// SDL2_02 [Moving Rectangle].nova
// Simple SDL2 example with moving rectangle.



// Using namespace declarations.
using namespace lib.emscripten;
using namespace lib.sdl2;



// The application class.
class SDL2_02_Moving_Rectangle
{
   // Static data members.
   private static SDL_Window window;
   private static SDL_Renderer renderer;
   private static SDL_Rect rect;


   // Application class's "main" function.
   public static void main( String[] args )
   {
      Stream.writeLine( "SDL2_02 [Moving Rectangle].nova" );


      // Disable the emscripten full-screen controls.
      Emscripten.disableControls( );

      // Setup SDL.
      SDL2.SDL_Init( SDL2.SDL_INIT_VIDEO );

      window = SDL2.SDL_CreateWindow( "SDL2_02 [Moving Rectangle]",
                                      SDL2.SDL_WINDOWPOS_CENTERED,
                                      SDL2.SDL_WINDOWPOS_CENTERED,
                                      640,
                                      480,
                                      SDL2.SDL_WINDOW_SHOWN );

      // Check for a null reference.
      if ( window == null )
      {
         // Output an error message.
         Stream.writeLine( "Failed to create window: " + SDL2.SDL_GetError( ) );

         // Abort the application.
         return;
      }

      renderer = SDL2.SDL_CreateRenderer( window, -1, SDL2.SDL_RENDERER_ACCELERATED | SDL2.SDL_RENDERER_PRESENTVSYNC );


      // Define the rectangle.
      rect = new SDL_Rect( -80, 100, 80, 80 );


      // Check for the emscripten environment.
      if ( Emscripten.isActive( ) )
      {
         int simulate_infinite_loop = 1;  // Call the function repeatedly.
         int fps = -1;  // Call the function as fast as the browser wants to render (typically 60fps).
         Emscripten.setMainLoop( renderFrame, fps, simulate_infinite_loop );
      }
      else
      {
         // Rendering and event processing loop.
         do
         {
            SDL_Event e = SDL2.SDL_PollEvent( );
            if ( e != null )
               if ( e.id == SDL2.SDL_QUIT )
                  break;

            renderFrame( );
         }
         while( true );
      }


      // Shutdown app.
      SDL2.SDL_DestroyRenderer( renderer );
      SDL2.SDL_DestroyWindow( window );
      SDL2.SDL_Quit( );
   }


   public static void renderFrame( )
   {
      // Set the background colour (dark blue).
      SDL2.SDL_SetRenderDrawColor( renderer, 0, 0, 128, 255 );

      // Clear the window.
      SDL2.SDL_RenderClear( renderer );

      // Set the rectangle colour (orange).
      SDL2.SDL_SetRenderDrawColor( renderer, 255, 128, 0, 255 );

      // Render the rectangle.
      SDL2.SDL_RenderFillRect( renderer, rect );

      // Update the screen.
      SDL2.SDL_RenderPresent( renderer );

      // Move the rectangle and wraparound if required.
      if ( ++rect.x > 640 )
         rect.x = -80;
   }
}