/*******************************************************************************
 * Copyright (c) 2004-2009 Gabor Bergmann and Daniel Varro
 * 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:
 *    Gabor Bergmann - initial API and implementation
 *******************************************************************************/

package org.eclipse.viatra2.gtasm.patternmatcher.incremental;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Random;
import java.util.Set;

import org.eclipse.viatra2.core.IEntity;
import org.eclipse.viatra2.core.IModelElement;
import org.eclipse.viatra2.gtasm.patternmatcher.ExecutionMode;
import org.eclipse.viatra2.gtasm.patternmatcher.IMatching;
import org.eclipse.viatra2.gtasm.patternmatcher.ParameterMode;
import org.eclipse.viatra2.gtasm.patternmatcher.PatternCallSignature;
import org.eclipse.viatra2.gtasm.patternmatcher.Scope;
import org.eclipse.viatra2.gtasm.patternmatcher.incremental.rete.matcher.RetePatternMatcher;
import org.eclipse.viatra2.gtasm.patternmatcher.incremental.rete.tuple.Tuple;
import org.eclipse.viatra2.gtasm.patternmatcher.incremental.rete.tuple.TupleMask;
import org.eclipse.viatra2.gtasm.patternmatcher.patterns.IPatternMatcher;


/**
 * @author Bergmann Gábor
 *
 */
public class ReteGTASMPatternMatcher implements IPatternMatcher {

	RetePatternMatcher matcher;
	Random random = null;
    

	/**
	 * @param matcher the GTASM-ignorant RetePatternMatcher to wrap
	 */
	public ReteGTASMPatternMatcher(RetePatternMatcher matcher) {
		super();
		this.matcher = matcher;
	}

	/**
	 * @param inputMapping quantification indicated by org.eclipse.viatra2.gtasmmodel.gtasm.metamodel.asm.enums.ValueKind.UNDEF_LITERAL
	 */
	public boolean match(Object[] inputMapping) {
		boolean[] fixed = new boolean[inputMapping.length];
		for (int i = 0; i < inputMapping.length; ++i) {
			fixed[i] = !org.eclipse.viatra2.gtasmmodel.gtasm.metamodel.asm.enums.ValueKind.UNDEF_LITERAL
					.equals(inputMapping[i]);
		}
		return matcher.count(inputMapping, fixed) != 0;
	}

	public IMatching match(Object[] inputMapping, PatternCallSignature[] signature) {
		boolean ignoreScope = isScopeIgnorable(signature);
		if (!ignoreScope)  // there needs to be scope checking, which is deadlock-prone to do in a matchfetcher!
		{
			ArrayList<IMatching> result = matchAll(inputMapping, signature, null);
			return result.isEmpty() ? null : result.iterator().next();
		} else
		{
			boolean[] fixed = new boolean[inputMapping.length];
			for (int i = 0; i < inputMapping.length; ++i) {
				fixed[i] = (signature[i].getParameterMode() == ParameterMode.INPUT);
			}

			// retrieving the projection
			Tuple match = matcher.matchOne(inputMapping, fixed);
			return match==null? null : new ReteMatching(match, matcher.getPosMapping());
		}
	
	}
	
	public ArrayList<IMatching> matchAll(Object[] inputMapping, PatternCallSignature[] signature, Integer[] quantificationOrder) {
	
		// analyzing the execution mode (quantification, bound variables)
		boolean[] fixed = new boolean[inputMapping.length];
		boolean[] quantified = new boolean[inputMapping.length];
		boolean hasExistential = false; // there are variables neither universally quantified not bound
		boolean hasUniversal = false;
		for (int i = 0; i < inputMapping.length; ++i) {
			fixed[i] = (signature[i].getParameterMode() == ParameterMode.INPUT);
			quantified[i] = (signature[i].getParameterMode() == ParameterMode.OUTPUT 
					&& signature[i].getExecutionMode() == ExecutionMode.MULTIPLE_RESULTS);
			if (!fixed[i]) {
				hasUniversal = hasUniversal || quantified[i];
				hasExistential = hasExistential || !quantified[i];
			}
		}
		boolean ignoreScope = isScopeIgnorable(signature);
		
		// default to single matching
		if (!hasUniversal && ignoreScope) {
			Tuple match = matcher.matchOne(inputMapping, fixed);
			return match==null? new ArrayList<IMatching>() :
				new ArrayList<IMatching>(Collections.singleton(new ReteMatching(match, matcher.getPosMapping())));
		}
		
