// Copyright (c) 2019, 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.naming.signature;

import static com.android.tools.r8.utils.DescriptorUtils.getClassBinaryNameFromDescriptor;
import static com.android.tools.r8.utils.DescriptorUtils.getDescriptorFromClassBinaryName;

import com.android.tools.r8.graph.AppView;
import com.android.tools.r8.graph.DexAnnotation;
import com.android.tools.r8.graph.DexAnnotationSet;
import com.android.tools.r8.graph.DexProgramClass;
import com.android.tools.r8.graph.DexString;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.utils.DescriptorUtils;
import com.android.tools.r8.utils.InternalOptions;
import com.android.tools.r8.utils.Reporter;
import com.android.tools.r8.utils.StringDiagnostic;
import com.android.tools.r8.utils.ThreadUtils;
import com.google.common.collect.Maps;
import java.lang.reflect.GenericSignatureFormatError;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.Supplier;

// TODO(b/129925954): Reimplement this by using the internal encoding and transformation logic.
public class GenericSignatureRewriter {

  private final AppView<?> appView;
  private final Map<DexType, DexString> renaming;
  private final InternalOptions options;
  private final Reporter reporter;

  public GenericSignatureRewriter(AppView<?> appView) {
    this(appView, Maps.newIdentityHashMap());
  }

  public GenericSignatureRewriter(AppView<?> appView, Map<DexType, DexString> renaming) {
    this.appView = appView;
    this.renaming = renaming;
    this.options = appView.options();
    this.reporter = options.reporter;
  }

  public void run(Iterable<? extends DexProgramClass> classes, ExecutorService executorService)
      throws ExecutionException {
    // Classes may not be the same as appInfo().classes() if applymapping is used on classpath
    // arguments. If that is the case, the ProguardMapMinifier will pass in all classes that is
    // either ProgramClass or has a mapping. This is then transitively called inside the
    // ClassNameMinifier.
    ThreadUtils.processItems(
        classes,
        clazz -> {
          GenericSignatureCollector genericSignatureCollector =
              new GenericSignatureCollector(clazz);
          GenericSignatureParser<DexType> genericSignatureParser =
              new GenericSignatureParser<>(genericSignatureCollector);
          clazz.setAnnotations(
              rewriteGenericSignatures(
                  clazz.annotations(),
                  genericSignatureParser::parseClassSignature,
                  genericSignatureCollector::getRenamedSignature,
                  (signature, e) ->
                      options.warningInvalidSignature(clazz, clazz.getOrigin(), signature, e)));
          clazz.forEachField(
              field ->
                  field.setAnnotations(
                      rewriteGenericSignatures(
                          field.annotations(),
                          genericSignatureParser::parseFieldSignature,
                          genericSignatureCollector::getRenamedSignature,
                          (signature, e) ->
                              options.warningInvalidSignature(
                                  field, clazz.getOrigin(), signature, e))));
          clazz.forEachMethod(
              method ->
                  method.setAnnotations(
                      rewriteGenericSignatures(
                          method.annotations(),
                          genericSignatureParser::parseMethodSignature,
                          genericSignatureCollector::getRenamedSignature,
                          (signature, e) ->
                              options.warningInvalidSignature(
                                  method, clazz.getOrigin(), signature, e))));
        },
        executorService);
  }

  private DexAnnotationSet rewriteGenericSignatures(
      DexAnnotationSet annotations,
      Consumer<String> parser,
      Supplier<String> collector,
      BiConsumer<String, GenericSignatureFormatError> parseError) {
    // There can be no more than one signature annotation in an annotation set.
    final int VALID = -1;
    int invalid = VALID;
    DexAnnotation[] rewrittenAnnotations = null;
    for (int i = 0; i < annotations.annotations.length && invalid == VALID; i++) {
      DexAnnotation annotation = annotations.annotations[i];
      if (DexAnnotation.isSignatureAnnotation(annotation, appView.dexItemFactory())) {
        if (rewrittenAnnotations == null) {
          rewrittenAnnotations = new DexAnnotation[annotations.annotations.length];
          System.arraycopy(annotations.annotations, 0, rewrittenAnnotations, 0, i);
        }
        String signature = DexAnnotation.getSignature(annotation);
        try {
          parser.accept(signature);
          String renamedSignature = collector.get();
          assert verifyConsistentRenaming(parser, collector, renamedSignature);
          DexAnnotation signatureAnnotation =
              DexAnnotation.createSignatureAnnotation(renamedSignature, appView.dexItemFactory());
          rewrittenAnnotations[i] = signatureAnnotation;
        } catch (GenericSignatureFormatError e) {
          parseError.accept(signature, e);
          invalid = i;
        }
      } else if (rewrittenAnnotations != null) {
        rewrittenAnnotations[i] = annotation;
      }
    }

    // Return the rewritten signatures if it was valid and could be rewritten.
    if (invalid == VALID) {
      return rewrittenAnnotations != null
          ? new DexAnnotationSet(rewrittenAnnotations)
          : annotations;
    }
    // Remove invalid signature if found.
    DexAnnotation[] prunedAnnotations =
        new DexAnnotation[annotations.annotations.length - 1];
    int dest = 0;
    for (int i = 0; i < annotations.annotations.length; i++) {
      if (i != invalid) {
        prunedAnnotations[dest++] = annotations.annotations[i];
      }
    }
    assert dest == prunedAnnotations.length;
    return new DexAnnotationSet(prunedAnnotations);
  }

