// European numeric dates: 01.10.2026, 14:32
const nameFormat = new Intl.DateTimeFormat('de-DE', { day: '2-digit', month: '2-digit', year: 'numeric', hour: '2-digit', minute: '2-digit' })
const dayFormat = new Intl.DateTimeFormat('de-DE', { day: '2-digit', month: '2-digit', year: '2-digit' })

/** A note is named by its title, or by when it was created if it has none */
export function notesDocName(doc: Pick<NotesDocSummary, 'title' | 'created'>): string {
  return doc.title || (doc.created ? nameFormat.format(new Date(doc.created)) : 'Untitled')
}

export function notesDocDay(iso: string | null): string {
  return iso ? dayFormat.format(new Date(iso)) : ''
}

export function useNotes() {
  const { data, error, status, refresh } = useFetch<NotesDocSummary[]>('/api/notes/docs', { key: 'notes-docs', default: () => [] })

  // Newest first by creation, so editing a note never moves it
  const docs = computed(() => data.value.toSorted((a, b) => (b.created ?? '').localeCompare(a.created ?? '') || b.id - a.id))

  /** Reflects a change in the browser without reloading the list */
  function patchSummary(id: number, changes: Partial<NotesDocSummary>) {
    data.value = data.value.map(doc => doc.id === id ? { ...doc, ...changes } : doc)
  }

  async function create() {
    const doc = await $fetch<NotesDoc>('/api/notes/docs', { method: 'POST' })
    data.value = [...data.value, doc]
    return doc
  }

  async function remove(id: number) {
    await $fetch(`/api/notes/docs/${id}`, { method: 'DELETE' })
    data.value = data.value.filter(doc => doc.id !== id)
  }

  return { docs, error, status, refresh, patchSummary, create, remove }
}

/**
 * `open`: the desktop sidebar (remembered in a cookie).
 * `drawerOpen`: the list that is pulled down from the top on mobile; it closes once a note is opened.
 */
export function useNotesSidebar() {
  const open = useCookie<boolean>('notes-sidebar', { default: () => true, maxAge: 60 * 60 * 24 * 365 })
  const drawerOpen = useState('notes-drawer', () => false)
  return {
    open,
    drawerOpen,
    toggle: () => { open.value = !open.value },
    /** The desktop sidebar, or the drawer below md */
    toggleList: () => {
      if (window.matchMedia('(max-width: 767px)').matches) drawerOpen.value = !drawerOpen.value
      else open.value = !open.value
    },
    closeOnMobile: () => { drawerOpen.value = false }
  }
}

/** Creates a note and opens it; used by the action bar */
export function useNewNote() {
  const { create } = useNotes()
  const { closeOnMobile } = useNotesSidebar()
  const toast = useToast()
  const creating = useState('notes-creating', () => false)

  async function createAndOpen() {
    creating.value = true
    try {
      const doc = await create()
      closeOnMobile()
      await navigateTo(`/notes/${doc.id}`)
    } catch (e) {
      toast.add({ title: 'Couldn\'t create a note', description: errorMessage(e), color: 'error', icon: 'i-lucide-triangle-alert' })
    } finally {
      creating.value = false
    }
  }

  return { creating, createAndOpen }
}

/** Deletes a note right away; used by the list's trash buttons */
export function useDeleteNote() {
  const { remove } = useNotes()
  const route = useRoute()
  const toast = useToast()

  return async function deleteNote(doc: NotesDocSummary) {
    try {
      // Leave the note first, so its last unsaved edits aren't saved into a deleted row
      if (String(doc.id) === route.params.id) await navigateTo('/notes')
      await remove(doc.id)
    } catch (e) {
      toast.add({ title: 'Couldn\'t delete the note', description: errorMessage(e), color: 'error', icon: 'i-lucide-triangle-alert' })
    }
  }
}

const SEARCH_DELAY_MS = 250

/**
 * The search over title and text. `query` is what's typed; `matches` the ids of matching notes, or null when
 * not searching. The list is mounted twice (sidebar and drawer), so the searching itself runs once, in notes.vue.
 */
export function useNotesSearch() {
  const query = useState('notes-search', () => '')
  const matches = useState<number[] | null>('notes-search-matches', () => null)
  const searching = useState('notes-searching', () => false)

  function runSearch() {
    let timer: ReturnType<typeof setTimeout> | undefined
    let latest = 0

    watch(query, (value) => {
      clearTimeout(timer)
      const q = value.trim()
      if (!q) {
        matches.value = null
        searching.value = false
        return
      }
      searching.value = true
      timer = setTimeout(async () => {
        const request = ++latest
        try {
          const docs = await $fetch<NotesDocSummary[]>('/api/notes/docs', { query: { q } })
          if (request === latest) matches.value = docs.map(doc => doc.id)
        } finally {
          if (request === latest) searching.value = false
        }
      }, SEARCH_DELAY_MS)
    })
  }

  return { query, matches, searching, runSearch }
}