		// retrieving the projection
		Collection<Tuple> unscopedMatches = matcher.matchAll(inputMapping, fixed);
	
		// processing matches, checking scopes
		if (unscopedMatches == null) return new ArrayList<IMatching>();
		ArrayList<IMatching> matchings = new ArrayList<IMatching>(unscopedMatches.size());
		TupleMask quantifiedMask = null;
		Set<Tuple> quantifiedProjections = null; 
		if (hasExistential) {
			quantifiedMask = new TupleMask(quantified);
			quantifiedProjections = new LinkedHashSet<Tuple>();
		}
		for (Tuple ps : /* productionNode */unscopedMatches) {
			//Tuple ps = boundary.unwrapTuple(um);
			Tuple quantifiedPart = null;
			if (hasExistential) {
				quantifiedPart = quantifiedMask.transform(ps);
				if (quantifiedProjections.contains(quantifiedPart)) continue; // not the first occurrence
			}
			boolean ok = true;
			if (!ignoreScope) for (int k = 0; (k < ps.getSize()) && ok; k++) {
				if (signature[k].getParameterMode() == ParameterMode.INPUT) {
					// ok = ok && (inputMapping[k]==ps.elements[k]);
					// should now be true
				} else // ParameterMode.OUTPUT
				{
					IEntity scopeParent = (IEntity) signature[k]
							.getParameterScope().getParent();
					Integer containmentMode = signature[k]
							.getParameterScope().getContainmentMode();
					if (containmentMode == Scope.BELOW) {
						// ok = ok &&
						// scopeParent.getAllComponents().contains
						// (ps.elements[k]);
						ok = ok
								&& ((IModelElement) ps.get(k))
										.isBelowNamespace(scopeParent);
					} else /* case Scope.IN: */
					{
						ok = ok
								&& scopeParent.equals(((IModelElement) ps
										.get(k)).getNamespace());
						// note: getNamespace returns null instead of the
						// (imaginary) modelspace root entity for top level
						// elements;
						// this is not a problem here as Scope.IN implies
						// scopeParent != root.
					}
	
				}
			}
	
			
			if (ok) {
				if (hasExistential) quantifiedProjections.add(quantifiedPart); 
				matchings.add(new ReteMatching(ps, matcher.getPosMapping()));
			}		
		}
		
		return matchings;
	}

	public IMatching matchRandomly(Object[] inputMapping, PatternCallSignature[] signature) {
		if(random == null){
			random = new Random();
		}
		// all unbounded parameters are set to return multiple results
		for(int j = 0; j < signature.length; j++)
		{
			// output parameters are in the front of the array
			if(signature[j].getParameterMode() == ParameterMode.OUTPUT)
				signature[j].setExecutionMode(ExecutionMode.MULTIPLE_RESULTS);
		}
		ArrayList<IMatching> allMatches = matchAll(inputMapping, signature, null);
		if (allMatches == null || allMatches.isEmpty()) return null;
		else return allMatches.get(random.nextInt(allMatches.size()));
	}

	boolean isScopeIgnorable(PatternCallSignature[] signature) {
		for (PatternCallSignature sig : signature) {
			if (sig.getParameterMode() == ParameterMode.OUTPUT) {
				Scope scope = sig.getParameterScope();
				if (scope.getContainmentMode() != Scope.BELOW || scope.getParent() != Scope.DEFAULT_PARENT)
					return false;
			}
		}
		return true;
	}

	/**
	 * Builds a mapping between parameter indices and scopes.
	 * @param signatures PatternCallSignature array, as present in an IPatternMatcher query
	 * @return a scope map suitable for ReteEngine.accessMatcherScoped()
	 */
	public static Map<Integer, Scope> buildAdditionalScopeMap(PatternCallSignature[] signatures) {
		Map<Integer, Scope> scopeMap = new HashMap<Integer, Scope>();
		for (int i=0; i<signatures.length; ++i) {
			PatternCallSignature signature = signatures[i];
			if (signature.getParameterMode().equals(ParameterMode.OUTPUT) && 
					! signature.getParameterScope().getParent().equals(Scope.DEFAULT_PARENT))
			{
				scopeMap.put(i, signature.getParameterScope());
			}
		}
		return scopeMap;
	}

}