/*******************************************************************************
 * Copyright (c) 2019 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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:
 *     Semantum Oy - initial API and implementation
 *******************************************************************************/
package org.simantics.internal;

import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;
import java.util.function.Consumer;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.simantics.UnhandledExceptionService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Antti Villberg
 */
public class UnhandledExceptionServiceImpl implements UnhandledExceptionService {

    private static final Logger LOGGER = LoggerFactory.getLogger(UnhandledExceptionServiceImpl.class);
    private static ServiceRegistration<?> service = null;

    private final List<Consumer<Throwable>>       handlers   = new ArrayList<>();

    /**
     * Invoked by the bundle activator to initialize the cache service.
     * 
     * @param context the bundle context to register the service with
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public synchronized static void initialize(BundleContext context) {
        if (service == null) {
            service = context.registerService(UnhandledExceptionService.class.getName(), new UnhandledExceptionServiceImpl(), new Hashtable());
        }
    }

    /**
     * Invoked by the bundle activator to close the cache service.
     */
    public synchronized static void close() {
        if (service != null) {
            service.unregister();
            service = null;
        }
    }

    @Override
    public synchronized void registerHandler(Consumer<Throwable> handler) {
        handlers.add(handler);
    }

    @Override
    public synchronized void handle(Throwable t) {
        for (Consumer<Throwable> handler : handlers) {
            try {
                handler.accept(t);
            } catch (Exception e) {
                handleException(handler, e);
            } catch (LinkageError e) {
                handleException(handler, e);
            } catch (AssertionError e) {
                handleException(handler, e);
            }
        }
    }

    protected void handleException(Object source, Throwable t) {
        LOGGER.error("{}: Unhandled exception handler {} caused unexpected exception", getClass().getSimpleName(), source, t);
    }

}