import { EditorView } from '@codemirror/view'
import { Transaction, EditorSelection } from '@codemirror/state'
import type { Extension } from '@codemirror/state'
import {
  INLINE_SEMANTIC_CHANGE_ANNOTATION,
  INLINE_SEMANTIC_TEXT_CHANGE_ANNOTATION,
} from '../inline-semantic-ops'

export function markdownPasteHandler(): Extension {
  return EditorView.domEventHandlers({
    paste: markdownDomPasteHandler,
  })
}

export function markdownDomPasteHandler(event: Event, view: EditorView): boolean {
  if (event.defaultPrevented) return false
  if (view.state.readOnly) return false

  const dt = (event as ClipboardEvent).clipboardData
  if (!dt) return false

  const sel = view.state.selection
  if (sel.ranges.length !== 1) return false

  // Delegate to image handler when files are present
  if (dt.files && dt.files.length > 0) return false

  // Delegate when clipboard has no text
  const text = dt.getData('text/plain')
  if (!text) return false

  const range = sel.main
  const from = range.from
  const to = range.to

  const pastedEnd = from + text.length

  view.dispatch({
    changes: { from, to, insert: text },
    selection: EditorSelection.single(pastedEnd),
    scrollIntoView: true,
    annotations: [
      Transaction.userEvent.of('input.paste'),
      INLINE_SEMANTIC_CHANGE_ANNOTATION.of({
        ops: [{ kind: 'synthesize-paste', range: { start: from, end: pastedEnd } }],
      }),
      INLINE_SEMANTIC_TEXT_CHANGE_ANNOTATION.of({
        from,
        to,
        insert: text,
      }),
    ],
  })

  event.preventDefault()
  return true
}