package org.simantics.databoard.serialization.impl;

import gnu.trove.map.hash.TObjectIntHashMap;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.List;

import org.simantics.databoard.binding.UnionBinding;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.binding.util.IsReferableQuery;
import org.simantics.databoard.binding.util.Result;
import org.simantics.databoard.serialization.SerializationException;
import org.simantics.databoard.serialization.Serializer;
import org.simantics.databoard.serialization.Serializer.CompositeSerializer;
import org.simantics.databoard.type.UnionType;
import org.simantics.databoard.util.binary.Endian;

public class UnionSerializer extends CompositeSerializer {

	UnionBinding binding;
	public Serializer[] componentSerializers;
	int tagTypeCount;
	Integer fixedSize;
	int minSize;
	
	/**
	 * 
	 * @param binding
	 * @param componentSerializers (optional) can be set later
	 */
	public UnionSerializer(UnionBinding binding, Serializer[] componentSerializers)				
	{
		super( IsReferableQuery.isReferable( binding.type() ) != Result.No );
		tagTypeCount = ((UnionType) binding.type()).components.length;
		this.binding = binding;
		this.componentSerializers = componentSerializers;
	}
	
	@Override
	public void finalizeConstruction() {
		// Calculate Fixed Size
		for (Serializer s : componentSerializers)
		{
			Integer fixedSizeOfComponentSerializer = s.getConstantSize();
			if (fixedSizeOfComponentSerializer==null) {
				fixedSize = null;
				break;
			}
			if (fixedSize!=null && fixedSizeOfComponentSerializer!=fixedSize) {
				fixedSize = null;
				break;
			}
			fixedSize = fixedSizeOfComponentSerializer;
		}
		if (componentSerializers.length == 0) fixedSize = 0;
		if (fixedSize!=null) fixedSize += Endian.getUIntLength(tagTypeCount-1);
		
		if (componentSerializers.length>0) {
			minSize = Integer.MAX_VALUE;
			for (Serializer s : componentSerializers) minSize = Math.min(minSize, s.getMinSize());
			minSize += Endian.getUIntLength( tagTypeCount-1 );
		}
			
	}

	@Override
	public Object deserialize(DataInput in, List<Object> identities) throws IOException {
		try {
			int tag = Endian.getUInt(in, tagTypeCount-1);
			return binding.create(tag, componentSerializers[tag].deserialize(in, identities));
		} catch (BindingException e) {
			throw new IOException( e ); 
		}
	}
	
	public Object deserializeToTry(DataInput in, List<Object> identities, Object dst) throws IOException 
	{
		if (binding.isTagMutable()) {
			return deserialize(in, identities);
		} else {
			deserializeTo(in, identities, dst);
			return dst;				
		}
	}
		
	
	@Override
	public void deserializeTo(DataInput in, List<Object> identities, Object obj) throws IOException {
		try {
			int tag = Endian.getUInt(in, tagTypeCount-1);
			int oldTag = binding.getTag(obj);
			Serializer cs = componentSerializers[tag];
			boolean csImmutable = binding.getComponentBinding(tag).isImmutable();
			
			if (oldTag==tag && !csImmutable) {
				Object component = binding.getValue(obj);
				component = componentSerializers[tag].deserializeToTry(in, identities, component);
				binding.setValue(obj, tag, component);
			} else {
				Object component = cs.deserialize(in, identities);
				binding.setValue(obj, tag, component);
			}
		} catch (BindingException e) {
			throw new IOException( e ); 
		}
	}

	@Override
	public void skip(DataInput in, List<Object> identities) throws IOException, SerializationException {
		int tag = Endian.getUInt(in, tagTypeCount-1);
		componentSerializers[tag].skip(in, identities);
	}
	
	@Override
	public void serialize(DataOutput out, TObjectIntHashMap<Object> identities, Object obj) throws IOException {
		try {
			int tag = binding.getTag(obj);
			Endian.putUInt(out, tag, tagTypeCount-1);
			componentSerializers[tag].serialize(out, identities, binding.getValue(obj));
		} catch (BindingException e) {
			throw new IOException( e ); 
		}
	}

	@Override
	public Integer getConstantSize() {
		return fixedSize;
	}

	@Override
	public int getSize(Object obj, TObjectIntHashMap<Object> identities) throws IOException {
		try {
			if (fixedSize!=null) return fixedSize;
			int tag = binding.getTag(obj);
			return Endian.getUIntLength( tagTypeCount-1 ) +
				componentSerializers[tag].getSize(binding.getValue(obj), identities);
		} catch (BindingException e) {
			throw new IOException( e ); 
		}
	}
	
	@Override
	public int getMinSize() {
		return minSize;
	}

	
}