package edu.stanford.peer.rbtm.engine;

import java.util.*;

import edu.stanford.peer.rbtm.credential.*;
import edu.stanford.peer.rbtm.util.*;

/*
 */
public abstract class AbstractProofNode implements ProofNode
{
	/** The EntityExpression this node is about. */
    EntityExpression   _roleExp;

	/** The proof _graph this node is in, this reference is used while processing 
	    this node */
    ProofGraph         _graph;

    /** Nodes that can reach this node directly, evidences are credentials. */
    protected HashSet  parents;  

    /** Nodes that this node can reach directly, evidecens are credentials. */
    protected HashSet  children; 

	/** Backward solutions on this node  */
    protected HashSet  backwardSolutions;

	/** Forward solutions on this node */
    protected HashSet  forwardSolutions;

    protected ArrayList  backwardListeners;
    protected ArrayList  forwardListeners;

    AbstractProofNode (ProofGraph graph, EntityExpression re, boolean trackAll)
    {
		_graph = graph;
        _roleExp = re;
        Debug.debugInfo("A new node is created for " + re);

        parents = new ResultEvidenceMap(trackAll);  
        children = new ResultEvidenceMap(trackAll); 
        backwardSolutions = new ResultEvidenceMap(trackAll);
		forwardSolutions = new ResultEvidenceMap(trackAll);
    
		backwardListeners = new HashSet();
		forwardListeners = new HashSet();

		// Call this in constructor instead of process methods, because
		// we want to record the fact that this node has been reached even 
		// without further processing
		finishInit();
    }

	/** 
	 * This method adds the node itself as both a forward solution and a backward
	 * aolution to itself.  If this behaviour is not appropriate, this method
	 * should be overriden.
	 */
	protected void finishInit()
	{
		ForwardSolution fs = _graph.getForwardSolution(_roleExp);
		if (fs != null) {
			forwardSolutionAdded(this, fs);
		}

		BackwardSolution bs = _graph.getBackwardSolution(_roleExp);
		if (bs != null) {
			backwardSolutionAdded(this, bs);
		}
	}

	public ProofGraph getGraph() {
		return _graph;
	}
	
	public EntityExpression getRoleExp() {
		return _roleExp;
	}

	public ResultEvidenceMap getForwardSolutions() {
		return forwardSolutions;
	}

	public ResultEvidenceMap getBackwardSolutions() {
		return backwardSolutions;
	}

    // The method that does the work when we visit a node
    public void forwardProcess() 
    {
        // first step: go over all credentials that have this as subject
        Iterator  credIt = _graph.findCredentialsBySubject(_roleExp);
        while (credIt.hasNext()) { 
            StaticCredential credential = (StaticCredential) credIt.next();
            ProofNode node = _graph.addForwardNode(credential.getDefinedRole());
			node.addParent(this, credential);
            //_graph.addProofEdge(this, node, credential);
        }

        // second step: find partial usage of this EntityExpression
		/*
        if (_roleExp instanceof Intersection) {
            return;
        }
        credIt = _graph.findCredentialsByPartialSubject(_roleExp);
        while (credIt.hasNext()) { 
            StaticCredential credential = (StaticCredential) credIt.next();
            ProofNode node = _graph.addForwardNode(credential.getDefinedRole());
            int j = ((Intersection) credential.getSubject()).getIndexOf(_roleExp);
            forward.solutionAdded(new PartialSolution(_roleExp, j));
        }
		*/
    }

    public void addBackwardListener(BackwardSolutionListener sl) {
        backwardListeners.add(sl);
    	propagateBackwardSolutionsTo(sl);
    }

    public void addForwardListener(ForwardSolutionListener sl) {
        forwardListeners.add(sl);
    	propagateForwardSolutionsTo(sl);
    }

