package org.oddjob.state;

import java.util.Date;

import org.apache.log4j.Logger;
import org.oddjob.arooa.life.ComponentPersistException;
import org.oddjob.images.IconHelper;
import org.oddjob.images.StateIcons;
import org.oddjob.persist.Persistable;

/**
 * Base functionality for changing {@link State}. This utility class is
 * responsible for notifying the change with the {@link StateHandler},
 * changing the icon, and persisting the job if necessary.
 * 
 * @author rob
 *
 * @param <S> The type of State.
 */
public class BaseStateChanger<S extends State> implements StateChanger<S> {
		
	private static final Logger logger = Logger.getLogger(BaseStateChanger.class);
	
	private final StateHandler<S> stateHandler;
	private final IconHelper iconHelper;
	private final Persistable persistable;
	private final S exceptionState;
	
	public BaseStateChanger(StateHandler<S> stateHandler,
			IconHelper iconHelper, Persistable persistable,
			S exceptionState) {
		this.stateHandler = stateHandler;
		this.iconHelper = iconHelper;
		this.persistable = persistable;
		this.exceptionState = exceptionState;
	}
	
		public void setState(S state) {
			setState(state, new Date());
		}
		
		public void setState(S state, Date date) {
			if (state == stateHandler.getState()) {
				return;
			}
			
			stateHandler.setState(state, date);
			iconHelper.changeIcon(StateIcons.iconFor(state));
			
			try {
				
				if (new IsSaveable().test(state)) {
						persistable.persist();
				}
				
				stateHandler.fireEvent();
				
				
			} catch (ComponentPersistException e) {
				logger.error("Failed persisting state " + state, e);
				setStateException(e);
			}
		}
		
		public void setStateException(Throwable t) {
			setStateException(t, new Date());
		}
		
		public void setStateException(Throwable t, Date date) {
			if (exceptionState == stateHandler.getState()) {
				return;
			}
			
			stateHandler.setStateException(exceptionState, t, date);
			iconHelper.changeIcon(IconHelper.EXCEPTION);
			
			if (new IsSaveable().test(exceptionState) &&
					!(t instanceof ComponentPersistException)) {
				try {
					persistable.persist();
				} catch (ComponentPersistException e) {
					logger.error("Failed persisting state " + exceptionState, e);
					stateHandler.setStateException(exceptionState, e, date);
				}
			}
			
			stateHandler.fireEvent();			
		}
}