/**
 * @file ral.h
 * @author your name (you@domain.com)
 * @brief Render Abstraction Layer
 * @details API that a graphics backend *must* implement
 * @version 0.1
 * @date 2024-03-31
 *
 * @copyright Copyright (c) 2024
 *
 */
#pragma once

#include "buf.h"
#include "defines.h"
#include "mem.h"
#include "ral_types.h"
#include "str.h"

// Unrelated forward declares
typedef struct arena arena;
struct GLFWwindow;

// Forward declare structs
typedef struct gpu_swapchain gpu_swapchain;
typedef struct gpu_device gpu_device;
typedef struct gpu_pipeline_layout gpu_pipeline_layout;
typedef struct gpu_pipeline gpu_pipeline;
typedef struct gpu_renderpass gpu_renderpass;
typedef struct gpu_cmd_encoder gpu_cmd_encoder;  // Recording
typedef struct gpu_cmd_buffer gpu_cmd_buffer;    // Ready for submission
typedef struct gpu_buffer gpu_buffer;
typedef struct gpu_texture gpu_texture;

#define MAX_SHADER_DATA_LAYOUTS 5
#define MAX_BUFFERS 256
#define MAX_TEXTURES 256

/** @brief A*/
// typedef struct gpu_bind_group

// Pools
typedef struct gpu_backend_pools {
  // pools for each gpu structure
} gpu_backend_pools;

/* typedef struct resource_pools resource_pools; */

typedef enum pipeline_kind {
  PIPELINE_GRAPHICS,
  PIPELINE_COMPUTE,
} pipeline_kind;

typedef struct shader_desc {
  const char* debug_name;
  str8 filepath;  // where it came from
  str8 code;      // Either GLSL or SPIRV bytecode
  bool is_spirv;
} shader_desc;

struct graphics_pipeline_desc {
  const char* debug_name;
  vertex_description vertex_desc;
  shader_desc vs; /** @brief Vertex shader stage */
  shader_desc fs; /** @brief Fragment shader stage */

  /* shader_data_layout data_layouts[MAX_SHADER_DATA_LAYOUTS]; */
  /* u32 data_layouts_count; */

  // Roughly equivalent to a descriptor set layout each. each layout can have multiple bindings
  // examples:
  // - uniform buffer reprensenting view projection matrix
  // - texture for shadow map ?
  shader_data data_layouts[MAX_SHADER_DATA_LAYOUTS];
  u32 data_layouts_count;

  // gpu_pipeline_layout* layout;
  gpu_renderpass* renderpass;

  bool wireframe;
  bool depth_test;
};

typedef struct gpu_renderpass_desc {
} gpu_renderpass_desc;

// --- Lifecycle functions

bool gpu_backend_init(const char* window_name, struct GLFWwindow* window);
void gpu_backend_shutdown();

// TEMP
bool gpu_backend_begin_frame();
void gpu_backend_end_frame();

bool gpu_device_create(gpu_device* out_device);
void gpu_device_destroy();

gpu_renderpass* gpu_renderpass_create(const gpu_renderpass_desc* description);
void gpu_renderpass_destroy(gpu_renderpass* pass);

gpu_pipeline* gpu_graphics_pipeline_create(struct graphics_pipeline_desc description);
void gpu_pipeline_destroy(gpu_pipeline* pipeline);

bool gpu_swapchain_create(gpu_swapchain* out_swapchain);
void gpu_swapchain_destroy(gpu_swapchain* swapchain);

gpu_cmd_encoder gpu_cmd_encoder_create();
void gpu_cmd_encoder_destroy(gpu_cmd_encoder* encoder);
void gpu_cmd_encoder_begin(gpu_cmd_encoder encoder);
void gpu_cmd_encoder_begin_render(gpu_cmd_encoder* encoder, gpu_renderpass* renderpass);
void gpu_cmd_encoder_end_render(gpu_cmd_encoder* encoder);
void gpu_cmd_encoder_begin_compute();
gpu_cmd_encoder* gpu_get_default_cmd_encoder();

/* Actual commands that we can encode */
void encode_buffer_copy(gpu_cmd_encoder* encoder, buffer_handle src, u64 src_offset,
                        buffer_handle dst, u64 dst_offset, u64 copy_size);
void encode_clear_buffer(gpu_cmd_encoder* encoder, buffer_handle buf);
void encode_set_pipeline(gpu_cmd_encoder* encoder, gpu_pipeline* pipeline);

/** @brief Upload CPU-side data as array of bytes to a GPU buffer */
void buffer_upload_bytes(buffer_handle gpu_buf, bytebuffer cpu_buf, u64 offset, u64 size);

// render pass
void encode_bind_pipeline(gpu_cmd_encoder* encoder, pipeline_kind kind, gpu_pipeline* pipeline);
void encode_bind_shader_data(gpu_cmd_encoder* encoder, u32 group, shader_data* data);
void encode_set_default_settings(gpu_cmd_encoder* encoder);
void encode_set_vertex_buffer(gpu_cmd_encoder* encoder, buffer_handle buf);
void encode_set_index_buffer(gpu_cmd_encoder* encoder, buffer_handle buf);
void encode_set_bind_group();  // TODO
void encode_draw(gpu_cmd_encoder* encoder);
void encode_draw_indexed(gpu_cmd_encoder* encoder, u64 index_count);

// FUTURE: compute passes

/** @brief Finish recording and return a command buffer that can be submitted to a queue */
gpu_cmd_buffer gpu_cmd_encoder_finish(gpu_cmd_encoder* encoder);

void gpu_queue_submit(gpu_cmd_buffer* buffer);

// Buffers
buffer_handle gpu_buffer_create(u64 size, gpu_buffer_type buf_type, gpu_buffer_flags flags,
                                const void* data);
void gpu_buffer_destroy(buffer_handle buffer);
void gpu_buffer_upload();
void gpu_buffer_bind(buffer_handle buffer);

// Textures
texture_handle gpu_texture_create(texture_desc desc, bool create_view, const void* data);
void gpu_texture_destroy();
void gpu_texture_upload();

// Samplers
void gpu_sampler_create();

// --- Vertex formats
bytebuffer vertices_as_bytebuffer(arena* a, vertex_format format, vertex_darray* vertices);

void vertex_desc_add(vertex_description* builder, const char* name, vertex_attrib_type type);

// TODO: Bindgroup texture samplers / shader resources

// TEMP

void gpu_temp_draw(size_t n_verts);

TYPED_POOL(gpu_buffer, buffer);
TYPED_POOL(gpu_texture, texture);

struct resource_pools {
  buffer_pool buffers;
  texture_pool textures;
};

// Must be implemented by backends
void resource_pools_init(arena* a, struct resource_pools* res_pools);

void copy_buffer_to_buffer_oneshot(buffer_handle src, u64 src_offset, buffer_handle dst,
                                   u64 dst_offset, u64 copy_size);
void copy_buffer_to_image_oneshot(buffer_handle src, texture_handle dst);

// --- Helpers