/* SPDX-FileCopyrightText: 2011 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

#pragma once

#include "COM_BufferArea.h"
#include "COM_BufferRange.h"
#include "COM_BuffersIterator.h"
#include "COM_Enums.h"

#include "BLI_math_base.hh"
#include "BLI_math_interp.hh"
#include "BLI_math_vector.h"
#include "BLI_math_vector_types.hh"
#include "BLI_rect.h"

#include <cstdint>
#include <cstring>

struct ColormanageProcessor;
struct ImBuf;

namespace blender::compositor {

enum class MemoryBufferExtend {
  Clip,
  Extend,
  Repeat,
};

/**
 * \brief a MemoryBuffer contains access to the data
 */
class MemoryBuffer {
 public:
  /**
   * Offset between elements.
   *
   * Should always be used for the x dimension when calculating buffer offsets.
   * It will be 0 when is_a_single_elem=true.
   * e.g: buffer_index = y * buffer.row_stride + x * buffer.elem_stride
   */
  int elem_stride;

  /**
   * Offset between rows.
   *
   * Should always be used for the y dimension when calculating buffer offsets.
   * It will be 0 when is_a_single_elem=true.
   * e.g: buffer_index = y * buffer.row_stride + x * buffer.elem_stride
   */
  int row_stride;

 private:
  /**
   * \brief the type of buffer DataType::Value, DataType::Vector, DataType::Color
   */
  DataType datatype_;

  /**
   * \brief region of this buffer inside
   */
  rcti rect_;

  /**
   * \brief the actual float buffer/data
   */
  float *buffer_;

  /**
   * \brief the number of channels of a single value in the buffer.
   * For value buffers this is 1, vector 3 and color 4
   */
  uint8_t num_channels_;

  /**
   * Whether buffer is a single element in memory.
   */
  bool is_a_single_elem_;

  /**
   * Whether MemoryBuffer owns buffer data.
   */
  bool owns_data_;

  /** Stride to make any x coordinate within buffer positive (non-zero). */
  int to_positive_x_stride_;

  /** Stride to make any y coordinate within buffer positive (non-zero). */
  int to_positive_y_stride_;

 public:
  /**
   * \brief construct new temporarily MemoryBuffer for a width and height.
   */
  MemoryBuffer(DataType data_type, int width, int height);

  /**
   * \brief construct new temporarily MemoryBuffer for an area
   */
  MemoryBuffer(DataType data_type, const rcti &rect, bool is_a_single_elem = false);

  /**
   * Construct MemoryBuffer from a float buffer. MemoryBuffer is not responsible for
   * freeing it.
   */
  MemoryBuffer(
      float *buffer, int num_channels, int width, int height, bool is_a_single_elem = false);

  /**
   * Construct MemoryBuffer from a float buffer area. MemoryBuffer is not responsible for
   * freeing given buffer.
   */
  MemoryBuffer(float *buffer, int num_channels, const rcti &rect, bool is_a_single_elem = false);

  /**
   * Copy constructor
   */
  MemoryBuffer(const MemoryBuffer &src);

  /**
   * \brief destructor
   */
  ~MemoryBuffer();

  /**
   * Whether buffer is a single element in memory independently of its resolution. True for set
   * operations buffers.
   */
  bool is_a_single_elem() const
  {
    return is_a_single_elem_;
  }

  float &operator[](int index)
  {
    BLI_assert(is_a_single_elem_ ? index < num_channels_ :
                                   index < get_coords_offset(get_width(), get_height()));
    return buffer_[index];
  }

  const float &operator[](int index) const
  {
    BLI_assert(is_a_single_elem_ ? index < num_channels_ :
                                   index < get_coords_offset(get_width(), get_height()));
    return buffer_[index];
  }

  /**
   * Get offset needed to jump from buffer start to given coordinates.
   */
  intptr_t get_coords_offset(int x, int y) const
  {
    return ((intptr_t)y - rect_.ymin) * row_stride + ((intptr_t)x - rect_.xmin) * elem_stride;
  }

