/*
 * 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.android.sync.importer;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ComparisonChain;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;
import com.google.idea.blaze.android.sync.importer.aggregators.TransitiveResourceMap;
import com.google.idea.blaze.android.sync.model.AndroidResourceModule;
import com.google.idea.blaze.android.sync.model.BlazeAndroidImportResult;
import com.google.idea.blaze.android.sync.model.BlazeResourceLibrary;
import com.google.idea.blaze.base.ideinfo.AndroidRuleIdeInfo;
import com.google.idea.blaze.base.ideinfo.ArtifactLocation;
import com.google.idea.blaze.base.ideinfo.RuleIdeInfo;
import com.google.idea.blaze.base.ideinfo.RuleKey;
import com.google.idea.blaze.base.ideinfo.RuleMap;
import com.google.idea.blaze.base.model.primitives.LanguageClass;
import com.google.idea.blaze.base.model.primitives.WorkspaceRoot;
import com.google.idea.blaze.base.projectview.ProjectViewSet;
import com.google.idea.blaze.base.scope.BlazeContext;
import com.google.idea.blaze.base.scope.output.IssueOutput;
import com.google.idea.blaze.base.scope.output.PerformanceWarning;
import com.google.idea.blaze.base.sync.projectview.ProjectViewRuleImportFilter;
import com.intellij.openapi.project.Project;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/** Builds a BlazeWorkspace. */
public final class BlazeAndroidWorkspaceImporter {

  private final BlazeContext context;
  private final RuleMap ruleMap;
  private final ProjectViewRuleImportFilter importFilter;

  public BlazeAndroidWorkspaceImporter(
      Project project,
      BlazeContext context,
      WorkspaceRoot workspaceRoot,
      ProjectViewSet projectViewSet,
      RuleMap ruleMap) {
    this.context = context;
    this.ruleMap = ruleMap;
    this.importFilter = new ProjectViewRuleImportFilter(project, workspaceRoot, projectViewSet);
  }

  public BlazeAndroidImportResult importWorkspace() {
    List<RuleIdeInfo> rules =
        ruleMap
            .rules()
            .stream()
            .filter(rule -> rule.kind.getLanguageClass() == LanguageClass.ANDROID)
            .filter(rule -> rule.androidRuleIdeInfo != null)
            .filter(importFilter::isSourceRule)
            .filter(rule -> !importFilter.excludeTarget(rule))
            .collect(Collectors.toList());

    TransitiveResourceMap transitiveResourceMap = new TransitiveResourceMap(ruleMap);

    WorkspaceBuilder workspaceBuilder = new WorkspaceBuilder();

    for (RuleIdeInfo rule : rules) {
      addSourceRule(workspaceBuilder, transitiveResourceMap, rule);
    }

    warnAboutGeneratedResources(workspaceBuilder.generatedResourceLocations);

    ImmutableList<AndroidResourceModule> androidResourceModules =
        buildAndroidResourceModules(workspaceBuilder);
    BlazeResourceLibrary resourceLibrary = createResourceLibrary(androidResourceModules);

    return new BlazeAndroidImportResult(androidResourceModules, resourceLibrary);
  }

  private void addSourceRule(
      WorkspaceBuilder workspaceBuilder,
      TransitiveResourceMap transitiveResourceMap,
      RuleIdeInfo rule) {
    AndroidRuleIdeInfo androidRuleIdeInfo = rule.androidRuleIdeInfo;
    assert androidRuleIdeInfo != null;
    if (shouldGenerateResources(androidRuleIdeInfo)
        && shouldGenerateResourceModule(androidRuleIdeInfo)) {
      AndroidResourceModule.Builder builder = new AndroidResourceModule.Builder(rule.key);
      workspaceBuilder.androidResourceModules.add(builder);

      for (ArtifactLocation artifactLocation : androidRuleIdeInfo.resources) {
        if (artifactLocation.isSource()) {
          builder.addResource(artifactLocation);
        } else {
          workspaceBuilder.generatedResourceLocations.add(artifactLocation);
        }
      }

      TransitiveResourceMap.TransitiveResourceInfo transitiveResourceInfo =
          transitiveResourceMap.get(rule.key);
      for (ArtifactLocation artifactLocation : transitiveResourceInfo.transitiveResources) {
        if (artifactLocation.isSource()) {
          builder.addTransitiveResource(artifactLocation);
        } else {
          workspaceBuilder.generatedResourceLocations.add(artifactLocation);
        }
      }
      for (RuleKey resourceDependency : transitiveResourceInfo.transitiveResourceRules) {
        if (!resourceDependency.equals(rule.key)) {
          builder.addTransitiveResourceDependency(resourceDependency);
        }
      }
    }
  }

  public static boolean shouldGenerateResources(AndroidRuleIdeInfo androidRuleIdeInfo) {
    // Generate an android resource module if this rule defines resources
    // We don't want to generate one if this depends on a legacy resource rule through :resources
    // In this case, the resource information is redundantly forwarded to this class for
    // backwards compatibility, but the android_resource rule itself is already generating
    // the android resource module
    return androidRuleIdeInfo.generateResourceClass && androidRuleIdeInfo.legacyResources == null;
  }

