//========= Copyright © 1996-2008, Valve LLC, All rights reserved. ============
//
// Purpose: Main class for the game engine
//
// $NoKeywords: $
//=============================================================================

#ifndef GAMEENGINE_H
#define GAMEENGINE_H

#include <set>
#include <map>

// Typedef for font handles
typedef int HGAMEFONT;

// Typedef for vertex buffer handles
typedef int HGAMEVERTBUF;

// Typedef for texture handles
typedef int HGAMETEXTURE;


// BDrawText position flags
#define TEXTPOS_TOP                      0x00000000
#define TEXTPOS_LEFT                     0x00000000
#define TEXTPOS_CENTER                   0x00000001
#define TEXTPOS_RIGHT                    0x00000002
#define TEXTPOS_VCENTER                  0x00000004
#define TEXTPOS_BOTTOM                   0x00000008

//
// Interface that needs to be implemented for game engines on all platforms
//
class IGameEngine
{
public:

	// Just here to stop warnings on non-virtual destructor in PS3 build
	virtual ~IGameEngine() {};

	// Check if the game engine is initialized ok and ready for use
	virtual bool BReadyForUse() = 0;

	// Check if the engine is shutting down
	virtual bool BShuttingDown() = 0;

	// Set the background color
	virtual void SetBackgroundColor( short a, short r, short g, short b ) = 0;

	// Start a frame, clear(), beginscene(), etc
	virtual bool StartFrame() = 0;

	// Finish a frame, endscene(), present(), etc.
	virtual void EndFrame() = 0;

	// Shutdown the game engine
	virtual void Shutdown() = 0;

	// Pump messages from the OS
	virtual void MessagePump() = 0;

	// Accessors for game screen size
	virtual int32 GetViewportWidth() = 0;
	virtual int32 GetViewportHeight() = 0;

	// Function for drawing text to the screen, dwFormat is a combination of flags like DT_LEFT, TEXTPOS_VCENTER etc...
	virtual bool BDrawString( HGAMEFONT hFont, RECT rect, DWORD dwColor, DWORD dwFormat, const char *pchText ) = 0;

	// Create a new font returning our internal handle value for it (0 means failure)
	virtual HGAMEFONT HCreateFont( int nHeight, int nFontWeight, bool bItalic, char * pchFont ) = 0;

	// Create a new texture returning our internal handle value for it (0 means failure)
	virtual HGAMETEXTURE HCreateTexture( byte *pRGBAData, uint32 uWidth, uint32 uHeight ) = 0;

	// Draw a line, the engine itself will manage batching these (although you can explicitly flush if you need to)
	virtual bool BDrawLine( float xPos0, float yPos0, DWORD dwColor0, float xPos1, float yPos1, DWORD dwColor1 ) = 0;

	// Flush the line buffer
	virtual bool BFlushLineBuffer() = 0;

	// Draw a point, the engine itself will manage batching these (although you can explicitly flush if you need to)
	virtual bool BDrawPoint( float xPos, float yPos, DWORD dwColor ) = 0;

	// Flush the point buffer
	virtual bool BFlushPointBuffer() = 0;

	// Draw a filled quad
	virtual bool BDrawFilledQuad( float xPos0, float yPos0, float xPos1, float yPos1, DWORD dwColor ) = 0;

	// Draw a textured rectangle 
	virtual bool BDrawTexturedQuad( float xPos0, float yPos0, float xPos1, float yPos1, 
		float u0, float v0, float u1, float v1, DWORD dwColor, HGAMETEXTURE hTexture ) = 0;

	// Flush any still cached quad buffers
	virtual bool BFlushQuadBuffer() = 0;

	// Get the current state of a key
	virtual bool BIsKeyDown( DWORD dwVK ) = 0;

	// Get the first (in some arbitrary order) key down, if any
	virtual bool BGetFirstKeyDown( DWORD *pdwVK ) = 0;

	// Get current tick count for the game engine
	virtual uint64 GetGameTickCount() = 0;

	// Tell the game engine to update current tick count
	virtual void UpdateGameTickCount() = 0;

	// Tell the game engine to sleep for a bit if needed to limit frame rate.  Returns
	// true if you need to keep calling it to sleep more to reach your limit, returns
	// false when you should proceed to the next frame.
	virtual bool BSleepForFrameRateLimit( uint32 ulMaxFrameRate ) = 0;

	// Get the tick count elapsed since the previous frame
	// bugbug - We use this time to compute things like thrust and acceleration in the game,
	//			so it's important in doesn't jump ahead by large increments... Need a better
	//			way to handle that.  
	virtual uint64 GetGameTicksFrameDelta() = 0;

	// Check if the game engine hwnd currently has focus (and a working d3d device)
	virtual bool BGameEngineHasFocus() = 0;

};

#endif // GAMEENGINE_H