/*****************************************************************************
The Dark Mod GPL Source Code

This file is part of the The Dark Mod Source Code, originally based
on the Doom 3 GPL Source Code as published in 2011.

The Dark Mod Source Code 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. For details, see LICENSE.TXT.

Project: The Dark Mod (http://www.thedarkmod.com/)

******************************************************************************/

#include "precompiled.h"
#include <mutex>
#pragma hdrstop

#include "renderer/tr_local.h"
#include "renderer/backend/VertexArrayState.h"

const int32 MAX_VERTCACHE_SIZE = INT_MAX;

idCVar idVertexCache::r_showVertexCache( "r_showVertexCache", "0", CVAR_INTEGER | CVAR_RENDERER, "Show VertexCache usage statistics" );
idCVar idVertexCache::r_frameVertexMemory( "r_frameVertexMemory", "4096", CVAR_INTEGER | CVAR_RENDERER | CVAR_ARCHIVE, "Initial amount of per-frame temporary vertex memory, in kB (max 131071)" );
idCVar idVertexCache::r_frameIndexMemory( "r_frameIndexMemory", "4096", CVAR_INTEGER | CVAR_RENDERER | CVAR_ARCHIVE, "Initial amount of per-frame temporary index memory, in kB (max 131071)" );
idCVarBool r_usePersistentMapping( "r_usePersistentMapping", "1", CVAR_RENDERER | CVAR_ARCHIVE, "Use persistent buffer mapping" );

idVertexCache		vertexCache;
uint32_t			staticVertexSize, staticIndexSize, staticShadowSize;

ALIGNTYPE16 const idDrawVert screenRectVerts[4] = {
	{idVec3( -1,-1,0 ),idVec2( 0,0 ), idVec3(), {idVec3(), idVec3()}, {255, 255, 255, 0}},
	{idVec3( +1,-1,0 ),idVec2( 1,0 ), idVec3(), {idVec3(), idVec3()}, {255, 255, 255, 0}},
	{idVec3( -1,+1,0 ),idVec2( 0,1 ), idVec3(), {idVec3(), idVec3()}, {255, 255, 255, 0}},
	{idVec3( +1,+1,0 ),idVec2( 1,1 ), idVec3(), {idVec3(), idVec3()}, {255, 255, 255, 0}},
};
ALIGNTYPE16 const glIndex_t screenRectIndices[6] = { 0, 2, 1, 1, 2, 3 };

static void ClearGeoBufferSet( geoBufferSet_t &gbs ) {
	gbs.mappedVertexBase = gbs.vertexBuffer.CurrentWriteLocation();
	gbs.mappedIndexBase = gbs.indexBuffer.CurrentWriteLocation();
	gbs.indexMemUsed.SetValue( 0 );
	gbs.vertexMemUsed.SetValue( 0 );
	gbs.allocations = 0;
}

static void SwitchFrameGeoBufferSet( geoBufferSet_t &gbs ) {
	int commitVertexBytes = Min( gbs.vertexMemUsed.GetValue(), (int)gbs.vertexBuffer.BytesRemaining() );
	gbs.vertexBuffer.Commit( commitVertexBytes );
	gbs.vertexBuffer.SwitchFrame();
	int commitIndexBytes = Min( gbs.indexMemUsed.GetValue(), (int)gbs.indexBuffer.BytesRemaining() );
	gbs.indexBuffer.Commit( commitIndexBytes );
	gbs.indexBuffer.SwitchFrame();
	ClearGeoBufferSet( gbs );
}

static void AllocGeoBufferSet( geoBufferSet_t &gbs, const int vertexBytes, const int indexBytes ) {
	gbs.vertexBuffer.InitWriteFrameAhead( GL_ARRAY_BUFFER, vertexBytes, VERTEX_CACHE_ALIGN );
	gbs.indexBuffer.InitWriteFrameAhead( GL_ELEMENT_ARRAY_BUFFER, indexBytes, INDEX_CACHE_ALIGN );
	GL_SetDebugLabel( GL_BUFFER, gbs.vertexBuffer.GetAPIObject(), "DynamicVertexCache" );
	GL_SetDebugLabel( GL_BUFFER, gbs.indexBuffer.GetAPIObject(), "DynamicIndexCache" );
	ClearGeoBufferSet( gbs );
}

static void FreeGeoBufferSet( geoBufferSet_t &gbs ) {
	gbs.vertexBuffer.Destroy();
	gbs.indexBuffer.Destroy();
}

