New rich text composer + autocomplete (#10159)

src/alf/util/flatten.ts

@@ -1,3 +1,39 @@
-import {StyleSheet} from 'react-native'
+import {type DimensionValue, StyleSheet} from 'react-native'
 
 export const flatten = StyleSheet.flatten
+
+/**
+ * Coerce a style value to a number. Padding values are typed as
+ * `DimensionValue` (numbers, percentages, "auto", etc.) but our ALF atoms
+ * are always plain numbers. Non-numeric values are treated as 0.
+ */
+function num(v: unknown): number {
+  return typeof v === 'number' ? v : 0
+}
+
+interface PaddingStyle {
+  padding?: DimensionValue
+  paddingHorizontal?: DimensionValue
+  paddingVertical?: DimensionValue
+  paddingTop?: DimensionValue
+  paddingBottom?: DimensionValue
+  paddingLeft?: DimensionValue
+  paddingRight?: DimensionValue
+}
+
+/**
+ * Extract resolved padding values from a style object. Returns numbers for
+ * each side, resolving shorthand properties (padding → paddingVertical →
+ * paddingTop/paddingBottom, etc.). Values are expected to be numbers — any
+ * non-numeric `DimensionValue` (e.g. percentages) is treated as 0.
+ */
+export function extractPadding(style: PaddingStyle | PaddingStyle[]) {
+  const s = flatten(style as any) ?? {}
+  const base = num(s.padding)
+  return {
+    paddingTop: num(s.paddingTop) || num(s.paddingVertical) || base,
+    paddingBottom: num(s.paddingBottom) || num(s.paddingVertical) || base,
+    paddingLeft: num(s.paddingLeft) || num(s.paddingHorizontal) || base,
+    paddingRight: num(s.paddingRight) || num(s.paddingHorizontal) || base,
+  }
+}