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package se.l4.commons.serialization;

import java.lang.reflect.Field;
import java.util.List;

import com.fasterxml.classmate.MemberResolver;
import com.fasterxml.classmate.ResolvedType;
import com.fasterxml.classmate.ResolvedTypeWithMembers;
import com.fasterxml.classmate.TypeResolver;
import com.fasterxml.classmate.members.ResolvedConstructor;
import com.fasterxml.classmate.members.ResolvedField;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;

import se.l4.commons.serialization.internal.TypeViaResolvedType;
import se.l4.commons.serialization.internal.reflection.FactoryDefinition;
import se.l4.commons.serialization.internal.reflection.FieldDefinition;
import se.l4.commons.serialization.internal.reflection.ReflectionNonStreamingSerializer;
import se.l4.commons.serialization.internal.reflection.ReflectionOnlySingleFactorySerializer;
import se.l4.commons.serialization.internal.reflection.ReflectionStreamingSerializer;
import se.l4.commons.serialization.internal.reflection.TypeInfo;
import se.l4.commons.serialization.spi.AbstractSerializerResolver;
import se.l4.commons.serialization.spi.SerializerResolver;
import se.l4.commons.serialization.spi.Type;
import se.l4.commons.serialization.spi.TypeEncounter;
import se.l4.commons.serialization.standard.CompactDynamicSerializer;
import se.l4.commons.serialization.standard.DynamicSerializer;
import se.l4.commons.serialization.standard.SimpleTypeSerializer;

/**
 * Serializer that will use reflection to access fields and methods in a
 * class. Will export anything annotated with {@link Expose}.
 *
 * 
 * 

 * 	{@link Named} can be used if you want a field to have a specific name
 * 		in serialized form.
 * 	
If you need to use a custom serializer for a field annotate it with
 * 		{@link Use}.
 * 	
{@link AllowAny} will cause dynamic serialization to be used for a
 * 		field.
 * 
 *
 * @author Andreas Holstenson
 */
public class ReflectionSerializer
	extends AbstractSerializerResolver
{
	public ReflectionSerializer()
	{
	}

	@Override
	@SuppressWarnings({ "unchecked", "rawtypes" })
	public Serializer find(TypeEncounter encounter)
	{
		Type type = encounter.getType();
		SerializerCollection collection = encounter.getCollection();

		ImmutableMap.Builder builder = ImmutableMap.builder();
		ImmutableMap.Builder nonRenamedFields = ImmutableMap.builder();

		TypeResolver typeResolver = new TypeResolver();
		MemberResolver memberResolver = new MemberResolver(typeResolver);

		Type[] params = type.getParameters();
		ResolvedType rt = params.length == 0
			? typeResolver.resolve(type.getErasedType())
			: resolveWithParams(typeResolver, type);

		ResolvedTypeWithMembers typeWithMembers = memberResolver.resolve(rt, null, null);

		for(ResolvedField field : typeWithMembers.getMemberFields())
		{
			Field reflectiveField = field.getRawMember();

			if(! reflectiveField.isAnnotationPresent(Expose.class))
			{
				continue;
			}

			// Resolve the serializer to use for the field
			ResolvedType fieldType = field.getType();

