fix: small findings with regard to deletes from sidebar

crates/bds-ui/src/i18n/mod.rs

@@ -1,3 +1,5 @@
+pub mod relative_date;
+
 use bds_core::i18n::{UiLocale, translate, translate_with};
 
 /// Shorthand for translate in view code.

crates/bds-ui/src/i18n/relative_date.rs

@@ -0,0 +1,163 @@
+use bds_core::i18n::{UiLocale, translate, translate_with};
+use chrono::{DateTime, Datelike, Local, NaiveDate};
+
+/// chrono format locale per sidebar_views.allium LocaleMapping
+/// (ui_locale → format_locale, e.g. "de" → "de-DE").
+fn format_locale(locale: UiLocale) -> chrono::Locale {
+    match locale {
+        UiLocale::En => chrono::Locale::en_US,
+        UiLocale::De => chrono::Locale::de_DE,
+        UiLocale::Fr => chrono::Locale::fr_FR,
+        UiLocale::It => chrono::Locale::it_IT,
+        UiLocale::Es => chrono::Locale::es_ES,
+    }
+}
+
+/// Per sidebar_views.allium RelativeDateFormat, with
+/// diff_days = (today - timestamp.date).days on local calendar dates:
+///   diff_days = 0 → locale time string
+///   diff_days = 1 → localized "Yesterday"
+///   diff_days < 7 → short weekday name
+///   otherwise     → short month name + numeric day
+pub fn format_relative_date(locale: UiLocale, unix_ms: i64, today: NaiveDate) -> String {
+    let timestamp = DateTime::from_timestamp_millis(unix_ms)
+        .unwrap_or_default()
+        .with_timezone(&Local);
+    let chrono_locale = format_locale(locale);
+    let diff_days = (today - timestamp.date_naive()).num_days();
+
+    if diff_days == 0 {
+        timestamp.format_localized("%X", chrono_locale).to_string()
+    } else if diff_days == 1 {
+        translate(locale, "sidebar.chatYesterday")
+    } else if diff_days < 7 {
+        timestamp.format_localized("%a", chrono_locale).to_string()
+    } else {
+        let month = timestamp.format_localized("%b", chrono_locale).to_string();
+        let day = timestamp.day().to_string();
+        translate_with(
+            locale,
+            "sidebar.relativeDateMonthDay",
+            &[("month", &month), ("day", &day)],
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::TimeZone;
+
+    fn local_ms(y: i32, mo: u32, d: u32, h: u32, mi: u32, s: u32) -> i64 {
+        Local
+            .with_ymd_and_hms(y, mo, d, h, mi, s)
+            .single()
+            .expect("unambiguous local time")
+            .timestamp_millis()
+    }
+
+    fn day(y: i32, mo: u32, d: u32) -> NaiveDate {
+        NaiveDate::from_ymd_opt(y, mo, d).expect("valid date")
+    }
+
+    // Reference "today" throughout: Tuesday, 2026-02-17.
+    const TODAY: (i32, u32, u32) = (2026, 2, 17);
+
+    fn today() -> NaiveDate {
+        day(TODAY.0, TODAY.1, TODAY.2)
+    }
+
+    #[test]
+    fn same_day_shows_locale_time() {
+        let ts = local_ms(2026, 2, 17, 14, 5, 7);
+        let en = format_relative_date(UiLocale::En, ts, today());
+        assert!(en.contains("05:07"), "expected time string, got {en}");
+        assert!(en.contains("PM"), "en-US uses 12-hour clock, got {en}");
+        let de = format_relative_date(UiLocale::De, ts, today());
+        assert!(de.contains("14:05"), "de-DE uses 24-hour clock, got {de}");
+    }
+
+    #[test]
+    fn one_day_ago_is_yesterday_even_under_24_hours() {
+        // 23:59 yesterday vs. any time today: calendar-day diff is 1.
+        let ts = local_ms(2026, 2, 16, 23, 59, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Yesterday");
+        assert_eq!(format_relative_date(UiLocale::De, ts, today()), "Gestern");
+    }
+
+    #[test]
+    fn two_days_ago_shows_short_weekday() {
+        // 2026-02-15 is a Sunday.
+        let ts = local_ms(2026, 2, 15, 12, 0, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Sun");
+        assert_eq!(format_relative_date(UiLocale::De, ts, today()), "So");
+    }
+
+    #[test]
+    fn six_days_ago_still_shows_weekday() {
+        // 2026-02-11 is a Wednesday: diff_days = 6 is the last weekday case.
+        let ts = local_ms(2026, 2, 11, 12, 0, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Wed");
+    }
+
+    #[test]
+    fn seven_days_ago_shows_month_and_day() {
+        // diff_days = 7 is the first month+day case.
+        let ts = local_ms(2026, 2, 10, 12, 0, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Feb 10");
+        assert_eq!(format_relative_date(UiLocale::De, ts, today()), "10. Feb");
+    }
+
+    #[test]
+    fn month_day_order_is_day_first_in_romance_locales() {
+        let ts = local_ms(2026, 2, 10, 12, 0, 0);
+        for locale in [UiLocale::Fr, UiLocale::It, UiLocale::Es] {
+            let result = format_relative_date(locale, ts, today());
+            assert!(
+                result.starts_with("10 "),
+                "expected day-first order for {locale}, got {result}"
+            );
+        }
+    }
+
+    #[test]
+    fn distant_past_shows_month_and_day() {
+        let ts = local_ms(2025, 6, 3, 12, 0, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Jun 3");
+    }
+
+    #[test]
+    fn future_timestamp_uses_weekday_branch() {
+        // Spec formula: diff_days < 7 → weekday; a future date has a
+        // negative diff and therefore falls into the weekday case.
+        // 2026-02-20 is a Friday.
+        let ts = local_ms(2026, 2, 20, 12, 0, 0);
+        assert_eq!(format_relative_date(UiLocale::En, ts, today()), "Fri");
+    }
+
+    #[test]
+    fn yesterday_is_translated_in_all_locales() {
+        let ts = local_ms(2026, 2, 16, 12, 0, 0);
+        for locale in UiLocale::all() {
+            let result = format_relative_date(*locale, ts, today());
+            assert_ne!(
+                result, "sidebar.chatYesterday",
+                "missing yesterday translation for {locale}"
+            );
+            assert!(!result.is_empty());
+        }
+    }
+
+    #[test]
+    fn month_day_pattern_exists_in_all_locales() {
+        let ts = local_ms(2025, 6, 3, 12, 0, 0);
+        for locale in UiLocale::all() {
+            let result = format_relative_date(*locale, ts, today());
+            assert_ne!(
+                result, "sidebar.relativeDateMonthDay",
+                "missing month-day pattern for {locale}"
+            );
+            assert!(result.contains('3'), "day missing for {locale}: {result}");
+        }
+    }
+}