"""Sentinel-3 SLSTR spectral response function interface.

See:
https://sentiwiki.copernicus.eu/web/s3-slstr-instrument?utm_source=chatgpt.com#S3SLSTRInstrument-SpectralResponseFunctionDataS3-SLSTR-Instrument-SRFD

"""

import logging
import os

from netCDF4 import Dataset

from pyspectral.raw_reader import InstrumentRSR
from pyspectral.utils import convert2hdf5 as tohdf5

LOG = logging.getLogger(__name__)

SLSTR_BAND_NAMES = ['ch1', 'ch2', 'ch3', 'ch4',
                    'ch5', 'ch6', 'ch7', 'ch8', 'ch9']


class SlstrRSR(InstrumentRSR):
    """Class for Sentinel-3 SLSTR RSR."""

    def __init__(self, bandname, platform_name):
        """Read the SLSTR relative spectral responses for all channels."""
        super(SlstrRSR, self).__init__(bandname, platform_name,
                                       SLSTR_BAND_NAMES)

        self.instrument = 'slstr'

        self._get_options_from_config()
        self._get_bandfilenames()

        LOG.debug("Filenames: %s", str(self.filenames))
        if os.path.exists(self.filenames[bandname]):
            self.requested_band_filename = self.filenames[bandname]
            self._load()
        else:
            raise IOError("Couldn't find an existing file for this band: " +
                          str(self.bandname))

        self.filename = self.requested_band_filename

    def _load(self, scale=1.0):
        """Load the SLSTR relative spectral responses."""
        LOG.debug("File: %s", str(self.requested_band_filename))
        ncf = Dataset(self.requested_band_filename, 'r')

        wvl = ncf.variables['wavelength'][:] * scale
        resp = ncf.variables['response'][:]

        self.rsr = {'wavelength': wvl, 'response': resp}


if __name__ == "__main__":
    for platform_name in ['Sentinel-3B', ]:
        tohdf5(SlstrRSR, platform_name, SLSTR_BAND_NAMES)
