;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.stream.Stream;
import javax.annotation.Nullable;

/** Invokes an external process */
public class ExternalTask {
  private static final Logger logger = Logger.getInstance(ExternalTask.class);

  static final OutputStream NULL_STREAM = ByteStreams.nullOutputStream();

  /** Builder for an external task */
  public static class Builder {
    private final ImmutableList.Builder<String> command = ImmutableList.builder();
    private final File workingDirectory;
    private final Map<String, String> environmentVariables = Maps.newHashMap();
    @Nullable private BlazeContext context;
    @Nullable private OutputStream stdout;
    @Nullable private OutputStream stderr;
    boolean redirectErrorStream = false;

    private Builder(WorkspaceRoot workspaceRoot) {
      this(workspaceRoot.directory());
    }

    private Builder(File workingDirectory) {
      this.workingDirectory = workingDirectory;
    }

    public Builder arg(String arg) {
      command.add(arg);
      return this;
    }

    public Builder args(String... args) {
      command.add(args);
      return this;
    }

    public Builder args(Collection<String> args) {
      command.addAll(args);
      return this;
    }

    public Builder args(Stream<String> args) {
      command.addAll(args.iterator());
      return this;
    }

    public Builder addBlazeCommand(BlazeCommand command) {
      this.command.addAll(command.toList());
      return this;
    }

    public Builder maybeArg(boolean b, String arg) {
      if (b) {
        command.add(arg);
      }
      return this;
    }

    public Builder context(@Nullable BlazeContext context) {
      this.context = context;
      return this;
    }

    public Builder redirectStderr(boolean redirectStderr) {
      this.redirectErrorStream = redirectStderr;
      return this;
    }

    public Builder stdout(@Nullable OutputStream stdout) {
      this.stdout = stdout;
      return this;
    }

    public Builder stderr(@Nullable OutputStream stderr) {
      this.stderr = stderr;
      return this;
    }

    public Builder environmentVar(String key, String value) {
      environmentVariables.put(key, value);
      return this;
    }

    public Builder environmentVars(Map<String, String> values) {
      environmentVariables.putAll(values);
      return this;
    }

    public ExternalTask build() {
      return new ExternalTask(
          context,
          workingDirectory,
          command.build(),
          environmentVariables,
          stdout,
          stderr,
          redirectErrorStream);
    }
  }

  private final File workingDirectory;

  private final List<String> command;

  private final Map<String, String> environmentVariables;

  @Nullable private final BlazeContext parentContext;

  private final boolean redirectErrorStream;

  private final OutputStream stdout;

  private final OutputStream stderr;

  private ExternalTask(
      @Nullable BlazeContext context,
      File workingDirectory,
      List<String> command,
      Map<String, String> environmentVariables,
      @Nullable OutputStream stdout,
      @Nullable OutputStream stderr,
      boolean redirectErrorStream) {
    this.workingDirectory = workingDirectory;
    this.command = command;
    this.environmentVariables = environmentVariables;
    this.parentContext = context;
    this.redirectErrorStream = redirectErrorStream;
    this.stdout = stdout != null ? stdout : NULL_STREAM;
    this.stderr = stderr != null ? stderr : NULL_STREAM;
  }

  public int run(BlazeScope... scopes) {
    Integer returnValue =
        Scope.push(
            parentContext,
            context -> {
              for (BlazeScope scope : scopes) {
                context.push(scope);
              }
              try {
                return invokeCommand(context);
              } catch (ProcessCanceledException e) {
                // Logging a ProcessCanceledException is an IJ error - mark context canceled instead
                context.setCancelled();
              }
              return -1;
            });
    return returnValue != null ? returnValue : -1;
  }

  private static void closeQuietly(OutputStream stream) {
    try {
      stream.close();
    } catch (IOException e) {
      Throwables.propagate(e);
    }
  }

  private int invokeCommand(BlazeContext context) {
    String executingTasksText =
        "Command: "
            + Joiner.on(" ").join(command)
            + SystemProperties.getLineSeparator()
            + SystemProperties.getLineSeparator();

    context.output(PrintOutput.log(executingTasksText));

    try {
      if (context.isEnding()) {
        return -1;
      }
      ProcessBuilder builder =
          new ProcessBuilder()
              .command(command)
              .redirectErrorStream(redirectErrorStream)
              .directory(workingDirectory);
      for (Map.Entry<String, String> entry : environmentVariables.entrySet()) {
        builder.environment().put(entry.getKey(), entry.getValue());
      }

      try {
        final Process process = builder.start();
        Thread shutdownHook = new Thread(process::destroy);
        try {
          Runtime.getRuntime().addShutdownHook(shutdownHook);
          // These tasks are non-interactive, so close the stream connected to the process's input.
          process.getOutputStream().close();
          Thread stdoutThread = ProcessUtil.forwardAsync(process.getInputStream(), stdout);
          Thread stderrThread = null;
          if (!redirectErrorStream) {
            stderrThread = ProcessUtil.forwardAsync(process.getErrorStream(), stderr);
          }
          process.waitFor();
          stdoutThread.join();
          if (!redirectErrorStream) {
            stderrThread.join();
          }
          int exitValue = process.exitValue();
          if (exitValue != 0) {
            context.setHasError();
          }
          return exitValue;
        } catch (InterruptedException e) {
          process.destroy();
          throw new ProcessCanceledException();
        } finally {
          try {
            Runtime.getRuntime().removeShutdownHook(shutdownHook);
          } catch (IllegalStateException e) {
            // we can't remove a shutdown hook if we are shutting down, do nothing about it
          }
        }
      } catch (IOException e) {
        logger.warn(e);
        IssueOutput.error(e.getMessage()).submit(context);
      }
    } finally {
      closeQuietly(stdout);
      closeQuietly(stderr);
    }
    return -1;
  }

  public static Builder builder() {
    return new Builder(new File("/"));
  }

  public static Builder builder(List<String> command) {
    return builder().args(command);
  }

  public static Builder builder(File workingDirectory) {
    return new Builder(workingDirectory);
  }

  public static Builder builder(WorkspaceRoot workspaceRoot) {
    return new Builder(workspaceRoot);
  }
}