/*
 * 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.idea.blaze.base.sync.sharding;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.idea.blaze.base.async.FutureUtil;
import com.google.idea.blaze.base.async.process.ExternalTask;
import com.google.idea.blaze.base.async.process.LineProcessingOutputStream;
import com.google.idea.blaze.base.async.process.PrintOutputLineProcessor;
import com.google.idea.blaze.base.bazel.BuildSystemProvider;
import com.google.idea.blaze.base.command.BlazeCommand;
import com.google.idea.blaze.base.command.BlazeCommandName;
import com.google.idea.blaze.base.command.BlazeFlags;
import com.google.idea.blaze.base.model.primitives.Kind;
import com.google.idea.blaze.base.model.primitives.TargetExpression;
import com.google.idea.blaze.base.model.primitives.WorkspacePath;
import com.google.idea.blaze.base.model.primitives.WorkspaceRoot;
import com.google.idea.blaze.base.prefetch.PrefetchService;
import com.google.idea.blaze.base.projectview.ProjectViewSet;
import com.google.idea.blaze.base.scope.BlazeContext;
import com.google.idea.blaze.base.scope.output.StatusOutput;
import com.google.idea.blaze.base.settings.Blaze;
import com.google.idea.blaze.base.sync.aspects.BuildResult;
import com.google.idea.blaze.base.sync.projectview.LanguageSupport;
import com.google.idea.blaze.base.sync.sharding.QueryResultLineProcessor.RuleTypeAndLabel;
import com.google.idea.blaze.base.sync.workspace.WorkspacePathResolver;
import com.google.idea.common.experiments.BoolExperiment;
import com.intellij.openapi.project.Project;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import javax.annotation.Nullable;

/** Expands wildcard target patterns into individual blaze targets. */
public class WildcardTargetExpander {

  private static final BoolExperiment filterByRuleType =
      new BoolExperiment("blaze.build.filter.by.rule.type", true);

  static class ExpandedTargetsResult {
    final List<TargetExpression> singleTargets;
    final BuildResult buildResult;

    ExpandedTargetsResult(List<TargetExpression> singleTargets, BuildResult buildResult) {
      this.singleTargets = singleTargets;
      this.buildResult = buildResult;
    }

    static ExpandedTargetsResult merge(ExpandedTargetsResult first, ExpandedTargetsResult second) {
      BuildResult buildResult = BuildResult.combine(first.buildResult, second.buildResult);
      List<TargetExpression> targets =
          ImmutableList.<TargetExpression>builder()
              .addAll(first.singleTargets)
              .addAll(second.singleTargets)
              .build();
      return new ExpandedTargetsResult(targets, buildResult);
    }
  }

  /**
   * Expand recursive wildcard blaze target patterns into single-package wildcard patterns, via a
   * file system traversal.
   *
   * <p>Exclude target patterns (beginning with '-') are not expanded.
   *
   * <p>Returns null if operation failed or was cancelled.
   */
  @Nullable
  static Map<TargetExpression, List<TargetExpression>> expandToNonRecursiveWildcardTargets(
      Project project,
      BlazeContext context,
      WorkspacePathResolver pathResolver,
      List<WildcardTargetPattern> wildcardPatterns) {

    Set<WildcardTargetPattern> excludes =
        wildcardPatterns
            .stream()
            .filter(WildcardTargetPattern::isExcluded)
            .collect(Collectors.toSet());

    Predicate<WorkspacePath> excludePredicate =
        workspacePath ->
            excludes.stream().anyMatch(pattern -> pattern.coversPackage(workspacePath));

    List<WildcardTargetPattern> includes = new ArrayList<>(wildcardPatterns);
    includes.removeAll(excludes);

    Set<File> toPrefetch =
        PackageLister.getDirectoriesToPrefetch(pathResolver, includes, excludePredicate);

    ListenableFuture<?> prefetchFuture =
        PrefetchService.getInstance().prefetchFiles(project, toPrefetch);
    if (!FutureUtil.waitForFuture(context, prefetchFuture)
        .withProgressMessage("Prefetching wildcard target pattern directories...")
        .timed("PrefetchingWildcardTargetDirectories")
        .onError("Prefetching wildcard target directories failed")
        .run()
        .success()) {
      return null;
    }

    return PackageLister.expandPackageTargets(
        Blaze.getBuildSystemProvider(project), context, pathResolver, includes);
  }

