splashboard 0.3.0

//! Shared helpers for the `clock_*` family. Every sibling fetcher lives in this module tree and
//! pulls from here for tz resolution, safe strftime, julian-day math, and the small placeholder
//! helper. Keeping these central avoids per-fetcher duplication while letting each sibling keep a
//! narrow public surface.

use std::fmt::Write;

use chrono::{DateTime, FixedOffset, Local, NaiveDate, Utc};

use crate::payload::{Body, Payload, TextBlockData};

pub const DEFAULT_FORMAT: &str = "%H:%M";

pub fn now_in(timezone: Option<&str>) -> DateTime<FixedOffset> {
    match timezone {
        None => Local::now().fixed_offset(),
        Some(name) => match name.parse::<chrono_tz::Tz>() {
            Ok(tz) => Utc::now().with_timezone(&tz).fixed_offset(),
            Err(_) => Local::now().fixed_offset(),
        },
    }
}

pub fn parse_tz(name: &str) -> Option<chrono_tz::Tz> {
    name.parse().ok()
}

pub fn safe_format(dt: &DateTime<FixedOffset>, fmt: &str) -> String {
    format_with(dt, fmt).unwrap_or_else(|| format_with(dt, DEFAULT_FORMAT).unwrap_or_default())
}

fn format_with(dt: &DateTime<FixedOffset>, fmt: &str) -> Option<String> {
    let mut buf = String::new();
    write!(&mut buf, "{}", dt.format(fmt)).ok()?;
    Some(buf)
}

pub fn julian_day(date: NaiveDate) -> i64 {
    let epoch = NaiveDate::from_ymd_opt(2000, 1, 1).expect("2000-01-01 always valid");
    2_451_545 + (date - epoch).num_days()
}

/// Two-line warning body — mirrors `fetcher::shape_mismatch_placeholder` so users see a
/// consistent "this widget is misconfigured" shape instead of a silent wrong render.
pub fn placeholder(msg: &str) -> Payload {
    Payload {
        icon: None,
        status: None,
        format: None,
        body: Body::TextBlock(TextBlockData {
            lines: vec![
                format!("⚠ {msg}"),
                "check [widget.options] in config".into(),
            ],
        }),
    }
}

pub fn parse_options<T: serde::de::DeserializeOwned + Default>(
    raw: Option<&toml::Value>,
) -> Result<T, String> {
    match raw {
        None => Ok(T::default()),
        Some(value) => value
            .clone()
            .try_into::<T>()
            .map_err(|e| format!("invalid options: {e}")),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::{TimeZone, Utc};

    #[test]
    fn safe_format_falls_back_on_invalid_directive() {
        let dt = Utc
            .with_ymd_and_hms(2026, 4, 22, 12, 34, 0)
            .unwrap()
            .fixed_offset();
        assert_eq!(safe_format(&dt, "%Q"), "12:34");
    }

    #[test]
    fn now_in_invalid_tz_does_not_panic() {
        let _ = now_in(Some("Not/AZone"));
    }

    #[test]
    fn julian_day_of_j2000_epoch() {
        let d = NaiveDate::from_ymd_opt(2000, 1, 1).unwrap();
        assert_eq!(julian_day(d), 2_451_545);
    }
}