/*
==============
idVertexCache::VertexPosition
==============
*/
void idVertexCache::VertexPosition( vertCacheHandle_t handle, attribBind_t attrib ) {
	GLuint vbo;
	if ( !handle.IsValid() ) {
		vbo = 0;
	} else {
		++vertexUseCount;
		if ( handle.isStatic ) {
			vbo = ( attrib == ATTRIB_REGULAR ? staticVertexBuffer : staticShadowBuffer );
		} else {
			vbo = dynamicData.vertexBuffer.GetAPIObject();
		}
	}

	if ( attrib == ATTRIB_REGULAR ) {
		vaState.BindVertexBufferAndSetVertexFormat( vbo, VF_REGULAR );
		assert( handle.offset % sizeof( idDrawVert ) == 0 );
		basePointer = handle.offset / sizeof( idDrawVert );
	} else if ( attrib == ATTRIB_SHADOW ) {
		vaState.BindVertexBufferAndSetVertexFormat( vbo, VF_SHADOW );
		assert( handle.offset % sizeof( shadowCache_t ) == 0 );
		basePointer = handle.offset / sizeof( shadowCache_t );
	} else {
		assert( 0 );
	}
}

/*
==============
idVertexCache::IndexPosition
==============
*/
void *idVertexCache::IndexPosition( vertCacheHandle_t handle ) {
	GLuint vbo;
	if ( !handle.IsValid() ) {
		vbo = 0;
	} else {
		++indexUseCount;
		if ( handle.isStatic ) {
			vbo = staticIndexBuffer;
		} else {
			vbo = dynamicData.indexBuffer.GetAPIObject();
		}
	}

	if ( vbo != currentIndexBuffer ) {
		qglBindBuffer( GL_ELEMENT_ARRAY_BUFFER, vbo );
		currentIndexBuffer = vbo;
	}

	return ( void * )( size_t )( handle.offset );
}

/*
==============
idVertexCache::UnbindIndex
==============
*/
void idVertexCache::UnbindIndex() {
	if ( currentIndexBuffer != 0 ) {
		qglBindBuffer( GL_ELEMENT_ARRAY_BUFFER, 0 );
		currentIndexBuffer = 0;
	}
}

//================================================================================

geoBufferSet_t::geoBufferSet_t() {}

/*
===========
idVertexCache::Init
===========
*/
void idVertexCache::Init() {
	currentFrame = 0;
	currentIndexCacheSize = idMath::Imin( MAX_VERTCACHE_SIZE, r_frameIndexMemory.GetInteger() * 1024 );
	currentVertexCacheSize = idMath::Imin( MAX_VERTCACHE_SIZE, r_frameVertexMemory.GetInteger() * 1024 );
	if ( currentIndexCacheSize <= 0 || currentVertexCacheSize <= 0 ) {
		common->FatalError( "Dynamic vertex cache size is invalid. Please adjust r_frameIndexMemory and r_frameVertexMemory." );
	}

	// 2.08 core context https://stackoverflow.com/questions/13403807/glvertexattribpointer-raising-gl-invalid-operation
	GLuint vao;
	qglGenVertexArrays( 1, &vao );
	qglBindVertexArray( vao ); 

	staticVertexBuffer = 0;
	staticIndexBuffer = 0;
	staticShadowBuffer = 0;
	
	AllocGeoBufferSet( dynamicData, currentVertexCacheSize, currentIndexCacheSize );
	EndFrame();
}

/*
===========
idVertexCache::PurgeAll

Used when toggling vertex programs on or off, because
the cached data isn't valid
===========
*/
void idVertexCache::PurgeAll() {
	Shutdown();
	Init();
}

/*
===========
idVertexCache::Shutdown
===========
*/
void idVertexCache::Shutdown() {
	ClearGeoBufferSet( dynamicData );
	FreeGeoBufferSet( dynamicData );

	if ( staticVertexBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticVertexBuffer );
		staticVertexBuffer = 0;
	}
	if ( staticIndexBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticIndexBuffer );
		staticIndexBuffer = 0;
	}
	if ( staticShadowBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticShadowBuffer );
		staticShadowBuffer = 0;
	}
}

/*
===========
idVertexCache::EndFrame
===========
*/
void idVertexCache::EndFrame() {
	// display debug information
	if ( r_showVertexCache.GetBool() ) {
		common->Printf( "vertex: %d times totaling %d kB, index: %d times totaling %d kB\n", vertexAllocCount, dynamicData.vertexMemUsed.GetValue() / 1024, indexAllocCount, dynamicData.indexMemUsed.GetValue() / 1024 );
	}

