package com.atlassian.webdriver.utils.element;
   
   import com.atlassian.webdriver.utils.Check;
   import org.apache.commons.lang.Validate;
   import org.openqa.selenium.By;
   import org.openqa.selenium.SearchContext;
   import org.openqa.selenium.WebDriver;
   import org.openqa.selenium.support.ui.ExpectedCondition;
   
  /**
   * Condition to wait for an element's visibility.
   *
   * @since 2.0
   */
  abstract class ElementVisibilityCondition implements ExpectedCondition<Boolean>
  {
  
      enum Visibility
      {
          VISIBLE,
          NOTVISIBLE
      }
  
      private final By by;
      private final SearchContext at;
      private final Visibility visibility;
  
      ElementVisibilityCondition(By by, Visibility visibility)
      {
          this(by, null, visibility);
      }
  
      ElementVisibilityCondition(By by, SearchContext el, Visibility visibility)
      {
          Validate.notNull(by, "by cannot be null.");
  
          this.by = by;
          this.at = el;
          this.visibility = visibility;
      }
  
      final public Boolean apply(WebDriver webDriver)
      {
          if (visibility.equals(Visibility.VISIBLE))
          {
              return Check.elementIsVisible(by, at == null ? webDriver : at);
          }
          else
          {
              return !Check.elementIsVisible(by, at == null ? webDriver : at);
          }
      }
  }