  /**
   * Calling this method will clobber the parsed signature in the collector - ideally with the same
   * string. Only use this after the original result has been collected.
   */
  private boolean verifyConsistentRenaming(
      Consumer<String> parser, Supplier<String> collector, String renamedSignature) {
    if (!options.testing.assertConsistentRenamingOfSignature) {
      return true;
    }
    parser.accept(renamedSignature);
    String reRenamedSignature = collector.get();
    assert renamedSignature.equals(reRenamedSignature);
    return true;
  }

  private class GenericSignatureCollector implements GenericSignatureAction<DexType> {
    private StringBuilder renamedSignature;
    private final DexProgramClass currentClassContext;
    private DexType lastWrittenType = null;

    GenericSignatureCollector(DexProgramClass clazz) {
      this.currentClassContext = clazz;
    }

    String getRenamedSignature() {
      return renamedSignature.toString();
    }

    @Override
    public void parsedSymbol(char symbol) {
      if (symbol == ';' && lastWrittenType == null) {
        // The type was never written (maybe because it was merged with it's subtype).
        return;
      }
      // If the super-class or interface has been merged, we will stop writing out type
      // arguments, resulting in a signature on the form '<>' if we do not remove it.
      if (symbol == '>' && removeWrittenCharacter(c -> c == '<')) {
        return;
      }
      renamedSignature.append(symbol);
    }

    @Override
    public void parsedIdentifier(String identifier) {
      renamedSignature.append(identifier);
    }

    @Override
    public DexType parsedTypeName(String name, ParserPosition parserPosition) {
      if (parserPosition == ParserPosition.ENCLOSING_INNER_OR_TYPE_ANNOTATION
          && lastWrittenType == null) {
        // We are writing type-arguments for a merged class.
        removeWrittenClassCharacter();
        return null;
      }
      String originalDescriptor = getDescriptorFromClassBinaryName(name);
      DexType type =
          appView.graphLense().lookupType(appView.dexItemFactory().createType(originalDescriptor));
      if (appView.appInfo().hasLiveness() && appView.withLiveness().appInfo().wasPruned(type)) {
        type = appView.dexItemFactory().objectType;
      }
      DexString renamedDescriptor = renaming.getOrDefault(type, type.descriptor);
      if (parserPosition == ParserPosition.CLASS_SUPER_OR_INTERFACE_ANNOTATION
          && currentClassContext != null) {
        // We may have merged the type down to the current class type.
        DexString classDescriptor = currentClassContext.type.descriptor;
        if (!originalDescriptor.equals(classDescriptor.toString())
            && renamedDescriptor.equals(classDescriptor)) {
          lastWrittenType = null;
          removeWrittenClassCharacter();
          return type;
        }
      }
      renamedSignature.append(getClassBinaryNameFromDescriptor(renamedDescriptor.toString()));
      lastWrittenType = type;
      return type;
    }

    private boolean removeWrittenCharacter(Predicate<Character> removeIf) {
      int index = renamedSignature.length() - 1;
      if (index < 0 || !removeIf.test(renamedSignature.charAt(index))) {
        return false;
      }
      renamedSignature.deleteCharAt(index);
      return true;
    }

    private void removeWrittenClassCharacter() {
      removeWrittenCharacter(c -> c == 'L');
    }

    @Override
    public DexType parsedInnerTypeName(DexType enclosingType, String name) {
      if (enclosingType == null) {
        // We are writing inner type names
        removeWrittenClassCharacter();
        return null;
      }
      assert enclosingType.isClassType();
      String enclosingDescriptor = enclosingType.toDescriptorString();
      DexType type =
          appView
              .dexItemFactory()
              .createType(
                  getDescriptorFromClassBinaryName(
                      getClassBinaryNameFromDescriptor(enclosingDescriptor)
                          + DescriptorUtils.INNER_CLASS_SEPARATOR
                          + name));
      String enclosingRenamedBinaryName =
          getClassBinaryNameFromDescriptor(
              renaming.getOrDefault(enclosingType, enclosingType.descriptor).toString());
      type = appView.graphLense().lookupType(type);
      DexString renamedDescriptor = renaming.get(type);
      if (renamedDescriptor != null) {
        // TODO(b/147504070): If this is a merged class equal to the class context, do not add.
        // Pick the renamed inner class from the fully renamed binary name.
        String fullRenamedBinaryName =
            getClassBinaryNameFromDescriptor(renamedDescriptor.toString());
        int innerClassPos = enclosingRenamedBinaryName.length() + 1;
        if (innerClassPos < fullRenamedBinaryName.length()) {
          renamedSignature.append(fullRenamedBinaryName.substring(innerClassPos));
        } else if (appView.options().keepInnerClassStructure()) {
          reporter.warning(
              new StringDiagnostic(
                  "Should have retained InnerClasses attribute of " + type + ".",
                  appView.appInfo().originFor(type)));
          renamedSignature.append(name);
        }
      } else {
        // Did not find the class - keep the inner class name as is.
        // TODO(b/110085899): Warn about missing classes in signatures?
        renamedSignature.append(name);
      }
      return type;
    }

    @Override
    public void start() {
      renamedSignature = new StringBuilder();
    }

    @Override
    public void stop() {
      // nothing to do
    }
  }
}