#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2019 Satpy developers
#
# This file is part of satpy.
#
# satpy is free software: you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
#
# satpy 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# satpy.  If not, see <http://www.gnu.org/licenses/>.
"""The ami_l1b reader tests package."""

import unittest
from unittest import mock

import dask.array as da
import numpy as np
import xarray as xr
from pytest import approx, raises  # noqa: PT013


class FakeDataset(object):
    """Mimic xarray Dataset object."""

    def __init__(self, info, attrs):
        """Initialize test data."""
        for var_name, var_data in list(info.items()):
            if isinstance(var_data, np.ndarray):
                info[var_name] = xr.DataArray(var_data)
        self.info = info
        self.attrs = attrs

    def __getitem__(self, key):
        """Mimic getitem method."""
        return self.info[key]

    def __contains__(self, key):
        """Mimic contains method."""
        return key in self.info

    def rename(self, *args, **kwargs):
        """Mimic rename method."""
        return self

    def close(self):
        """Act like close method."""
        return


class TestAMIL1bNetCDFBase(unittest.TestCase):
    """Common setup for NC_ABI_L1B tests."""

    @mock.patch("satpy.readers.ami_l1b.xr")
    def setUp(self, xr_, counts=None):
        """Create a fake dataset using the given counts data."""
        from satpy.readers.ami_l1b import AMIL1bNetCDF

        if counts is None:
            rad_data = (np.arange(10.).reshape((2, 5)) + 1.) * 50.
            rad_data = (rad_data + 1.) / 0.5
            rad_data = rad_data.astype(np.uint16)
            counts = xr.DataArray(
                da.from_array(rad_data, chunks="auto"),
                dims=("y", "x"),
                attrs={
                    "channel_name": "VI006",
                    "detector_side": 2,
                    "number_of_total_pixels": 484000000,
                    "number_of_error_pixels": 113892451,
                    "max_pixel_value": 32768,
                    "min_pixel_value": 6,
                    "average_pixel_value": 8228.98770845248,
                    "stddev_pixel_value": 13621.130386551,
                    "number_of_total_bits_per_pixel": 16,
                    "number_of_data_quality_flag_bits_per_pixel": 2,
                    "number_of_valid_bits_per_pixel": 12,
                    "data_quality_flag_meaning":
                        "0:good_pixel, 1:conditionally_usable_pixel, 2:out_of_scan_area_pixel, 3:error_pixel",
                    "ground_sample_distance_ew": 1.4e-05,
                    "ground_sample_distance_ns": 1.4e-05,
                }
            )
        sc_position = xr.DataArray(0., attrs={
            "sc_position_center_pixel": [-26113466.1974016, 33100139.1630508, 3943.75470244799],
        })
        xr_.open_dataset.return_value = FakeDataset(
            {
                "image_pixel_values": counts,
                "sc_position": sc_position,
                "gsics_coeff_intercept": [0.1859369],
                "gsics_coeff_slope": [0.9967594],
            },
            {
                "satellite_name": "GK-2A",
                "observation_start_time": 623084431.957882,
                "observation_end_time": 623084975.606133,
                "projection_type": "GEOS",
                "sub_longitude": 2.23751210105673,
                "cfac": 81701355.6133574,
                "lfac": -81701355.6133574,
                "coff": 11000.5,
                "loff": 11000.5,
                "nominal_satellite_height": 42164000.,
                "earth_equatorial_radius": 6378137.,
                "earth_polar_radius": 6356752.3,
                "number_of_columns": 22000,
                "number_of_lines": 22000,
                "observation_mode": "FD",
                "channel_spatial_resolution": "0.5",
                "Radiance_to_Albedo_c": 1,
                "DN_to_Radiance_Gain": -0.0144806550815701,
                "DN_to_Radiance_Offset": 118.050903320312,
                "Teff_to_Tbb_c0": -0.141418528203155,
                "Teff_to_Tbb_c1": 1.00052232906885,
                "Teff_to_Tbb_c2": -0.00000036287276076109,
                "light_speed": 2.9979245800E+08,
                "Boltzmann_constant_k": 1.3806488000E-23,
                "Plank_constant_h": 6.6260695700E-34,
            }
        )

        self.reader = AMIL1bNetCDF("filename",
                                   {"platform_shortname": "gk2a"},
                                   {"file_type": "ir087"},)


class TestAMIL1bNetCDF(TestAMIL1bNetCDFBase):
    """Test the AMI L1b reader."""

