// 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.

#include <cmath>

#include <cstddef>

#include <cstdint>

#include <vector>

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

#include "lib/jxl/enc_ans.h"

#include "lib/jxl/enc_ans_params.h"

#include "lib/jxl/enc_bit_writer.h"

#include "lib/jxl/image.h"

#include "lib/jxl/pack_signed.h"

#include "lib/jxl/splines.h"

namespace jxl {

struct AuxOut;

enum class LayerType : uint8_t;

class QuantizedSplineEncoder {

 public:

  // Only call if HasAny().

  static void Tokenize(const QuantizedSpline& spline,

                       std::vector<Token>* const tokens) {

    tokens->emplace_back(kNumControlPointsContext,

                         spline.control_points_.size());

    for (const auto& point : spline.control_points_) {

      tokens->emplace_back(kControlPointsContext, PackSigned(point.first));

      tokens->emplace_back(kControlPointsContext, PackSigned(point.second));

    }

    const auto encode_dct = [tokens](const int dct[32]) {

      for (int i = 0; i < 32; ++i) {

        tokens->emplace_back(kDCTContext, PackSigned(dct[i]));

      }

    };

    for (const auto& dct : spline.color_dct_) {

      encode_dct(dct);

    }

    encode_dct(spline.sigma_dct_);

  }

};

namespace {

void EncodeAllStartingPoints(const std::vector<Spline::Point>& points,

                             std::vector<Token>* tokens) {

  int64_t last_x = 0;

  int64_t last_y = 0;

  for (size_t i = 0; i < points.size(); i++) {

    const int64_t x = std::lround(points[i].x);

    const int64_t y = std::lround(points[i].y);

    if (i == 0) {

      tokens->emplace_back(kStartingPositionContext, x);

      tokens->emplace_back(kStartingPositionContext, y);

    } else {

      tokens->emplace_back(kStartingPositionContext, PackSigned(x - last_x));

      tokens->emplace_back(kStartingPositionContext, PackSigned(y - last_y));

    }

    last_x = x;

    last_y = y;

  }

}

}  // namespace

Status EncodeSplines(const Splines& splines, BitWriter* writer,

                     const LayerType layer,

                     const HistogramParams& histogram_params, AuxOut* aux_out) {

  JXL_ENSURE(splines.HasAny());

  const std::vector<QuantizedSpline>& quantized_splines =

      splines.QuantizedSplines();

  std::vector<std::vector<Token>> tokens(1);

  tokens[0].emplace_back(kNumSplinesContext, quantized_splines.size() - 1);

  EncodeAllStartingPoints(splines.StartingPoints(), tokens.data());

  tokens[0].emplace_back(kQuantizationAdjustmentContext,

                         PackSigned(splines.GetQuantizationAdjustment()));

  for (const QuantizedSpline& spline : quantized_splines) {

    QuantizedSplineEncoder::Tokenize(spline, tokens.data());

  }

  EntropyEncodingData codes;

  JXL_ASSIGN_OR_RETURN(

      size_t cost,

      BuildAndEncodeHistograms(writer->memory_manager(), histogram_params,

                               kNumSplineContexts, tokens, &codes, writer,

                               layer, aux_out));

  (void)cost;

  JXL_RETURN_IF_ERROR(WriteTokens(tokens[0], codes, 0, writer, layer, aux_out));

  return true;

}

Splines FindSplines(const Image3F& opsin) {

  // TODO(user): implement spline detection.

  return {};

}

}  // namespace jxl