/*******************************************************************************
 *  Copyright (c) 2010 Association for Decentralized Information Management in
 *  Industry THTH ry.
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  which accompanies this distribution, and is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *
 *  Contributors:
 *      VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.databoard.binding.reflection;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.adapter.AdaptException;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.UnionBinding;
import org.simantics.databoard.binding.error.BindingConstructionException;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.serialization.Serializer;
import org.simantics.databoard.serialization.SpecializedSerializerProvider;
import org.simantics.databoard.type.UnionType;

/**
 * Bindings an abstract class with @Union annotation to a DataBoard's UnionType.
 * 
 * Example of usage:
 *  @Union({Rectangle.class, Circle.class, Triangle.class}) class Shape {}
 *  	
 *  class Rectangle extends Shape { public int width, height; }
 *  class Circle extends Shape { public int radius; }		
 *  class Triangle extends Shape { public int sideLength; }		
 *
 * @author Toni Kalajainen
 */
class UnionClassBinding extends UnionBinding implements SpecializedSerializerProvider {

	Class<?>[] componentClasses;
	Serializer specializedSerializer;
	
	public UnionClassBinding(UnionType type) 
	throws BindingConstructionException {
		this.type = type;
	}
	
	@Override
	public Object create(int tag, Object value) {
		return value;
	}

    @Override
    public void setValue(Object union, int tag, Object value)
	throws BindingException {
    	if (tag != getTag(union)) throw new BindingException("Cannot change the class of an instance");
    	Binding cb = getComponentBinding(tag);
    	cb.readFrom(cb, value, union);
    }
	
	@Override
	public int getTag(Object obj) throws BindingException {
		for (int i=0; i<componentClasses.length; i++)
			if (componentClasses[i].isInstance(obj)) return i;
		throw new BindingException(obj.getClass().getSimpleName()+" is not a known component class");
	}
	@Override
	public Object getValue(Object obj) {
		return obj;
	}
	@Override
	public boolean isInstance(Object obj) {
		for (Class<?> c : componentClasses) 
			if (c.isInstance(obj)) return true;					
		return false;
	}

    @Override
    public Serializer getSpecializedSerializer() {
        return specializedSerializer;
    }


	transient Boolean isImmutable;
	
	@Override
	public synchronized boolean isImmutable() {
		if ( isImmutable == null ) {
			boolean b = true;
			for ( Binding cb : getComponentBindings() ) {
				b &= cb.isImmutable();
				if (!b) break;
			}
			isImmutable = b;
		}
		return isImmutable;
	}

	@Override
    public Object readFromTry(Binding srcBinding, Object src, Object dst) throws BindingException
    {
		UnionBinding sb = (UnionBinding) srcBinding;
		int st = sb.getTag(src);
		int dt = getTag(dst);
		Binding scb = sb.getComponentBinding(st);
		Object sv = sb.getValue(src);
		
		
		if (st==dt) {
			// Same Tag
			Object dv = getValue(dst);
			Binding dcb = getComponentBinding(dt);
			dcb.readFrom(scb, sv, dv);
			return dv;
		} else {
			// Different Tag -> return cloned or (same, if immutable) value
			try {
				Binding dcb = getComponentBinding(st);
				return Bindings.adapt(src, scb, dcb);
			} catch(AdaptException e) {
				throw new BindingException(e);
			}
		}
		
	}	
	
	/**
	 * Returns true if the tag of this union type can be modified
	 *  
	 * @return
	 */
	public boolean isTagMutable() {
		return true;
	}
 
	@Override
	protected boolean baseEquals(Object obj) {
		if (!super.baseEquals(obj)) return false;	

		UnionClassBinding o = (UnionClassBinding)obj;
		if (isImmutable != o.isImmutable) return false;
		if (specializedSerializer != o.specializedSerializer) return false;
		if (componentClasses.length != o.componentClasses.length) return false;
		
		for (int i = 0; i < componentClasses.length; i++) {
			if (!componentClasses[i].equals(o.componentClasses[i]))
				return false;
		}
		
		return true;
	}
	
	@Override
	public int baseHashCode() {
		int code = super.baseHashCode();
		for (int i = 0; i < componentClasses.length; i++)
			code = 23 * code + componentClasses.hashCode();
		
		return code;
	}
}