import { computed, type Ref, shallowRef } from "vue";

export const writable = <T>(upstream: () => T) => {
  // it's a bit weird, but this essentially guarantees that the ref gets reset
  // immediately as expected. this also gets around the double-calling that
  // using `watch` would cause.
  const computable = computed(() => shallowRef(upstream()));

  return computed<T>({
    get() {
      return computable.value.value;
    },
    set(next) {
      computable.value.value = next;
    },
  });
};