  /**
   * Get buffer element at given coordinates.
   */
  float *get_elem(int x, int y)
  {
    BLI_assert(has_coords(x, y));
    return buffer_ + get_coords_offset(x, y);
  }

  /**
   * Get buffer element at given coordinates.
   */
  const float *get_elem(int x, int y) const
  {
    BLI_assert(has_coords(x, y));
    return buffer_ + get_coords_offset(x, y);
  }

  /**
   * Get buffer element at given coordinates, clamped to border.
   */
  const float *get_elem_clamped(int x, int y) const
  {
    const int clamped_x = math::clamp(x, 0, this->get_width() - 1);
    const int clamped_y = math::clamp(y, 0, this->get_height() - 1);
    return buffer_ + get_coords_offset(clamped_x, clamped_y);
  }

  void read_elem(int x, int y, float *out) const
  {
    memcpy(out, get_elem(x, y), get_elem_bytes_len());
  }

  void read_elem_clamped(int x, int y, float *out) const
  {
    memcpy(out, get_elem_clamped(x, y), get_elem_bytes_len());
  }

  void read_elem_checked(int x, int y, float *out) const
  {
    if (!has_coords(x, y)) {
      clear_elem(out);
    }
    else {
      read_elem(x, y, out);
    }
  }

  void read_elem_checked(float x, float y, float *out) const
  {
    read_elem_checked(floor_x(x), floor_y(y), out);
  }

  /* Equivalent to the GLSL texture() function with bilinear interpolation and extended boundary
   * conditions. The coordinates are thus expected to have half-pixels offsets. A float4 is always
   * returned regardless of the number of channels of the buffer, the remaining channels will be
   * initialized with the template float4(0, 0, 0, 1). */
  float4 texture_bilinear_extend(float2 coordinates) const
  {
    if (is_a_single_elem_) {
      float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f);
      memcpy(result, buffer_, get_elem_bytes_len());
      return result;
    }

    const int2 size = int2(get_width(), get_height());
    const float2 texel_coordinates = (coordinates * float2(size)) - 0.5f;

    float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f);
    math::interpolate_bilinear_fl(
        buffer_, result, size.x, size.y, num_channels_, texel_coordinates.x, texel_coordinates.y);
    return result;
  }

  /* Equivalent to the GLSL texture() function with nearest interpolation and extended boundary
   * conditions. The coordinates are thus expected to have half-pixels offsets. A float4 is always
   * returned regardless of the number of channels of the buffer, the remaining channels will be
   * initialized with the template float4(0, 0, 0, 1). */
  float4 texture_nearest_extend(float2 coordinates) const
  {
    if (is_a_single_elem_) {
      float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f);
      memcpy(result, buffer_, get_elem_bytes_len());
      return result;
    }

    const int2 size = int2(get_width(), get_height());
    const float2 texel_coordinates = coordinates * float2(size);

    float4 result = float4(0.0f, 0.0f, 0.0f, 1.0f);
    math::interpolate_nearest_fl(
        buffer_, result, size.x, size.y, num_channels_, texel_coordinates.x, texel_coordinates.y);
    return result;
  }

  void read_elem_bilinear(float x, float y, float *out) const
  {
    read(out, x, y, PixelSampler::Bilinear);
  }

  void read_elem_bicubic_bspline(float x, float y, float *out) const
  {
    if (is_a_single_elem_) {
      memcpy(out, buffer_, get_elem_bytes_len());
      return;
    }

    math::interpolate_cubic_bspline_fl(buffer_,
                                       out,
                                       this->get_width(),
                                       this->get_height(),
                                       num_channels_,
                                       get_relative_x(x),
                                       get_relative_y(y));
  }

  void read_elem_sampled(float x, float y, PixelSampler sampler, float *out) const
  {
    read(out, x, y, sampler);
  }

  void read_elem_filtered(
      float x, float y, float dx[2], float dy[2], bool extend_boundary, float *out) const;

