//==============================================================================
/// Summary:
/// This function sets the root page for the navigation stack. The root page is 'below'
/// all other normal pages and cannot be popped like a normal page.
/// When we set a new root page, we first check if we have an existing root page.
/// If we do, we run the usual canClose() then onClose() function pair, then we 
/// set it and call the onOpen() for the new root page.
/// 
/// \param %rootPage (guiControl) The new guiControl that is being set as the root page of the navigation stack
function UINavigation::setRootPage(%this, %rootPage)
{
   if(!isObject(%this.pageStack))
   {
      %this.pageStack = new ArrayObject();  
   }
   
   if(isObject(%this.rootPage))
   {
      %canClose = true;
      if(%this.rootPage.isMethod("canClose"))
         %canClose = %this.rootPage.call("canClose");
         
      if(!%canClose)
         return; //if we're not allowed to close, just bail out wholesale because clearly 
                  //something is blocking changes to pages
         
      %this.remove(%this.rootPage);
      if(%this.rootPage.isMethod("onClose"))
         %this.rootPage.call("onClose");
         
      %this.rootPage.navigation = "";
   }
      
   %this.rootPage = %rootPage;
   
   %this.add(%rootPage);
   if(%this.resizePages)
   {
      %rootPage.resize(%this.position.x, %this.position.y, 
         %this.extent.x, %this.extent.y);
   }
   %rootPage.navigation = %this;
   
   if(%rootPage.isMethod("onOpen"))
      %rootPage.call("onOpen");
}

//==============================================================================
/// Summary:
/// This function pushes a page onto the given UINavigation-classed GUIContainer's stack
/// The order of operations is thus:
/// 1) check to see if the new page being pushed says it can open via the canOpen() function. 
///    If this method is not defined, it defaults to true, as there's no impediment to continuing
///    If this check returns false, the pushPage event cancels.
/// 2) check to see if the current page on the stack says it can close. Similar to 
///    the canOpen() check on the new page, we default to true
///    If this check returns false, the pushPage event cancels.
/// 3) Call - if defined - onClose() on the current top page of the stack
/// 4) Add the new page onto the stack
/// 5) Call - if defined - onOpen() on the new page
/// 6) Finally, if we defined a callback, call that.
/// With this all run, the previous top page has done any cleanup work it needed to
/// and the new top page has been opened successfully.
/// 
/// \param %newPage (guiControl) The new guiControl that is being added onto the page stack
/// \param %callback[optional]: (Evaluable string) A evalable statement to invoke when the push has been completed
function UINavigation::pushPage(%this, %newPage, %callback)
{
   if(!isObject(%this.pageStack))
   {
      %this.pageStack = new ArrayObject();
   }
   
   %canChange = true;
   if(%newPage.isMethod("canOpen"))
      %canChange = %newPage.call("canOpen");
      
   if(!%canChange)
      return;
      
   %currentPage = %this.getCurrentPage();
   if(isObject(%currentPage))
   {
      if(%currentPage.isMethod("canClose"))
         %canChange = %currentPage.call("canClose");
         
      if(!%canChange)
         return;
         
      if(%currentPage.isMethod("onClose"))
         %currentPage.call("onClose");
   }
   
   %this.pageStack.push_back(%newPage);
   %this.add(%newPage);
   if(%this.resizePages)
   {
      %newPage.resize(%this.position.x, %this.position.y, 
         %this.extent.x, %this.extent.y);
   }
   
   if(%newPage.isMethod("onOpen"))
      %newPage.call("onOpen");
   
   %newPage.navigation = %this;
   
   if(%callback !$= "")
   eval(%callback);
}

//==============================================================================
/// Summary:
/// This function pops the topmost page off the given UINavigation-classed GUIContainer's stack
/// The order of operations is thus:
/// 1) check to see if the top page being popped says it can close via the canClose() function. 
///    If this method is not defined, it defaults to true, as there's no impediment to continuing
///    If this check returns false, the popPage event cancels.
/// 2) check to see if the previous page on the stack says it can open. Similar to 
///    the canClose() check on the new page, we default to true
///    If this check returns false, the popPage event cancels.
/// 3) Call - if defined - onClose() on the current top page of the stack
/// 4) Remove the top page
/// 5) Call - if defined - onOpen() on the now topmost page
/// 6) Finally, if we defined a callback, call that.
/// With this all run, the previous top page has done any cleanup work it needed to
/// and the new top page has been opened successfully.
/// 
/// \param %callback[optional] (Evaluable string) A evalable statement to invoke when the pop has been completed
function UINavigation::popPage(%this, %callback)
{
   if(%this.pageStack.count() == 0)
      return;
      
