feat: src/useUndo.ts (#13)

Author: tapiwamakandigona

src/useUndo.ts

@@ -0,0 +1,28 @@
+import { useState, useCallback, useRef } from "react";
+
+export function useUndo<T>(initial: T) {
+  const [state, setState] = useState<T>(initial);
+  const history = useRef<T[]>([initial]);
+  const idx = useRef(0);
+
+  const set = useCallback((val: T | ((p: T) => T)) => {
+    setState(prev => {
+      const next = typeof val === "function" ? (val as (p: T) => T)(prev) : val;
+      history.current = history.current.slice(0, idx.current + 1);
+      history.current.push(next);
+      if (history.current.length > 50) history.current.shift();
+      else idx.current++;
+      return next;
+    });
+  }, []);
+
+  const undo = useCallback(() => {
+    if (idx.current > 0) { idx.current--; setState(history.current[idx.current]); }
+  }, []);
+
+  const redo = useCallback(() => {
+    if (idx.current < history.current.length - 1) { idx.current++; setState(history.current[idx.current]); }
+  }, []);
+
+  return { state, set, undo, redo, canUndo: idx.current > 0, canRedo: idx.current < history.current.length - 1 };
+}