package com.atlassian.pageobjects.elements.query.webdriver;
   
   import com.atlassian.pageobjects.elements.query.AbstractTimedQuery;
   import com.atlassian.pageobjects.elements.query.ExpirationHandler;
   import com.atlassian.pageobjects.elements.query.util.Clock;
   import com.atlassian.pageobjects.elements.query.util.SystemClock;
   import com.google.common.base.Supplier;
   
   import javax.annotation.concurrent.NotThreadSafe;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * <p>
   * Generic, WebDriver-based implementation of {@link com.atlassian.pageobjects.elements.query.TimedQuery}.
   *
   * <p>
   * It accepts a supplier of the target value and uses it to retrieve current value od the query. The functions are
   * supposed to throw {@link com.atlassian.pageobjects.elements.query.webdriver.GenericWebDriverTimedQuery.InvalidValue}
   * to indicate that the current value should not be accepted as valid and returned by the query.
   *
   */
  @NotThreadSafe
  public class GenericWebDriverTimedQuery<T> extends AbstractTimedQuery<T>
  {
      protected final Supplier<T> valueSupplier;
      private boolean invalidValue;
  
      public GenericWebDriverTimedQuery(Supplier<T> supplier, Clock clock, long defTimeout,
              long interval, ExpirationHandler eh)
      {
          super(clock, defTimeout, interval, eh);
          this.valueSupplier = checkNotNull(supplier);
      }
  
      public GenericWebDriverTimedQuery(Supplier<T> supplier, long defTimeout, long interval,
              ExpirationHandler eh)
      {
          this(supplier, SystemClock.INSTANCE, defTimeout, interval, eh);
      }
  
      public GenericWebDriverTimedQuery(Supplier<T> supplier, long defTimeout, long interval)
      {
          this(supplier, SystemClock.INSTANCE, defTimeout, interval, ExpirationHandler.RETURN_CURRENT);
      }
  
      public GenericWebDriverTimedQuery(Supplier<T> supplier, long defTimeout)
      {
          this(supplier, SystemClock.INSTANCE, defTimeout, DEFAULT_INTERVAL, ExpirationHandler.RETURN_CURRENT);
      }
  
      public GenericWebDriverTimedQuery(GenericWebDriverTimedQuery<T> origin, long timeout)
      {
          this(origin.valueSupplier, origin.clock(), timeout, origin.interval(), origin.expirationHandler());
      }
  
      @Override
      protected final boolean shouldReturn(final T currentEval)
      {
          return !invalidValue;
      }
  
      @Override
      protected final T currentValue()
      {
          invalidValue = false;
          try
          {
              return valueSupplier.get();
          }
          catch (InvalidValue e)
          {
              invalidValue = true;
              return (T)e.value;
          }
      }
  
      public static final class InvalidValue extends RuntimeException
      {
          private static final long serialVersionUID = -4972134972343443297L;
  
          private final Object value;
  
          public InvalidValue(final Object value)
          {
              this.value = value;
          }
  
          @Override
          public Throwable fillInStackTrace()
          {
              return this;
          }
          
      }
  }