package cz.cuni.amis.utils.future;
   
   import java.util.concurrent.Future;
   import java.util.concurrent.TimeUnit;
   
   import cz.cuni.amis.utils.NullCheck;
   import cz.cuni.amis.utils.TimeUnitToMillis;
   import cz.cuni.amis.utils.exception.PogamutTimeoutException;
   
  /**
   * Used to combine multiple Future<Boolean> together into one Future<Boolean>.
   * <p><p>
   * During construction of the instance of this class you have to specify an array of
   * booleans you want to combine - then all methods will wait for all futures to end
   * (e.g. get(), etc.).
   * <p><p>
   * Note that you will probably want to use getAll() method to get respective Future results.
   * 
   * @author Jimmy
   *
   */
  public class CombinedBooleanFuture implements IFuture<Boolean> {
  	
  	private IFuture<Boolean>[] futures;
  	
  	public CombinedBooleanFuture(IFuture<Boolean>[] futures) {
  		this.futures = futures;
  		NullCheck.check(this.futures, "futures");
  	}
  
  	@Override
  	public boolean cancel(boolean mayInterruptIfRunning) {
  		boolean canceled = true;
  		for (Future<Boolean> future : futures) {
  			canceled = canceled && future.cancel(mayInterruptIfRunning);
  		}
  		return canceled;
  	}
  
  	@Override
  	public Boolean get() {
  		boolean result = true;
  		for (IFuture<Boolean> future : futures) {
  			Boolean futureResult = future.get(); 
  			result = result && (futureResult != null ? futureResult : false);
  		}
  		return result;
  	}
  
  	@Override
  	public Boolean get(long timeout, TimeUnit unit) {
  		long timeoutMillis = TimeUnitToMillis.toMillis(timeout, unit);
  		long start = System.currentTimeMillis();
  		boolean result = true;
  		for (IFuture<Boolean> future : futures) {
  			long futureStart = System.currentTimeMillis();
  			if (futureStart - start > timeoutMillis) throw new PogamutTimeoutException("timeouted after " + timeout + " " + unit, this);
  			Boolean futureResult = future.get(timeoutMillis - (futureStart - start), TimeUnit.MILLISECONDS);
  			result = result && (futureResult != null ? futureResult : false);
  		}
  		return result;
  	}
  	
  	public Boolean[] getAll(long timeout, TimeUnit unit) {
  		long timeoutMillis = TimeUnitToMillis.toMillis(timeout, unit);
  		long start = System.currentTimeMillis();
  		Boolean[] results = new Boolean[futures.length];
  		int i = 0;
  		for (IFuture<Boolean> future : futures) {
  			long futureStart = System.currentTimeMillis();
  			if (futureStart - start > timeoutMillis) throw new PogamutTimeoutException("timeouted after " + timeout + " " + unit, this);
  			results[i++] = future.get(timeoutMillis - (futureStart - start), TimeUnit.MILLISECONDS);
  		}
  		return results;
  	} 
  
  	@Override
  	public boolean isCancelled() {
  		boolean result = false;
  		for (Future<Boolean> future : futures) {
  			Boolean futureResult = future.isCancelled(); 
  			result = result || (futureResult != null ? futureResult : false);			
  		}
  		return result;
  	}
  
  	@Override
  	public boolean isDone() {
  		boolean result = true;
  		for (Future<Boolean> future : futures) {			
  			result = result && future.isDone();
  		}
  		return result;
  	}
  	
  	public Future<Boolean>[] getFutures() {
  		return futures;
  	}
  
 }