package top.infra.jackson2;
   
   import com.fasterxml.jackson.databind.AnnotationIntrospector;
   import com.fasterxml.jackson.databind.BeanDescription;
   import com.fasterxml.jackson.databind.JavaType;
   import com.fasterxml.jackson.databind.JsonSerializer;
   import com.fasterxml.jackson.databind.SerializationConfig;
   import com.fasterxml.jackson.databind.introspect.AnnotatedClass;
   import com.fasterxml.jackson.databind.jsontype.NamedType;
  import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;
  import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
  import com.fasterxml.jackson.databind.ser.Serializers;
  
  import org.apache.commons.lang3.tuple.Pair;
  
  import java.util.Collection;
  
  import top.infra.jackson2.ser.PairSerializer;
  
  /**
   * {@link com.fasterxml.jackson.databind.ser.BasicSerializerFactory#buildMapEntrySerializer(SerializationConfig, JavaType, BeanDescription, boolean, JavaType, JavaType)}.
   * {@link com.fasterxml.jackson.databind.ser.BeanSerializerFactory}
   * com.fasterxml.jackson.datatype.guava.GuavaSerializers
   */
  public class CommonsLangSerializers extends Serializers.Base {
  
      @Override
      public JsonSerializer<?> findSerializer(
          final SerializationConfig config, final JavaType type, final BeanDescription beanDesc) {
          // see: BasicSerializerFactory.buildContainerSerializer
          if (Pair.class.isAssignableFrom(type.getRawClass())) {
              // Let's see what we can learn about element/content/value type, type serializer for it:
              JavaType lType = type.containedTypeOrUnknown(0);
              JavaType rType = type.containedTypeOrUnknown(1);
              boolean staticTyping = false;
              final TypeSerializer kts = createTypeSerializer(config, lType);
              final TypeSerializer vts = createTypeSerializer(config, rType);
              return new PairSerializer(type, lType, rType, staticTyping, kts, vts, null);
          }
          return super.findSerializer(config, type, beanDesc);
      }
  
      /**
       * see: {@link com.fasterxml.jackson.databind.ser.BasicSerializerFactory#createTypeSerializer(SerializationConfig, JavaType)}.
       */
      public TypeSerializer createTypeSerializer(final SerializationConfig config, final JavaType baseType) {
          if (baseType == null) {
              return null;
          }
          final BeanDescription bean = config.introspectClassAnnotations(baseType.getRawClass());
          final AnnotatedClass ac = bean.getClassInfo();
          final AnnotationIntrospector ai = config.getAnnotationIntrospector();
          TypeResolverBuilder<?> b = ai.findTypeResolver(config, ac, baseType);
          /* Ok: if there is no explicit type info handler, we may want to
           * use a default. If so, config object knows what to use.
           */
          Collection<NamedType> subtypes = null;
          if (b == null) {
              b = config.getDefaultTyper(baseType);
          } else {
              subtypes = config.getSubtypeResolver().collectAndResolveSubtypesByClass(config, ac);
          }
          if (b == null) {
              return null;
          }
          // 10-Jun-2015, tatu: Since not created for Bean Property, no need for post-processing
          //    wrt EXTERNAL_PROPERTY
          return b.buildTypeSerializer(config, baseType, subtypes);
      }
  }