#ifndef SHEET_H
#define SHEET_H

#include <cfloat>
#include <QObject>
#include <QVector>

class QImage;

/// Temperatures are stores into a matrix of double values
typedef QVector< QVector<double> > TemperatureMatrix;

/// A rectangular sheet where heat is simulated
class Sheet : public QObject
{
	Q_OBJECT
	Q_DISABLE_COPY(Sheet)

  protected:
	/// A sheet is a matrix of temperatures
	TemperatureMatrix temperatures1;
	/// But two marixes are used to simulate the generations
	TemperatureMatrix temperatures2;
	/// The current updated matrix in the simulation
	TemperatureMatrix* current = &temperatures1;
	/// The next generation will be stored in this matrix
	TemperatureMatrix* next = &temperatures2;
	/// The minimum temperature loaded from CSV file
	double minimum = DBL_MAX;
	/// The maximum temperature loaded from CSV file
	double maximum = DBL_MIN;
	/// The epsilon used to detect if no change in the sheet and stop
	double epsilon = 0.001;
	/// The current generation simulated
	unsigned long long generation = 0;
	/// True if the simulation is in progress
	bool simulating = false;

  public:
	/// Constructor
	explicit Sheet(QObject* parent = nullptr);
	/// Get the minimum temperature of the sheet
	inline double getMinimum() const { return this->minimum; }
	/// Get the maximum temperature of the sheet
	inline double getMaximum() const { return this->maximum; }
	/// Get the epsilon used to stop the simulation when the temperature stabilishes
	inline double getEpsilon() const { return this->epsilon; }
	/// Loads a sheet from a CSV or CST file
	/// @return A sheet pointer if the file is valid, nullptr otherwise
	static Sheet* load(const QString& filePath, QObject* parent = nullptr);
	/// Load the temperatures from the csv file
	/// @return true on success, false on error
	bool loadCsv(const QString& filePath);
	/// Load the temperatures from the csv file using the given separator
	/// @return true on success, false on error
	bool loadCsv(const QString& filePath, char separator);
	/// Get the number of rows
	inline int getRows() const { return this->temperatures1.count(); }
	/// Get the number of columns
	inline int getColumns() const { return this->temperatures1.count() > 0 ? this->temperatures1[0].count() : 0; }
	/// Get the current generation
	inline unsigned long long getGeneration() const { return this->generation; }
	/// Get read-only access to the current matrix
	inline const TemperatureMatrix& getCurrentMatrix() const { return *this->current; }
  #ifdef HEAT_TRANSMISSION_GUI
	/// Fills the given image with pixels sampled from the temperatures of this sheet
	/// @return true on success, false otherwise
	bool fillImage(QImage& image);
  #endif
	/// Start the simulation at full speed of this machine
	/// @param epsilon The simulation will stop when all cells have a temperature change less than
	/// this real number. For example 0.000001. It must be greater than 0.0.
	/// @return true If simulation started, false if epsilon is negative or zero
	bool startSimulation(double epsilon);
	/// Stop the simulation
	void stopSimulation();

  signals:
	/// Emitted when the simulation has finished
	/// @param generations The number of generations done
	void simulationDone(unsigned long long generations);

  protected:
	/// Load the temperatures from csv line using the given separator
	/// @return true on success, false on error
	bool loadLine(const QString& line, char separator);
	/// Updates the matrixes with the next generation of heat transfer
	/// @return The maximum heat change detected into a cell
	double updateGeneration();
	/// Updates the temperature of a cell from current matrix to the next one
	/// as the average of the four neighbors in the four cardinal points
	/// @return the difference of temperature from old state to the new one
	double updateCell(int row, int col);
};

#endif // SHEET_H