@val external localStorage: {..} = "localStorage"

let storageKey = (courseId: string, lessonId: string) =>
  `annotation:${courseId}:${lessonId}`

let saveNote = (courseId: string, lessonId: string, note: string) => {
  let key = storageKey(courseId, lessonId)
  localStorage["setItem"](key, note)
}

let loadNote = (courseId: string, lessonId: string) => {
  let key = storageKey(courseId, lessonId)
  let value: Nullable.t<string> = localStorage["getItem"](key)
  Nullable.toOption(value)
}

let deleteNote = (courseId: string, lessonId: string) => {
  let key = storageKey(courseId, lessonId)
  localStorage["removeItem"](key)
}