   %currentPage = %this.getCurrentPage();
   if(isObject(%currentPage))
   {
      %canChange = true;
      if(%currentPage.isMethod("canClose"))
         %canChange = %currentPage.call("canClose");
         
      if(!%canChange)
         return;
   }
   
   %prevPage = %this.getPreviousPage();
   if(isObject(%prevPage))
   {
      %canChange = true;
      if(%prevPage.isMethod("canOpen"))
         %canChange = %prevPage.call("canOpen");
         
      if(!%canChange)
         return;
   }
      
   if(isObject(%currentPage))
   {
      if(%currentPage.isMethod("onClose"))
      {
         %currentPage.call("onClose");
      }    
      
      %this.pageStack.pop_back();
      %this.remove(%currentPage);
      
      %currentPage.navigation = "";
   }
   
   %newTopPage = %this.getCurrentPage();
   if(%newTopPage.isMethod("onOpen"))
      %newTopPage.call("onOpen");
   
   if(%callback !$= "")
   eval(%callback);
}

//==============================================================================
/// Summary:
/// In order tops the topmost page in a loop until it has closed the entire stack,
/// leaving only the root page
/// 
/// \param %callback[optional] (Evaluable String) A evalable statement to invoke when the pop has been completed
function UINavigation::popToRoot(%this, %callback)
{
   %pageChanged = false;
   while(%this.getPageCount() != 0)
   {
      %currentPage = %this.getCurrentPage();
      if(isObject(%currentPage))
      {
         if(%currentPage.isMethod("canClose"))
            %canChange = %currentPage.call("canClose");
            
         if(!%canChange)
            return;
      }
      
      %prevPage = %this.getPreviousPage();
      if(isObject(%prevPage))
      {
         if(%prevPage.isMethod("canOpen"))
            %canChange = %prevPage.call("canOpen");
            
         if(!%canChange)
            return;
      }
         
      if(isObject(%currentPage))
      {
         if(%currentPage.isMethod("onClose"))
         {
            %currentPage.call("onClose");
         }    

         %this.pageStack.pop_back();
         %this.remove(%currentPage);
         
         %currentPage.navigation = "";
      }
      
      %newTopPage = %this.getCurrentPage();
      if(%newTopPage.isMethod("onOpen"))
         %newTopPage.call("onOpen");
         
      %pageChanged = true;
   }
   
   if(%pageChanged && %callback !$= "")
      eval(%callback);
}

//==============================================================================
/// Summary:
/// Gets the current, topmost page on the stack. If no non-root pages are on the stack
/// the root page is returned
function UINavigation::getCurrentPage(%this)
{
   if(isObject(%this.pageStack) && %this.pageStack.count() != 0)
   {
      return %this.pageStack.getKey(%this.pageStack.count()-1);
   }
   else
   {
      if(isObject(%this.rootPage))
         return %this.rootPage;
   }
   
   return 0;
}

//==============================================================================
/// Summary:
/// Gets the page just under the topmost page in the stack. If there is no previous page
/// then the root page is returned
function UINavigation::getPreviousPage(%this)
{
   if(isObject(%this.pageStack) && %this.pageStack.count() > 1)
   {
      return %this.pageStack.getKey(%this.pageStack.count()-2);
   }
   else
   {
      if(isObject(%this.rootPage))
         return %this.rootPage;
   }
   
   return 0;
}   

//==============================================================================
/// Summary:
/// Gets the number of pages on the stack.
function UINavigation::getPageCount(%this)
{
   %count = 0;
   if(isObject(%this.pageStack))
      %count = %this.pageStack.count();
      
   if(isObject(%this.rootPage))
      %count++;
      
   return %count;
}