using Socialize.Api.Modules.CalendarIntegrations.Services;

namespace Socialize.Tests.CalendarIntegrations;

public class IcsCalendarParserTests
{
    private readonly IcsCalendarParser _parser = new();

    [Fact]
    public void Parse_preserves_all_day_calendar_dates()
    {
        string ics = """
                     BEGIN:VCALENDAR
                     BEGIN:VEVENT
                     UID:christmas-eve
                     SUMMARY:Christmas Eve
                     DTSTART;VALUE=DATE:20261224
                     DTEND;VALUE=DATE:20261225
                     END:VEVENT
                     END:VCALENDAR
                     """;

        ParsedCalendarEvent calendarEvent = Assert.Single(_parser.Parse(
            ics,
            new DateOnly(2026, 12, 1),
            new DateOnly(2026, 12, 31)));

        Assert.True(calendarEvent.IsAllDay);
        Assert.Equal(new DateOnly(2026, 12, 24), calendarEvent.StartDate);
        Assert.Equal(new DateOnly(2026, 12, 25), calendarEvent.EndDate);
        Assert.Null(calendarEvent.StartUtc);
    }

    [Fact]
    public void Parse_keeps_floating_timed_events_as_local_values_without_utc_conversion()
    {
        string ics = """
                     BEGIN:VCALENDAR
                     BEGIN:VEVENT
                     UID:floating
                     SUMMARY:Local planning
                     DTSTART:20260510T090000
                     DTEND:20260510T100000
                     END:VEVENT
                     END:VCALENDAR
                     """;

        ParsedCalendarEvent calendarEvent = Assert.Single(_parser.Parse(
            ics,
            new DateOnly(2026, 5, 1),
            new DateOnly(2026, 5, 31)));

        Assert.False(calendarEvent.IsAllDay);
        Assert.True(calendarEvent.IsFloatingTime);
        Assert.Equal(new DateTime(2026, 5, 10, 9, 0, 0), calendarEvent.StartLocalDateTime);
        Assert.Null(calendarEvent.StartUtc);
    }

    [Fact]
    public void Parse_converts_timezone_bearing_timed_events_when_timezone_is_known()
    {
        string ics = """
                     BEGIN:VCALENDAR
                     BEGIN:VEVENT
                     UID:timed
                     SUMMARY:Launch
                     DTSTART;TZID=America/Toronto:20260510T090000
                     DTEND;TZID=America/Toronto:20260510T100000
                     END:VEVENT
                     END:VCALENDAR
                     """;

        ParsedCalendarEvent calendarEvent = Assert.Single(_parser.Parse(
            ics,
            new DateOnly(2026, 5, 1),
            new DateOnly(2026, 5, 31)));

        Assert.False(calendarEvent.IsFloatingTime);
        Assert.Equal("America/Toronto", calendarEvent.TimeZoneId);
        Assert.Equal(TimeSpan.Zero, calendarEvent.StartUtc?.Offset);
        Assert.Equal(13, calendarEvent.StartUtc?.Hour);
    }

    [Fact]
    public void Parse_expands_yearly_recurrence_inside_requested_range()
    {
        string ics = """
                     BEGIN:VCALENDAR
                     BEGIN:VEVENT
                     UID:mothers-day
                     SUMMARY:Mother's Day
                     DTSTART;VALUE=DATE:20240512
                     DTEND;VALUE=DATE:20240513
                     RRULE:FREQ=YEARLY;COUNT=5
                     END:VEVENT
                     END:VCALENDAR
                     """;

        IReadOnlyCollection<ParsedCalendarEvent> events = _parser.Parse(
            ics,
            new DateOnly(2026, 1, 1),
            new DateOnly(2027, 12, 31));

        Assert.Collection(
            events,
            first => Assert.Equal(new DateOnly(2026, 5, 12), first.StartDate),
            second => Assert.Equal(new DateOnly(2027, 5, 12), second.StartDate));
        Assert.All(events, calendarEvent => Assert.Equal("mothers-day", calendarEvent.RecurrenceId));
    }

    [Fact]
    public void Parse_unfolds_folded_text_lines()
    {
        string ics = """
                     BEGIN:VCALENDAR
                     BEGIN:VEVENT
                     UID:folded
                     SUMMARY:Long
                      title
                     DTSTART;VALUE=DATE:20260510
                     END:VEVENT
                     END:VCALENDAR
                     """;

        ParsedCalendarEvent calendarEvent = Assert.Single(_parser.Parse(
            ics,
            new DateOnly(2026, 5, 1),
            new DateOnly(2026, 5, 31)));

        Assert.Equal("Longtitle", calendarEvent.Title);
    }
}