"""US-009: Utility function and data processing tests."""
import pytest
import math
from pathlib import Path
from datetime import datetime


class TestRiskValueToLevel:
    def test_high(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.9) == "high"
        assert risk_value_to_level(0.8) == "high"
        assert risk_value_to_level(1.0) == "high"

    def test_medium_high(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.7) == "medium_high"
        assert risk_value_to_level(0.6) == "medium_high"

    def test_medium(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.5) == "medium"
        assert risk_value_to_level(0.4) == "medium"

    def test_medium_low(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.3) == "medium_low"
        assert risk_value_to_level(0.2) == "medium_low"

    def test_low(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.1) == "low"
        assert risk_value_to_level(0.0) == "low"

    def test_negative_value(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(-0.1) == "low"

    def test_boundaries(self):
        from utils.risk import risk_value_to_level
        assert risk_value_to_level(0.8) == "high"
        assert risk_value_to_level(0.6) == "medium_high"
        assert risk_value_to_level(0.4) == "medium"
        assert risk_value_to_level(0.2) == "medium_low"


class TestCalculateTrend:
    def test_upward_trend(self):
        from utils.risk import calculate_trend
        assert calculate_trend([0.1, 0.3, 0.5, 0.7, 0.9]) == "up"

    def test_downward_trend(self):
        from utils.risk import calculate_trend
        assert calculate_trend([0.9, 0.7, 0.5, 0.3, 0.1]) == "down"

    def test_stable(self):
        from utils.risk import calculate_trend
        assert calculate_trend([0.5, 0.51, 0.49, 0.5, 0.5]) == "stable"

    def test_single_value(self):
        from utils.risk import calculate_trend
        assert calculate_trend([0.5]) == "stable"

    def test_empty_list(self):
        from utils.risk import calculate_trend
        assert calculate_trend([]) == "stable"

    def test_all_zeros(self):
        from utils.risk import calculate_trend
        assert calculate_trend([0.0, 0.0, 0.0]) == "stable"


class TestValidateDateFormat:
    def test_valid_dates(self):
        from utils.date_helpers import validate_date_format
        assert validate_date_format("20231201")
        assert validate_date_format("20240101")
        assert validate_date_format("20221215")

    def test_invalid_dates(self):
        from utils.date_helpers import validate_date_format
        assert not validate_date_format("2023-12-01")
        assert not validate_date_format("2023121")
        assert not validate_date_format("202312011")
        assert not validate_date_format("abc")
        assert not validate_date_format("")

    def test_edge_cases(self):
        from utils.date_helpers import validate_date_format
        assert not validate_date_format("2023-1-1")
        assert not validate_date_format("2023/12/01")


class TestGetLatestDate:
    def test_returns_valid_format(self):
        from utils.date_helpers import get_latest_date
        result = get_latest_date()
        assert len(result) == 8
        assert result.isdigit()
        int(result)

    def test_consistent_result(self):
        from utils.date_helpers import get_latest_date
        d1 = get_latest_date()
        d2 = get_latest_date()
        assert d1 == d2


class TestGridIdConversion:
    def test_roundtrip(self):
        from routers.alerts import lat_lon_to_grid_id, grid_id_to_center
        lat, lon = 30.5, 114.3
        grid_id = lat_lon_to_grid_id(lat, lon)
        rlat, rlon = grid_id_to_center(grid_id)
        assert abs(lat - rlat) < 0.001
        assert abs(lon - rlon) < 0.001

    def test_multiple_locations(self):
        from routers.alerts import lat_lon_to_grid_id, grid_id_to_center
        test_points = [
            (30.59276, 114.30524),  # Wuhan center area
            (30.0, 114.0),
            (31.0, 115.0),
        ]
        for lat, lon in test_points:
            grid_id = lat_lon_to_grid_id(lat, lon)
            rlat, rlon = grid_id_to_center(grid_id)
            assert abs(lat - rlat) < 0.001, f"lat mismatch: {lat} vs {rlat}"
            assert abs(lon - rlon) < 0.001, f"lon mismatch: {lon} vs {rlon}"


class TestParseGeoJSON:
    def test_parse_valid_file(self):
        from utils.geojson import parse_geojson_file
        from config import DATA_DIR
        filepath = DATA_DIR / "risk_20231201.geojson"
        grids = parse_geojson_file(filepath)
        assert len(grids) > 0
        g = grids[0]
        assert "grid_id" in g
        assert "latitude" in g
        assert "longitude" in g
        assert "risk_value" in g
        assert "risk_level" in g
        assert isinstance(g["risk_value"], (int, float))
        assert g["risk_level"] in ("high", "medium_high", "medium", "medium_low", "low")

    def test_parse_nonexistent_file(self):
        from utils.geojson import parse_geojson_file
        grids = parse_geojson_file(Path("/nonexistent/file.geojson"))
        assert grids == []


class TestNoNaNNorInf:
    """Verify no NaN or Inf propagation in calculations."""

    def test_risk_value_to_level_no_nan(self):
        from utils.risk import risk_value_to_level
        result = risk_value_to_level(float('nan'))
        assert result in ("high", "medium_high", "medium", "medium_low", "low")

    def test_trend_no_nan(self):
        from utils.risk import calculate_trend
        result = calculate_trend([0.5, float('nan')])
        assert result in ("up", "down", "stable")