/**
 *
 */
package org.dcache.services.info.secondaryInfoProviders;

import java.util.ArrayList;
import java.util.Collection;

import org.dcache.services.info.base.StateExhibitor;
import org.dcache.services.info.base.StatePathPredicate;
import org.dcache.services.info.base.StateUpdate;
import org.dcache.services.info.base.StateWatcher;

/**
 * Provide a skeleton, basic implementation of a StateWatcher with
 * static StatePathPredicates.  Sub-classes of this class must
 * implement a getPredicates() method that returns an array of
 * Strings (the predicates).
 *
 * @author Paul Millar <paul.millar@desy.de>
 */
public abstract class AbstractStateWatcher implements StateWatcher
{
    private long _counter;
    private final Collection<StatePathPredicate> _predicates = new ArrayList<>();

    public AbstractStateWatcher()
    {
        String[] paths = getPredicates();

        for (String path : paths) {
            _predicates.add(StatePathPredicate.parsePath(path));
        }
    }


    /**
     * Override this method.  The method must return valid output
     * when called from the constructor.
     * @return an array of Strings, each a StatePathPredicate.
     */
    protected abstract String[] getPredicates();

    @Override
    public synchronized void trigger(StateUpdate update, StateExhibitor currentState,
            StateExhibitor futureState)
    {
        _counter++;
    }

    @Override
    public Collection<StatePathPredicate> getPredicate()
    {
        return _predicates;
    }

    /**
     * Since we expect a single instance per class, just return the simple class name.
     */
    @Override
    public String toString()
    {
        return this.getClass().getSimpleName();
    }

    public synchronized long getCount()
    {
        return _counter;
    }
}