import { keymap } from 'prosemirror-keymap';
import { ResolvedPos, Schema } from 'prosemirror-model';
import { Plugin, EditorState, Transaction, Selection } from 'prosemirror-state';
import {
  findParentNodeOfTypeClosestToPos,
  hasParentNodeOfType,
} from 'prosemirror-utils';
import { getCursor, isEmptyNode, pipe } from '../../../utils';
import { CommandDispatch } from '../../../types';

const deleteCurrentItem = ($from: ResolvedPos) => (
  tr: Transaction,
): Transaction => {
  return tr.delete($from.before($from.depth) - 1, $from.end($from.depth) + 1);
};

const setTextSelection = (pos: number) => (tr: Transaction): Transaction => {
  const newSelection = Selection.findFrom(tr.doc.resolve(pos), -1, true);
  if (newSelection) {
    tr.setSelection(newSelection);
  }
  return tr;
};

export function keymapPlugin(schema: Schema): Plugin | undefined {
  return keymap({
    Backspace: (state: EditorState, dispatch: CommandDispatch) => {
      const $cursor = getCursor(state.selection);
      const {
        paragraph,
        codeBlock,
        listItem,
        table,
        layoutColumn,
      } = state.schema.nodes;
      if (!$cursor || $cursor.parent.type !== codeBlock) {
        return false;
      }

      if (
        $cursor.pos === 1 ||
        (hasParentNodeOfType(listItem)(state.selection) &&
          $cursor.parentOffset === 0)
      ) {
        const node = findParentNodeOfTypeClosestToPos($cursor, codeBlock);

        if (!node) {
          return false;
        }

        dispatch(
          state.tr
            .setNodeMarkup(node.pos, node.node.type, node.node.attrs, [])
            .setBlockType($cursor.pos, $cursor.pos, paragraph),
        );
        return true;
      }

      if (
        dispatch &&
        $cursor.node &&
        isEmptyNode(schema)($cursor.node()) &&
        (hasParentNodeOfType(layoutColumn)(state.selection) ||
          hasParentNodeOfType(table)(state.selection))
      ) {
        const { tr } = state;
        const insertPos = $cursor.pos;
        dispatch(
          pipe(
            deleteCurrentItem($cursor),
            setTextSelection(insertPos),
          )(tr).scrollIntoView(),
        );

        return true;
      }

      // Handle not nested empty code block
      if (isEmptyNode(schema)($cursor.node())) {
        dispatch(deleteCurrentItem($cursor)(state?.tr));
        return true;
      }

      return false;
    },
  });
}

export default keymapPlugin;