functional

src/store.ts

@@ -0,0 +1,52 @@
+import type { Config, Selections } from "./types";
+
+type Listener = () => void;
+
+/**
+ * Minimal reactive store: holds the immutable config plus mutable user
+ * selections, and notifies subscribers on any change.
+ */
+export class Store {
+  private listeners = new Set<Listener>();
+
+  constructor(
+    public readonly config: Config,
+    private selections: Selections
+  ) {}
+
+  getSelections(): Selections {
+    return this.selections;
+  }
+
+  onChange(listener: Listener): void {
+    this.listeners.add(listener);
+  }
+
+  private update(patch: Partial<Selections>): void {
+    this.selections = { ...this.selections, ...patch };
+    this.emit();
+  }
+
+  setSelectedPlan(planId: string): void {
+    this.update({ selectedPlanId: planId });
+  }
+
+  setTargetDate(date: Date): void {
+    this.update({ targetDate: date });
+  }
+
+  setMissingPeriodActive(periodId: string, isActive: boolean): void {
+    const next = new Set(this.selections.activeMissingPeriodIds);
+    if (isActive) next.add(periodId);
+    else next.delete(periodId);
+    this.update({ activeMissingPeriodIds: next });
+  }
+
+  setExtraExcludedDays(count: number): void {
+    this.update({ extraExcludedDays: Math.max(0, Math.floor(count) || 0) });
+  }
+
+  private emit(): void {
+    for (const l of this.listeners) l();
+  }
+}