import { atom } from 'nanostores'

// URLs of preview targets that have unsaved spot-editor changes, keyed by
// `target.url` so the rail can render a VS Code-style "modified" dot on the tab
// without threading editor state up through the pane. The editor in
// `preview-file.tsx` is the sole writer; the rail tabs are the readers.
export const $dirtyPreviewUrls = atom<Record<string, true>>({})

export function setPreviewDirty(url: string, dirty: boolean): void {
  if (!url) {
    return
  }

  const current = $dirtyPreviewUrls.get()
  const has = Boolean(current[url])

  if (dirty === has) {
    return
  }

  if (dirty) {
    $dirtyPreviewUrls.set({ ...current, [url]: true })

    return
  }

  const next = { ...current }
  delete next[url]
  $dirtyPreviewUrls.set(next)
}