    def _check_orbital_parameters(self, orb_params):
        """Check that orbital parameters match expected values."""
        exp_params = {
            "projection_altitude": 35785863.0,
            "projection_latitude": 0.0,
            "projection_longitude": 128.2,
            "satellite_actual_altitude": 35782654.56070405,
            "satellite_actual_latitude": 0.005364927,
            "satellite_actual_longitude": 128.2707,
        }
        for key, val in exp_params.items():
            assert val == approx(orb_params[key], abs=1e-3)

    def test_filename_grouping(self):
        """Test that filenames are grouped properly."""
        from satpy.readers import group_files
        filenames = [
            "gk2a_ami_le1b_ir087_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_ir096_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_ir105_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_ir112_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_ir123_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_ir133_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_nr013_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_nr016_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_sw038_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_vi004_fd010ge_201909300300.nc",
            "gk2a_ami_le1b_vi005_fd010ge_201909300300.nc",
            "gk2a_ami_le1b_vi006_fd005ge_201909300300.nc",
            "gk2a_ami_le1b_vi008_fd010ge_201909300300.nc",
            "gk2a_ami_le1b_wv063_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_wv069_fd020ge_201909300300.nc",
            "gk2a_ami_le1b_wv073_fd020ge_201909300300.nc"]
        groups = group_files(filenames, reader="ami_l1b")
        assert len(groups) == 1
        assert len(groups[0]["ami_l1b"]) == 16

    def test_basic_attributes(self):
        """Test getting basic file attributes."""
        from datetime import datetime
        assert self.reader.start_time == datetime(2019, 9, 30, 3, 0, 31, 957882)
        assert self.reader.end_time == datetime(2019, 9, 30, 3, 9, 35, 606133)

    def test_get_dataset(self):
        """Test gettting radiance data."""
        from satpy.tests.utils import make_dataid
        key = make_dataid(name="VI006", calibration="radiance")
        res = self.reader.get_dataset(key, {
            "file_key": "image_pixel_values",
            "standard_name": "toa_outgoing_radiance_per_unit_wavelength",
            "units": "W m-2 um-1 sr-1",
        })
        exp = {"calibration": "radiance",
               "modifiers": (),
               "platform_name": "GEO-KOMPSAT-2A",
               "sensor": "ami",
               "units": "W m-2 um-1 sr-1"}
        for key, val in exp.items():
            assert val == res.attrs[key]
        self._check_orbital_parameters(res.attrs["orbital_parameters"])

    def test_bad_calibration(self):
        """Test that asking for a bad calibration fails."""
        from satpy.tests.utils import make_dataid
        with raises(ValueError, match="_bad_ invalid value for .*"):
            _ = make_dataid(name="VI006", calibration="_bad_")

    @mock.patch("satpy.readers.abi_base.geometry.AreaDefinition")
    def test_get_area_def(self, adef):
        """Test the area generation."""
        self.reader.get_area_def(None)

        assert adef.call_count == 1
        call_args = tuple(adef.call_args)[0]
        exp = {"a": 6378137.0, "b": 6356752.3, "h": 35785863.0,
               "lon_0": 128.2, "proj": "geos", "units": "m"}
        for key, val in exp.items():
            assert key in call_args[3]
            assert val == approx(call_args[3][key])
        assert call_args[4] == self.reader.nc.attrs["number_of_columns"]
        assert call_args[5] == self.reader.nc.attrs["number_of_lines"]
        np.testing.assert_allclose(call_args[6],
                                   [-5511022.902, -5511022.902, 5511022.902, 5511022.902])

    def test_get_dataset_vis(self):
        """Test get visible calibrated data."""
        from satpy.tests.utils import make_dataid
        key = make_dataid(name="VI006", calibration="reflectance")
        res = self.reader.get_dataset(key, {
            "file_key": "image_pixel_values",
            "standard_name": "toa_bidirectional_reflectance",
            "units": "%",
        })
        exp = {"calibration": "reflectance",
               "modifiers": (),
               "platform_name": "GEO-KOMPSAT-2A",
               "sensor": "ami",
               "units": "%"}
        for key, val in exp.items():
            assert val == res.attrs[key]
        self._check_orbital_parameters(res.attrs["orbital_parameters"])

    def test_get_dataset_counts(self):
        """Test get counts data."""
        from satpy.tests.utils import make_dataid
        key = make_dataid(name="VI006", calibration="counts")
        res = self.reader.get_dataset(key, {
            "file_key": "image_pixel_values",
            "standard_name": "counts",
            "units": "1",
        })
        exp = {"calibration": "counts",
               "modifiers": (),
               "platform_name": "GEO-KOMPSAT-2A",
               "sensor": "ami",
               "units": "1"}
        for key, val in exp.items():
            assert val == res.attrs[key]
        self._check_orbital_parameters(res.attrs["orbital_parameters"])


class TestAMIL1bNetCDFIRCal(TestAMIL1bNetCDFBase):
    """Test IR specific things about the AMI reader."""