  /**
   * Get channel value at given coordinates.
   */
  float &get_value(int x, int y, int channel)
  {
    BLI_assert(has_coords(x, y) && channel >= 0 && channel < num_channels_);
    return buffer_[get_coords_offset(x, y) + channel];
  }

  /**
   * Get channel value at given coordinates.
   */
  const float &get_value(int x, int y, int channel) const
  {
    BLI_assert(has_coords(x, y) && channel >= 0 && channel < num_channels_);
    return buffer_[get_coords_offset(x, y) + channel];
  }

  /**
   * Get the buffer row end.
   */
  const float *get_row_end(int y) const
  {
    BLI_assert(has_y(y));
    return buffer_ + (is_a_single_elem() ? num_channels_ : get_coords_offset(get_width(), y));
  }

  /**
   * Get the number of elements in memory for a row. For single element buffers it will always
   * be 1.
   */
  int get_memory_width() const
  {
    return is_a_single_elem() ? 1 : get_width();
  }

  /**
   * Get number of elements in memory for a column. For single element buffers it will
   * always be 1.
   */
  int get_memory_height() const
  {
    return is_a_single_elem() ? 1 : get_height();
  }

  uint8_t get_num_channels() const
  {
    return num_channels_;
  }

  uint8_t get_elem_bytes_len() const
  {
    return num_channels_ * sizeof(float);
  }

  /**
   * Get all buffer elements as a range with no offsets.
   */
  BufferRange<float> as_range()
  {
    return BufferRange<float>(buffer_, 0, buffer_len(), elem_stride);
  }

  BufferRange<const float> as_range() const
  {
    return BufferRange<const float>(buffer_, 0, buffer_len(), elem_stride);
  }

  BufferArea<float> get_buffer_area(const rcti &area)
  {
    return BufferArea<float>(buffer_, get_width(), area, elem_stride);
  }

  BufferArea<const float> get_buffer_area(const rcti &area) const
  {
    return BufferArea<const float>(buffer_, get_width(), area, elem_stride);
  }

  BuffersIterator<float> iterate_with(Span<MemoryBuffer *> inputs);
  BuffersIterator<float> iterate_with(Span<MemoryBuffer *> inputs, const rcti &area);

  /**
   * \brief get the data of this MemoryBuffer
   * \note buffer should already be available in memory
   */
  float *get_buffer()
  {
    return buffer_;
  }

  /**
   * Converts a single elem buffer to a full size buffer (allocates memory for all
   * elements in resolution).
   */
  MemoryBuffer *inflate() const;

  inline void wrap_pixel(float &x,
                         float &y,
                         MemoryBufferExtend extend_x,
                         MemoryBufferExtend extend_y) const
  {
    const float w = (float)get_width();
    const float h = (float)get_height();
    x = x - rect_.xmin;
    y = y - rect_.ymin;

    switch (extend_x) {
      case MemoryBufferExtend::Clip:
        break;
      case MemoryBufferExtend::Extend:
        if (x < 0) {
          x = 0.0f;
        }
        if (x >= w) {
          x = w - 1;
        }
        break;
      case MemoryBufferExtend::Repeat:
        x = floored_fmod(x, w);
        break;
    }

    switch (extend_y) {
      case MemoryBufferExtend::Clip:
        break;
      case MemoryBufferExtend::Extend:
        if (y < 0) {
          y = 0.0f;
        }
        if (y >= h) {
          y = h - 1;
        }
        break;
      case MemoryBufferExtend::Repeat:
        y = floored_fmod(y, h);
        break;
    }

    x = x + rect_.xmin;
    y = y + rect_.ymin;
  }

  inline void read(float *result,
                   float x,
                   float y,
                   PixelSampler sampler = PixelSampler::Nearest,
                   MemoryBufferExtend extend_x = MemoryBufferExtend::Clip,
                   MemoryBufferExtend extend_y = MemoryBufferExtend::Clip) const
  {
    /* Extend is completely ignored for constants. This may need to be fixed in the future. */
    if (is_a_single_elem_) {
      memcpy(result, buffer_, get_elem_bytes_len());
      return;
    }

