package fr.lifl.stc.stan.dsl;

public class FlowChecker
{
    private PolicyManager policies;
    
    public FlowChecker(PolicyManager pm)
    {
        policies = pm;
    }

    public boolean check(Flow f)
        throws FlowCheckerException
    {
        
//         System.out.println("VSS? : " + (f.link & Flow.VSS));
//         System.out.println("RSS? : " + (f.link & Flow.RSS));
//         System.out.println("RSP? : " + (f.link & Flow.RSP));
//         System.out.println("VSP? : " + (f.link & Flow.VSP));
//         System.out.println("RPP? : " + (f.link & Flow.RPP));
//         System.out.println("RSS? : " + (f.link & Flow.RPP));
//         System.out.println("RPS? : " + (f.link & Flow.RPS));
//         System.out.println("VPS? : " + (f.link & Flow.VPS));
        
        
        /* Secret to Public is always forbidden */
        if ( (f.link & (Flow.RPS | Flow.VPS) ) != 0 )
            throw new FlowCheckerException("Illegal Secret to Public flow : " + f);

        /* Secret to Secret */
        if ( (f.link & (Flow.RSS | Flow.VSS) ) != 0 )
        {
            /* Secret to Secret on same Class */
            if ( f.srcType.equals(f.dstType) )
            {
                /* Secret to Secret on same Instance */
                if ( f.src == Flow.FLOW_THIS && f.src == f.dst )
                {
                    //System.out.println("share this<->this SS");
                }
                /* is it a strict secret ? */
                else
                {
                    if ( policies.strictSecretHas(f.srcType) )
                        throw new FlowCheckerException("Strict secret violation : " + f);
                }
            }
            else
            {
                /* If we have a share with policy for this 'Secret to
                 * Secret', don't complain.
                 */
                if ( ! policies.shareWithHas(f.srcType, f.dstType) )
                    throw new FlowCheckerException("Illegal flow between : " + f);
            }
        }

        return true;
    }
}