/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */

// @flow

/**
 * Source tree reducer
 * @module reducers/source-tree
 */

import type { SourceTreeAction, FocusItem } from "../actions/types";

export type SourceTreeState = {
  expanded: Set<string>,
  focusedItem: ?FocusItem,
};

export function initialSourcesTreeState(): SourceTreeState {
  return {
    expanded: new Set(),
    focusedItem: null,
  };
}

export default function update(
  state: SourceTreeState = initialSourcesTreeState(),
  action: SourceTreeAction
): SourceTreeState {
  switch (action.type) {
    case "SET_EXPANDED_STATE":
      return updateExpanded(state, action);

    case "SET_FOCUSED_SOURCE_ITEM":
      return { ...state, focusedItem: action.item };
  }

  return state;
}

function updateExpanded(state, action) {
  return {
    ...state,
    expanded: new Set(action.expanded),
  };
}

type OuterState = {
  sourceTree: SourceTreeState,
};

export function getExpandedState(state: OuterState) {
  return state.sourceTree.expanded;
}

export function getFocusedSourceItem(state: OuterState): ?FocusItem {
  return state.sourceTree.focusedItem;
}