Dashboard: show calories left inside the Today ring

crates/openmacro-app/assets/main.css

@@ -445,6 +445,11 @@ h3 { font-size: 14px; margin: 0 0 8px; color: var(--muted); font-weight: 600; }
 
 .hero { display: flex; align-items: center; gap: 18px; }
 .hero-num { font-size: 26px; font-weight: 700; font-variant-numeric: tabular-nums; }
+.hero-ring { display: grid; place-items: center; flex-shrink: 0; }
+.hero-ring > * { grid-area: 1 / 1; }
+.hero-ring-label { display: flex; flex-direction: column; align-items: center; line-height: 1.15; }
+.hero-ring-num { font-size: 18px; font-weight: 700; font-variant-numeric: tabular-nums; }
+.hero-ring-label .muted { font-size: 11px; }
 
 .week-bars { display: grid; grid-template-columns: repeat(7, 1fr); gap: 6px; height: 120px; }
 .week-col { display: flex; flex-direction: column; align-items: center; gap: 6px; font-size: 11px; }

crates/openmacro-app/src/components/dashboard.rs

@@ -39,6 +39,11 @@ pub fn Dashboard() -> Element {
 
     let today_kcal = day_totals(&log, today).get_or_zero(Nutrient::Energy);
     let today_target = coach.target_for(today).kcal;
+    let (left_text, is_over) = remaining_text(
+        prefs::energy_value(today_kcal),
+        prefs::energy_value(today_target),
+    );
+    let left_word = if is_over { "over" } else { "left" };
 
     // Expenditure tile.
     let expenditure = coach.expenditure_kcal();
@@ -233,7 +238,13 @@ pub fn Dashboard() -> Element {
             }
         }
         section { class: "card hero",
-            Ring { fraction: today_kcal / today_target.max(1.0), size: 88 }
+            div { class: "hero-ring",
+                Ring { fraction: today_kcal / today_target.max(1.0), size: 88 }
+                div { class: "hero-ring-label",
+                    span { class: "hero-ring-num", "{left_text}" }
+                    span { class: "muted", "{energy_unit} {left_word}" }
+                }
+            }
             div {
                 div { class: "muted", "Today" }
                 div { class: "hero-num", "{today_text}" }
@@ -353,6 +364,15 @@ pub fn Dashboard() -> Element {
     }
 }
 
+/// What is left of today's target, or how far past it, in the user's energy
+/// unit. Both are rounded before subtracting, so the number always matches
+/// the "eaten / target" figures shown beside it. `{:.0}` rounds ties to
+/// even, so this rounds the same way.
+fn remaining_text(eaten: f64, target: f64) -> (String, bool) {
+    let left = target.round_ties_even() - eaten.round_ties_even();
+    (fmt0(left.abs()), left < 0.0)
+}
+
 #[component]
 fn WeighInCard() -> Element {
     let state = use_context::<AppState>();
@@ -401,3 +421,39 @@ fn WeighInCard() -> Element {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn remaining_against_target() {
+        assert_eq!(remaining_text(988.0, 1894.0), ("906".into(), false));
+        assert_eq!(remaining_text(0.0, 1894.0), ("1894".into(), false));
+        assert_eq!(remaining_text(1894.0, 1894.0), ("0".into(), false));
+        assert_eq!(remaining_text(2014.0, 1894.0), ("120".into(), true));
+    }
+
+    #[test]
+    fn matches_the_rounded_figures() {
+        // Shown as "1000 / 1895", so 895 left, not 894.
+        assert_eq!(remaining_text(1000.4, 1894.6), ("895".into(), false));
+        // Shown as "1894 / 1894": ties round to even, like `{:.0}`.
+        assert_eq!(remaining_text(1894.5, 1893.6), ("0".into(), false));
+        assert_eq!(remaining_text(1894.3, 1894.0), ("0".into(), false));
+        assert_eq!(remaining_text(1894.7, 1894.0), ("1".into(), true));
+    }
+
+    #[test]
+    fn rounds_like_the_figures_beside_it() {
+        for eaten in [0.0, 0.5, 1.5, 2.5, 987.5, 1000.4, 1894.49, 1894.5, 2013.6] {
+            for target in [1893.5, 1894.0, 1894.5, 1894.6, 2633.2] {
+                let (text, over) = remaining_text(eaten, target);
+                let diff =
+                    fmt0(target).parse::<f64>().unwrap() - fmt0(eaten).parse::<f64>().unwrap();
+                assert_eq!(text, fmt0(diff.abs()), "{eaten} of {target}");
+                assert_eq!(over, diff < 0.0, "{eaten} of {target}");
+            }
+        }
+    }
+}