#ifndef FESA_ANALYSIS_THERMAL_TIME_GRID_H_
#define FESA_ANALYSIS_THERMAL_TIME_GRID_H_

#include <cstdint>

#include "fesa/core/status.h"

namespace fesa {

/// @brief Carries one stored time and its actual integration coefficient.
struct ThermalTimeFrame {
  double time;
  double delta;
};

/// @brief Stores an O(1) fixed-increment grid with exact input-cell endpoint
/// tests.
class ThermalTimeGrid final {
 public:
  /// @brief Checks finite positive controls and the uint32 INC bound before
  /// use.
  static Result<ThermalTimeGrid> Create(double period, double increment,
                                        std::uint32_t maximum = 100U);
  /// @brief Returns the number of completed increments, excluding initial time.
  std::uint32_t Count() const noexcept;
  /// @brief Returns fl(index * nominal increment), or the exact final input
  /// time.
  /// @pre index is in [0, Count()].
  double Time(std::uint32_t index) const noexcept;
  /// @brief Returns the actual coefficient, never a difference of stored times.
  /// @pre index is in [1, Count()].
  double Delta(std::uint32_t index) const noexcept;
  /// @brief Checks index, finite values and strict increase for one frame in
  /// O(1).
  Result<ThermalTimeFrame> Frame(std::uint32_t index) const;

 private:
  /// @brief Stores controls only after count and terminal interval validation.
  ThermalTimeGrid(double period, double increment, std::uint32_t count,
                  double final_delta);
  double period_;
  double increment_;
  std::uint32_t count_;
  double final_delta_;
};

}  // namespace fesa
#endif  // FESA_ANALYSIS_THERMAL_TIME_GRID_H_