	// check if we need to increase the buffer size
	if ( dynamicData.indexMemUsed.GetValue() > currentIndexCacheSize ) {
		while ( currentIndexCacheSize <= MAX_VERTCACHE_SIZE / VERTCACHE_NUM_FRAMES / 2 && currentIndexCacheSize < dynamicData.indexMemUsed.GetValue() ) {
			currentIndexCacheSize *= 2;
		}
	}
	if ( dynamicData.vertexMemUsed.GetValue() > currentVertexCacheSize ) {
		while ( currentVertexCacheSize < MAX_VERTCACHE_SIZE / VERTCACHE_NUM_FRAMES / 2 && currentVertexCacheSize < dynamicData.vertexMemUsed.GetValue() ) {
			currentVertexCacheSize *= 2;
		}
	}

	// switch dynamic buffer to next frame
	SwitchFrameGeoBufferSet( dynamicData );
	currentFrame++;
	indexAllocCount = indexUseCount = vertexAllocCount = vertexUseCount = 0;

	// check if we need to resize current buffer set
	if (
		(int)dynamicData.vertexBuffer.BytesRemaining() < currentVertexCacheSize ||
		(int)dynamicData.indexBuffer.BytesRemaining() < currentIndexCacheSize
	) {
		common->Printf( "Resizing dynamic VertexCache: index %d kb -> %d kb, vertex %d kb -> %d kb\n", dynamicData.indexBuffer.BytesRemaining() / 1024, currentIndexCacheSize / 1024, dynamicData.indexBuffer.BytesRemaining() / 1024, currentVertexCacheSize / 1024 );
		FreeGeoBufferSet( dynamicData );
		AllocGeoBufferSet( dynamicData, currentVertexCacheSize, currentIndexCacheSize );
	}

	vaState.BindVertexBuffer();
	qglBindBuffer( GL_ELEMENT_ARRAY_BUFFER, currentIndexBuffer = 0 );

	// 2.08 temp helper for RB_DrawFullScreenQuad on core contexts
	screenRectSurf.ambientCache = AllocVertex( screenRectVerts, sizeof( screenRectVerts ) );
	screenRectSurf.indexCache = AllocIndex( &screenRectIndices, sizeof( screenRectIndices ) );
	screenRectSurf.numIndexes = 6;
}

/*
==============
idVertexCache::ActuallyAlloc
==============
*/
vertCacheHandle_t idVertexCache::ActuallyAlloc( geoBufferSet_t &vcs, const void *data, int bytes, cacheType_t type ) {
	if ( bytes == 0 ) {
		return NO_CACHE;
	}
	assert( ( ( ( uintptr_t )( data ) ) & 15 ) == 0 );
	const int alignSize = ( type == CACHE_INDEX ) ? INDEX_CACHE_ALIGN : VERTEX_CACHE_ALIGN;
	const int alignedBytes = ALIGN( bytes, alignSize );
	assert( ( alignedBytes & 15 ) == 0 );

	// thread safe interlocked adds
	byte **base = NULL;
	int	endPos = 0;
	int mapOffset = 0;

	if ( type == CACHE_INDEX ) {
		base = &vcs.mappedIndexBase;
		endPos = vcs.indexMemUsed.Add( alignedBytes );
		mapOffset = (intptr_t)vcs.indexBuffer.BufferOffset( vcs.mappedIndexBase );
		if ( endPos > currentIndexCacheSize ) {
			// out of index cache, will be resized next frame
			return NO_CACHE;
		}
		indexAllocCount++;
	} else if ( type == CACHE_VERTEX ) {
		base = &vcs.mappedVertexBase;
		endPos = vcs.vertexMemUsed.Add( alignedBytes );
		mapOffset = (intptr_t)vcs.vertexBuffer.BufferOffset( vcs.mappedVertexBase );
		if ( endPos > currentVertexCacheSize ) {
			// out of vertex cache, will be resized next frame
			return NO_CACHE;
		}
		vertexAllocCount++;
	} else {
		assert( false );
		return NO_CACHE;
	}
	vcs.allocations++;

	int offset = endPos - alignedBytes;

