"""
Tests for src/analyzer/utils/dates.py

Tests cover:
- parse_date(): parsing common date formats
- format_date(): formatting dates for display
"""
import pytest
from datetime import datetime
from src.analyzer.utils.dates import parse_date, format_date


class TestParseDate:
    """Test parse_date() function for flexible date parsing."""

    def test_parse_date_iso_with_time(self):
        result = parse_date("2024-12-31T23:59:59")
        assert result == datetime(2024, 12, 31, 23, 59, 59)

    def test_parse_date_iso_date_only(self):
        result = parse_date("2024-12-31")
        assert result == datetime(2024, 12, 31)

    def test_parse_date_uk_format(self):
        result = parse_date("31/12/2024")
        assert result == datetime(2024, 12, 31)

    def test_parse_date_already_datetime(self):
        dt = datetime(2024, 12, 31)
        result = parse_date(dt)
        assert result == dt

    def test_parse_date_none(self):
        assert parse_date(None) is None

    def test_parse_date_empty_string(self):
        assert parse_date("") is None

    def test_parse_date_invalid(self):
        assert parse_date("not a date") is None

    def test_parse_date_partial_iso(self):
        # Should handle truncated ISO format
        result = parse_date("2024-12-31T23:59:59.123456")
        assert result == datetime(2024, 12, 31, 23, 59, 59)

    def test_parse_date_with_timezone(self):
        # Should parse up to the format length
        result = parse_date("2024-12-31T23:59:59Z")
        assert result == datetime(2024, 12, 31, 23, 59, 59)


class TestFormatDate:
    """Test format_date() function for date formatting."""

    def test_format_date_date_only(self):
        result = format_date("2024-12-31")
        assert result == "2024-12-31"

    def test_format_date_with_time(self):
        result = format_date("2024-12-31T14:30:00")
        assert result == "2024-12-31 14:30:00"

    def test_format_date_midnight(self):
        # Midnight (00:00:00) should show date only
        result = format_date("2024-12-31T00:00:00")
        assert result == "2024-12-31"

    def test_format_date_explicit_include_time(self):
        result = format_date("2024-12-31", include_time=True)
        assert result == "2024-12-31 00:00:00"

    def test_format_date_none(self):
        result = format_date(None)
        assert result == "—"

    def test_format_date_empty_string(self):
        result = format_date("")
        assert result == "—"

    def test_format_date_invalid(self):
        result = format_date("not a date")
        assert result == "not a date"

    def test_format_date_datetime_object(self):
        dt = datetime(2024, 12, 31, 14, 30, 0)
        result = format_date(dt)
        assert result == "2024-12-31 14:30:00"

    def test_format_date_uk_format_input(self):
        result = format_date("31/12/2024")
        assert result == "2024-12-31"


class TestDateRoundTrip:
    """Test parsing and formatting work together correctly."""

    def test_roundtrip_date_only(self):
        original = "2024-12-31"
        parsed = parse_date(original)
        formatted = format_date(parsed)
        assert formatted == original

    def test_roundtrip_with_time(self):
        original = "2024-12-31T14:30:00"
        parsed = parse_date(original)
        formatted = format_date(parsed)
        assert formatted == "2024-12-31 14:30:00"

    def test_roundtrip_uk_format(self):
        original = "31/12/2024"
        parsed = parse_date(original)
        formatted = format_date(parsed)
        # UK format should convert to ISO format
        assert formatted == "2024-12-31"


class TestEdgeCases:
    """Test edge cases and corner scenarios."""

    def test_parse_date_leap_year(self):
        result = parse_date("2024-02-29")
        assert result == datetime(2024, 2, 29)

    def test_parse_date_year_boundaries(self):
        # Test year start and end
        assert parse_date("2024-01-01") == datetime(2024, 1, 1)
        assert parse_date("2024-12-31") == datetime(2024, 12, 31)

    def test_format_date_preserves_seconds(self):
        result = format_date("2024-12-31T23:59:59")
        assert "59:59" in result

    def test_parse_date_with_extra_text(self):
        # Should handle ISO string with extra characters after
        result = parse_date("2024-12-31 (deadline)")
        # First 10 chars match date format
        assert result == datetime(2024, 12, 31)

    def test_format_date_with_microseconds(self):
        # Datetime with microseconds should format cleanly
        dt = datetime(2024, 12, 31, 14, 30, 0, 123456)
        result = format_date(dt)
        assert result == "2024-12-31 14:30:00"


class TestIntegrationWithChatTools:
    """Test compatibility with existing chat_tools.py usage."""

    def test_deadline_sorting_compatible(self):
        """Ensure parse_date works for deadline sorting logic."""
        dates = [
            "2024-12-31",
            "2024-01-15",
            "2024-06-30",
            None,
            "",
        ]

        # Should be able to parse all dates for sorting
        parsed = [parse_date(d) for d in dates]

        # None values should be handled
        assert parsed[-2] is None
        assert parsed[-1] is None

        # Valid dates should be in order
        valid_dates = [p for p in parsed if p is not None]
        assert len(valid_dates) == 3

    def test_format_date_for_display(self):
        """Ensure format_date produces user-friendly output."""
        # Common patterns from grant data
        test_cases = [
            ("2024-12-31", "2024-12-31"),
            ("2024-12-31T23:59:59", "2024-12-31 23:59:59"),
            (None, "—"),
            ("", "—"),
        ]

        for input_val, expected in test_cases:
            result = format_date(input_val)
            assert result == expected


if __name__ == "__main__":
    pytest.main([__file__, "-v"])