/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

//=============================================================================
//
// Implementation base for graphics driver
//
//=============================================================================

#ifndef AGS_ENGINE_GFX_GFX_DRIVER_BASE_H
#define AGS_ENGINE_GFX_GFX_DRIVER_BASE_H

#include "common/std/memory.h"
#include "common/std/map.h"
#include "common/std/vector.h"
#include "ags/engine/gfx/ddb.h"
#include "ags/shared/gfx/gfx_def.h"
#include "ags/engine/gfx/graphics_driver.h"
#include "ags/shared/util/scaling.h"

namespace AGS3 {
namespace AGS {
namespace Engine {

using Shared::Bitmap;
using Shared::PlaneScaling;

// Sprite batch, defines viewport and an optional model transformation for the list of sprites
struct SpriteBatchDesc {
	uint32_t                 Parent = UINT32_MAX;
	// View rectangle for positioning and clipping, in resolution coordinates
	// (this may be screen or game frame resolution, depending on circumstances)
	Rect                     Viewport;
	// Optional model transformation, to be applied to each sprite
	SpriteTransform          Transform;
	// Optional flip, applied to the whole batch as the last transform
	Shared::GraphicFlip      Flip = Shared::kFlip_None;
	// Optional bitmap to draw sprites upon. Used exclusively by the software rendering mode.
	PBitmap                  Surface;
	// Optional filter flags; this lets to filter certain batches out during some operations,
	// such as fading effects or making screenshots.
	uint32_t				 FilterFlags = 0u;

	SpriteBatchDesc() = default;
	SpriteBatchDesc(uint32_t parent, const Rect viewport, const SpriteTransform & transform,
		Shared::GraphicFlip flip = Shared::kFlip_None, PBitmap surface = nullptr, uint32_t filter_flags = 0)
		: Parent(parent)
		, Viewport(viewport)
		, Transform(transform)
		, Flip(flip)
		, Surface(surface)
		, FilterFlags(filter_flags) {
	}
};

typedef std::vector<SpriteBatchDesc> SpriteBatchDescs;

// The single sprite entry in the render list
template<class T_DDB>
struct SpriteDrawListEntry {
	T_DDB *ddb = nullptr; // TODO: use shared pointer?
	uint32_t node = 0; // sprite batch / scene node index
	int x = 0, y = 0; // sprite position, in local batch / node coordinates
	bool skip = false;

	SpriteDrawListEntry() = default;
	SpriteDrawListEntry(T_DDB * ddb_, uint32_t node_, int x_, int y_)
		: ddb(ddb_)
		, node(node_)
		, x(x_)
		, y(y_)
		, skip(false) {
	}
};


// GraphicsDriverBase - is the parent class for all graphics drivers in AGS,
// that incapsulates the most common functionality.
class GraphicsDriverBase : public IGraphicsDriver {
public:
	GraphicsDriverBase();

	bool        IsModeSet() const override;
	bool        IsNativeSizeValid() const override;
	bool        IsRenderFrameValid() const override;
	DisplayMode GetDisplayMode() const override;
	Size        GetNativeSize() const override;
	Rect        GetRenderDestination() const override;

	bool		SetVsync(bool enabled) override;
	bool		GetVsync() const override;

	void 		BeginSpriteBatch(const Rect &viewport, const SpriteTransform &transform,
						 		 Shared::GraphicFlip flip = Shared::kFlip_None, PBitmap surface = nullptr,
								 uint32_t filter_flags = 0) override;
	void        EndSpriteBatch() override;
	void        ClearDrawLists() override;

	void        SetCallbackForPolling(GFXDRV_CLIENTCALLBACK callback) override {
		_pollingCallback = callback;
	}
	void        SetCallbackToDrawScreen(GFXDRV_CLIENTCALLBACK callback, GFXDRV_CLIENTCALLBACK post_callback) override {
		_drawScreenCallback = callback;
		_drawPostScreenCallback = post_callback;
	}
	void        SetCallbackOnInit(GFXDRV_CLIENTCALLBACKINITGFX callback) override {
		_initGfxCallback = callback;
	}
	void        SetCallbackOnSpriteEvt(GFXDRV_CLIENTCALLBACKEVT callback) override {
		_spriteEvtCallback = callback;
	}

protected:
	// Special internal values, applied to DrawListEntry
	static const uintptr_t DRAWENTRY_STAGECALLBACK = 0x0;
	static const uintptr_t DRAWENTRY_FADE = 0x1;
	static const uintptr_t DRAWENTRY_TINT = 0x2;

