text: #pragma once
  
  #include <DataTypes/DataTypesNumber.h>
  #include <Columns/ColumnsNumber.h>
  #include <Columns/ColumnConst.h>
  #include <Common/typeid_cast.h>
  #include <Functions/IFunction.h>
  #include <Functions/FunctionHelpers.h>
  #include <ext/range.h>
  #include <math.h>
  #include <array>
  
  #define DEGREES_IN_RADIANS (M_PI / 180.0)
  
  namespace DB
  {
  
  namespace ErrorCodes
  {
      extern const int ARGUMENT_OUT_OF_BOUND;
      extern const int ILLEGAL_COLUMN;
  }
  
  const Float64 EARTH_RADIUS_IN_METERS = 6372797.560856;
  
  static inline Float64 degToRad(Float64 angle) { return angle * DEGREES_IN_RADIANS; }
  static inline Float64 radToDeg(Float64 angle) { return angle / DEGREES_IN_RADIANS; }
  
  /**
   *  The function calculates distance in meters between two points on Earth specified by longitude and latitude in degrees.
   *  The function uses great circle distance formula https://en.wikipedia.org/wiki/Great-circle_distance.
   *  Throws exception when one or several input values are not within reasonable bounds.
   *  Latitude must be in [-90, 90], longitude must be [-180, 180]
   *
   */
  class FunctionGreatCircleDistance : public IFunction
  {
  public:
  
      static constexpr auto name = "greatCircleDistance";
      static FunctionPtr create(const Context &) { return std::make_shared<FunctionGreatCircleDistance>(); }
  
  private:
  
      enum class instr_type : uint8_t
      {
          get_float_64,
          get_const_float_64
      };
  
      using instr_t = std::pair<instr_type, const IColumn *>;
      using instrs_t = std::array<instr_t, 4>;
  
      String getName() const override { return name; }
  
      size_t getNumberOfArguments() const override { return 4; }
  
      DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
      {
          for (const auto arg_idx : ext::range(0, arguments.size()))
          {
              const auto arg = arguments[arg_idx].get();
              if (!checkDataType<DataTypeFloat64>(arg))
                  throw Exception(
                      "Illegal type " + arg->getName() + " of argument " + std::to_string(arg_idx + 1) + " of function " + getName() + ". Must be Float64",
                      ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
          }
  
          return std::make_shared<DataTypeFloat64>();
      }
  
      instrs_t getInstructions(const Block & block, const ColumnNumbers & arguments, bool & out_const)
      {
          instrs_t result;
          out_const = true;
  
          for (const auto arg_idx : ext::range(0, arguments.size()))
          {
              const auto column = block.getByPosition(arguments[arg_idx]).column.get();
  
              if (const auto col = checkAndGetColumn<ColumnVector<Float64>>(column))
              {
                  out_const = false;
                  result[arg_idx] = instr_t{instr_type::get_float_64, col};
              }
              else if (const auto col = checkAndGetColumnConst<ColumnVector<Float64>>(column))
              {
                  result[arg_idx] = instr_t{instr_type::get_const_float_64, col};
              }
              else
                  throw Exception("Illegal column " + column->getName() + " of argument of function " + getName(),
                      ErrorCodes::ILLEGAL_COLUMN);
          }
  
          return result;
      }
  
      /// https://en.wikipedia.org/wiki/Great-circle_distance
      Float64 greatCircleDistance(Float64 lon1Deg, Float64 lat1Deg, Float64 lon2Deg, Float64 lat2Deg)
      {
          if (lon1Deg < -180 || lon1Deg > 180 ||
              lon2Deg < -180 || lon2Deg > 180 ||
              lat1Deg < -90 || lat1Deg > 90 ||
              lat2Deg < -90 || lat2Deg > 90)
          {
              throw Exception("Arguments values out of bounds for function " + getName(), ErrorCodes::ARGUMENT_OUT_OF_BOUND);
          }
  
