/*
 * SPDX-FileCopyrightText: (C) 2025 a dinosaur
 * SPDX-License-Identifier: Zlib
 */

#include "nehe.h"


typedef struct
{
	float x, y, z;
	float u, v;
} Vertex;

static const Vertex vertices[] =
{
	// Front Face
	{ -1.0f, -1.0f,  1.0f, 0.0f, 0.0f },
	{  1.0f, -1.0f,  1.0f, 1.0f, 0.0f },
	{  1.0f,  1.0f,  1.0f, 1.0f, 1.0f },
	{ -1.0f,  1.0f,  1.0f, 0.0f, 1.0f },
	// Back Face
	{ -1.0f, -1.0f, -1.0f, 1.0f, 0.0f },
	{ -1.0f,  1.0f, -1.0f, 1.0f, 1.0f },
	{  1.0f,  1.0f, -1.0f, 0.0f, 1.0f },
	{  1.0f, -1.0f, -1.0f, 0.0f, 0.0f },
	// Top Face
	{ -1.0f,  1.0f, -1.0f, 0.0f, 1.0f },
	{ -1.0f,  1.0f,  1.0f, 0.0f, 0.0f },
	{  1.0f,  1.0f,  1.0f, 1.0f, 0.0f },
	{  1.0f,  1.0f, -1.0f, 1.0f, 1.0f },
	// Bottom Face
	{ -1.0f, -1.0f, -1.0f, 1.0f, 1.0f },
	{  1.0f, -1.0f, -1.0f, 0.0f, 1.0f },
	{  1.0f, -1.0f,  1.0f, 0.0f, 0.0f },
	{ -1.0f, -1.0f,  1.0f, 1.0f, 0.0f },
	// Right face
	{  1.0f, -1.0f, -1.0f, 1.0f, 0.0f },
	{  1.0f,  1.0f, -1.0f, 1.0f, 1.0f },
	{  1.0f,  1.0f,  1.0f, 0.0f, 1.0f },
	{  1.0f, -1.0f,  1.0f, 0.0f, 0.0f },
	// Left Face
	{ -1.0f, -1.0f, -1.0f, 0.0f, 0.0f },
	{ -1.0f, -1.0f,  1.0f, 1.0f, 0.0f },
	{ -1.0f,  1.0f,  1.0f, 1.0f, 1.0f },
	{ -1.0f,  1.0f, -1.0f, 0.0f, 1.0f }
};

static const uint16_t indices[] =
{
	 0,  1,  2,   2,  3,  0,  // Front
	 4,  5,  6,   6,  7,  4,  // Back
	 8,  9, 10,  10, 11,  8,  // Top
	12, 13, 14,  14, 15, 12,  // Bottom
	16, 17, 18,  18, 19, 16,  // Right
	20, 21, 22,  22, 23, 20   // Left
};


static SDL_GPUGraphicsPipeline* pso = NULL;
static SDL_GPUBuffer* vtxBuffer = NULL;
static SDL_GPUBuffer* idxBuffer = NULL;
static SDL_GPUSampler* sampler = NULL;
static SDL_GPUTexture* texture = NULL;

static float projection[16];

static float xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;


static bool Lesson6_Init(NeHeContext* restrict ctx)
{
	SDL_GPUShader* vertexShader, * fragmentShader;
	if (!NeHe_LoadShaders(ctx, &vertexShader, &fragmentShader, "lesson6",
		&(const NeHeShaderProgramCreateInfo){ .vertexUniforms = 1, .fragmentSamplers = 1 }))
	{
		return false;
	}

	const SDL_GPUVertexAttribute vertexAttribs[] =
	{
		{
			.location = 0,
			.buffer_slot = 0,
			.format = SDL_GPU_VERTEXELEMENTFORMAT_FLOAT3,
			.offset = offsetof(Vertex, x)
		},
		{
			.location = 1,
			.buffer_slot = 0,
			.format = SDL_GPU_VERTEXELEMENTFORMAT_FLOAT2,
			.offset = offsetof(Vertex, u)
		}
	};
	pso = SDL_CreateGPUGraphicsPipeline(ctx->device, &(const SDL_GPUGraphicsPipelineCreateInfo)
	{
		.vertex_shader = vertexShader,
		.fragment_shader = fragmentShader,
		.primitive_type = SDL_GPU_PRIMITIVETYPE_TRIANGLELIST,
		.vertex_input_state =
		{
			.vertex_buffer_descriptions = &(const SDL_GPUVertexBufferDescription)
			{
				.slot = 0,
				.pitch = sizeof(Vertex),
				.input_rate = SDL_GPU_VERTEXINPUTRATE_VERTEX
			},
			.num_vertex_buffers = 1,
			.vertex_attributes = vertexAttribs,
			.num_vertex_attributes = SDL_arraysize(vertexAttribs)
		},
		.rasterizer_state =
		{
			.fill_mode = SDL_GPU_FILLMODE_FILL,
			.cull_mode = SDL_GPU_CULLMODE_NONE,
			.front_face = SDL_GPU_FRONTFACE_COUNTER_CLOCKWISE
		},
		.depth_stencil_state =
		{
			.compare_op = SDL_GPU_COMPAREOP_LESS_OR_EQUAL,
			.enable_depth_test = true,
			.enable_depth_write = true
		},
		.target_info =
		{
			.color_target_descriptions = &(const SDL_GPUColorTargetDescription)
			{
				.format = SDL_GetGPUSwapchainTextureFormat(ctx->device, ctx->window)
			},
			.num_color_targets = 1,
			.depth_stencil_format = appConfig.createDepthFormat,
			.has_depth_stencil_target = true
		}
	});
	SDL_ReleaseGPUShader(ctx->device, fragmentShader);
	SDL_ReleaseGPUShader(ctx->device, vertexShader);
	if (!pso)
	{
		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_CreateGPUGraphicsPipeline: %s", SDL_GetError());
		return false;
	}

