content: /*
   *  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.causeway.core.metamodel.facets.object.mixin;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.util.function.BiConsumer;
  
  import org.apache.causeway.commons.internal.exceptions._Exceptions;
  import org.apache.causeway.commons.internal.reflection._GenericResolver.ResolvedMethod;
  import org.apache.causeway.core.metamodel.facetapi.Facet;
  import org.apache.causeway.core.metamodel.facetapi.FacetAbstract;
  import org.apache.causeway.core.metamodel.facetapi.FacetHolder;
  import org.apache.causeway.core.metamodel.facets.FacetedMethod;
  import org.apache.causeway.core.metamodel.facets.actions.contributing.ContributingFacet;
  
  import lombok.Getter;
  import org.jspecify.annotations.NonNull;
  import lombok.experimental.Accessors;
  
  //@Log4j2
  public abstract class MixinFacetAbstract
  extends FacetAbstract
  implements MixinFacet {
  
      @Getter(onMethod_={@Override})
      private final @NonNull String mainMethodName;
      @Getter(onMethod_={@Override}) @Accessors(fluent=true)
      private @NonNull Contributing contributing = Contributing.UNSPECIFIED;
  
      private final @NonNull Class<?> mixinType;
      private final @NonNull Class<?> holderType;
      private final @NonNull Constructor<?> constructor;
  
      private static final Class<? extends Facet> type() {
          return MixinFacet.class;
      }
  
      protected MixinFacetAbstract(
              final Class<?> mixinType,
              final String mainMethodName,
              final Constructor<?> constructor,
              final FacetHolder holder) {
  
          super(type(), holder);
          this.mainMethodName = mainMethodName;
          this.mixinType = mixinType;
          this.constructor = constructor;
          // by mixin convention: first constructor argument is identified as the holder type
          this.holderType = constructor.getParameterTypes()[0];
      }
  
      @Override
      public boolean isMixinFor(final Class<?> candidateDomainType) {
          return candidateDomainType == null
                  ? false
                  : holderType.isAssignableFrom(candidateDomainType);
      }
  
      @Override
      public Object instantiate(final Object mixee) {
          if(constructor == null) {
              throw _Exceptions.unrecoverable(
                      "Failed to instantiate mixin. "
                      + "Invalid mix-in declaration of type %s, missing contructor", mixinType);
          }
          if(mixee == null) {
              return null;
          }
          if(!isMixinFor(mixee.getClass())) {
              throw _Exceptions.illegalArgument(
                      "Failed to instantiate mixin. "
                      + "Mixin class %s is not a mixin for supplied object [%s]. "
                      + "Mixin construction expects type: %s",
                      mixinType.getName(), mixee, holderType);
          }
          try {
              var mixinPojo = constructor.newInstance(mixee);
              getServiceInjector().injectServicesInto(mixinPojo);
              return mixinPojo;
          } catch (InvocationTargetException | InstantiationException | IllegalAccessException e) {
              throw _Exceptions.unrecoverable(e,
                      "Failed to instantiate mixin. "
                      + "Invalid mix-in declaration of type %s, "
                      + "failing instance construction with %s", mixinType, e);
          }
      }
  
      @Override
      public boolean isCandidateForMain(final ResolvedMethod method) {
          /* include methods from super classes or interfaces
           *
           * it is sufficient to detect any match;
           * mixin invocation will take care of calling the right method,
           * that is in terms of type-hierarchy the 'nearest' to this mixin;
           */
          return method.name().equals(getMainMethodName())
                  && method.method().getDeclaringClass()
                      .isAssignableFrom(constructor.getDeclaringClass());
      }
  
      @Override
      public void visitAttributes(final BiConsumer<String, Object> visitor) {
          super.visitAttributes(visitor);
          visitor.accept("mixinType", mixinType);
          visitor.accept("contributing", contributing);
          visitor.accept("mainMethodName", mainMethodName);
          visitor.accept("holderType", holderType);
      }
  
      /**
       * Framework internal: copy the mixin-sort ({@link MixinFacet.Contributing})
       * information from the {@link FacetedMethod}
       * (as eg. associated with mixin main method 'act')
       * to the {@link MixinFacet} that is held by the mixin's type spec.
       */
      public void initMixinSortFrom(final FacetedMethod facetedMethod) {
          this.contributing = facetedMethod
                  .lookupFacet(ContributingFacet.class)
                  .map(ContributingFacet::contributed)
                  .orElse(Contributing.AS_ACTION); // if not specified, defaults to ACTION
      }
  
  }
  