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

let use = (courseId: string) => {
  let (state, setState) = React.useState(() => AnnotationTypes.initialState)

  let selectLesson = (lesson: AnnotationTypes.lesson) => {
    let savedNote = AnnotationStorage.loadNote(courseId, lesson.id)
    let notes = Dict.make()
    switch savedNote {
    | Some(note) => Dict.set(notes, lesson.id, note)
    | None => ()
    }
    setState(_ => {
      selectedLesson: Some(lesson),
      isPenOpen: true,
      notes,
    })
  }

  let updateNote = (lessonId: string, note: string) => {
    AnnotationStorage.saveNote(courseId, lessonId, note)
    setState(prev => {
      let notes = Dict.make()
      Dict.set(notes, lessonId, note)
      {...prev, notes}
    })
  }

  let closePen = () => {
    setState(prev => {...prev, isPenOpen: false, selectedLesson: None})
  }

  let getNote = (lessonId: string) => {
    Dict.get(state.notes, lessonId)
  }

  (state, selectLesson, updateNote, closePen, getNote)
}