"""Tests for the format_dt helper used by both IRC plugins.

The function is duplicated in both plugins (Limnoria and Sopel) since they
can't share imports. This tests the logic independently of either IRC framework.
"""
from datetime import datetime
from zoneinfo import ZoneInfo


def format_dt(iso_string: str | None, tz_name: str = "America/New_York") -> str:
    if not iso_string:
        return "never"
    dt = datetime.fromisoformat(iso_string)
    local = dt.astimezone(ZoneInfo(tz_name))
    return local.strftime("%a %b %-d, %-I:%M %p %Z")


def test_format_dt_est():
    result = format_dt("2026-01-15T03:00:00+00:00")
    assert result == "Wed Jan 14, 10:00 PM EST"


def test_format_dt_edt():
    result = format_dt("2026-03-12T02:00:00+00:00")
    assert result == "Wed Mar 11, 10:00 PM EDT"


def test_format_dt_none():
    assert format_dt(None) == "never"


def test_format_dt_empty_string():
    assert format_dt("") == "never"


def test_format_dt_custom_timezone():
    result = format_dt("2026-03-12T02:00:00+00:00", "America/Chicago")
    assert "CDT" in result or "CST" in result


def test_format_dt_no_seconds_or_microseconds():
    result = format_dt("2026-03-12T02:30:45.123456+00:00")
    assert ":45" not in result
    assert ".123456" not in result
    assert "10:30 PM" in result


def test_format_dt_single_digit_day():
    result = format_dt("2026-03-05T03:00:00+00:00")
    assert "Wed Mar 4," in result
    assert " 04," not in result


def test_format_dt_single_digit_hour():
    result = format_dt("2026-01-15T06:00:00+00:00")
    assert "1:00 AM" in result
    assert "01:00" not in result