	if ((texture = NeHe_LoadTexture(ctx, "Data/NeHe.bmp", true, false)) == NULL)
	{
		return false;
	}

	sampler = SDL_CreateGPUSampler(ctx->device, &(const SDL_GPUSamplerCreateInfo)
	{
		.min_filter = SDL_GPU_FILTER_LINEAR,
		.mag_filter = SDL_GPU_FILTER_LINEAR
	});
	if (!sampler)
	{
		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "SDL_CreateGPUSampler: %s", SDL_GetError());
		return false;
	}

	if (!NeHe_CreateVertexIndexBuffer(ctx, &vtxBuffer, &idxBuffer,
		vertices, sizeof(vertices),
		indices, sizeof(indices)))
	{
		return false;
	}

	return true;
}

static void Lesson6_Quit(NeHeContext* restrict ctx)
{
	SDL_ReleaseGPUBuffer(ctx->device, idxBuffer);
	SDL_ReleaseGPUBuffer(ctx->device, vtxBuffer);
	SDL_ReleaseGPUSampler(ctx->device, sampler);
	SDL_ReleaseGPUTexture(ctx->device, texture);
	SDL_ReleaseGPUGraphicsPipeline(ctx->device, pso);
}

static void Lesson6_Resize(NeHeContext* restrict ctx, int width, int height)
{
	(void)ctx;

	// Avoid division by zero by clamping height
	height = SDL_max(height, 1);
	// Recalculate projection matrix
	Mtx_Perspective(projection, 45.0f, (float)width / (float)height, 0.1f, 100.0f);
}

static void Lesson6_Draw(NeHeContext* restrict ctx, SDL_GPUCommandBuffer* restrict cmd, SDL_GPUTexture* restrict swapchain)
{
	const SDL_GPUColorTargetInfo colorInfo =
	{
		.texture = swapchain,
		.clear_color = { 0.0f, 0.0f, 0.0f, 0.5f },
		.load_op = SDL_GPU_LOADOP_CLEAR,
		.store_op = SDL_GPU_STOREOP_STORE
	};

	const SDL_GPUDepthStencilTargetInfo depthInfo =
	{
		.texture = ctx->depthTexture,
		.clear_depth = 1.0f,  // Ensure depth buffer clears to furthest value
		.load_op = SDL_GPU_LOADOP_CLEAR,
		.store_op = SDL_GPU_STOREOP_DONT_CARE,
		.stencil_load_op = SDL_GPU_LOADOP_DONT_CARE,
		.stencil_store_op = SDL_GPU_STOREOP_DONT_CARE,
		.cycle = true
	};

	// Begin pass & bind pipeline state
	SDL_GPURenderPass* pass = SDL_BeginGPURenderPass(cmd, &colorInfo, 1, &depthInfo);
	SDL_BindGPUGraphicsPipeline(pass, pso);

	// Bind texture
	SDL_BindGPUFragmentSamplers(pass, 0, &(const SDL_GPUTextureSamplerBinding)
	{
		.texture = texture,
		.sampler = sampler
	}, 1);

	// Bind vertex & index buffers
	SDL_BindGPUVertexBuffers(pass, 0, &(const SDL_GPUBufferBinding)
	{
		.buffer = vtxBuffer,
		.offset = 0
	}, 1);
	SDL_BindGPUIndexBuffer(pass, &(const SDL_GPUBufferBinding)
	{
		.buffer = idxBuffer,
		.offset = 0
	}, SDL_GPU_INDEXELEMENTSIZE_16BIT);

	float model[16];
	struct { float modelViewProj[16], color[4]; } u;

	// Move cube 5 units into the screen and apply some rotations
	Mtx_Translation(model, 0.0f, 0.0f, -5.0f);
	Mtx_Rotate(model, xRot, 1.0f, 0.0f, 0.0f);
	Mtx_Rotate(model, yRot, 0.0f, 1.0f, 0.0f);
	Mtx_Rotate(model, zRot, 0.0f, 0.0f, 1.0f);

	// Push shader uniforms
	Mtx_Multiply(u.modelViewProj, projection, model);
	SDL_memcpy(u.color, (float[4]){ 1.0f, 1.0f, 1.0f, 1.0f }, sizeof(float) * 4);
	SDL_PushGPUVertexUniformData(cmd, 0, &u, sizeof(u));

	// Draw textured cube
	SDL_DrawGPUIndexedPrimitives(pass, SDL_arraysize(indices), 1, 0, 0, 0);

	SDL_EndGPURenderPass(pass);

	xRot += 0.3f;
	yRot += 0.2f;
	zRot += 0.4f;
}


const struct AppConfig appConfig =
{
	.title = "NeHe's Texture Mapping Tutorial",
	.width = 640, .height = 480,
	.createDepthFormat = SDL_GPU_TEXTUREFORMAT_D16_UNORM,
	.init = Lesson6_Init,
	.quit = Lesson6_Quit,
	.resize = Lesson6_Resize,
	.draw = Lesson6_Draw
};