slightly better

src/stores/mappingMode.ts

@@ -0,0 +1,34 @@
+import { atom } from 'nanostores'
+
+export interface MappingModeState {
+  isActive: boolean
+  activeLFO: number | null
+}
+
+export const mappingMode = atom<MappingModeState>({
+  isActive: false,
+  activeLFO: null
+})
+
+export function enterMappingMode(lfoIndex: number): void {
+  mappingMode.set({
+    isActive: true,
+    activeLFO: lfoIndex
+  })
+}
+
+export function exitMappingMode(): void {
+  mappingMode.set({
+    isActive: false,
+    activeLFO: null
+  })
+}
+
+export function toggleMappingMode(lfoIndex: number): void {
+  const current = mappingMode.get()
+  if (current.isActive && current.activeLFO === lfoIndex) {
+    exitMappingMode()
+  } else {
+    enterMappingMode(lfoIndex)
+  }
+}