/*******************************************************************************
 * Copyright (c) 2007, 2010 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:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.db.common.procedure;

import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

import org.simantics.db.AsyncReadGraph;
import org.simantics.db.common.utils.Logger;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.procedure.AsyncProcedure;

public class BlockingAsyncProcedure<Result> implements AsyncProcedure<Result> {

	final private Object key;
    private Result result = null;
    private Throwable exception = null;
    final private AsyncProcedure<Result> procedure;
    final private Semaphore semaphore = new Semaphore(0);
//    final private AtomicBoolean latch;
    
    public BlockingAsyncProcedure(AsyncProcedure<Result> procedure, Object key) {
//    	assert(procedure != null);
    	this.key = key;
        this.procedure = procedure;
        if(key == null)
        	System.err.println("asd");
        //System.err.println("BlockingAsyncProcedure " + key);
//        latch = new AtomicBoolean(false);
    }
    
    @Override
    public void execute(AsyncReadGraph graph, Result result) {
        this.result = result;
        semaphore.release();
//        if(latch.compareAndSet(false, true)) {
        	try {
        		if(procedure != null) procedure.execute(graph, result);
        	} catch (Throwable throwable) {
            	Logger.defaultLogError("AsyncProcedure.execute threw for " + procedure, throwable);
        	}
//        	} finally {
////        		System.err.println("ResultCallWrappedSingleQueryProcedure4 dec " + key);
//        	}
//        } else {
//        	Logger.defaultLogError("Procedure was called many times (this time is execute)");
//        }
    }

    @Override
    public void exception(AsyncReadGraph graph, Throwable t) {
        this.exception = t;
        semaphore.release();
//        if(latch.compareAndSet(false, true)) {
        	try {
        		if(procedure != null) procedure.exception(graph, t);
        	} catch (Throwable throwable) {
            	Logger.defaultLogError("AsyncProcedure.exception threw for " + procedure, throwable);
        	} finally {
        	}
//        } else {
//        	Logger.defaultLogError("Procedure was called many times (this time is exception)");
//        }
        
    }
    
    public Result get() throws DatabaseException {
    	
    	try {
			boolean success = semaphore.tryAcquire(10, TimeUnit.SECONDS);
			if(!success) throw new DatabaseException("Timeout while waiting for async request to complete: " + key);
		} catch (InterruptedException e) {
			throw new DatabaseException(e);
		}
    	
    	if(exception != null) {
    		if(exception instanceof DatabaseException) throw (DatabaseException)exception;
    		throw new DatabaseException(exception);
    	} else {
    		return result;
    	}
    	
    }
    
    public Result getResult() {
        return result;
    }
    
    public Throwable getException() {
        return exception;
    }
	
    @Override
    public String toString() {
        return "." + procedure; 
    }
    
}