          Float64 lon1Rad = degToRad(lon1Deg);
          Float64 lat1Rad = degToRad(lat1Deg);
          Float64 lon2Rad = degToRad(lon2Deg);
          Float64 lat2Rad = degToRad(lat2Deg);
          Float64 u = sin((lat2Rad - lat1Rad) / 2);
          Float64 v = sin((lon2Rad - lon1Rad) / 2);
          return 2.0 * EARTH_RADIUS_IN_METERS * asin(sqrt(u * u + cos(lat1Rad) * cos(lat2Rad) * v * v));
      }
  
  
      void executeImpl(Block & block, const ColumnNumbers & arguments, const size_t result) override
      {
          const auto size = block.rows();
  
          bool result_is_const{};
          auto instrs = getInstructions(block, arguments, result_is_const);
  
          if (result_is_const)
          {
              const auto & colLon1 = static_cast<const ColumnConst *>(block.getByPosition(arguments[0]).column.get())->getValue<Float64>();
              const auto & colLat1 = static_cast<const ColumnConst *>(block.getByPosition(arguments[1]).column.get())->getValue<Float64>();
              const auto & colLon2 = static_cast<const ColumnConst *>(block.getByPosition(arguments[2]).column.get())->getValue<Float64>();
              const auto & colLat2 = static_cast<const ColumnConst *>(block.getByPosition(arguments[3]).column.get())->getValue<Float64>();
  
              Float64 res = greatCircleDistance(colLon1, colLat1, colLon2, colLat2);
              block.getByPosition(result).column = block.getByPosition(result).type->createConstColumn(size, res);
          }
          else
          {
              const auto dst = std::make_shared<ColumnVector<Float64>>();
              block.getByPosition(result).column = dst;
              auto & dst_data = dst->getData();
              dst_data.resize(size);
              Float64 vals[instrs.size()];
              for (const auto row : ext::range(0, size))
              {
                  for (const auto idx : ext::range(0, instrs.size()))
                  {
                      if (instr_type::get_float_64 == instrs[idx].first)
                          vals[idx] = static_cast<const ColumnVector<Float64> *>(instrs[idx].second)->getData()[row];
                      else if (instr_type::get_const_float_64 == instrs[idx].first)
                          vals[idx] = static_cast<const ColumnConst *>(instrs[idx].second)->getValue<Float64>();
                      else
                          throw std::logic_error{"unknown instr_type"};
                  }
                  dst_data[row] = greatCircleDistance(vals[0], vals[1], vals[2], vals[3]);
              }
          }
      }
  };
  
  
  /**
   * The function checks if a point is in one of ellipses in set.
   * The number of arguments must be 2 + 4*N where N is the number of ellipses.
   * The arguments must be arranged as follows: (x, y, x_0, y_0, a_0, b_0, ..., x_i, y_i, a_i, b_i)
   * All ellipses parameters must be const values;
   *
   * The function first checks bounding box condition.
   * If a point is inside an ellipse's bounding box, the quadratic condition is evaluated.
   *
   * Here we assume that points in one block are close and are likely to fit in one ellipse,
   * so the last success ellipse index is remembered to check this ellipse first for next point.
   *
   */
  class FunctionPointInEllipses : public IFunction
  {
  public:
  
      static constexpr auto name = "pointInEllipses";
      static FunctionPtr create(const Context &) { return std::make_shared<FunctionPointInEllipses>(); }
  
  private:
  
      struct Ellipse {
          Float64 x;
          Float64 y;
          Float64 a;
          Float64 b;
      };
  
      String getName() const override { return name; }
  
      bool isVariadic() const override { return true; }
  
      size_t getNumberOfArguments() const override { return 0; }
  
      DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
      {
          if (arguments.size() < 6 || arguments.size() % 4 != 2)
          {
              throw Exception(
                  "Incorrect number of arguments of function " + getName() + ". Must be 2 for your point plus 4 * N for ellipses (x_i, y_i, a_i, b_i).");
          }
  
          /// For array on stack, see below.
          if (arguments.size() > 10000)
          {
              throw Exception(
                  "Number of arguments of function " + getName() + " is too large.");
          }
  
          for (const auto arg_idx : ext::range(0, arguments.size()))
          {
              const auto arg = arguments[arg_idx].get();
              if (!checkDataType<DataTypeFloat64>(arg))
              {
                  throw Exception(
                      "Illegal type " + arg->getName() + " of argument " + std::to_string(arg_idx + 1) + " of function " + getName() + ". Must be Float64",
                      ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
              }
          }
  
          return std::make_shared<DataTypeUInt8>();
      }
  
      void executeImpl(Block & block, const ColumnNumbers & arguments, const size_t result) override
      {
          const auto size = block.rows();
  
