ResamplingAlgorithms.h

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// SPDX-License-Identifier: LGPL-3.0-or-later
/***********************************************************************************/
/*  Copyright 2009 WSL Institute for Snow and Avalanche Research    SLF-DAVOS      */
/***********************************************************************************/
/* This file is part of MeteoIO.
    MeteoIO is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    MeteoIO is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public License
    along with MeteoIO.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef RESAMPLINGALGORITHMS_H
#define RESAMPLINGALGORITHMS_H
 
#include <meteoio/dataClasses/MeteoData.h>
#include <meteoio/IOUtils.h>
 
#include <string>
#include <vector>
 
#ifdef _MSC_VER
        #pragma warning(disable:4512) //we don't need any = operator!
#endif
 
namespace mio {
class ResamplingAlgorithms {
 
        public:
                enum GapType {
                        INTERPOLATION,       // Valid data points on both sides of the gap
                        EXTRAPOLATION_BEGIN, // No valid points before the gap (extrapolate forward)
                        EXTRAPOLATION_END,   // No valid points after the gap (extrapolate backward)
                        NO_VALID_POINTS     // No valid points at all for this parameter
                };
 
                typedef struct GAP_INFO {
                        // --- Constructor ---
                        GAP_INFO() : before(), after(), beforeIdx(IOUtils::npos), afterIdx(IOUtils::npos),
                                     gapType(INTERPOLATION), scannedBeforeLimit(IOUtils::npos), scannedAfterLimit(IOUtils::npos) {}
                        
                        // --- Public methods for anchor points ---
                        void extend(const size_t& idx, const std::vector<MeteoData>& vecM) {
                                if (idx<beforeIdx) setBefore(idx, vecM); 
                                if (idx>afterIdx) setAfter(idx, vecM);
                        }
                        void setBefore(const size_t& idx, const std::vector<MeteoData>& vecM) {
                                if (idx>=vecM.size()) return; 
                                beforeIdx=idx; before=vecM[idx].date;
                                // Reset scanning limit when we find a valid anchor
                                scannedBeforeLimit = IOUtils::npos;
                        }
                        void setAfter(const size_t& idx, const std::vector<MeteoData>& vecM) {
                                if (idx>=vecM.size()) return; 
                                afterIdx=idx; after=vecM[idx].date;
                                // Reset scanning limit when we find a valid anchor
                                scannedAfterLimit = IOUtils::npos;
                        }
                        
                        std::string toString() const {
                                std::ostringstream os; 
                                if (before.isUndef()) {
                                        os << "Undefined";
                                } else {
                                        os << " [" << before.toString(Date::ISO) << " (" << beforeIdx << ") - " << after.toString(Date::ISO) << " (" << afterIdx << ")]";
                                }
                                return os.str();
                        }
                        double size() const {return std::abs(after.getJulian(true)-before.getJulian(true));}
                        
                        // --- Search methods (now part of gap_info for better encapsulation) ---
                        size_t searchBackward(const size_t& pos, const size_t& paramindex, const std::vector<MeteoData>& vecM, 
                                             const Date& resampling_date, const double& i_max_gap_size);
                        size_t searchForward(const size_t& pos, const size_t& paramindex, const std::vector<MeteoData>& vecM, 
                                             const Date& resampling_date, const double& i_max_gap_size, const size_t& indexP1);
 
                        // --- Public members: Anchor points for interpolation ---
                        Date before; //< Date of the last valid point before the gap
                        Date after; 
                        size_t beforeIdx; 
                        size_t afterIdx; 
                        GapType gapType;
                        
                private:
                        // --- Private members: Scanning boundaries for caching ---
                        // These track how far we've scanned when we haven't found anchor points yet
                        size_t scannedBeforeLimit; //< Furthest index scanned backward (only valid if beforeIdx == npos)
                        size_t scannedAfterLimit;  //< Furthest index scanned forward (only valid if afterIdx == npos)
                } gap_info;
                
                enum ResamplingPosition {
                        exact_match,  // Resampling date exactly matches an existing data point
                        in_gap,       // Resampling date falls between two existing data points
                        begin,        // Resampling date is before the first data point (extrapolation)
                        end               // Resampling date is after the last data point (extrapolation)
                };
                
        public:
                
                ResamplingAlgorithms(const std::string& i_algoname, const std::string& i_parname, const double& dflt_max_gap_size, const std::vector< std::pair<std::string, std::string> >& /*vecArgs*/)
                                    : algo(i_algoname), parname(i_parname), max_gap_size(dflt_max_gap_size), gaps() {}
 
                virtual ~ResamplingAlgorithms() {}
                
                // findGap now takes stationHash for caching
                gap_info findGap(const std::string& stationHash, const size_t& pos, const size_t& paramindex, const std::vector<MeteoData>& vecM, const Date& resampling_date,
                         const double& i_max_gap_size);
 
                //return true if resampling took place, false otherwise
                virtual bool resample(const std::string& stationHash, const size_t& index, const ResamplingPosition& position, const size_t& paramindex,
                              const std::vector<MeteoData>& vecM, MeteoData& md, const gap_info& gap) = 0;
                
                virtual bool allowResample(const gap_info& gap, const ResamplingPosition& position) const;
                
                void resetResampling() {gaps.clear();} //invalidate all gaps, usually after rebuffering
 
                const std::string getAlgo() const {return algo;}
                double getMaxGapSize() const {return max_gap_size;}
 
                virtual std::string toString() const = 0;
 
        protected:
                bool extrapolate = false;       
                static double partialAccumulateAtLeft(const std::vector<MeteoData>& vecM, const size_t& paramindex,
                                                      const size_t& pos, const Date& curr_date);
                static double partialAccumulateAtRight(const std::vector<MeteoData>& vecM, const size_t& paramindex,
                                                       const size_t& pos, const Date& curr_date);
                void getNearestValidPts(const std::string& stationHash, const size_t& pos, const size_t& paramindex, const std::vector<MeteoData>& vecM, const Date& resampling_date,
                                               const double& i_max_gap_size, size_t& indexP1, size_t& indexP2);
                static double linearInterpolation(const double& x1, const double& y1,
                                                  const double& x2, const double& y2, const double& x3);
                static Date getDailyStart(const Date& resampling_date);
                static size_t getDailyValue(const std::vector<MeteoData>& vecM, const size_t& paramindex, size_t pos, const Date& intervalStart, const Date& intervalEnd);
 
                const std::string algo, parname;
                double max_gap_size;
 
                private:
                std::map<std::string, gap_info> gaps;
                
};
 
class ResamplingAlgorithmsFactory {
        public:
                static ResamplingAlgorithms* getAlgorithm(const std::string& i_algoname, const std::string& parname, const double& max_gap_size, const std::vector< std::pair<std::string, std::string> >& vecArgs, const Config &cfg);
};
 
} //end namespace
#endif