import {
  chainCommands,
  createParagraphNear,
  deleteSelection,
  joinBackward,
  joinForward,
  liftEmptyBlock,
  selectAll,
  selectNodeBackward,
  selectNodeForward,
  splitBlock
} from "prosemirror-commands";
import { EditorState } from "prosemirror-state";
import { UxCommand } from "./constants";
import { filter, not, textSelected } from "./predicate";
import { Dispatch } from "./types";

const deleteBackwardChain = chainCommands(deleteSelection, joinBackward, selectNodeBackward);
const deleteForwardChain = chainCommands(deleteSelection, joinForward, selectNodeForward);
const enterChain = chainCommands(createParagraphNear, liftEmptyBlock, splitBlock);

export function deleteBackward(state: EditorState, dispatch?: Dispatch) {
  return deleteBackwardChain(state, dispatch);
}

export function deleteForward(state: EditorState, dispatch?: Dispatch) {
  return deleteForwardChain(state, dispatch);
}

export function enter(state: EditorState, dispatch?: Dispatch) {
  return enterChain(state, dispatch);
}

// It's easy to accidentally use keyboard shortcuts in the wrong context and
// invoke an unintended browser behaviour.
export function preventDefault() {
  return true;
}

export { selectAll };

export const ux = {
  [UxCommand.DeleteBackward]: deleteBackward,
  [UxCommand.DeleteForward]: deleteForward,
  [UxCommand.Enter]: enter,
  [UxCommand.Lift]: preventDefault,
  [UxCommand.SelectAll]: selectAll,
  [UxCommand.Sink]: preventDefault,
  [UxCommand.TabForward]: filter(not(textSelected), preventDefault),
  [UxCommand.TabBackward]: filter(not(textSelected), preventDefault)
};