			Serializer serializer;
			if(reflectiveField.isAnnotationPresent(Use.class))
			{
				// Serializer has been set to a specific type
				Use annotation = reflectiveField.getAnnotation(Use.class);
				if(Serializer.class.isAssignableFrom(annotation.value()))
				{
					try
					{
						serializer = (Serializer) collection.getInstanceFactory().create(annotation.value());
					}
					catch(Exception e)
					{
						throw new SerializationException("Unable to create " + annotation.value() + " for " + type + "; " + e.getMessage(), e);
					}
				}
				else if(SerializerResolver.class.isAssignableFrom(annotation.value()))
				{
					serializer = collection.findVia((Class) annotation.value(), new TypeViaResolvedType(fieldType), reflectiveField.getAnnotations());
				}
				else
				{
					throw new SerializationException("Unable to create " + annotation.value() + " for " +  type + "; Class either needs to a Serializer or a SerializerResolver");
				}
			}
			else if(reflectiveField.isAnnotationPresent(AllowAny.class))
			{
				AllowAny allowAny = reflectiveField.getAnnotation(AllowAny.class);
				serializer = allowAny.compact()
					? new CompactDynamicSerializer(collection)
					: new DynamicSerializer(collection);
			}
			else if(reflectiveField.isAnnotationPresent(AllowSimpleTypes.class))
			{
				serializer = new SimpleTypeSerializer();
			}
			else
			{
				// Dynamically find a suitable type
				try
				{
					serializer = collection.find(new TypeViaResolvedType(fieldType), reflectiveField.getAnnotations());
				}
				catch(SerializationException e)
				{
					throw new SerializationException("Could not resolve " + field.getName() + " for " + type.getErasedType() + "; " + e.getMessage(), e);
				}
			}

			if(serializer == null)
			{
				throw new SerializationException("Could not resolve " + field.getName() + " for " + type.getErasedType() + "; No serializer found");
			}

			boolean skipIfDefault = reflectiveField.isAnnotationPresent(SkipDefaultValue.class);

			// Force the field to be accessible
			reflectiveField.setAccessible(true);

			// Define how we access this field
			String name = getName(reflectiveField);
			FieldDefinition def = new FieldDefinition(reflectiveField, name, serializer, fieldType.getErasedType(), skipIfDefault);
			builder.put(name, def);
			nonRenamedFields.put(reflectiveField.getName(), def);
		}

		// Create field map and cache
		ImmutableMap fields = builder.build();
		ImmutableMap nonRenamed = builder.build();
		FieldDefinition[] fieldsCache = fields.values().toArray(new FieldDefinition[0]);

		// Get all of the factories
		boolean hasSerializerInFactory = false;
		List> factories = Lists.newArrayList();

		for(ResolvedConstructor constructor : typeWithMembers.getConstructors())
		{
			FactoryDefinition def = new FactoryDefinition<>(collection, fields, nonRenamed, constructor);
			hasSerializerInFactory |= def.hasSerializedFields();

			if(def.hasSerializedFields() || def.isInjectable())
			{
				factories.add(def);
			}
		}

		if(factories.isEmpty())
		{
			throw new SerializationException("Unable to create any instance of " + type + ", at least a default constructor is needed");
		}

		FactoryDefinition[] factoryCache = factories.toArray(new FactoryDefinition[factories.size()]);

		// Create the actual serializer to use
		TypeInfo typeInfo = new TypeInfo((Class) type.getErasedType(), factoryCache, fields, fieldsCache);

		if(hasSerializerInFactory)
		{
			FactoryDefinition factoryWithEverything = typeInfo.findSingleFactoryWithEverything();
			if(factoryWithEverything == null)
			{
				// There is no factory that takes in every single field, use a non-streaming serializer
				return new ReflectionNonStreamingSerializer<>(typeInfo);
			}
			else
			{
				return new ReflectionOnlySingleFactorySerializer<>(typeInfo, factoryWithEverything);
			}
		}
		else
		{
			return new ReflectionStreamingSerializer<>(typeInfo);
		}
	}

	private static ResolvedType resolveWithParams(TypeResolver typeResolver, Type type)
	{
		if(type instanceof TypeViaResolvedType)
		{
			return ((TypeViaResolvedType) type).getResolvedType();
		}

		return null;
	}

	private static String getName(Field field)
	{
		if(field.isAnnotationPresent(Expose.class))
		{
			Expose annotation = field.getAnnotation(Expose.class);
			if(! "".equals(annotation.value()))
			{
				return annotation.value();
			}
		}

		return field.getName();
	}
}