Function columnViewReducer

app/useColumnView/index.ts:345–453

(
  state: ColumnViewState,
  action: ColumnViewAction
)

    9. Move forward to the next state
*/
function columnViewReducer(
  state: ColumnViewState,
  action: ColumnViewAction
): ColumnViewState {
  switch (action.type) {
    case "SET_SELECTED_NODE_ID":
      return {
        ...state,
        selectedNodeId: action.id,
        highlightedNodeId: action.id,
        selectedNodeSource: action.source,
      };
    case "MOVE_DOWN": {
      if (state.highlightedNodeId === state.rootNodeId) {
        return moveToChildren(state);
      }

      const id = getHighlightedSibling(state, state.nodeTable, 1);

      if (!id) {
        return state;
      }

      return {
        ...state,
        selectedNodeId: id,
        highlightedNodeId: id,
      };
    }
    case "MOVE_UP": {
      const id = getHighlightedSibling(state, state.nodeTable, -1);

      if (!id) {
        return state;
      }

      return {
        ...state,
        selectedNodeId: id,
        highlightedNodeId: id,
      };
    }
    case "MOVE_TO_CHILDREN": {
      return moveToChildren(state);
    }
    case "MOVE_TO_PARENT": {
      const { highlightedNodeId } = state;

      if (!highlightedNodeId) {
        return state;
      }

      const highlightedNode = state.nodeTable[highlightedNodeId];

      if (!highlightedNode || !highlightedNode.parentId) {
        return state;
      }