// Copyright (c) 2020, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.features;

import com.android.tools.r8.FeatureSplit;
import com.android.tools.r8.ProgramResource;
import com.android.tools.r8.ProgramResourceProvider;
import com.android.tools.r8.ResourceException;
import com.android.tools.r8.experimental.startup.StartupConfiguration;
import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexProgramClass;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.graph.GraphLens;
import com.android.tools.r8.graph.ProgramDefinition;
import com.android.tools.r8.graph.ProgramMethod;
import com.android.tools.r8.graph.PrunedItems;
import com.android.tools.r8.shaking.AppInfoWithLiveness;
import com.android.tools.r8.synthesis.SyntheticItems;
import com.android.tools.r8.utils.InternalOptions;
import com.android.tools.r8.utils.Reporter;
import com.google.common.collect.Sets;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.Set;

public class ClassToFeatureSplitMap {

  private final FeatureSplit baseStartup;
  private final Map<DexType, FeatureSplit> classToFeatureSplitMap;
  private final Map<FeatureSplit, String> representativeStringsForFeatureSplit;

  private ClassToFeatureSplitMap(
      FeatureSplit baseStartup,
      Map<DexType, FeatureSplit> classToFeatureSplitMap,
      Map<FeatureSplit, String> representativeStringsForFeatureSplit) {
    this.baseStartup = baseStartup;
    this.classToFeatureSplitMap = classToFeatureSplitMap;
    this.representativeStringsForFeatureSplit = representativeStringsForFeatureSplit;
  }

  public static ClassToFeatureSplitMap createEmptyClassToFeatureSplitMap() {
    return new ClassToFeatureSplitMap(FeatureSplit.BASE, new IdentityHashMap<>(), null);
  }

  public static ClassToFeatureSplitMap createInitialClassToFeatureSplitMap(
      InternalOptions options) {
    return createInitialClassToFeatureSplitMap(
        options.dexItemFactory(),
        options.featureSplitConfiguration,
        options.getStartupOptions().getStartupConfiguration(),
        options.reporter);
  }

  public static ClassToFeatureSplitMap createInitialClassToFeatureSplitMap(
      DexItemFactory dexItemFactory,
      FeatureSplitConfiguration featureSplitConfiguration,
      StartupConfiguration startupConfiguration,
      Reporter reporter) {
    if (featureSplitConfiguration == null && startupConfiguration == null) {
      return createEmptyClassToFeatureSplitMap();
    }

    Map<DexType, FeatureSplit> classToFeatureSplitMap = new IdentityHashMap<>();
    Map<FeatureSplit, String> representativeStringsForFeatureSplit = new IdentityHashMap<>();
    if (featureSplitConfiguration != null) {
      for (FeatureSplit featureSplit : featureSplitConfiguration.getFeatureSplits()) {
        String representativeType = null;
        for (ProgramResourceProvider programResourceProvider :
            featureSplit.getProgramResourceProviders()) {
          try {
            for (ProgramResource programResource : programResourceProvider.getProgramResources()) {
              for (String classDescriptor : programResource.getClassDescriptors()) {
                DexType type = dexItemFactory.createType(classDescriptor);
                classToFeatureSplitMap.put(type, featureSplit);
                if (representativeType == null
                    || classDescriptor.compareTo(representativeType) > 0) {
                  representativeType = classDescriptor;
                }
              }
            }
          } catch (ResourceException e) {
            throw reporter.fatalError(e.getMessage());
          }
        }
        if (representativeType != null) {
          representativeStringsForFeatureSplit.put(featureSplit, representativeType);
        }
      }
    }

    FeatureSplit baseStartup;
    if (startupConfiguration != null && startupConfiguration.hasStartupClasses()) {
      DexType representativeType = null;
      for (DexType startupClass : startupConfiguration.getStartupClasses()) {
        if (classToFeatureSplitMap.containsKey(startupClass)) {
          continue;
        }
        classToFeatureSplitMap.put(startupClass, FeatureSplit.BASE_STARTUP);
        if (representativeType == null
            || startupClass.getDescriptor().compareTo(representativeType.getDescriptor()) > 0) {
          representativeType = startupClass;
        }
      }
      baseStartup = FeatureSplit.BASE_STARTUP;
      representativeStringsForFeatureSplit.put(
          baseStartup, representativeType.toDescriptorString());
    } else {
      baseStartup = FeatureSplit.BASE;
    }
    return new ClassToFeatureSplitMap(
        baseStartup, classToFeatureSplitMap, representativeStringsForFeatureSplit);
  }

  public int compareFeatureSplits(FeatureSplit featureSplitA, FeatureSplit featureSplitB) {
    assert featureSplitA != null;
    assert featureSplitB != null;
    if (featureSplitA == featureSplitB) {
      return 0;
    }
    // Base bigger than any other feature
    if (featureSplitA.isBase()) {
      return 1;
    }
    if (featureSplitB.isBase()) {
      return -1;
    }
    return representativeStringsForFeatureSplit
        .get(featureSplitA)
        .compareTo(representativeStringsForFeatureSplit.get(featureSplitB));
  }