	// Called after graphics driver was initialized for use for the first time
	virtual void OnInit();
	// Called just before graphics mode is going to be uninitialized and its
	// resources released
	virtual void OnUnInit();
	// Called after new mode was successfully initialized
	virtual void OnModeSet(const DisplayMode &mode);
	// Called when the new native size is set
	virtual void OnSetNativeRes(const GraphicResolution &native_res);
	// Called before display mode is going to be released
	virtual void OnModeReleased();
	// Called when new render frame is set
	virtual void OnSetRenderFrame(const Rect &dst_rect);
	// Called when the new filter is set
	virtual void OnSetFilter();

	// Try changing vsync setting; fills new current mode in vsync_res,
	// returns whether the new setting was set successfully.
	virtual bool SetVsyncImpl(bool vsync, bool &vsync_res) { return false; }

	// Initialize sprite batch and allocate necessary resources
	virtual void InitSpriteBatch(size_t index, const SpriteBatchDesc &desc) = 0;
	// Gets the index of a last draw entry (sprite)
	virtual size_t GetLastDrawEntryIndex() = 0;
	// Clears sprite lists
	virtual void ResetAllBatches() = 0;

	void         OnScalingChanged();

	DisplayMode         _mode;          // display mode settings
	Rect                _srcRect;       // rendering source rect
	int                 _srcColorDepth; // rendering source color depth (in bits per pixel)
	Rect                _dstRect;       // rendering destination rect
	Rect                _filterRect;    // filter scaling destination rect (before final scaling)
	PlaneScaling        _scaling;       // native -> render dest coordinate transformation

	// Capability flags
	bool				_capsVsync = false; // is vsync available

	// Callbacks
	GFXDRV_CLIENTCALLBACK _pollingCallback;
	GFXDRV_CLIENTCALLBACK _drawScreenCallback;
	GFXDRV_CLIENTCALLBACK _drawPostScreenCallback;
	GFXDRV_CLIENTCALLBACKEVT _spriteEvtCallback;
	GFXDRV_CLIENTCALLBACKINITGFX _initGfxCallback;

	// Sprite batch parameters
	SpriteBatchDescs _spriteBatchDesc;
	// The range of sprites in this sprite batch (counting nested sprites):
	// the index of a first of the current batch, and the next index past the last one.
	std::vector<std::pair<size_t, size_t>> _spriteBatchRange;
	// The index of a currently filled sprite batch
	size_t _actSpriteBatch;
	// The index of a currently rendered sprite batch
	// (or -1 / UINT32_MAX if we are outside of the render pass)
	uint32_t _rendSpriteBatch;
};




// Parent class for the video memory DDBs
class BaseDDB : public IDriverDependantBitmap {
public:
	int GetWidth() const override {
		return _width;
	}
	int GetHeight() const override {
		return _height;
	}
	int GetColorDepth() const override {
		return _colDepth;
	}

	int _width = 0, _height = 0;
	int _colDepth = 0;
	bool _hasAlpha = false; // has meaningful alpha channel
	bool _opaque = false;   // no mask color

protected:
	BaseDDB() {}
	virtual ~BaseDDB() {}
};

// A base parent for the otherwise opaque texture data object;
// TextureData refers to the pixel data itself, with no additional
// properties. It may be shared between multiple sprites if necessary.
struct TextureData {
	uint32_t ID = UINT32_MAX;
	bool RenderTarget = false; // replace with flags later
	virtual ~TextureData() = default;
protected:
	TextureData() = default;
};

