/* SPDX-FileCopyrightText: 2016 by Mike Erwin. All rights reserved.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup gpu
 *
 * GPU vertex format
 */

#pragma once

#include "BLI_assert.h"
#include "BLI_compiler_compat.h"
#include "BLI_math_vector_types.hh"
#include "BLI_string_ref.hh"
#include "BLI_sys_types.h"

#include "GPU_format.hh"

namespace blender::gpu {

enum class VertAttrType : uint8_t {
  Invalid = 0,

#define DECLARE(a, b, c, blender_enum, d, e, f, g, h) blender_enum = int(DataFormat::blender_enum),

#define GPU_VERTEX_FORMAT_EXPAND(impl) \
  SNORM_8_8_8_8_(impl) \
\
  SNORM_16_16_(impl) \
  SNORM_16_16_16_16_(impl) \
\
  UNORM_8_8_8_8_(impl) \
\
  UNORM_16_16_(impl) \
  UNORM_16_16_16_16_(impl) \
\
  SINT_8_8_8_8_(impl) \
\
  SINT_16_16_(impl) \
  SINT_16_16_16_16_(impl) \
\
  SINT_32_(impl) \
  SINT_32_32_(impl) \
  SINT_32_32_32_(impl) \
  SINT_32_32_32_32_(impl) \
\
  UINT_8_8_8_8_(impl) \
\
  UINT_16_16_(impl) \
  UINT_16_16_16_16_(impl) \
\
  UINT_32_(impl) \
  UINT_32_32_(impl) \
  UINT_32_32_32_(impl) \
  UINT_32_32_32_32_(impl) \
\
  SFLOAT_32_(impl) \
  SFLOAT_32_32_(impl) \
  SFLOAT_32_32_32_(impl) \
  SFLOAT_32_32_32_32_(impl) \
\
  SNORM_10_10_10_2_(impl) \
  UNORM_10_10_10_2_(impl) \
\
  /* UFLOAT_11_11_10_(impl) Available on Metal (and maybe VK) but not on GL. */ \
  /* UFLOAT_9_9_9_EXP_5_(impl) Available on Metal (and maybe VK) but not on GL. */

  GPU_VERTEX_FORMAT_EXPAND(DECLARE)
#undef DECLARE

#define DECLARE(a, b, c, blender_enum, d, e, f, g, h) \
  blender_enum##_DEPRECATED = int(DataFormat::blender_enum),

/* Deprecated formats. To be removed in 5.0. Needed for python shaders. */
#define GPU_VERTEX_DEPRECATED_FORMAT_EXPAND(impl) \
  SNORM_8_(impl) \
  SNORM_8_8_(impl) \
  SNORM_8_8_8_(impl) \
  SNORM_16_(impl) \
  SNORM_16_16_16_(impl) \
  UNORM_8_(impl) \
  UNORM_8_8_(impl) \
  UNORM_8_8_8_(impl) \
  UNORM_16_(impl) \
  UNORM_16_16_16_(impl) \
  SINT_8_(impl) \
  SINT_8_8_(impl) \
  SINT_8_8_8_(impl) \
  SINT_16_(impl) \
  SINT_16_16_16_(impl) \
  UINT_8_(impl) \
  UINT_8_8_(impl) \
  UINT_8_8_8_(impl) \
  UINT_16_(impl) \
  UINT_16_16_16_(impl)

      GPU_VERTEX_DEPRECATED_FORMAT_EXPAND(DECLARE)

#undef DECLARE
};

/* TODO: Should reuse GPU_VERTEX_FORMAT_EXPAND, but we need to have `s/unorm` types first. */
#define GPU_VERTEX_FORMAT_EXPAND_TYPED(impl) \
  SINT_8_8_8_8_(impl) \
\
  SINT_16_16_(impl) \
  SINT_16_16_16_16_(impl) \
\
  SINT_32_(impl) \
  SINT_32_32_(impl) \
  SINT_32_32_32_(impl) \
  SINT_32_32_32_32_(impl) \
\
  UINT_8_8_8_8_(impl) \
\
  UINT_16_16_(impl) \
  UINT_16_16_16_16_(impl) \
\
  UINT_32_(impl) \
  UINT_32_32_(impl) \
  UINT_32_32_32_(impl) \
  UINT_32_32_32_32_(impl) \
\
  SFLOAT_32_(impl) \
  SFLOAT_32_32_(impl) \
  SFLOAT_32_32_32_(impl) \
  SFLOAT_32_32_32_32_(impl) \
\
  /* UFLOAT_11_11_10_(impl) Available on Metal (and maybe VK) but not on GL. */ \
  /* UFLOAT_9_9_9_EXP_5_(impl) Available on Metal (and maybe VK) but not on GL. */