  /**
   * Returns the base startup if there are any startup classes given on input. Otherwise returns
   * base.
   */
  public FeatureSplit getBaseStartup() {
    return baseStartup;
  }

  public Map<FeatureSplit, Set<DexProgramClass>> getFeatureSplitClasses(
      Set<DexProgramClass> classes, SyntheticItems syntheticItems) {
    Map<FeatureSplit, Set<DexProgramClass>> result = new IdentityHashMap<>();
    for (DexProgramClass clazz : classes) {
      FeatureSplit featureSplit = getFeatureSplit(clazz, syntheticItems);
      if (featureSplit != null && !featureSplit.isBase()) {
        result.computeIfAbsent(featureSplit, ignore -> Sets.newIdentityHashSet()).add(clazz);
      }
    }
    return result;
  }

  public FeatureSplit getFeatureSplit(ProgramDefinition clazz, SyntheticItems syntheticItems) {
    return getFeatureSplit(clazz.getContextType(), syntheticItems);
  }

  public FeatureSplit getFeatureSplit(DexType type, SyntheticItems syntheticItems) {
    FeatureSplit feature = classToFeatureSplitMap.get(type);
    if (feature != null) {
      return feature;
    }
    feature = syntheticItems.getContextualFeatureSplit(type, this);
    if (feature != null) {
      return feature;
    }
    return FeatureSplit.BASE;
  }

  // Note, this predicate may be misleading as the map does not include synthetics.
  // In practice it should not be an issue as there should not be a way to have a feature shrink
  // to only contain synthetic content. At a minimum the entry points of the feature must remain.
  public boolean isEmpty() {
    return classToFeatureSplitMap.isEmpty();
  }

  public boolean isInBase(DexProgramClass clazz, SyntheticItems syntheticItems) {
    return getFeatureSplit(clazz, syntheticItems).isBase();
  }

  public boolean isInBaseOrSameFeatureAs(
      DexProgramClass clazz, ProgramDefinition context, SyntheticItems syntheticItems) {
    return isInBaseOrSameFeatureAs(clazz.getContextType(), context, syntheticItems);
  }

  public boolean isInBaseOrSameFeatureAs(
      DexType clazz, ProgramDefinition context, SyntheticItems syntheticItems) {
    FeatureSplit split = getFeatureSplit(clazz, syntheticItems);
    return split.isBase() || split == getFeatureSplit(context, syntheticItems);
  }

  public boolean isInFeature(DexProgramClass clazz, SyntheticItems syntheticItems) {
    return !isInBase(clazz, syntheticItems);
  }

  public boolean isInSameFeatureOrBothInSameBase(
      ProgramMethod a, ProgramMethod b, SyntheticItems syntheticItems) {
    return isInSameFeatureOrBothInSameBase(a.getHolder(), b.getHolder(), syntheticItems);
  }

  public boolean isInSameFeatureOrBothInSameBase(
      DexProgramClass a, DexProgramClass b, SyntheticItems syntheticItems) {
    return getFeatureSplit(a, syntheticItems) == getFeatureSplit(b, syntheticItems);
  }

  public ClassToFeatureSplitMap rewrittenWithLens(GraphLens lens) {
    Map<DexType, FeatureSplit> rewrittenClassToFeatureSplitMap = new IdentityHashMap<>();
    classToFeatureSplitMap.forEach(
        (type, featureSplit) -> {
          DexType rewrittenType = lens.lookupType(type);
          if (rewrittenType.isIntType()) {
            // The type was removed by enum unboxing.
            return;
          }
          FeatureSplit existing = rewrittenClassToFeatureSplitMap.put(rewrittenType, featureSplit);
          // If we map two classes to the same class then they must be from the same feature split.
          assert existing == null || existing == featureSplit;
        });
    return new ClassToFeatureSplitMap(
        baseStartup, rewrittenClassToFeatureSplitMap, representativeStringsForFeatureSplit);
  }

  public ClassToFeatureSplitMap withoutPrunedItems(PrunedItems prunedItems) {
    Map<DexType, FeatureSplit> rewrittenClassToFeatureSplitMap = new IdentityHashMap<>();
    classToFeatureSplitMap.forEach(
        (type, featureSplit) -> {
          if (!prunedItems.getRemovedClasses().contains(type)) {
            rewrittenClassToFeatureSplitMap.put(type, featureSplit);
          }
        });
    return new ClassToFeatureSplitMap(
        baseStartup, rewrittenClassToFeatureSplitMap, representativeStringsForFeatureSplit);
  }

  // Static helpers to avoid verbose predicates.

  private static ClassToFeatureSplitMap getMap(AppView<AppInfoWithLiveness> appView) {
    return appView.appInfo().getClassToFeatureSplitMap();
  }

  public static boolean isInFeature(DexProgramClass clazz, AppView<AppInfoWithLiveness> appView) {
    return getMap(appView).isInFeature(clazz, appView.getSyntheticItems());
  }
}