package org.simantics.databoard.serialization;

import java.util.HashMap;
import java.util.Map;

import org.simantics.databoard.binding.Binding;

/**
 *
 * 
 * @author Toni Kalajainen
 */
public abstract class SerializerFactory implements SerializerScheme {

	/**
	 * Map of failed constructions. 
	 */
	protected Map<Binding, SerializerConstructionException> failures = new HashMap<Binding, SerializerConstructionException>();
	
	/**
	 * Repository where serializers are placed. 
	 */
	Map<Binding, Serializer> repository;	
	
	/**
	 * Map that contains in incomplete constructions.
	 */
	Map<Binding, Serializer> inprogress = new HashMap<Binding, Serializer>();
	
	/**
	 * Construct a new serializer.
	 */
	public SerializerFactory() {
		this.repository = new HashMap<Binding, Serializer>();
	}
	
	/**
	 * Construct a new serializer factory that places constructed serializers
	 * into user given repository.
	 * 
	 * @param repository
	 */
	public SerializerFactory(Map<Binding, Serializer> repository) {
		this.repository = repository;
	}
	
	public Map<Binding, Serializer> getRepository() {
		return repository;
	}
	
	/**
	 * Constructs a serilizer for a binding. Implement this.
	 * It should use the inprogress -map for construction of 
	 * serializers that have component types.
	 * 
	 *  e.g. 
	 *   inprogress.put(binding, notCompletelyConstructedSerializer);
	 *   Serializer componentSerializer = construct( componentBinding );
	 *   notCompletelyConstructedSerializer.setComponent( componentSerializer );
	 *   inprogress.remove(binding);
	 *   
	 * try-finally is not needed.
	 * 
	 * @param request
	 * @return
	 * @throws SerializerConstructionException
	 */
	protected abstract Serializer doConstruct(Binding request) throws SerializerConstructionException;
	
	public Serializer construct(Binding request) throws SerializerConstructionException
	{
		// Optimization: if binding provides a cached serializer, just return it.
		{ Serializer ser = request.cachedSerializer(); if (ser != null) return ser; } 
		{ Serializer ser = repository.get(request); if(ser != null) return ser; }
		{ Serializer ser = inprogress.get(request); if(ser != null) return ser; }
		{ SerializerConstructionException e = failures.get(request); if(e != null) throw e; }
		
		// Start construction
		try {			
			Serializer binding = doConstruct(request);
			repository.put(request, binding);
			request.cacheSerializer(binding);
			return binding;
		} catch (SerializerConstructionException e) {
			inprogress.remove( request );
			failures.put(request, e);
			throw e;
		}
	}

	@Override
	public Serializer getSerializer(Binding binding)
			throws SerializerConstructionException {		
		return construct(binding);
	}
	
	public Serializer getSerializerUnchecked(Binding binding)
			throws RuntimeSerializerConstructionException {
		try {
			return construct(binding);
		} catch (SerializerConstructionException e) {
			throw new RuntimeSerializerConstructionException(e);
		}
	}	
	
	
}