/* Must be implemented for each type used in vertex format.
 * Should contain the associated VertAttrType just like below. */
template<typename T> struct AttrType {};

#define ATTR_TYPE_MAPPING(_type, b, c, blender_enum, d, e, f, g, h) \
  template<> struct AttrType<_type> { \
    static constexpr VertAttrType type = VertAttrType::blender_enum; \
  };

GPU_VERTEX_FORMAT_EXPAND_TYPED(ATTR_TYPE_MAPPING)

#undef ATTR_TYPE_MAPPING

inline constexpr DataFormat to_data_format(VertAttrType format)
{
  return DataFormat(int(format));
}

class Shader;

}  // namespace blender::gpu

constexpr static int GPU_VERT_ATTR_MAX_LEN = 16;
constexpr static int GPU_VERT_ATTR_MAX_NAMES = 6;
constexpr static int GPU_VERT_ATTR_NAMES_BUF_LEN = 256;
constexpr static int GPU_VERT_FORMAT_MAX_NAMES = 63; /* More than enough, actual max is ~30. */
/* Computed as GPU_VERT_ATTR_NAMES_BUF_LEN / 30 (actual max format name). */
constexpr static int GPU_MAX_SAFE_ATTR_NAME = 12;

enum GPUVertCompType {
  GPU_COMP_I8 = 0,
  GPU_COMP_U8,
  GPU_COMP_I16,
  GPU_COMP_U16,
  GPU_COMP_I32,
  GPU_COMP_U32,

  GPU_COMP_F32,

  GPU_COMP_I10,
  /* Warning! adjust GPUVertAttr if changing. */

  GPU_COMP_MAX
};

enum GPUVertFetchMode {
  GPU_FETCH_FLOAT = 0,
  GPU_FETCH_INT,
  GPU_FETCH_INT_TO_FLOAT_UNIT, /* 127 (ubyte) -> 0.5 (and so on for other int types) */
  /* Warning! adjust GPUVertAttr if changing. */
};

struct GPUVertAttr {
  /* To replace fetch_mode, comp_type, comp_len, size. */
  struct Type {
    blender::gpu::VertAttrType format;

    size_t size() const
    {
      return to_bytesize(to_data_format(format));
    };

    int comp_len() const
    {
      return format_component_len(to_data_format(format));
    }

    GPUVertFetchMode fetch_mode() const;
    GPUVertCompType comp_type() const;
  } type;
  /* from beginning of vertex, in bytes */
  uint8_t offset;
  /* up to GPU_VERT_ATTR_MAX_NAMES */
  uint8_t name_len;
  uchar names[GPU_VERT_ATTR_MAX_NAMES];
};

BLI_STATIC_ASSERT(GPU_VERT_ATTR_NAMES_BUF_LEN <= 256,
                  "We use uchar as index inside the name buffer "
                  "so GPU_VERT_ATTR_NAMES_BUF_LEN needs to be "
                  "smaller than GPUVertFormat->name_offset and "
                  "GPUVertAttr->names maximum value");

struct GPUVertFormat {
  /** 0 to 16 (GPU_VERT_ATTR_MAX_LEN). */
  uint attr_len : 5;
  /** Total count of active vertex attribute names. (max GPU_VERT_FORMAT_MAX_NAMES) */
  uint name_len : 6;
  /** Stride in bytes, 1 to 1024. */
  uint stride : 11;
  /** Has the format been packed. */
  uint packed : 1;
  /** Current offset in names[]. */
  uint name_offset : 8;
  /** Store each attribute in one contiguous buffer region. */
  uint deinterleaved : 1;

  GPUVertAttr attrs[GPU_VERT_ATTR_MAX_LEN];
  char names[GPU_VERT_ATTR_NAMES_BUF_LEN];

  void pack();
  uint attribute_add(blender::StringRef name, blender::gpu::VertAttrType type, size_t offset = -1);
};

#define GPU_VERTEX_FORMAT_ADD_ATTR(attr) \
  format.attribute_add( \
      #attr, blender::gpu::AttrType<decltype(attr)>::type, offsetof(VertT, attr)); \
  BLI_STATIC_ASSERT(offsetof(VertT, attr) < 255, #attr " has offset greater than 255") \
  BLI_STATIC_ASSERT(offsetof(VertT, attr) % 4 == 0, #attr " is not aligned to 4 bytes")