  public static boolean shouldGenerateResourceModule(AndroidRuleIdeInfo androidRuleIdeInfo) {
    return androidRuleIdeInfo.resources.stream().anyMatch(ArtifactLocation::isSource);
  }

  private void warnAboutGeneratedResources(Set<ArtifactLocation> generatedResourceLocations) {
    for (ArtifactLocation artifactLocation : generatedResourceLocations) {
      IssueOutput.warn(
              String.format(
                  "Dropping generated resource directory '%s', "
                      + "R classes will not contain resources from this directory",
                  artifactLocation.getExecutionRootRelativePath()))
          .submit(context);
    }
  }

  @Nullable
  private BlazeResourceLibrary createResourceLibrary(
      Collection<AndroidResourceModule> androidResourceModules) {
    Set<ArtifactLocation> result = Sets.newHashSet();
    for (AndroidResourceModule androidResourceModule : androidResourceModules) {
      result.addAll(androidResourceModule.transitiveResources);
    }
    for (AndroidResourceModule androidResourceModule : androidResourceModules) {
      result.removeAll(androidResourceModule.resources);
    }
    if (!result.isEmpty()) {
      return new BlazeResourceLibrary(
          ImmutableList.copyOf(result.stream().sorted().collect(Collectors.toList())));
    }
    return null;
  }

  @NotNull
  private ImmutableList<AndroidResourceModule> buildAndroidResourceModules(
      WorkspaceBuilder workspaceBuilder) {
    // Filter empty resource modules
    Stream<AndroidResourceModule> androidResourceModuleStream =
        workspaceBuilder
            .androidResourceModules
            .stream()
            .map(AndroidResourceModule.Builder::build)
            .filter(androidResourceModule -> !androidResourceModule.isEmpty())
            .filter(androidResourceModule -> !androidResourceModule.resources.isEmpty());
    List<AndroidResourceModule> androidResourceModules =
        androidResourceModuleStream.collect(Collectors.toList());

    // Detect, filter, and warn about multiple R classes
    Multimap<String, AndroidResourceModule> javaPackageToResourceModule =
        ArrayListMultimap.create();
    for (AndroidResourceModule androidResourceModule : androidResourceModules) {
      RuleIdeInfo rule = ruleMap.get(androidResourceModule.ruleKey);
      AndroidRuleIdeInfo androidRuleIdeInfo = rule.androidRuleIdeInfo;
      assert androidRuleIdeInfo != null;
      javaPackageToResourceModule.put(
          androidRuleIdeInfo.resourceJavaPackage, androidResourceModule);
    }

    List<AndroidResourceModule> result = Lists.newArrayList();
    for (String resourceJavaPackage : javaPackageToResourceModule.keySet()) {
      Collection<AndroidResourceModule> androidResourceModulesWithJavaPackage =
          javaPackageToResourceModule.get(resourceJavaPackage);

      if (androidResourceModulesWithJavaPackage.size() == 1) {
        result.addAll(androidResourceModulesWithJavaPackage);
      } else {
        StringBuilder messageBuilder = new StringBuilder();
        messageBuilder
            .append("Multiple R classes generated with the same java package ")
            .append(resourceJavaPackage)
            .append(".R: ");
        messageBuilder.append('\n');
        for (AndroidResourceModule androidResourceModule : androidResourceModulesWithJavaPackage) {
          messageBuilder.append("  ").append(androidResourceModule.ruleKey).append('\n');
        }
        String message = messageBuilder.toString();
        context.output(new PerformanceWarning(message));
        IssueOutput.warn(message).submit(context);

        result.add(selectBestAndroidResourceModule(androidResourceModulesWithJavaPackage));
      }
    }

    Collections.sort(result, (lhs, rhs) -> RuleKey.COMPARATOR.compare(lhs.ruleKey, rhs.ruleKey));
    return ImmutableList.copyOf(result);
  }

  private AndroidResourceModule selectBestAndroidResourceModule(
      Collection<AndroidResourceModule> androidResourceModulesWithJavaPackage) {
    return androidResourceModulesWithJavaPackage
        .stream()
        .max(
            (lhs, rhs) ->
                ComparisonChain.start()
                    .compare(lhs.resources.size(), rhs.resources.size()) // Most resources wins
                    .compare(
                        lhs.transitiveResources.size(),
                        rhs.transitiveResources.size()) // Most transitive resources wins
                    .compare(
                        rhs.ruleKey.toString().length(),
                        lhs.ruleKey
                            .toString()
                            .length()) // Shortest label wins - note lhs, rhs are flipped
                    .result())
        .get();
  }

  static class WorkspaceBuilder {
    List<AndroidResourceModule.Builder> androidResourceModules = Lists.newArrayList();
    Set<ArtifactLocation> generatedResourceLocations = Sets.newHashSet();
  }
}