"""Unit tests for strava_mcp_server.utils — pure functions, no external dependencies."""

from datetime import datetime, timezone

from strava_mcp_server.utils import (
    parse_iso_to_unix,
    format_date_iso,
    format_date_human,
)


class TestParseIsoToUnix:
    def test_full_iso_with_z(self):
        result = parse_iso_to_unix("2024-01-15T12:00:00Z")
        assert result == int(
            datetime(2024, 1, 15, 12, 0, 0, tzinfo=timezone.utc).timestamp()
        )

    def test_full_iso_with_offset(self):
        result = parse_iso_to_unix("2024-01-15T13:00:00+01:00")
        assert result == int(
            datetime(2024, 1, 15, 12, 0, 0, tzinfo=timezone.utc).timestamp()
        )

    def test_date_only(self):
        result = parse_iso_to_unix("2024-06-01")
        assert result == int(
            datetime(2024, 6, 1, 0, 0, 0, tzinfo=timezone.utc).timestamp()
        )

    def test_none_returns_none(self):
        assert parse_iso_to_unix(None) is None

    def test_empty_string_returns_none(self):
        assert parse_iso_to_unix("") is None

    def test_invalid_string_returns_none(self):
        assert parse_iso_to_unix("not-a-date") is None

    def test_returns_int(self):
        result = parse_iso_to_unix("2024-01-01T00:00:00Z")
        assert isinstance(result, int)


class TestFormatDateIso:
    def test_z_suffix_normalized(self):
        result = format_date_iso("2024-01-15T12:00:00Z")
        assert result == "2024-01-15T12:00:00Z"

    def test_offset_preserved(self):
        # format_date_iso preserves timezone offset info; normalization to UTC
        # is the caller's responsibility if needed.
        result = format_date_iso("2024-01-15T13:00:00+01:00")
        assert result == "2024-01-15T13:00:00+01:00"

    def test_datetime_object(self):
        dt = datetime(2024, 3, 10, 8, 30, 0, tzinfo=timezone.utc)
        result = format_date_iso(dt)
        assert result == "2024-03-10T08:30:00Z"

    def test_none_returns_na(self):
        assert format_date_iso(None) == "N/A"

    def test_empty_string_returns_na(self):
        assert format_date_iso("") == "N/A"

    def test_invalid_string_returned_as_is(self):
        result = format_date_iso("not-a-date")
        assert result == "not-a-date"


class TestFormatDateHuman:
    def test_iso_with_z(self):
        result = format_date_human("2024-01-15T08:30:00Z")
        assert result == "15.01.2024 08:30"

    def test_iso_with_offset(self):
        # +01:00 → displayed in local time of the datetime (13:00 in +01 = 13:00 displayed)
        result = format_date_human("2024-01-15T13:45:00+01:00")
        assert result == "15.01.2024 13:45"

    def test_datetime_object(self):
        dt = datetime(2024, 12, 31, 23, 59, tzinfo=timezone.utc)
        result = format_date_human(dt)
        assert result == "31.12.2024 23:59"

    def test_none_returns_na(self):
        assert format_date_human(None) == "N/A"

    def test_empty_string_returns_na(self):
        assert format_date_human("") == "N/A"

    def test_format_pattern(self):
        result = format_date_human("2024-06-01T00:00:00Z")
        # Ensure it matches DD.MM.YYYY HH:MM
        import re

        assert re.match(r"\d{2}\.\d{2}\.\d{4} \d{2}:\d{2}", result)