    this->wrap_pixel(x, y, extend_x, extend_y);

    if (sampler == PixelSampler::Nearest) {
      read_elem_checked(int(floorf(x + 0.5f)), int(floorf(y + 0.5f)), result);
      return;
    }

    x = get_relative_x(x);
    y = get_relative_y(y);
    const float w = get_width();
    const float h = get_height();

    /* Compute (linear interpolation) intersection with Clip. */
    float mult = 1.0f;
    if (extend_x == MemoryBufferExtend::Clip) {
      mult = std::min(x + 1.0f, w - x);
    }
    if (extend_y == MemoryBufferExtend::Clip) {
      mult = std::min(mult, std::min(y + 1.0f, h - y));
    }
    if (mult <= 0.0f) {
      clear_elem(result);
      return;
    }

    if (sampler == PixelSampler::Bilinear) {
      /* Sample using Extend or Repeat. */
      math::interpolate_bilinear_wrap_fl(buffer_,
                                         result,
                                         w,
                                         h,
                                         num_channels_,
                                         x,
                                         y,
                                         extend_x == MemoryBufferExtend::Repeat,
                                         extend_y == MemoryBufferExtend::Repeat);
    }
    else { /* #PixelSampler::Bicubic */
      /* Sample using Extend (Repeat is not implemented by `interpolate_cubic_bspline`). */
      math::interpolate_cubic_bspline_fl(buffer_, result, w, h, num_channels_, x, y);
    }

    /* Multiply by Clip intersection. */
    if (mult < 1.0f) {
      for (int i = 0; i < num_channels_; ++i) {
        result[i] *= mult;
      }
    }
  }
  void write_pixel(int x, int y, const float color[4]);
  void add_pixel(int x, int y, const float color[4]);
  inline void read_bilinear(float *result,
                            float x,
                            float y,
                            MemoryBufferExtend extend_x = MemoryBufferExtend::Clip,
                            MemoryBufferExtend extend_y = MemoryBufferExtend::Clip) const
  {
    float u = x;
    float v = y;
    this->wrap_pixel(u, v, extend_x, extend_y);
    if ((extend_x != MemoryBufferExtend::Repeat && (u < 0.0f || u >= get_width())) ||
        (extend_y != MemoryBufferExtend::Repeat && (v < 0.0f || v >= get_height())))
    {
      copy_vn_fl(result, num_channels_, 0.0f);
      return;
    }
    if (is_a_single_elem_) {
      memcpy(result, buffer_, sizeof(float) * num_channels_);
    }
    else {
      math::interpolate_bilinear_wrap_fl(buffer_,
                                         result,
                                         get_width(),
                                         get_height(),
                                         num_channels_,
                                         u,
                                         v,
                                         extend_x == MemoryBufferExtend::Repeat,
                                         extend_y == MemoryBufferExtend::Repeat);
    }
  }

  /**
   * \brief Apply a color processor on the given area.
   */
  void apply_processor(ColormanageProcessor &processor, const rcti area);

