/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.beam.sdk.schemas.utils;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import net.bytebuddy.ByteBuddy;
import net.bytebuddy.description.method.MethodDescription.ForLoadedMethod;
import net.bytebuddy.dynamic.DynamicType;
import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.dynamic.scaffold.InstrumentedType;
import net.bytebuddy.implementation.FixedValue;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
import net.bytebuddy.implementation.bytecode.ByteCodeAppender.Size;
import net.bytebuddy.implementation.bytecode.Removal;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.member.MethodInvocation;
import net.bytebuddy.implementation.bytecode.member.MethodReturn;
import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import net.bytebuddy.matcher.ElementMatchers;
import org.apache.beam.sdk.annotations.Experimental;
import org.apache.beam.sdk.annotations.Experimental.Kind;
import org.apache.beam.sdk.schemas.FieldValueGetter;
import org.apache.beam.sdk.schemas.FieldValueSetter;
import org.apache.beam.sdk.schemas.FieldValueTypeInformation;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.schemas.SchemaUserTypeCreator;
import org.apache.beam.sdk.schemas.utils.ByteBuddyUtils.ConstructorCreateInstruction;
import org.apache.beam.sdk.schemas.utils.ByteBuddyUtils.ConvertType;
import org.apache.beam.sdk.schemas.utils.ByteBuddyUtils.ConvertValueForGetter;
import org.apache.beam.sdk.schemas.utils.ByteBuddyUtils.InjectPackageStrategy;
import org.apache.beam.sdk.schemas.utils.ByteBuddyUtils.StaticFactoryMethodInstruction;
import org.apache.beam.sdk.schemas.utils.ReflectUtils.ClassWithSchema;
import org.apache.beam.sdk.util.common.ReflectHelpers;
import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.Maps;

/** A set of utilities to generate getter and setter classes for JavaBean objects. */
@Experimental(Kind.SCHEMAS)
public class JavaBeanUtils {
  /** Create a {@link Schema} for a Java Bean class. */
  public static Schema schemaFromJavaBeanClass(
      Class<?> clazz, FieldValueTypeSupplier fieldValueTypeSupplier) {
    return StaticSchemaInference.schemaFromClass(clazz, fieldValueTypeSupplier);
  }

  // Make sure that there are matching setters and getters.
  public static void validateJavaBean(
      List<FieldValueTypeInformation> getters, List<FieldValueTypeInformation> setters) {
    Map<String, FieldValueTypeInformation> setterMap =
        setters.stream()
            .collect(Collectors.toMap(FieldValueTypeInformation::getName, Function.identity()));

    for (FieldValueTypeInformation type : getters) {
      FieldValueTypeInformation setterType = setterMap.get(type.getName());
      if (setterType == null) {
        throw new RuntimeException(
            "JavaBean contained a getter for field "
                + type.getName()
                + "but did not contain a matching setter.");
      }
      if (!type.getType().equals(setterType.getType())) {
        throw new RuntimeException(
            "JavaBean contained setter for field "
                + type.getName()
                + " that had a mismatching type.");
      }
      if (!type.isNullable() == setterType.isNullable()) {
        throw new RuntimeException(
            "JavaBean contained setter for field "
                + type.getName()
                + " that had a mismatching nullable attribute.");
      }
    }
  }

  // Static ByteBuddy instance used by all helpers.
  private static final ByteBuddy BYTE_BUDDY = new ByteBuddy();

  private static final Map<ClassWithSchema, List<FieldValueTypeInformation>> CACHED_FIELD_TYPES =
      Maps.newConcurrentMap();

  public static List<FieldValueTypeInformation> getFieldTypes(
      Class<?> clazz, Schema schema, FieldValueTypeSupplier fieldValueTypeSupplier) {
    return CACHED_FIELD_TYPES.computeIfAbsent(
        new ClassWithSchema(clazz, schema), c -> fieldValueTypeSupplier.get(clazz, schema));
  }

  // The list of getters for a class is cached, so we only create the classes the first time
  // getSetters is called.
  private static final Map<ClassWithSchema, List<FieldValueGetter>> CACHED_GETTERS =
      Maps.newConcurrentMap();

  /**
   * Return the list of {@link FieldValueGetter}s for a Java Bean class
   *
   * <p>The returned list is ordered by the order of fields in the schema.
   */
  public static List<FieldValueGetter> getGetters(
      Class<?> clazz, Schema schema, FieldValueTypeSupplier fieldValueTypeSupplier) {
    return CACHED_GETTERS.computeIfAbsent(
        new ClassWithSchema(clazz, schema),
        c -> {
          List<FieldValueTypeInformation> types = fieldValueTypeSupplier.get(clazz, schema);
          return types.stream().map(JavaBeanUtils::createGetter).collect(Collectors.toList());
        });
  }

