// Copyright (c) the JPEG XL Project Authors. All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

#ifndef LIB_JXL_SPLINES_H_

#define LIB_JXL_SPLINES_H_

#include <stddef.h>

#include <stdint.h>

#include <utility>

#include <vector>

#include "lib/jxl/ans_params.h"

#include "lib/jxl/aux_out.h"

#include "lib/jxl/aux_out_fwd.h"

#include "lib/jxl/base/status.h"

#include "lib/jxl/chroma_from_luma.h"

#include "lib/jxl/dec_ans.h"

#include "lib/jxl/dec_bit_reader.h"

#include "lib/jxl/entropy_coder.h"

#include "lib/jxl/image.h"

namespace jxl {

static constexpr float kDesiredRenderingDistance = 1.f;

enum SplineEntropyContexts : size_t {

  kQuantizationAdjustmentContext = 0,

  kStartingPositionContext,

  kNumSplinesContext,

  kNumControlPointsContext,

  kControlPointsContext,

  kDCTContext,

  kNumSplineContexts

};

struct Spline {

  struct Point {

    Point() : x(0.0f), y(0.0f) {}

    Point(float x, float y) : x(x), y(y) {}

    float x, y;

    bool operator==(const Point& other) const {

      return std::fabs(x - other.x) < 1e-3f && std::fabs(y - other.y) < 1e-3f;

    }

  };

  std::vector<Point> control_points;

  // X, Y, B.

  float color_dct[3][32];

  // Splines are draws by normalized Gaussian splatting. This controls the

  // Gaussian's parameter along the spline.

  float sigma_dct[32];

};

class QuantizedSplineEncoder;

class QuantizedSpline {

 public:

  QuantizedSpline() = default;

  explicit QuantizedSpline(const Spline& original,

                           int32_t quantization_adjustment, float y_to_x,

                           float y_to_b);

  Status Dequantize(const Spline::Point& starting_point,

                    int32_t quantization_adjustment, float y_to_x, float y_to_b,

                    Spline& result) const;

  Status Decode(const std::vector<uint8_t>& context_map,

                ANSSymbolReader* decoder, BitReader* br,

                size_t max_control_points, size_t* total_num_control_points);

 private:

  friend class QuantizedSplineEncoder;

  std::vector<std::pair<int64_t, int64_t>>

      control_points_;  // Double delta-encoded.

  int color_dct_[3][32] = {};

  int sigma_dct_[32] = {};

};

// A single "drawable unit" of a spline, i.e. a line of the region in which we

// render each Gaussian. The structure doesn't actually depend on the exact

// row, which allows reuse for different y values (which are tracked

// separately).

struct SplineSegment {

  float center_x, center_y;

  float maximum_distance;

  float inv_sigma;

  float sigma_over_4_times_intensity;

  float color[3];

};

class Splines {

 public:

  Splines() = default;

  explicit Splines(const int32_t quantization_adjustment,

                   std::vector<QuantizedSpline> splines,

                   std::vector<Spline::Point> starting_points)

      : quantization_adjustment_(quantization_adjustment),

        splines_(std::move(splines)),

        starting_points_(std::move(starting_points)) {}

  bool HasAny() const { return !splines_.empty(); }

  void Clear();

  Status Decode(BitReader* br, size_t num_pixels);

  void AddTo(Image3F* opsin, const Rect& opsin_rect,

             const Rect& image_rect) const;

  void AddToRow(float* JXL_RESTRICT row_x, float* JXL_RESTRICT row_y,

                float* JXL_RESTRICT row_b, const Rect& image_row) const;

  void SubtractFrom(Image3F* opsin) const;

  const std::vector<QuantizedSpline>& QuantizedSplines() const {

    return splines_;

  }

  const std::vector<Spline::Point>& StartingPoints() const {

    return starting_points_;

  }

  int32_t GetQuantizationAdjustment() const { return quantization_adjustment_; }

  Status InitializeDrawCache(size_t image_xsize, size_t image_ysize,

                             const ColorCorrelationMap& cmap);

 private:

  template <bool>

  void ApplyToRow(float* JXL_RESTRICT row_x, float* JXL_RESTRICT row_y,

                  float* JXL_RESTRICT row_b, const Rect& image_row) const;

  template <bool>

  void Apply(Image3F* opsin, const Rect& opsin_rect,

             const Rect& image_rect) const;

  // If positive, quantization weights are multiplied by 1 + this/8, which

  // increases precision. If negative, they are divided by 1 - this/8. If 0,

  // they are unchanged.

  int32_t quantization_adjustment_ = 0;

  std::vector<QuantizedSpline> splines_;

  std::vector<Spline::Point> starting_points_;

  std::vector<SplineSegment> segments_;

  std::vector<size_t> segment_indices_;

  std::vector<size_t> segment_y_start_;

};

}  // namespace jxl

#endif  // LIB_JXL_SPLINES_H_