    /**
     * Add a node as a parent to this node
     * @param  node: the parent node
     */
    public void addParent(ProofNode node, Object evidence) {
        if (! parents.contains(node.getRoleExp()) {  
			parents.add(node);
			addForwardListener(node);
        }
    }

    public void addChild(ProofNode node, Object evidence) {
	    if (children.putResultEvidence(node.getRoleExp(), evidence)) {  
    		addBackwardListener(node);
	    }
    }

    public void backwardSolutionAdded(ProofNode s, BackwardSolution r)
    {
        if (backwardSolutions.putResultEvidence(r, s)) {   // when solution r is new
            Debug.debugInfo("Solution added: " + getRoleExp() + "; " + s.getRoleExp() + "; " + r);
			propagateBackwardSolution(r);
        }
    }

    public void forwardSolutionAdded(ProofNode s, ForwardSolution r) {
		/*
       if (r instanceof PartialSolution) {
            Intersection re = r.getIntersection();
            Integer index = r.getNumber();
            HashMap value = (HashMap) partialSols.get(re);
            if (value == null) {   // first piece
                value = new HashMap();
                partialSols.put(re, value);
            }
            SmallSet evidences = value.get(index);
            if (evidences == null) { // A new piece
                evidences = new SmallSet(s);
                value.put(index, evidences);
                if (value.size() == re.getK()) { // have all pieces
                    // Add an edge from current node to re
                    // addEdge();
                }
            } else if (trackAll) {
                evidences.add(s);
            }
			return;
        } 
		*/
		if (forwardSolutions.putResultEvidence(r, s)) {
			Debug.debugInfo("Forward solution added to: " + getRoleExp() + "; " + s.getRoleExp() + "; " + r);
			propagateForwardSolution(r);
		}
    }

    protected void propagateBackwardSolutionsTo(BackwardSolutionListener listener)
    {
    	Object[] sols = backwardSolutions.resultSet().toArray();
    	for (int i=0; i<sols.length; i++) {
        	 listener.backwardSolutionAdded(this, (BackwardSolution)(sols[i]));
    	}
    }

    protected void propagateForwardSolutionsTo(ForwardSolutionListener listener)
    {
    	Object[] sols = forwardSolutions.resultSet().toArray();
    	for (int i=0; i<sols.length; i++) {
        	 listener.forwardSolutionAdded(this, (ForwardSolution)(sols[i]));
    	}
    }

    protected void propagateBackwardSolution(BackwardSolution g)
    {
    	Object[] listeners = backwardListeners.toArray();
    	for (int i=0; i<listeners.length; i++) {
    	    ((BackwardSolutionListener)listeners[i]).backwardSolutionAdded(this, g);
    	}
    }

    protected void propagateForwardSolution(ForwardSolution g)
    {
    	Object[] listeners = forwardListeners.toArray();
    	for (int i=0; i<listeners.length; i++) {
    	    ((ForwardSolutionListener)listeners[i]).forwardSolutionAdded(this, g);
    	}
    }


    // boolean hasParent(ProofNode node) { return parents.containsResult(node._roleExp); }


	//////////// code for SelectiveProofNode
    /*
     * The following two fields store desired goals.  Only desired goals are 
     * passed through edges.  Setting them to null means all goals are 
     * desired.
     * In backward search, if child A.r only wants to see one solution, while 
     * child A.r1.r2 wants to see all solutions.  All goals are desired, so
     * they are passed to A.r as well.  But A.r should have only one desired
     * solution, and so A.r will not propagate them further.
     */
    // SmallSet  backwardGoals = new SmallSet(); 
    // SmallSet  forwardGoals = new SmallSet();

    /* 
    void enableBackwardGoal(EntityExpression g)
    {
        if (backwardGoals != null && ! backwardGoals.containsGoal(g)) { 
    		// has not been enabled before
            backwardGoals.addGoal(g);
            if (backwardSoltuions.containsResult(g)) {
    			propagateBackwardSolution(g);
            }
            // Enable this backward goal for all parents
            Object[] list = parents.toArray();  // inform listeners
            for (int i=0; i<list.length; i++) {
                ((ProofNode)list[i]).enableBackwardGoal(g);
            }
        }
    }

    void enableAllBackwardGoals()
    {
        if (backwardGoals == null ) {
            backwardGoals = null;
            // if have been procesed, loop over all parents, and enable them
            // if haven't been processed, just enable it
        }
    }
    */
} // End of class ProofNode