  private static <T> FieldValueGetter createGetter(FieldValueTypeInformation typeInformation) {
    DynamicType.Builder<FieldValueGetter> builder =
        ByteBuddyUtils.subclassGetterInterface(
            BYTE_BUDDY,
            typeInformation.getMethod().getDeclaringClass(),
            new ConvertType(false).convert(typeInformation.getType()));
    builder = implementGetterMethods(builder, typeInformation);
    try {
      return builder
          .make()
          .load(
              ReflectHelpers.findClassLoader(
                  typeInformation.getMethod().getDeclaringClass().getClassLoader()),
              ClassLoadingStrategy.Default.INJECTION)
          .getLoaded()
          .getDeclaredConstructor()
          .newInstance();
    } catch (InstantiationException
        | IllegalAccessException
        | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(
          "Unable to generate a getter for getter '" + typeInformation.getMethod() + "'");
    }
  }

  private static DynamicType.Builder<FieldValueGetter> implementGetterMethods(
      DynamicType.Builder<FieldValueGetter> builder, FieldValueTypeInformation typeInformation) {
    return builder
        .method(ElementMatchers.named("name"))
        .intercept(FixedValue.reference(typeInformation.getName()))
        .method(ElementMatchers.named("get"))
        .intercept(new InvokeGetterInstruction(typeInformation));
  }

  // The list of setters for a class is cached, so we only create the classes the first time
  // getSetters is called.
  private static final Map<ClassWithSchema, List<FieldValueSetter>> CACHED_SETTERS =
      Maps.newConcurrentMap();

  /**
   * Return the list of {@link FieldValueSetter}s for a Java Bean class
   *
   * <p>The returned list is ordered by the order of fields in the schema.
   */
  public static List<FieldValueSetter> getSetters(
      Class<?> clazz, Schema schema, FieldValueTypeSupplier fieldValueTypeSupplier) {
    return CACHED_SETTERS.computeIfAbsent(
        new ClassWithSchema(clazz, schema),
        c -> {
          List<FieldValueTypeInformation> types = fieldValueTypeSupplier.get(clazz, schema);
          return types.stream().map(JavaBeanUtils::createSetter).collect(Collectors.toList());
        });
  }

  private static FieldValueSetter createSetter(FieldValueTypeInformation typeInformation) {
    DynamicType.Builder<FieldValueSetter> builder =
        ByteBuddyUtils.subclassSetterInterface(
            BYTE_BUDDY,
            typeInformation.getMethod().getDeclaringClass(),
            new ConvertType(false).convert(typeInformation.getType()));
    builder = implementSetterMethods(builder, typeInformation.getMethod());
    try {
      return builder
          .make()
          .load(
              ReflectHelpers.findClassLoader(
                  typeInformation.getMethod().getDeclaringClass().getClassLoader()),
              ClassLoadingStrategy.Default.INJECTION)
          .getLoaded()
          .getDeclaredConstructor()
          .newInstance();
    } catch (InstantiationException
        | IllegalAccessException
        | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(
          "Unable to generate a setter for setter '" + typeInformation.getMethod() + "'");
    }
  }

  private static DynamicType.Builder<FieldValueSetter> implementSetterMethods(
      DynamicType.Builder<FieldValueSetter> builder, Method method) {
    FieldValueTypeInformation javaTypeInformation = FieldValueTypeInformation.forSetter(method);
    return builder
        .method(ElementMatchers.named("name"))
        .intercept(FixedValue.reference(javaTypeInformation.getName()))
        .method(ElementMatchers.named("set"))
        .intercept(new InvokeSetterInstruction(method));
  }

  // The list of constructors for a class is cached, so we only create the classes the first time
  // getConstructor is called.
  public static final Map<ClassWithSchema, SchemaUserTypeCreator> CACHED_CREATORS =
      Maps.newConcurrentMap();

  public static SchemaUserTypeCreator getConstructorCreator(
      Class clazz,
      Constructor constructor,
      Schema schema,
      FieldValueTypeSupplier fieldValueTypeSupplier) {
    return CACHED_CREATORS.computeIfAbsent(
        new ClassWithSchema(clazz, schema),
        c -> {
          List<FieldValueTypeInformation> types = fieldValueTypeSupplier.get(clazz, schema);
          return createConstructorCreator(clazz, constructor, schema, types);
        });
  }

  public static <T> SchemaUserTypeCreator createConstructorCreator(
      Class<T> clazz,
      Constructor<T> constructor,
      Schema schema,
      List<FieldValueTypeInformation> types) {
    try {
      DynamicType.Builder<SchemaUserTypeCreator> builder =
          BYTE_BUDDY
              .with(new InjectPackageStrategy(clazz))
              .subclass(SchemaUserTypeCreator.class)
              .method(ElementMatchers.named("create"))
              .intercept(new ConstructorCreateInstruction(types, clazz, constructor));
      return builder
          .make()
          .load(
              ReflectHelpers.findClassLoader(clazz.getClassLoader()),
              ClassLoadingStrategy.Default.INJECTION)
          .getLoaded()
          .getDeclaredConstructor()
          .newInstance();
    } catch (InstantiationException
        | IllegalAccessException
        | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(
          "Unable to generate a creator for class " + clazz + " with schema " + schema);
    }
  }

