// 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.synthesis;

import com.android.tools.r8.cf.CfVersion;
import com.android.tools.r8.graph.Code;
import com.android.tools.r8.graph.DexAnnotationSet;
import com.android.tools.r8.graph.DexEncodedMethod;
import com.android.tools.r8.graph.DexItemFactory;
import com.android.tools.r8.graph.DexMethod;
import com.android.tools.r8.graph.DexProto;
import com.android.tools.r8.graph.DexString;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.graph.GenericSignature.MethodTypeSignature;
import com.android.tools.r8.graph.MethodAccessFlags;
import com.android.tools.r8.graph.ParameterAnnotationsList;
import com.android.tools.r8.synthesis.SyntheticNaming.SyntheticKind;
import java.util.function.Consumer;

public class SyntheticMethodBuilder {

  public interface SyntheticCodeGenerator {
    Code generate(DexMethod method);
  }

  private final DexItemFactory factory;
  private final DexType holderType;
  private final SyntheticKind syntheticKind;
  private DexString name = null;
  private DexProto proto = null;
  private CfVersion classFileVersion;
  private SyntheticCodeGenerator codeGenerator = null;
  private MethodAccessFlags accessFlags = null;
  private MethodTypeSignature genericSignature = MethodTypeSignature.noSignature();
  private DexAnnotationSet annotations = DexAnnotationSet.empty();
  private ParameterAnnotationsList parameterAnnotationsList = ParameterAnnotationsList.empty();
  private Consumer<DexEncodedMethod> onBuildConsumer = null;

  SyntheticMethodBuilder(SyntheticClassBuilder<?, ?> parent) {
    this.factory = parent.getFactory();
    this.holderType = parent.getType();
    this.syntheticKind = parent.getSyntheticKind();
  }

  SyntheticMethodBuilder(DexItemFactory factory, DexType holderType, SyntheticKind syntheticKind) {
    this.factory = factory;
    this.holderType = holderType;
    this.syntheticKind = syntheticKind;
  }

  public SyntheticMethodBuilder setName(String name) {
    return setName(factory.createString(name));
  }

  public SyntheticMethodBuilder setName(DexString name) {
    assert name != null;
    assert this.name == null;
    this.name = name;
    return this;
  }

  public SyntheticMethodBuilder setProto(DexProto proto) {
    this.proto = proto;
    return this;
  }

  public SyntheticMethodBuilder setClassFileVersion(CfVersion classFileVersion) {
    this.classFileVersion = classFileVersion;
    return this;
  }

  public SyntheticMethodBuilder setCode(SyntheticCodeGenerator codeGenerator) {
    this.codeGenerator = codeGenerator;
    return this;
  }

  public SyntheticMethodBuilder setAccessFlags(MethodAccessFlags accessFlags) {
    this.accessFlags = accessFlags;
    return this;
  }

  public SyntheticMethodBuilder setGenericSignature(MethodTypeSignature genericSignature) {
    this.genericSignature = genericSignature;
    return this;
  }

  public SyntheticMethodBuilder setAnnotations(DexAnnotationSet annotations) {
    this.annotations = annotations;
    return this;
  }

  public SyntheticMethodBuilder setParameterAnnotationsList(
      ParameterAnnotationsList parameterAnnotationsList) {
    this.parameterAnnotationsList = parameterAnnotationsList;
    return this;
  }

  public SyntheticMethodBuilder setOnBuildConsumer(Consumer<DexEncodedMethod> onBuildConsumer) {
    this.onBuildConsumer = onBuildConsumer;
    return this;
  }

  DexEncodedMethod build() {
    assert name != null;
    boolean isCompilerSynthesized = true;
    DexMethod methodSignature = getMethodSignature();
    MethodAccessFlags accessFlags = getAccessFlags();
    DexEncodedMethod method =
        new DexEncodedMethod(
            methodSignature,
            accessFlags,
            genericSignature,
            annotations,
            parameterAnnotationsList,
            accessFlags.isAbstract() ? null : getCodeObject(methodSignature),
            isCompilerSynthesized,
            classFileVersion);
    assert isValidSyntheticMethod(method, syntheticKind);
    if (onBuildConsumer != null) {
      onBuildConsumer.accept(method);
    }
    return method;
  }

  /**
   * Predicate for what is a "supported" synthetic method.
   *
   * <p>This method is used when identifying synthetic methods in the program input and should be as
   * narrow as possible.
   *
   * <p>Methods in fixed suffix synthetics are identified differently (through the class name) and
   * can have different properties.
   */
  public static boolean isValidSyntheticMethod(
      DexEncodedMethod method, SyntheticKind syntheticKind) {
    return isValidSingleSyntheticMethod(method) || syntheticKind.isFixedSuffixSynthetic;
  }

  public static boolean isValidSingleSyntheticMethod(DexEncodedMethod method) {
    return method.isStatic()
        && method.isNonAbstractNonNativeMethod()
        && method.isPublic()
        && method.annotations().isEmpty()
        && method.getParameterAnnotations().isEmpty();
  }

  private DexMethod getMethodSignature() {
    return factory.createMethod(holderType, proto, name);
  }

  private MethodAccessFlags getAccessFlags() {
    return accessFlags;
  }

  private Code getCodeObject(DexMethod methodSignature) {
    return codeGenerator.generate(methodSignature);
  }
}