//==============================================================================
//	
//	Copyright (c) 2014-
//	Authors:
//	* Joachim Klein <klein@tcs.inf.tu-dresden.de> (TU Dresden)
//	
//------------------------------------------------------------------------------
//	
//	This file is part of PRISM.
//	
//	PRISM is free software; you can redistribute it and/or modify
//	it under the terms of the GNU General Public License as published by
//	the Free Software Foundation; either version 2 of the License, or
//	(at your option) any later version.
//	
//	PRISM is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//	GNU General Public License for more details.
//	
//	You should have received a copy of the GNU General Public License
//	along with PRISM; if not, write to the Free Software Foundation,
//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//	
//==============================================================================


package explicit;

import java.util.BitSet;

import parser.type.TypeBool;
import parser.type.TypeDouble;
import parser.type.TypeInt;
import prism.PrismException;
import prism.PrismNotSupportedException;

/**
 * Base class for the results of a product operation between a model and
 * an automaton. Provides infrastructure for converting information on the
 * states between the original model, the automaton and the product model.
 *
 * The mapping between product states and the constituent parts is
 * specified via the (abstract) functions getModelState() and getAutomatonState().
 *
 * @param <M> The type of the product model, e.g, DTMC, MDP, ...
 */
public abstract class Product<M extends Model> implements ModelTransformation<M, M>
{
	protected M originalModel = null;
	protected M productModel = null;

	/**
	 * For the given productState index, return the corresponding
	 * state index in the original model.
	 */
	public abstract int getModelState(int productState);

	/**
	 * For the given productState index, return the corresponding
	 * state index in the automaton.
	 */
	public abstract int getAutomatonState(int productState);

	/**
	 * Constructor.
 	 * @param originalModel the original model
	 */
	public Product(M originalModel)
	{
		this.originalModel = originalModel;
	}

	/**
	 * Constructor.
 	 * @param productModel the product model
 	 * @param originalModel the original model
	 */
	public Product(M productModel, M originalModel)
	{
		this.originalModel = originalModel;
		this.productModel = productModel;
	}

	/**
	 * Get the product model.
	 */
	public M getProductModel()
	{
		return productModel;
	}

	@Override
	public M getTransformedModel()
	{
		return getProductModel();
	}

	@Override
	public M getOriginalModel()
	{
		return originalModel;
	}

	/**
	 * Lifts a BitSet over states in the automaton to a BitSet
	 * over states in the product model: A bit is set in the
	 * result for a product state if the bit is set in the parameter
	 * for the corresponding automaton state.
	 * @param automataStates a BitSet over states of the automaton for this product.
	 */
	public BitSet liftFromAutomaton(BitSet automataStates)
	{
		BitSet result = new BitSet();

		for (int productState = 0; productState < productModel.getNumStates(); productState++) {
			if (automataStates.get(getAutomatonState(productState))) {
				result.set(productState, true);
			}
		}

		return result;
	}

	/**
	 * Lifts a BitSet over states in the original model to a BitSet
	 * over states in the product model: A bit is set in the
	 * result for a product state if the bit is set in the parameter
	 * for the corresponding original model state.
	 * @param modelStates a BitSet over states of the original model for this product.
	 */
	public BitSet liftFromModel(BitSet modelStates)
	{
		BitSet result = new BitSet();

		for (int productState = 0; productState < productModel.getNumStates(); productState++) {
			if (modelStates.get(getModelState(productState))) {
				result.set(productState, true);
			}
		}

		return result;
	}

	/**
	 * Project state values from the product model back to the original model. This function
	 * assumes that the product model has at most one initial state per state in the original
	 * model. The value of this state is then projected to the corresponding state of the
	 * original model.
	 * @param sv the state values in the product model
	 * @return the corresponding state values in the original model
	 * @throws PrismException
	 */
	@Override
	public StateValues projectToOriginalModel(StateValues sv) throws PrismException
	{
		// the resulting state values have one value per state in the original model
		StateValues result = new StateValues(sv.type, getOriginalModel().getNumStates());

		// iterate over all the initial states in the product
		for (Integer productState : productModel.getInitialStates()) {
			// get the state index of the corresponding state in the original model
			int modelState = getModelState(productState);

			if (sv.type instanceof TypeBool) {
				result.setBooleanValue(modelState, (Boolean) sv.getValue(productState));
			} else if (sv.type instanceof TypeInt) {
				result.setIntValue(modelState, (Integer) sv.getValue(productState));
			} else if (sv.type instanceof TypeDouble) {
				result.setDoubleValue(modelState, (Double) sv.getValue(productState));
			} else {
				throw new PrismNotSupportedException("Handling for type "+sv.type+" not implemented.");
			}
		}

		return result;
	}

}