//! Date/time parsing helpers for user-supplied schedule inputs.

/// Parse an optional datetime string for scheduled publishing.
///
/// Accepts ISO 8601 (RFC 3339) or HTML `datetime-local` format (`%Y-%m-%dT%H:%M`).
/// Returns `Some(Some(dt))` for a valid datetime, `Some(None)` for empty string
/// (clear schedule), or `None` for absent input (no change).
pub fn parse_schedule_datetime(s: Option<&str>) -> Option<Option<chrono::DateTime<chrono::Utc>>> {
    s.map(|s| {
        if s.is_empty() {
            None
        } else {
            chrono::DateTime::parse_from_rfc3339(s)
                .map(|dt| dt.with_timezone(&chrono::Utc))
                .or_else(|_| {
                    chrono::NaiveDateTime::parse_from_str(s, "%Y-%m-%dT%H:%M")
                        .map(|naive| naive.and_utc())
                })
                .ok()
        }
    })
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn parse_schedule_datetime_none_input() {
        assert!(parse_schedule_datetime(None).is_none());
    }

    #[test]
    fn parse_schedule_datetime_empty_clears() {
        assert_eq!(parse_schedule_datetime(Some("")), Some(None));
    }

    #[test]
    fn parse_schedule_datetime_rfc3339() {
        assert!(
            parse_schedule_datetime(Some("2026-04-29T12:00:00Z"))
                .unwrap()
                .is_some()
        );
    }

    #[test]
    fn parse_schedule_datetime_html_local() {
        assert!(
            parse_schedule_datetime(Some("2026-04-29T12:00"))
                .unwrap()
                .is_some()
        );
    }
}