// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <limits>
#include <type_traits>

#include "Common/CommonFuncs.h"
#include "Common/CommonTypes.h"
#include "VideoCommon/DataReader.h"
#include "VideoCommon/VertexLoader.h"
#include "VideoCommon/VertexLoader_Position.h"
#include "VideoCommon/VertexLoaderManager.h"
#include "VideoCommon/VertexLoaderUtils.h"
#include "VideoCommon/VideoCommon.h"

template <typename T>
float PosScale(T val, float scale)
{
	return val * scale;
}

template <>
float PosScale(float val, float scale)
{
	return val;
}

template <typename T, int N>
void Pos_ReadDirect(VertexLoader* loader)
{
	static_assert(N <= 3, "N > 3 is not sane!");
	auto const scale = loader->m_posScale;
	DataReader dst(g_vertex_manager_write_ptr, nullptr);
	DataReader src(g_video_buffer_read_ptr, nullptr);

	for (int i = 0; i < N; ++i)
	{
		float value = PosScale(src.Read<T>(), scale);
		if (loader->m_counter < 3)
			VertexLoaderManager::position_cache[loader->m_counter][i] = value;
		dst.Write(value);
	}

	g_vertex_manager_write_ptr = dst.GetPointer();
	g_video_buffer_read_ptr = src.GetPointer();
	LOG_VTX();
}

template <typename I, typename T, int N>
void Pos_ReadIndex(VertexLoader* loader)
{
	static_assert(std::is_unsigned<I>::value, "Only unsigned I is sane!");
	static_assert(N <= 3, "N > 3 is not sane!");

	auto const index = DataRead<I>();
	loader->m_vertexSkip = index == std::numeric_limits<I>::max();
	auto const data = reinterpret_cast<const T*>(VertexLoaderManager::cached_arraybases[ARRAY_POSITION] + (index * g_main_cp_state.array_strides[ARRAY_POSITION]));
	auto const scale = loader->m_posScale;
	DataReader dst(g_vertex_manager_write_ptr, nullptr);

	for (int i = 0; i < N; ++i)
	{
		float value = PosScale(Common::FromBigEndian(data[i]), scale);
		if (loader->m_counter < 3)
			VertexLoaderManager::position_cache[loader->m_counter][i] = value;
		dst.Write(value);
	}

	g_vertex_manager_write_ptr = dst.GetPointer();
	LOG_VTX();
}

static TPipelineFunction tableReadPosition[4][8][2] = {
	{
		{nullptr, nullptr,},
		{nullptr, nullptr,},
		{nullptr, nullptr,},
		{nullptr, nullptr,},
		{nullptr, nullptr,},
	},
	{
		{Pos_ReadDirect<u8, 2>, Pos_ReadDirect<u8, 3>,},
		{Pos_ReadDirect<s8, 2>, Pos_ReadDirect<s8, 3>,},
		{Pos_ReadDirect<u16, 2>, Pos_ReadDirect<u16, 3>,},
		{Pos_ReadDirect<s16, 2>, Pos_ReadDirect<s16, 3>,},
		{Pos_ReadDirect<float, 2>, Pos_ReadDirect<float, 3>,},
	},
	{
		{Pos_ReadIndex<u8, u8, 2>, Pos_ReadIndex<u8, u8, 3>,},
		{Pos_ReadIndex<u8, s8, 2>, Pos_ReadIndex<u8, s8, 3>,},
		{Pos_ReadIndex<u8, u16, 2>, Pos_ReadIndex<u8, u16, 3>,},
		{Pos_ReadIndex<u8, s16, 2>, Pos_ReadIndex<u8, s16, 3>,},
		{Pos_ReadIndex<u8, float, 2>, Pos_ReadIndex<u8, float, 3>,},
	},
	{
		{Pos_ReadIndex<u16, u8, 2>, Pos_ReadIndex<u16, u8, 3>,},
		{Pos_ReadIndex<u16, s8, 2>, Pos_ReadIndex<u16, s8, 3>,},
		{Pos_ReadIndex<u16, u16, 2>, Pos_ReadIndex<u16, u16, 3>,},
		{Pos_ReadIndex<u16, s16, 2>, Pos_ReadIndex<u16, s16, 3>,},
		{Pos_ReadIndex<u16, float, 2>, Pos_ReadIndex<u16, float, 3>,},
	},
};

static int tableReadPositionVertexSize[4][8][2] = {
	{
		{0, 0,}, {0, 0,}, {0, 0,}, {0, 0,}, {0, 0,},
	},
	{
		{2, 3,}, {2, 3,}, {4, 6,}, {4, 6,}, {8, 12,},
	},
	{
		{1, 1,}, {1, 1,}, {1, 1,}, {1, 1,}, {1, 1,},
	},
	{
		{2, 2,}, {2, 2,}, {2, 2,}, {2, 2,}, {2, 2,},
	},
};

unsigned int VertexLoader_Position::GetSize(u64 _type, unsigned int _format, unsigned int _elements)
{
	return tableReadPositionVertexSize[_type][_format][_elements];
}

TPipelineFunction VertexLoader_Position::GetFunction(u64 _type, unsigned int _format, unsigned int _elements)
{
	return tableReadPosition[_type][_format][_elements];
}