	// Actually perform the data transfer
	if ( data != NULL ) {
		void* dst = *base + offset;
		const byte* src = (byte*)data;
		assert_16_byte_aligned( dst );
		assert_16_byte_aligned( src );
		SIMDProcessor->MemcpyNT( dst, src, bytes );
	}

	return vertCacheHandle_t::Create(
		bytes,
		(mapOffset + offset),
		currentFrame & VERTCACHE_FRAME_MASK,
		false //&vcs == &staticData
	);
}

struct StaticCacheSource {
	const void *ptr;
	int size;
	bool owned;		// if true, Mem_Free is called on pointer after upload
};
typedef idList<StaticCacheSource> StaticList;
StaticList staticVertexList, staticIndexList, staticShadowList;

/*
==============
idVertexCache::PrepareStaticCacheForUpload
==============
*/
void idVertexCache::PrepareStaticCacheForUpload() {
	vaState.BindVertexBuffer( 0 );

	// upload function to be called twice for vertex and index data
	auto upload = [](GLuint buffer, GLenum bufferType, int size, StaticList &staticList ) {
		int offset = 0;
		byte* ptr = (byte*)Mem_Alloc16( size );
		for ( auto& entry : staticList ) {
			memcpy( ptr + offset, entry.ptr, entry.size );
			offset += entry.size;
			if ( entry.owned ) {
				Mem_Free( (void*)entry.ptr );
				entry.ptr = nullptr;
			}
		}
		qglBindBuffer( bufferType, buffer );
		if ( GLAD_GL_ARB_buffer_storage ) {
			qglBufferStorage( bufferType, size, ptr, 0 );
		} else {
			qglBufferData( bufferType, size, ptr, GL_STATIC_DRAW );
		}
		Mem_Free16( ptr );
		staticList.ClearFree();
	};

	if ( staticVertexBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticVertexBuffer );
	}
	if ( staticIndexBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticIndexBuffer );
	}
	if ( staticShadowBuffer != 0 ) {
		qglDeleteBuffers( 1, &staticShadowBuffer );
	}
	qglGenBuffers( 1, &staticVertexBuffer );
	qglGenBuffers( 1, &staticIndexBuffer );
	qglGenBuffers( 1, &staticShadowBuffer );

	staticVertexSize = ALIGN( staticVertexSize, VERTEX_CACHE_ALIGN );
	upload( staticVertexBuffer, GL_ARRAY_BUFFER, staticVertexSize, staticVertexList );
	staticIndexSize = ALIGN( staticIndexSize, INDEX_CACHE_ALIGN );
	upload( staticIndexBuffer, GL_ELEMENT_ARRAY_BUFFER, staticIndexSize, staticIndexList );
	staticShadowSize = ALIGN( staticShadowSize, SHADOW_CACHE_ALIGN );
	upload( staticShadowBuffer, GL_ARRAY_BUFFER, staticShadowSize, staticShadowList );

	GL_SetDebugLabel( GL_BUFFER, staticVertexBuffer, "StaticVertexCache" );
	GL_SetDebugLabel( GL_BUFFER, staticIndexBuffer, "StaticIndexCache" );
	GL_SetDebugLabel( GL_BUFFER, staticShadowBuffer, "StaticShadowCache" );

	qglBindBuffer( GL_ARRAY_BUFFER, 0 );
	qglBindBuffer( GL_ELEMENT_ARRAY_BUFFER, currentIndexBuffer = 0 );
}

vertCacheHandle_t idVertexCache::AllocStaticVertex( const void* data, int bytes ) {
	if ( !staticVertexList.Num() )
		staticVertexSize = 0;
	staticVertexList.Append( StaticCacheSource{ data, bytes, false } );
	staticVertexSize += bytes;
	return vertCacheHandle_t::Create( bytes, staticVertexSize - bytes, 0, true );
}

vertCacheHandle_t idVertexCache::AllocStaticShadow( void* data, int bytes ) {
	if ( !staticShadowList.Num() )
		staticShadowSize = 0;
	staticShadowList.Append( StaticCacheSource{ data, bytes, true } );
	staticShadowSize += bytes;
	return vertCacheHandle_t::Create( bytes, staticShadowSize - bytes, 0, true );
}

vertCacheHandle_t idVertexCache::AllocStaticIndex( const void* data, int bytes ) {
	if ( !staticIndexList.Num() )
		staticIndexSize = 0;
	staticIndexList.Append( StaticCacheSource{ data, bytes, false } );
	staticIndexSize += bytes;
	return vertCacheHandle_t::Create( bytes, staticIndexSize - bytes, 0, true );
}