  /** Runs a sharded blaze query to expand wildcard targets to individual blaze targets */
  static ExpandedTargetsResult expandToSingleTargets(
      Project project,
      BlazeContext context,
      WorkspaceRoot workspaceRoot,
      ProjectViewSet projectViewSet,
      List<TargetExpression> allTargets) {
    ShardedTargetList shards =
        BlazeBuildTargetSharder.shardTargets(
            allTargets, BlazeBuildTargetSharder.PACKAGE_SHARD_SIZE);
    ImmutableSet<String> handledRuleTypes = handledRuleTypes(projectViewSet);
    ExpandedTargetsResult output = null;
    for (int i = 0; i < shards.shardedTargets.size(); i++) {
      List<TargetExpression> shard = shards.shardedTargets.get(i);
      context.output(
          new StatusOutput(
              String.format(
                  "Expanding wildcard target patterns, shard %s of %s",
                  i + 1, shards.shardedTargets.size())));
      ExpandedTargetsResult result =
          queryIndividualTargets(project, context, workspaceRoot, handledRuleTypes, shard);
      output = output == null ? result : ExpandedTargetsResult.merge(output, result);
      if (output.buildResult == BuildResult.FATAL_ERROR) {
        return output;
      }
    }
    return output;
  }

  /** Runs a blaze query to expand the input target patterns to individual blaze targets. */
  private static ExpandedTargetsResult queryIndividualTargets(
      Project project,
      BlazeContext context,
      WorkspaceRoot workspaceRoot,
      ImmutableSet<String> handledRuleTypes,
      List<TargetExpression> targetPatterns) {
    BlazeCommand.Builder builder =
        BlazeCommand.builder(getBinaryPath(project), BlazeCommandName.QUERY)
            .addBlazeFlags(BlazeFlags.KEEP_GOING)
            .addBlazeFlags("--output=label_kind")
            .addBlazeFlags(queryString(targetPatterns));

    ImmutableList.Builder<TargetExpression> output = ImmutableList.builder();

    // it's fine to include wildcards here; they're guaranteed not to clash with actual labels.
    Set<String> explicitTargets =
        targetPatterns.stream().map(TargetExpression::toString).collect(Collectors.toSet());
    Predicate<RuleTypeAndLabel> filter =
        !filterByRuleType.getValue()
            ? t -> true
            : t -> handledRuleTypes.contains(t.ruleType) || explicitTargets.contains(t.label);

    int retVal =
        ExternalTask.builder(workspaceRoot)
            .addBlazeCommand(builder.build())
            .context(context)
            .stdout(LineProcessingOutputStream.of(new QueryResultLineProcessor(output, filter)))
            .stderr(LineProcessingOutputStream.of(new PrintOutputLineProcessor(context)))
            .build()
            .run();

    BuildResult buildResult = BuildResult.fromExitCode(retVal);
    return new ExpandedTargetsResult(output.build(), buildResult);
  }

  private static ImmutableSet<String> handledRuleTypes(ProjectViewSet projectViewSet) {
    return ImmutableSet.copyOf(
        LanguageSupport.createWorkspaceLanguageSettings(projectViewSet)
            .getAvailableTargetKinds()
            .stream()
            .map(Kind::toString)
            .collect(Collectors.toList()));
  }

  private static String queryString(List<TargetExpression> targets) {
    StringBuilder builder = new StringBuilder();
    for (TargetExpression target : targets) {
      boolean excluded = target.isExcluded();
      if (builder.length() == 0) {
        if (excluded) {
          continue; // an excluded target at the start of the list has no effect
        }
        builder.append(target);
      } else {
        if (excluded) {
          builder.append(" - ");
          // trim leading '-'
          String excludedTarget = target.toString();
          builder.append(excludedTarget, 1, excludedTarget.length());
        } else {
          builder.append(" + ");
          builder.append(target);
        }
      }
    }
    return builder.toString();
  }

  private static String getBinaryPath(Project project) {
    BuildSystemProvider buildSystemProvider = Blaze.getBuildSystemProvider(project);
    return buildSystemProvider.getSyncBinaryPath();
  }
}