Merge pull request #586 from MarekSpodBiedry:issue-578

crates/core/src/date.rs

@@ -59,6 +59,14 @@ pub fn serial_from_unix_ms(ms: f64) -> f64 {
     25569.0 + ms / 86_400_000.0
 }
 
+/// Converts a 1900-system serial (as the clock supplies it) to the serial of the same instant in `sys`.
+pub fn serial_in_system(sys: DateSystem, serial_1900: f64) -> f64 {
+    match sys {
+        DateSystem::D1900 => serial_1900,
+        DateSystem::D1904 => serial_1900 - 1462.0,
+    }
+}
+
 pub fn civil_from_days(z: i64) -> (i32, u32, u32) {
     let z = z + 719468;
     let era = if z >= 0 { z } else { z - 146096 } / 146097;

crates/engine/src/cf.rs

@@ -184,7 +184,7 @@ impl CfCache {
                 },
                 CfRule::TimePeriod { period, style } => match v.as_f64() {
                     Some(n) => {
-                        let today = gridcraft_calc::now_serial().floor();
+                        let today = gridcraft_core::date::serial_in_system(wb.date_system, gridcraft_calc::now_serial()).floor();
                         let d = n.floor();
                         let wd = gridcraft_core::date::datetime_from_serial(wb.date_system, today).map(|x| x.weekday as f64).unwrap_or(0.0);
                         let week_start = today - wd;

crates/engine/src/cmd/print.rs

@@ -391,7 +391,7 @@ pub struct HfContext {
 
 /// Today's date and the current time as headers and footers show them (`&D`, `&T`).
 pub fn hf_date_time(wb: &Workbook) -> (String, String) {
-    let now = gridcraft_calc::now_serial();
+    let now = gridcraft_core::date::serial_in_system(wb.date_system, gridcraft_calc::now_serial());
     let date = crate::display::format(&Value::Number(now.floor()), "m/d/yyyy", wb).text;
     let time = crate::display::format(&Value::Number(now), "h:mm AM/PM", wb).text;
     (date, time)
@@ -1765,6 +1765,14 @@ mod tests {
         }
     }
 
+    #[test]
+    fn header_footer_date_follows_the_workbook_date_system() {
+        let mut wb = Workbook::new();
+        let date_1900 = hf_date_time(&wb).0;
+        wb.date_system = gridcraft_core::DateSystem::D1904;
+        assert_eq!(hf_date_time(&wb).0, date_1900);
+    }
+
     #[test]
     fn header_footer_section_edits_are_undoable_and_views_are_per_sheet() {
         let mut s = s();

crates/functions/src/date.rs

@@ -1,6 +1,6 @@
 //! Date and time functions.
 
-use gridcraft_core::date::{DateTime, datetime_from_serial, days_in_month, days_in_month_in, is_leap, serial_from_ymd};
+use gridcraft_core::date::{DateTime, datetime_from_serial, days_in_month, days_in_month_in, is_leap, serial_from_ymd, serial_in_system};
 use gridcraft_core::parse::parse_input;
 use gridcraft_core::{CellError, DateSystem, Value};
 
@@ -98,10 +98,10 @@ fn second(a: &[Arg], _c: &mut dyn Ctx) -> R<Value> {
 }
 
 fn now(_a: &[Arg], c: &mut dyn Ctx) -> R<Value> {
-    num_val(c.now_serial())
+    num_val(serial_in_system(c.date_system(), c.now_serial()))
 }
 fn today(_a: &[Arg], c: &mut dyn Ctx) -> R<Value> {
-    num_val(c.now_serial().floor())
+    num_val(serial_in_system(c.date_system(), c.now_serial()).floor())
 }
 
 fn weekday(a: &[Arg], c: &mut dyn Ctx) -> R<Value> {
@@ -794,6 +794,11 @@ mod tests {
         close(crate::call(spec, &[n(0.0)], &mut ctx), 6.0);
         let spec = crate::lookup("YEAR").unwrap();
         close(crate::call(spec, &[n(0.0)], &mut ctx), 1904.0);
+        // The clock is 2026-10-07 12:00; in the 1904 system that is serial 44840.5.
+        close(crate::call(crate::lookup("NOW").unwrap(), &[], &mut ctx), 44840.5);
+        let today = crate::call(crate::lookup("TODAY").unwrap(), &[], &mut ctx);
+        close(today.clone(), 44840.0);
+        close(crate::call(spec, &[crate::Arg::val(today)], &mut ctx), 2026.0);
         // No fictitious day here: 1904 is a real leap year and 1900 is before the epoch.
         let spec = crate::lookup("DATE").unwrap();
         close(crate::call(spec, &[n(1904.0), n(2.0), n(29.0)], &mut ctx), 59.0);

crates/ui-egui/src/keymap.rs

@@ -179,12 +179,14 @@ pub(crate) fn dispatch(app: &mut SheetApp, ctx: &egui::Context, key: Key, physic
         }
         Shortcut::Dialog(name, params) => app.open_dialog(name, params),
         Shortcut::Date | Shortcut::Time => {
-            let now = gridcraft_engine::calc::now_serial();
-            let (value, format) = if shortcut == Shortcut::Date { (now.floor(), "m/d/yyyy") } else { (now.fract(), "h:mm AM/PM") };
             let text = app
                 .session
                 .active()
-                .map(|d| gridcraft_engine::display::format(&gridcraft_engine::core::Value::Number(value), format, &d.wb).text)
+                .map(|d| {
+                    let now = gridcraft_engine::core::date::serial_in_system(d.wb.date_system, gridcraft_engine::calc::now_serial());
+                    let (value, format) = if shortcut == Shortcut::Date { (now.floor(), "m/d/yyyy") } else { (now.fract(), "h:mm AM/PM") };
+                    gridcraft_engine::display::format(&gridcraft_engine::core::Value::Number(value), format, &d.wb).text
+                })
                 .unwrap_or_default();
             edit_with(app, text);
         }

crates/ui-egui/src/ribbon.rs

@@ -2458,11 +2458,13 @@ pub fn shortcut(app: &mut SheetApp, key: Key, m: Modifiers) {
         }
         Key::Semicolon => {
             // Insert today's date.
-            let today = gridcraft_engine::calc::now_serial().floor();
             let text = app
                 .session
                 .active()
-                .map(|d| gridcraft_engine::display::format(&gridcraft_engine::core::Value::Number(today), "m/d/yyyy", &d.wb).text)
+                .map(|d| {
+                    let today = gridcraft_engine::core::date::serial_in_system(d.wb.date_system, gridcraft_engine::calc::now_serial()).floor();
+                    gridcraft_engine::display::format(&gridcraft_engine::core::Value::Number(today), "m/d/yyyy", &d.wb).text
+                })
                 .unwrap_or_default();
             app.begin_edit(Some(text), false);
             None