  void copy_from(const MemoryBuffer *src, const rcti &area);
  void copy_from(const MemoryBuffer *src, const rcti &area, int to_x, int to_y);
  void copy_from(const MemoryBuffer *src,
                 const rcti &area,
                 int channel_offset,
                 int elem_size,
                 int to_channel_offset);
  void copy_from(const MemoryBuffer *src,
                 const rcti &area,
                 int channel_offset,
                 int elem_size,
                 int to_x,
                 int to_y,
                 int to_channel_offset);
  void copy_from(const uchar *src, const rcti &area);
  void copy_from(const uchar *src,
                 const rcti &area,
                 int channel_offset,
                 int elem_size,
                 int elem_stride,
                 int row_stride,
                 int to_channel_offset);
  void copy_from(const uchar *src,
                 const rcti &area,
                 int channel_offset,
                 int elem_size,
                 int elem_stride,
                 int row_stride,
                 int to_x,
                 int to_y,
                 int to_channel_offset);
  void copy_from(const struct ImBuf *src,
                 const rcti &area,
                 bool ensure_premultiplied = false,
                 bool ensure_linear_space = false);
  void copy_from(const struct ImBuf *src,
                 const rcti &area,
                 int channel_offset,
                 int elem_size,
                 int to_channel_offset,
                 bool ensure_premultiplied = false,
                 bool ensure_linear_space = false);
  void copy_from(const struct ImBuf *src,
                 const rcti &src_area,
                 int channel_offset,
                 int elem_size,
                 int to_x,
                 int to_y,
                 int to_channel_offset,
                 bool ensure_premultiplied = false,
                 bool ensure_linear_space = false);

  void fill(const rcti &area, const float *value);
  void fill(const rcti &area, int channel_offset, const float *value, int value_size);
  /**
   * \brief add the content from other_buffer to this MemoryBuffer
   * \param other_buffer: source buffer
   *
   * \note take care when running this on a new buffer since it won't fill in
   *       uninitialized values in areas where the buffers don't overlap.
   */
  void fill_from(const MemoryBuffer &src);

  /**
   * \brief get the rect of this MemoryBuffer
   */
  const rcti &get_rect() const
  {
    return rect_;
  }

  /**
   * \brief get the width of this MemoryBuffer
   */
  const int get_width() const
  {
    return BLI_rcti_size_x(&rect_);
  }

  /**
   * \brief get the height of this MemoryBuffer
   */
  const int get_height() const
  {
    return BLI_rcti_size_y(&rect_);
  }

  /**
   * \brief clear the buffer. Make all pixels black transparent.
   */
  void clear();

  float get_max_value() const;
  float get_max_value(const rcti &rect) const;

 private:
  void set_strides();
  const int64_t buffer_len() const
  {
    return int64_t(get_memory_width()) * int64_t(get_memory_height());
  }

  void clear_elem(float *out) const
  {
    memset(out, 0, num_channels_ * sizeof(float));
  }

  template<typename T> T get_relative_x(T x) const
  {
    return x - rect_.xmin;
  }

  template<typename T> T get_relative_y(T y) const
  {
    return y - rect_.ymin;
  }

  template<typename T> bool has_coords(T x, T y) const
  {
    return has_x(x) && has_y(y);
  }

  template<typename T> bool has_x(T x) const
  {
    return x >= rect_.xmin && x < rect_.xmax;
  }

  template<typename T> bool has_y(T y) const
  {
    return y >= rect_.ymin && y < rect_.ymax;
  }

  /* Fast `floor(..)` functions. The caller should check result is within buffer bounds.
   * It `ceil(..)` in near cases and when given coordinate
   * is negative and less than buffer rect `min - 1`. */
  int floor_x(float x) const
  {
    return (int)(x + to_positive_x_stride_) - to_positive_x_stride_;
  }

  int floor_y(float y) const
  {
    return (int)(y + to_positive_y_stride_) - to_positive_y_stride_;
  }

  void copy_single_elem_from(const MemoryBuffer *src,
                             int channel_offset,
                             int elem_size,
                             int to_channel_offset);
  void copy_rows_from(const MemoryBuffer *src, const rcti &src_area, int to_x, int to_y);
  void copy_elems_from(const MemoryBuffer *src,
                       const rcti &area,
                       int channel_offset,
                       int elem_size,
                       int to_x,
                       int to_y,
                       int to_channel_offset);

#ifdef WITH_CXX_GUARDEDALLOC
  MEM_CXX_CLASS_ALLOC_FUNCS("COM:MemoryBuffer")
#endif
};

}  // namespace blender::compositor