#define _ATTR_EXPAND1(a) GPU_VERTEX_FORMAT_ADD_ATTR(a)
#define _ATTR_EXPAND2(a, b) \
  _ATTR_EXPAND1(a) \
  GPU_VERTEX_FORMAT_ADD_ATTR(b)
#define _ATTR_EXPAND3(a, b, c) \
  _ATTR_EXPAND2(a, b) \
  GPU_VERTEX_FORMAT_ADD_ATTR(c)
#define _ATTR_EXPAND4(a, b, c, d) \
  _ATTR_EXPAND3(a, b, c) \
  GPU_VERTEX_FORMAT_ADD_ATTR(d)
#define _ATTR_EXPAND5(a, b, c, d, e) \
  _ATTR_EXPAND4(a, b, c, d) \
  GPU_VERTEX_FORMAT_ADD_ATTR(e)
#define _ATTR_EXPAND6(a, b, c, d, e, f) \
  _ATTR_EXPAND5(a, b, c, d, e) \
  GPU_VERTEX_FORMAT_ADD_ATTR(f)
#define _ATTR_EXPAND7(a, b, c, d, e, f, g) \
  _ATTR_EXPAND6(a, b, c, d, e, f) \
  GPU_VERTEX_FORMAT_ADD_ATTR(g)
#define _ATTR_EXPAND8(a, b, c, d, e, f, g, h) \
  _ATTR_EXPAND7(a, b, c, d, e, f, g) \
  GPU_VERTEX_FORMAT_ADD_ATTR(h)
#define _ATTR_EXPAND9(a, b, c, d, e, f, g, h, i) \
  _ATTR_EXPAND8(a, b, c, d, e, f, g, h) \
  GPU_VERTEX_FORMAT_ADD_ATTR(i)
#define _ATTR_EXPAND10(a, b, c, d, e, f, g, h, i, j) \
  _ATTR_EXPAND9(a, b, c, d, e, f, g, h, i) \
  GPU_VERTEX_FORMAT_ADD_ATTR(j)
#define _ATTR_EXPAND11(a, b, c, d, e, f, g, h, i, j, k) \
  _ATTR_EXPAND10(a, b, c, d, e, f, g, h, i, j) \
  GPU_VERTEX_FORMAT_ADD_ATTR(k)
#define _ATTR_EXPAND12(a, b, c, d, e, f, g, h, i, j, k, l) \
  _ATTR_EXPAND11(a, b, c, d, e, f, g, h, i, j, k) \
  GPU_VERTEX_FORMAT_ADD_ATTR(l)
#define _ATTR_EXPAND13(a, b, c, d, e, f, g, h, i, j, k, l, m) \
  _ATTR_EXPAND12(a, b, c, d, e, f, g, h, i, j, k, l) \
  GPU_VERTEX_FORMAT_ADD_ATTR(m)
#define _ATTR_EXPAND14(a, b, c, d, e, f, g, h, i, j, k, l, m, n) \
  _ATTR_EXPAND13(a, b, c, d, e, f, g, h, i, j, k, l, m) \
  GPU_VERTEX_FORMAT_ADD_ATTR(n)
#define _ATTR_EXPAND15(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) \
  _ATTR_EXPAND14(a, b, c, d, e, f, g, h, i, j, k, l, m, n) \
  GPU_VERTEX_FORMAT_ADD_ATTR(o)
#define _ATTR_EXPAND16(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) \
  _ATTR_EXPAND15(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) \
  GPU_VERTEX_FORMAT_ADD_ATTR(p)
/* We only support up to GPU_VERT_ATTR_MAX_LEN attribute per format. */

#define GPU_VERTEX_FORMAT_ADD_ATTR_EXPAND(...) VA_NARGS_CALL_OVERLOAD(_ATTR_EXPAND, __VA_ARGS__)

