Add pomodoro timer

src/pomodoro/hooks.ts

@@ -0,0 +1,30 @@
+import {
+  Dispatch,
+  MutableRefObject,
+  SetStateAction,
+  useEffect,
+  useRef,
+  useState,
+} from 'react'
+
+export function useRefState<S>(
+  initialState: S | (() => S)
+): [S, Dispatch<SetStateAction<S>>, MutableRefObject<S>] {
+  const [state, setState] = useState<S>(initialState)
+  const stateRef = useRef(state)
+  useEffect(() => {
+    stateRef.current = state
+  }, [state])
+  return [state, setState, stateRef]
+}
+
+export function useTimer() {}
+
+export function useValueRef<V>(value: V) {
+  const ref = useRef(value)
+  useEffect(() => {
+    ref.current = value
+  }, [value])
+
+  return ref
+}