    def setUp(self):
        """Create test data for IR calibration tests."""
        from satpy.tests.utils import make_dataid
        count_data = (np.arange(10).reshape((2, 5))) + 7000
        count_data = count_data.astype(np.uint16)
        count = xr.DataArray(
            da.from_array(count_data, chunks="auto"),
            dims=("y", "x"),
            attrs={
                "channel_name": "IR087",
                "detector_side": 2,
                "number_of_total_pixels": 484000000,
                "number_of_error_pixels": 113892451,
                "max_pixel_value": 32768,
                "min_pixel_value": 6,
                "average_pixel_value": 8228.98770845248,
                "stddev_pixel_value": 13621.130386551,
                "number_of_total_bits_per_pixel": 16,
                "number_of_data_quality_flag_bits_per_pixel": 2,
                "number_of_valid_bits_per_pixel": 13,
                "data_quality_flag_meaning":
                    "0:good_pixel, 1:conditionally_usable_pixel, 2:out_of_scan_area_pixel, 3:error_pixel",
                "ground_sample_distance_ew": 1.4e-05,
                "ground_sample_distance_ns": 1.4e-05,
            }
        )
        self.ds_id = make_dataid(name="IR087", wavelength=[8.415, 8.59, 8.765],
                                 calibration="brightness_temperature")
        self.ds_info = {
            "file_key": "image_pixel_values",
            "wavelength": [8.415, 8.59, 8.765],
            "standard_name": "toa_brightness_temperature",
            "units": "K",
        }
        super(TestAMIL1bNetCDFIRCal, self).setUp(counts=count)

    def test_default_calibrate(self):
        """Test default (pyspectral) IR calibration."""
        from satpy.readers.ami_l1b import rad2temp
        with mock.patch("satpy.readers.ami_l1b.rad2temp", wraps=rad2temp) as r2t_mock:
            res = self.reader.get_dataset(self.ds_id, self.ds_info)
            r2t_mock.assert_called_once()
        expected = np.array([[238.34385135, 238.31443527, 238.28500087, 238.25554813, 238.22607701],
                             [238.1965875, 238.16707956, 238.13755317, 238.10800829, 238.07844489]])
        np.testing.assert_allclose(res.data.compute(), expected, equal_nan=True)
        # make sure the attributes from the file are in the data array
        assert res.attrs["standard_name"] == "toa_brightness_temperature"

    def test_infile_calibrate(self):
        """Test IR calibration using in-file coefficients."""
        from satpy.readers.ami_l1b import rad2temp
        self.reader.calib_mode = "FILE"
        with mock.patch("satpy.readers.ami_l1b.rad2temp", wraps=rad2temp) as r2t_mock:
            res = self.reader.get_dataset(self.ds_id, self.ds_info)
            r2t_mock.assert_not_called()
        expected = np.array([[238.34385135, 238.31443527, 238.28500087, 238.25554813, 238.22607701],
                             [238.1965875, 238.16707956, 238.13755317, 238.10800829, 238.07844489]])
        # file coefficients are pretty close, give some wiggle room
        np.testing.assert_allclose(res.data.compute(), expected, equal_nan=True, atol=0.04)
        # make sure the attributes from the file are in the data array
        assert res.attrs["standard_name"] == "toa_brightness_temperature"

    def test_gsics_radiance_corr(self):
        """Test IR radiance adjustment using in-file GSICS coefs."""
        from satpy.readers.ami_l1b import rad2temp
        self.reader.calib_mode = "GSICS"
        expected = np.array([[238.036797, 238.007106, 237.977396, 237.947668, 237.91792],
                             [237.888154, 237.85837, 237.828566, 237.798743, 237.768902]])
        with mock.patch("satpy.readers.ami_l1b.rad2temp", wraps=rad2temp) as r2t_mock:
            res = self.reader.get_dataset(self.ds_id, self.ds_info)
            r2t_mock.assert_not_called()
        # file coefficients are pretty close, give some wiggle room
        np.testing.assert_allclose(res.data.compute(), expected, equal_nan=True, atol=0.01)
        # make sure the attributes from the file are in the data array
        assert res.attrs["standard_name"] == "toa_brightness_temperature"

    def test_user_radiance_corr(self):
        """Test IR radiance adjustment using user-supplied coefs."""
        from satpy.readers.ami_l1b import rad2temp
        self.reader.calib_mode = "FILE"
        self.reader.user_calibration = {"IR087": {"slope": 0.99669,
                                                  "offset": 0.16907}}
        expected = np.array([[238.073713, 238.044043, 238.014354, 237.984647, 237.954921],
                             [237.925176, 237.895413, 237.865631, 237.835829, 237.806009]])
        with mock.patch("satpy.readers.ami_l1b.rad2temp", wraps=rad2temp) as r2t_mock:
            res = self.reader.get_dataset(self.ds_id, self.ds_info)
            r2t_mock.assert_not_called()
        # file coefficients are pretty close, give some wiggle room
        np.testing.assert_allclose(res.data.compute(), expected, equal_nan=True, atol=0.01)
        # make sure the attributes from the file are in the data array
        assert res.attrs["standard_name"] == "toa_brightness_temperature"
