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 * Copyright (C) gempa GmbH                                                *
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 *                                                                         *
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 * gempa GmbH.                                                             *
 ***************************************************************************/



#ifndef SEISCOMP_TTT_LIBTAU_H
#define SEISCOMP_TTT_LIBTAU_H


#include <string>
#include <seiscomp/seismology/ttt.h>

extern "C" {

#include <libtau/tau.h>

}


namespace Seiscomp {
namespace TTT {


/**
 * TTTLibTau
 *
 * A class to compute seismic travel times for 1D models like "iasp91".
 */
class SC_SYSTEM_CORE_API LibTau : public TravelTimeTableInterface {
	public:
		/**
		 * Construct a TravelTimeTable object for the specified model.
		 * Currently only "iasp91" is supported.
		 */
		LibTau() = default;
		~LibTau();

		LibTau(const LibTau &other);
		LibTau &operator=(const LibTau &other);


	public:
		bool setModel(const std::string &model) override;
		const std::string &model() const override;


		/**
		 * Select a branch of traveltimes to be computed. Currently only
		 * "all" is supported. Use the default!
		 */
		void setBranch(const std::string &branch="all");


		/**
		 * Compute the traveltime(s) for the branch selected using setBranch()
		 *
		 * It should be noted that in this implementation it is extremely
		 * important to compute as many travel times for the same focal
		 * depth as possible. Changing the depth will always result in
		 * the time-consuming re-computation of some internal tables,
		 * which can be avoided by as many consecutive compute() calls as
		 * possible, for the same depth.
		 * @param lat1 The source latitude in degrees
		 * @param lon1 The source longitude in degrees
		 * @param dep1 The source depth in km
		 * @param lat2 The receiver latitude in degrees
		 * @param lon2 The receiver longitude in degrees
		 * @param elev2 The receiver elevation in meter.
		 *              Elevation correction is not implemented and this
		 *              parameter is ignored.
		 * @param ellc Toggle earth ellipticity correction.
		 * @returns A TravelTimeList of travel times sorted by time.
		 */
		TravelTimeList *compute(double lat1, double lon1, double dep1,
		                        double lat2, double lon2, double elev2 = 0.,
		                        int ellc = 1) override;


		/**
		 * Compute the traveltime for the branch selected using setBranch()
		 * and the first (fastest) phase.
		 * @param lat1 The source latitude in degrees
		 * @param lon1 The source longitude in degrees
		 * @param dep1 The source depth in km
		 * @param lat2 The receiver latitude in degrees
		 * @param lon2 The receiver longitude in degrees
		 * @param elev2 The receiver elevation in meter.
		 *              Elevation correction is not implemented and this
		 *              parameter is ignored.
		 * @param ellc Toggle earth ellipticity correction.
		 * @returns A TravelTime
		 */
		TravelTime computeFirst(double lat1, double lon1, double dep1,
		                        double lat2, double lon2, double elev2 = 0.,
		                        int ellc = 1) override;


	private:
		TravelTimeList *compute(double delta, double depth);
		TravelTime computeFirst(double delta, double depth);

		/**
		 * Sets the source depth.
		 * @param depth The source depth in km
		 */
		void setDepth(double depth);

		void initPath(const std::string &model);


		libtau             _handle;
		double             _depth{-1};
		std::string        _model;
		bool               _initialized{false};
};


}
}


#endif