ClimateFile.hpp

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// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2026 Caleb Buahin
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

 
#ifndef OPENSWMM_CLIMATE_FILE_HPP
#define OPENSWMM_CLIMATE_FILE_HPP
 
#include <string>
#include <cstdio>
#include <cmath>
 
namespace openswmm {
namespace climate {
 
// ============================================================================
// Enums
// ============================================================================
 
enum class ClimateFileFormat {
    UNKNOWN,
    USER_PREPARED, 
    GHCND,         
    TD3200,        
    DLY0204        
};

enum ClimateVar { TMIN = 0, TMAX = 1, EVAP = 2, WIND = 3 };

enum WindFieldType { WDMV = 0, AWND = 1 };

enum TempUnits { DEG_C10 = 0, DEG_C = 1, DEG_F = 2 };
 
// ============================================================================
// Daily climate record (output of a lookup)
// ============================================================================
 
struct DailyClimateRecord {
    double tmin = NAN; 
    double tmax = NAN; 
    double evap = NAN; 
    double wind = NAN; 
};
 
// ============================================================================
// ClimateFileReader
// ============================================================================

class ClimateFileReader {
public:
    ClimateFileReader() = default;
    ~ClimateFileReader();

    ClimateFileReader(const ClimateFileReader&) = delete;
    ClimateFileReader& operator=(const ClimateFileReader&) = delete;

    bool open(const std::string& path, double start_oa_date, int unit_system, int temp_units = -1);

    void close();

    bool getRecord(double oa_date, DailyClimateRecord& rec);

    void setDayOffset(double days) { day_offset_ = days; }

    ClimateFileFormat format() const { return format_; }

    bool isOpen() const { return file_ != nullptr; }
 
private:
    static constexpr double MISSING = -1.0e10;
    static constexpr double MM_PER_INCH = 25.4;
    static constexpr int MAX_LINE = 512;
 
    // File state
    std::FILE* file_ = nullptr;
    ClimateFileFormat format_ = ClimateFileFormat::UNKNOWN;
    int unit_system_ = 0; // 0=US, 1=SI
 
    // Current month buffer: [variable][day], day 0 unused, 1-31 valid
    double file_data_[4][32] = {};
    int buf_year_ = -1;
    int buf_month_ = -1;
    double day_offset_ = 0.0; // see setDayOffset()
 
    // GHCND header-derived field positions
    int field_pos_[4] = {-1, -1, -1, -1}; // column start for TMIN,TMAX,EVAP,WIND
    int date_field_pos_ = 0;
    int wind_type_ = WDMV;
    int temp_units_ = DEG_C10;
 
    // Saved line from month-boundary read-ahead
    char saved_line_[MAX_LINE + 1] = {};
    bool has_saved_line_ = false;
 
    // Format detection
    ClimateFileFormat detectFormat(const char* first_line);
    bool isGhcndFormat(const char* line);
 
    // Month buffering
    bool bufferMonth(int year, int month);
    void clearBuffer();
 
    // Format-specific line parsers (populate file_data_ for one line)
    void parseUserLine(const char* line);
    void parseGhcndLine(const char* line);
    void parseTD3200Line(const char* line);
    void parseDLY0204Line(const char* line);
 
    // Helpers
    static void oaDateToYMD(double oa_date, int& y, int& m, int& d);
    double convertTemp(double raw) const;
    double convertEvap(double raw) const;
    double convertWind(double raw, int wind_type) const;
};
 
} // namespace climate
} // namespace openswmm
 
#endif // OPENSWMM_CLIMATE_FILE_HPP