// 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.bazel.commands;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.devtools.build.lib.analysis.NoBuildEvent;
import com.google.devtools.build.lib.analysis.NoBuildRequestFinishedEvent;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.pkgcache.PackageCacheOptions;
import com.google.devtools.build.lib.query2.AbstractBlazeQueryEnvironment;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Setting;
import com.google.devtools.build.lib.query2.engine.QueryEvalResult;
import com.google.devtools.build.lib.query2.engine.QueryException;
import com.google.devtools.build.lib.query2.engine.QueryExpression;
import com.google.devtools.build.lib.query2.engine.ThreadSafeOutputFormatterCallback;
import com.google.devtools.build.lib.runtime.BlazeCommand;
import com.google.devtools.build.lib.runtime.BlazeCommandResult;
import com.google.devtools.build.lib.runtime.Command;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.build.lib.runtime.KeepGoingOption;
import com.google.devtools.build.lib.runtime.LoadingPhaseThreadsOption;
import com.google.devtools.build.lib.runtime.commands.QueryCommand;
import com.google.devtools.build.lib.util.AbruptExitException;
import com.google.devtools.build.lib.util.ExitCode;
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsParsingResult;
import java.io.IOException;
import java.util.EnumSet;

/** Fetches external repositories. Which is so fetch. */
@Command(
    name = FetchCommand.NAME,
    options = {PackageCacheOptions.class, KeepGoingOption.class, LoadingPhaseThreadsOption.class},
    help = "resource:fetch.txt",
    shortDescription = "Fetches external repositories that are prerequisites to the targets.",
    allowResidue = true,
    completion = "label")
public final class FetchCommand implements BlazeCommand {
  // TODO(kchodorow): add an option to force-fetch targets, even if they're already downloaded.
  // TODO(kchodorow): this would be a great time to check for difference and invalidate the upward
  //                  transitive closure for local repositories.

  public static final String NAME = "fetch";

  @Override
  public void editOptions(OptionsParser optionsParser) { }

  @Override
  public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult options) {
    if (options.getResidue().isEmpty()) {
      env.getReporter().handle(Event.error(String.format(
          "missing fetch expression. Type '%s help fetch' for syntax and help",
          env.getRuntime().getProductName())));
      return BlazeCommandResult.exitCode(ExitCode.COMMAND_LINE_ERROR);
    }

    try {
      env.setupPackageCache(options);
    } catch (InterruptedException e) {
      env.getReporter().handle(Event.error("fetch interrupted"));
      return BlazeCommandResult.exitCode(ExitCode.INTERRUPTED);
    } catch (AbruptExitException e) {
      env.getReporter().handle(Event.error(null, "Unknown error: " + e.getMessage()));
      return BlazeCommandResult.exitCode(e.getExitCode());
    }

    PackageCacheOptions pkgOptions = options.getOptions(PackageCacheOptions.class);
    if (!pkgOptions.fetch) {
      env.getReporter().handle(Event.error(null, "You cannot run fetch with --fetch=false"));
      return BlazeCommandResult.exitCode(ExitCode.COMMAND_LINE_ERROR);
    }

    // Querying for all of the dependencies of the targets has the side-effect of populating the
    // Skyframe graph for external targets, which requires downloading them. The JDK is required to
    // build everything but isn't counted as a dep in the build graph so we add it manually.
    ImmutableList.Builder<String> labelsToLoad = new ImmutableList.Builder<String>()
        .addAll(options.getResidue());

    String query = Joiner.on(" union ").join(labelsToLoad.build());
    query = "deps(" + query + ")";

    LoadingPhaseThreadsOption threadsOption = options.getOptions(LoadingPhaseThreadsOption.class);
    AbstractBlazeQueryEnvironment<Target> queryEnv =
        QueryCommand.newQueryEnvironment(
            env,
            options.getOptions(KeepGoingOption.class).keepGoing,
            false,
            Lists.<String>newArrayList(),
            threadsOption.threads,
            EnumSet.noneOf(Setting.class));

    // 1. Parse query:
    QueryExpression expr;
    try {
      expr = QueryExpression.parse(query, queryEnv);
    } catch (QueryException e) {
      env.getReporter().handle(Event.error(
          null, "Error while parsing '" + query + "': " + e.getMessage()));
      return BlazeCommandResult.exitCode(ExitCode.COMMAND_LINE_ERROR);
    }

    env.getReporter()
        .post(
            new NoBuildEvent(
                env.getCommandName(),
                env.getCommandStartTime(),
                true,
                true,
                env.getCommandId().toString()));

    // 2. Evaluate expression:
    QueryEvalResult queryEvalResult = null;
    try {
      queryEvalResult =
          queryEnv.evaluateQuery(
              expr,
              new ThreadSafeOutputFormatterCallback<Target>() {
                @Override
                public void processOutput(Iterable<Target> partialResult) {
                  // Throw away the result.
                }
              });
    } catch (InterruptedException e) {
      env.getReporter()
          .post(
              new NoBuildRequestFinishedEvent(
                  ExitCode.COMMAND_LINE_ERROR, env.getRuntime().getClock().currentTimeMillis()));
      return BlazeCommandResult.exitCode(ExitCode.COMMAND_LINE_ERROR);
    } catch (QueryException e) {
      // Keep consistent with reportBuildFileError()
      env.getReporter().handle(Event.error(e.getMessage()));
      env.getReporter()
          .post(
              new NoBuildRequestFinishedEvent(
                  ExitCode.COMMAND_LINE_ERROR, env.getRuntime().getClock().currentTimeMillis()));
      return BlazeCommandResult.exitCode(ExitCode.COMMAND_LINE_ERROR);
    } catch (IOException e) {
      // Should be impossible since our OutputFormatterCallback doesn't throw IOException.
      throw new IllegalStateException(e);
    }

    if (queryEvalResult.getSuccess()) {
      env.getReporter().handle(Event.progress("All external dependencies fetched successfully."));
    }
    ExitCode exitCode =
        queryEvalResult.getSuccess() ? ExitCode.SUCCESS : ExitCode.COMMAND_LINE_ERROR;
    env.getReporter()
        .post(
            new NoBuildRequestFinishedEvent(
                exitCode, env.getRuntime().getClock().currentTimeMillis()));
    return BlazeCommandResult.exitCode(exitCode);
  }
}