  public static SchemaUserTypeCreator getStaticCreator(
      Class clazz, Method creator, Schema schema, FieldValueTypeSupplier fieldValueTypeSupplier) {
    return CACHED_CREATORS.computeIfAbsent(
        new ClassWithSchema(clazz, schema),
        c -> {
          List<FieldValueTypeInformation> types = fieldValueTypeSupplier.get(clazz, schema);
          return createStaticCreator(clazz, creator, schema, types);
        });
  }

  public static <T> SchemaUserTypeCreator createStaticCreator(
      Class<T> clazz, Method creator, Schema schema, List<FieldValueTypeInformation> types) {
    try {
      DynamicType.Builder<SchemaUserTypeCreator> builder =
          BYTE_BUDDY
              .with(new InjectPackageStrategy(clazz))
              .subclass(SchemaUserTypeCreator.class)
              .method(ElementMatchers.named("create"))
              .intercept(new StaticFactoryMethodInstruction(types, clazz, creator));

      return builder
          .make()
          .load(
              ReflectHelpers.findClassLoader(clazz.getClassLoader()),
              ClassLoadingStrategy.Default.INJECTION)
          .getLoaded()
          .getDeclaredConstructor()
          .newInstance();
    } catch (InstantiationException
        | IllegalAccessException
        | NoSuchMethodException
        | InvocationTargetException e) {
      throw new RuntimeException(
          "Unable to generate a creator for " + clazz + " with schema " + schema);
    }
  }

  // Implements a method to read a public getter out of an object.
  private static class InvokeGetterInstruction implements Implementation {
    private final FieldValueTypeInformation typeInformation;

    InvokeGetterInstruction(FieldValueTypeInformation typeInformation) {
      this.typeInformation = typeInformation;
    }

    @Override
    public InstrumentedType prepare(InstrumentedType instrumentedType) {
      return instrumentedType;
    }

    @Override
    public ByteCodeAppender appender(final Target implementationTarget) {
      return (methodVisitor, implementationContext, instrumentedMethod) -> {
        // this + method parameters.
        int numLocals = 1 + instrumentedMethod.getParameters().size();

        // StackManipulation that will read the value from the class field.
        StackManipulation readValue =
            new StackManipulation.Compound(
                // Method param is offset 1 (offset 0 is the this parameter).
                MethodVariableAccess.REFERENCE.loadFrom(1),
                // Invoke the getter
                MethodInvocation.invoke(new ForLoadedMethod(typeInformation.getMethod())));

        StackManipulation stackManipulation =
            new StackManipulation.Compound(
                new ConvertValueForGetter(readValue).convert(typeInformation.getType()),
                MethodReturn.REFERENCE);

        StackManipulation.Size size = stackManipulation.apply(methodVisitor, implementationContext);
        return new Size(size.getMaximalSize(), numLocals);
      };
    }
  }

  // Implements a method to write a public set out on an object.
  private static class InvokeSetterInstruction implements Implementation {
    // Setter method that wil be invoked
    private Method method;

    InvokeSetterInstruction(Method method) {
      this.method = method;
    }

    @Override
    public InstrumentedType prepare(InstrumentedType instrumentedType) {
      return instrumentedType;
    }

    @Override
    public ByteCodeAppender appender(final Target implementationTarget) {
      return (methodVisitor, implementationContext, instrumentedMethod) -> {
        FieldValueTypeInformation javaTypeInformation = FieldValueTypeInformation.forSetter(method);
        // this + method parameters.
        int numLocals = 1 + instrumentedMethod.getParameters().size();

        // The instruction to read the field.
        StackManipulation readField = MethodVariableAccess.REFERENCE.loadFrom(2);

        boolean setterMethodReturnsVoid = method.getReturnType().equals(Void.TYPE);
        // Read the object onto the stack.
        StackManipulation stackManipulation =
            new StackManipulation.Compound(
                // Object param is offset 1.
                MethodVariableAccess.REFERENCE.loadFrom(1),
                // Do any conversions necessary.
                new ByteBuddyUtils.ConvertValueForSetter(readField)
                    .convert(javaTypeInformation.getType()),
                // Now update the field and return void.
                MethodInvocation.invoke(new ForLoadedMethod(method)));
        if (!setterMethodReturnsVoid) {
          // Discard return type;
          stackManipulation = new StackManipulation.Compound(stackManipulation, Removal.SINGLE);
        }
        stackManipulation = new StackManipulation.Compound(stackManipulation, MethodReturn.VOID);

        StackManipulation.Size size = stackManipulation.apply(methodVisitor, implementationContext);
        return new Size(size.getMaximalSize(), numLocals);
      };
    }
  }
}