#define GPU_VERTEX_FORMAT_FUNC(_VertT, ...) \
  static GPUVertFormat &format() \
  { \
    using VertT = _VertT; \
    static GPUVertFormat format = {}; \
    if (format.attr_len == 0) { \
      GPU_VERTEX_FORMAT_ADD_ATTR_EXPAND(__VA_ARGS__) \
      format.stride = sizeof(VertT); \
      BLI_STATIC_ASSERT(sizeof(VertT) < 1024, "Vertex format is too big") \
      format.packed = true; \
      BLI_STATIC_ASSERT_ALIGN(VertT, 4) \
    } \
    return format; \
  }

namespace blender::gpu {

/** Generic vertex format for single attribute buffers. */
template<typename T> struct GenericVertexFormat {
  T attr;
  GPU_VERTEX_FORMAT_FUNC(GenericVertexFormat, attr);
};

template<> struct GenericVertexFormat<int8_t> {
  /* This is a workaround to reinterpret int8_t into padded vertex format to be able to upload it
   * on any GPU. The shaders then need to read uint32_t and use shifts and mask to decode in
   * individual bytes. */
  uint32_t attr;
  GPU_VERTEX_FORMAT_FUNC(GenericVertexFormat, attr);
};

template<> struct GenericVertexFormat<uint8_t> {
  /* This is a workaround to reinterpret uint8_t into padded vertex format to be able to upload it
   * on any GPU. The shaders then need to read uint32_t and use shifts and mask to decode in
   * individual bytes. */
  uint32_t attr;
  GPU_VERTEX_FORMAT_FUNC(GenericVertexFormat, attr);
};

template<> struct GenericVertexFormat<bool> {
  /* This is a workaround to reinterpret bool into padded vertex format to be able to upload it
   * on any GPU. The shaders then need to read uint32_t and use shifts and mask to decode in
   * individual bytes. */
  uint32_t attr;
  GPU_VERTEX_FORMAT_FUNC(GenericVertexFormat, attr);
};

}  // namespace blender::gpu

void GPU_vertformat_clear(GPUVertFormat *);
void GPU_vertformat_copy(GPUVertFormat *dest, const GPUVertFormat &src);
void GPU_vertformat_from_shader(GPUVertFormat *format, const blender::gpu::Shader *shader);

uint GPU_vertformat_attr_add(GPUVertFormat *format,
                             blender::StringRef name,
                             blender::gpu::VertAttrType type);
/* Legacy/unsafe version.
 * TODO: Replace by vertex_format_combine. */
uint GPU_vertformat_attr_add_legacy(
    GPUVertFormat *, blender::StringRef name, GPUVertCompType, uint comp_len, GPUVertFetchMode);

void GPU_vertformat_alias_add(GPUVertFormat *, blender::StringRef alias);

/**
 * Return a vertex format from a single attribute description.
 * The attribute ID is ensured to be 0.
 */
GPUVertFormat GPU_vertformat_from_attribute(blender::StringRef name,
                                            blender::gpu::VertAttrType type);

/**
 * Makes vertex attribute from the next vertices to be accessible in the vertex shader.
 * For an attribute named "attr" you can access the next nth vertex using "attr{number}".
 * Use this function after specifying all the attributes in the format.
 *
 * NOTE: This does NOT work when using indexed rendering.
 * NOTE: Only works for first attribute name. (this limitation can be changed if needed)
 *
 * WARNING: this function creates a lot of aliases/attributes, make sure to keep the attribute
 * name short to avoid overflowing the name-buffer.
 */
void GPU_vertformat_multiload_enable(GPUVertFormat *format, int load_count);

/**
 * Make attribute layout non-interleaved.
 * Warning! This does not change data layout!
 * Use direct buffer access to fill the data.
 * This is for advanced usage.
 *
 * De-interleaved data means all attribute data for each attribute
 * is stored continuously like this:
 * 000011112222
 * instead of:
 * 012012012012
 *
 * \note This is per attribute de-interleaving, NOT per component.
 */
void GPU_vertformat_deinterleave(GPUVertFormat *format);

int GPU_vertformat_attr_id_get(const GPUVertFormat *, blender::StringRef name);

BLI_INLINE const char *GPU_vertformat_attr_name_get(const GPUVertFormat *format,
                                                    const GPUVertAttr *attr,
                                                    uint n_idx)
{
  return format->names + attr->names[n_idx];
}

/**
 * \warning Can only rename using a string with same character count.
 * \warning This removes all other aliases of this attribute.
 */
void GPU_vertformat_attr_rename(GPUVertFormat *format, int attr, const char *new_name);

/**
 * \warning Always add a prefix to the result of this function as
 * the generated string can start with a number and not be a valid attribute name.
 */
void GPU_vertformat_safe_attr_name(blender::StringRef attr_name, char *r_safe_name, uint max_len);