// Generic TextureTile base
struct TextureTile {
	int x = 0, y = 0;
	int width = 0, height = 0;
	// allocWidth and allocHeight tell the actual allocated texture size
	int allocWidth = 0, allocHeight = 0;
};


// VideoMemoryGraphicsDriver - is the parent class for the graphic drivers
// which drawing method is based on passing the sprite stack into GPU,
// rather than blitting to flat screen bitmap.
class VideoMemoryGraphicsDriver : public GraphicsDriverBase {
public:
	VideoMemoryGraphicsDriver();
	~VideoMemoryGraphicsDriver() override;

	bool RequiresFullRedrawEachFrame() override { return true; }
	bool HasAcceleratedTransform() override { return true; }
	// NOTE: although we do use ours, we do not let engine draw upon it;
	// only plugin handling are allowed to request our mem buffer
	// for compatibility reasons.
	bool UsesMemoryBackBuffer() override { return false; }

	Bitmap *GetMemoryBackBuffer() override;
	void SetMemoryBackBuffer(Bitmap *backBuffer) override;
	Bitmap *GetStageBackBuffer(bool mark_dirty) override;
	void SetStageBackBuffer(Bitmap *backBuffer) override;
	bool GetStageMatrixes(RenderMatrixes &rm) override;
	// Creates new texture using given parameters
	IDriverDependantBitmap *CreateDDB(int width, int height, int color_depth, bool opaque) override = 0;
	// Creates new texture and copy bitmap contents over
	IDriverDependantBitmap *CreateDDBFromBitmap(Bitmap *bitmap, bool has_alpha, bool opaque = false) override;
	// Get shared texture from cache, or create from bitmap and assign ID
	IDriverDependantBitmap *GetSharedDDB(uint32_t sprite_id, Bitmap *bitmap, bool has_alpha, bool opaque) override;
	// Removes the shared texture reference, will force the texture to recreate next time
	void ClearSharedDDB(uint32_t sprite_id) override;
	// Updates shared texture data, but only if it is present in the cache
	void UpdateSharedDDB(uint32_t sprite_id, Bitmap *bitmap, bool has_alpha, bool opaque) override;
	void DestroyDDB(IDriverDependantBitmap* ddb) override;

	// Sets stage screen parameters for the current batch.
	void SetStageScreen(const Size &sz, int x = 0, int y = 0) override;

protected:
	// Create texture data with the given parameters
	virtual TextureData *CreateTextureData(int width, int height, bool opaque, bool as_render_target = false) = 0;
	// Update texture data from the given bitmap
	virtual void UpdateTextureData(TextureData *txdata, Bitmap *bmp, bool has_alpha, bool opaque) = 0;
	// Create DDB using preexisting texture data
	virtual IDriverDependantBitmap *CreateDDB(std::shared_ptr<TextureData> txdata,
		  int width, int height, int color_depth, bool opaque) = 0;
	// Retrieve shared texture data object from the given DDB
	virtual std::shared_ptr<TextureData> GetTextureData(IDriverDependantBitmap *ddb) = 0;
	virtual void DestroyDDBImpl(IDriverDependantBitmap* ddb) = 0;

	// Stage screens are raw bitmap buffers meant to be sent to plugins on demand
	// at certain drawing stages. If used at least once these buffers are then
	// rendered as additional sprites in their respected order.
	// Presets a stage screen with the given position (size is obligatory, offsets not).
	void SetStageScreen(size_t index, const Size &sz, int x = 0, int y = 0);
	// Returns a raw bitmap for the given stage screen.
	Bitmap *GetStageScreenRaw(size_t index);
	// Updates and returns a DDB for the given stage screen, and optional x,y position;
	// clears the raw bitmap after copying to the texture.
	IDriverDependantBitmap *UpdateStageScreenDDB(size_t index, int &x, int &y);
	// Disposes all the stage screen raw bitmaps and DDBs.
	void DestroyAllStageScreens();
	// Use engine callback to pass a render event;
	// returns a DDB if anything was drawn onto the current stage screen
	// (in which case it also fills optional x,y position),
	// or nullptr if this entry should be skipped.
	IDriverDependantBitmap *DoSpriteEvtCallback(int evt, int data, int &x, int &y);