          /// Prepare array of ellipses.
          size_t ellipses_count = (arguments.size() - 2) / 4;
          Ellipse ellipses[ellipses_count];
  
          for (const auto ellipse_idx : ext::range(0, ellipses_count))
          {
              Float64 ellipse_data[4];
              for (const auto idx : ext::range(0, 4))
              {
                  int arg_idx = 2 + 4 * ellipse_idx + idx;
                  const auto column = block.getByPosition(arguments[arg_idx]).column.get();
                  if (const auto col = checkAndGetColumnConst<ColumnVector<Float64>>(column))
                  {
                      ellipse_data[idx] = col->getValue<Float64>();
                  }
                  else
                  {
                      throw Exception(
                          "Illegal type " + column->getName() + " of argument " + std::to_string(arg_idx + 1) + " of function " + getName() + ". Must be const Float64",
                          ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
                  }
              }
              ellipses[ellipse_idx] = Ellipse{ellipse_data[0], ellipse_data[1], ellipse_data[2], ellipse_data[3]};
          }
  
          int const_cnt = 0;
          for (const auto idx : ext::range(0, 2))
          {
              const auto column = block.getByPosition(arguments[idx]).column.get();
              if (typeid_cast<const ColumnConst *> (column))
              {
                  ++const_cnt;
              }
              else if (!typeid_cast<const ColumnVector<Float64> *> (column))
              {
                  throw Exception("Illegal column " + column->getName() + " of argument of function " + getName(),
                      ErrorCodes::ILLEGAL_COLUMN);
              }
          }
  
          const auto col_x = block.getByPosition(arguments[0]).column.get();
          const auto col_y = block.getByPosition(arguments[1]).column.get();
          if (const_cnt == 0)
          {
                  const auto col_vec_x = static_cast<const ColumnVector<Float64> *> (col_x);
                  const auto col_vec_y = static_cast<const ColumnVector<Float64> *> (col_y);
  
                  const auto dst = std::make_shared<ColumnVector<UInt8>>();
                  block.getByPosition(result).column = dst;
                  auto & dst_data = dst->getData();
                  dst_data.resize(size);
  
                  size_t start_index = 0;
                  for (const auto row : ext::range(0, size))
                  {
                      dst_data[row] = isPointInEllipses(col_vec_x->getData()[row], col_vec_y->getData()[row], ellipses, ellipses_count, start_index);
                  }
              }
              else if (const_cnt == 2)
              {
                  const auto col_const_x = static_cast<const ColumnConst *> (col_x);
                  const auto col_const_y = static_cast<const ColumnConst *> (col_y);
                  size_t start_index = 0;
                  UInt8 res = isPointInEllipses(col_const_x->getValue<Float64>(), col_const_y->getValue<Float64>(), ellipses, ellipses_count, start_index);
                  block.getByPosition(result).column = DataTypeUInt8().createConstColumn(size, UInt64(res));
              }
              else
              {
                  throw Exception(
                      "Illegal types " + col_x->getName() + ", " + col_y->getName() + " of arguments 1, 2 of function " + getName() + ". Both must be either const or vector",
                      ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
              }
      }
  
      static bool isPointInEllipses(Float64 x, Float64 y, const Ellipse * ellipses, size_t ellipses_count, size_t & start_index)
      {
          size_t index = 0 + start_index;
          for (size_t i = 0; i < ellipses_count; ++i)
          {
              Ellipse el = ellipses[index];
              double p1 = ((x - el.x) / el.a);
              double p2 = ((y - el.y) / el.b);
              if (x <= el.x + el.a && x >= el.x - el.a && y <= el.y + el.b && y >= el.y - el.b /// Bounding box check
                  && p1 * p1 + p2 * p2 <= 1.0)    /// Precise check
              {
                  start_index = index;
                  return true;
              }
              ++index;
              if (index == ellipses_count)
              {
                  index = 0;
              }
          }
          return false;
      }
  };
  
  }
  
  #undef DEGREES_IN_RADIANS
  