"""
These tests use local files in the desi_test_data/ directory that are reduced
from these real data files:

* https://data.desi.lbl.gov/public/edr/spectro/redux/fuji/healpix/sv3/dark/260/26065/coadd-sv3-dark-26065.fits
* https://data.desi.lbl.gov/public/edr/spectro/redux/fuji/healpix/sv3/dark/260/26065/spectra-sv3-dark-26065.fits
* https://data.desi.lbl.gov/public/edr/spectro/redux/fuji/tiles/cumulative/169/20210419/coadd-5-169-thru20210419.fits
* https://data.desi.lbl.gov/public/edr/spectro/redux/fuji/tiles/cumulative/169/20210419/spectra-5-169-thru20210419.fits

Tests that use the real data files are prohibitively slow because of their
size, >~ 1 GB. The reduced files are generated by generate_desi_test_data.py.
"""
from astropy.io import fits
from astropy.utils.exceptions import AstropyUserWarning
import pytest

# Package
from ..desi import (coadd_loader, spectra_loader)
from ....spectra import SpectrumList


has_importlib = True
try:
    from importlib.resources import files
except ImportError:
    from pkg_resources import resource_filename as files
    has_importlib = False


@pytest.fixture(scope="function")
def local_filename(request):
    if has_importlib:
        return files('specutils.io.default_loaders.tests') / 'desi_test_data' / request.param
    else:
        return files('specutils.io.default_loaders.tests', f'desi_test_data/{request.param}')


@pytest.mark.parametrize('local_filename, loader', [('coadd-sv3-dark-26065.fits', coadd_loader),
                                                    ('spectra-sv3-dark-26065.fits', spectra_loader),
                                                    ('coadd-5-169-thru20210419.fits', coadd_loader),
                                                    ('spectra-5-169-thru20210419.fits', spectra_loader)], indirect=['local_filename'])
def test_loader(local_filename, loader):
    """Test the 'bare' loader function in desi.py.
    """
    spectrum = loader(local_filename)  # noqa
    assert spectrum[0].meta['band'] == 'b'
    assert spectrum[1].meta['band'] == 'r'
    assert spectrum[2].meta['band'] == 'z'


@pytest.mark.parametrize('local_filename', ['coadd-sv3-dark-26065.fits',
                                            'spectra-sv3-dark-26065.fits',
                                            'coadd-5-169-thru20210419.fits',
                                            'spectra-5-169-thru20210419.fits'], indirect=['local_filename'])
def test_SpectrumList_reader(local_filename):
    """Test the class method. This also triggers the identify functions.
    """
    spectrum = SpectrumList.read(local_filename)  # noqa
    assert spectrum[0].meta['band'] == 'b'
    assert spectrum[1].meta['band'] == 'r'
    assert spectrum[2].meta['band'] == 'z'


@pytest.mark.parametrize('local_filename, fmt', [('coadd-sv3-dark-26065.fits', 'DESI coadd'),
                                                 ('spectra-sv3-dark-26065.fits', 'DESI spectra'),
                                                 ('coadd-5-169-thru20210419.fits', 'DESI coadd'),
                                                 ('spectra-5-169-thru20210419.fits', 'DESI spectra')], indirect=['local_filename'])
def test_SpectrumList_reader_fileobj(local_filename, fmt):
    """Test reading an open file-like object.
    """
    with open(local_filename, 'rb') as fileobj:
        spectrum = SpectrumList.read(fileobj, format=fmt)  # noqa
    assert spectrum[0].meta['band'] == 'b'
    assert spectrum[1].meta['band'] == 'r'
    assert spectrum[2].meta['band'] == 'z'


@pytest.mark.parametrize('local_filename, fmt', [('coadd-sv3-dark-26065.fits', 'DESI coadd'),
                                                 ('spectra-sv3-dark-26065.fits', 'DESI spectra'),
                                                 ('coadd-5-169-thru20210419.fits', 'DESI coadd'),
                                                 ('spectra-5-169-thru20210419.fits', 'DESI spectra')], indirect=['local_filename'])
def test_SpectrumList_reader_hdulist(local_filename, fmt):
    """Test reading a HDUList.
    """
    with fits.open(local_filename, mode='readonly') as hdulist:
        spectrum = SpectrumList.read(hdulist, format=fmt)  # noqa
    assert spectrum[0].meta['band'] == 'b'
    assert spectrum[1].meta['band'] == 'r'
    assert spectrum[2].meta['band'] == 'z'


@pytest.mark.parametrize('local_filename, fmt', [('coadd-sv3-dark-26065.fits', 'DESI coadd')], indirect=['local_filename'])
def test_trigger_missing_extname(local_filename, fmt):
    """Trigger a warning about a HDU not having an EXTNAME.
    """
    with fits.open(local_filename, mode='readonly') as hdulist:
        del hdulist[2].header['EXTNAME']
        with pytest.warns(AstropyUserWarning) as w:
            spectrum = SpectrumList.read(hdulist, format=fmt)  # noqa
        assert len(w) > 0
        assert str(w[0].message) == "HDU 2 has no EXTNAME and will not be read!"


@pytest.mark.parametrize('local_filename, fmt', [('coadd-sv3-dark-26065.fits', 'DESI coadd')], indirect=['local_filename'])
def test_trigger_unexpected_extname(local_filename, fmt):
    """Trigger a warning about a HDU having an unexpected EXTNAME.
    """
    with fits.open(local_filename, mode='readonly') as hdulist:
        hdulist[2].header['EXTNAME'] = ('EXT_FIBERMAP', 'unexpected extname')
        with pytest.warns(AstropyUserWarning) as w:
            spectrum = SpectrumList.read(hdulist, format=fmt)  # noqa
        assert len(w) > 0
        assert str(w[0].message) == "HDU 2, EXTNAME='EXT_FIBERMAP' is unexpected and will not be read!"