	// Prepare and get fx item from the pool
	IDriverDependantBitmap *MakeFx(int r, int g, int b);
	// Resets fx pool counter
	void ResetFxPool();
	// Disposes all items in the fx pool
	void DestroyFxPool();

	// Prepares bitmap to be applied to the texture, copies pixels to the provided buffer
	void BitmapToVideoMem(const Bitmap *bitmap, const bool has_alpha, const TextureTile *tile,
						  uint8_t *dst_ptr, const int dst_pitch, const bool usingLinearFiltering);
	// Same but optimized for opaque source bitmaps which ignore transparent "mask color"
	void BitmapToVideoMemOpaque(const Bitmap *bitmap, const TextureTile *tile,
								uint8_t *dst_ptr, const int dst_pitch);

	// Stage virtual screen is used to let plugins draw custom graphics
	// in between render stages (between room and GUI, after GUI, and so on)
	PBitmap _stageVirtualScreen;
	IDriverDependantBitmap *_stageVirtualScreenDDB;
	// Stage matrixes are used to let plugins with hardware acceleration know model matrix;
	// these matrixes are filled compatible with each given renderer
	RenderMatrixes _stageMatrixes;

	// Color component shifts in video bitmap format (set by implementations)
	int _vmem_a_shift_32;
	int _vmem_r_shift_32;
	int _vmem_g_shift_32;
	int _vmem_b_shift_32;

private:
	// Stage virtual screens are used to let plugins draw custom graphics
	// in between render stages (between room and GUI, after GUI, and so on).
	// TODO: possibly may be optimized further by having only 1 bitmap/ddb
	// pair, and subbitmaps for raw drawing on separate stages.
	struct StageScreen {
		Rect Position; // bitmap size and pos preset (bitmap may be created later)
		std::unique_ptr<Bitmap> Raw;
		IDriverDependantBitmap *DDB = nullptr;
	};
	std::vector<StageScreen> _stageScreens;
	// Flag which indicates whether stage screen was drawn upon during engine
	// callback and has to be inserted into sprite stack.
	bool _stageScreenDirty;

	// Fx quads pool (for screen overlay effects)
	struct ScreenFx {
		Bitmap *Raw = nullptr;
		IDriverDependantBitmap *DDB = nullptr;
		int Red = -1;
		int Green = -1;
		int Blue = -1;
	};
	std::vector<ScreenFx> _fxPool;
	size_t _fxIndex; // next free pool item

	// specialized method to convert bitmap to video memory depending on bit depth
	template<typename T, bool HasAlpha>
	void BitmapToVideoMemImpl(const Bitmap *bitmap, const TextureTile *tile, uint8_t *dst_ptr, const int dst_pitch);

	template<typename T>
	void BitmapToVideoMemOpaqueImpl(const Bitmap *bitmap, const TextureTile *tile, uint8_t *dst_ptr, const int dst_pitch);

	template<typename T, bool HasAlpha>
	void BitmapToVideoMemLinearImpl(const Bitmap *bitmap, const TextureTile *tile, uint8_t *dst_ptr, const int dst_pitch);

	// Texture short-term cache:
	// - caches textures while they are in the immediate use;
	// - this lets to share same texture data among multiple sprites on screen.
	// TextureCacheItem stores weak references to the existing texture tiles,
	// identified by an arbitrary uint32 number.
	// TODO: a curious topic to consider: reuse released TextureData for
	// textures of the same size (research potential performance impact).
	struct TextureCacheItem {
		GraphicResolution Res;
		std::weak_ptr<TextureData> Data;
		TextureCacheItem() = default;
		TextureCacheItem(std::shared_ptr<TextureData> data, const GraphicResolution &res)
			: Data(data), Res(res) {}
	};
	std::unordered_map<uint32_t, TextureCacheItem> _txRefs;
};

} // namespace Engine
} // namespace AGS
} // namespace AGS3

#endif