Moves showLightbox to redux

ts/state/selectors/lightbox.ts

@@ -0,0 +1,35 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { createSelector } from 'reselect';
+import type { MediaItemType } from '../../types/MediaItem';
+import type { StateType } from '../reducer';
+import type { LightboxStateType } from '../ducks/lightbox';
+
+export const getLightboxState = (state: StateType): LightboxStateType =>
+  state.lightbox;
+
+export const shouldShowLightbox = createSelector(
+  getLightboxState,
+  ({ isShowingLightbox }): boolean => isShowingLightbox
+);
+
+export const getIsViewOnce = createSelector(
+  getLightboxState,
+  (state): boolean => (state.isShowingLightbox ? state.isViewOnce : false)
+);
+
+export const getSelectedIndex = createSelector(
+  getLightboxState,
+  (state): number =>
+    state.isShowingLightbox
+      ? state.media.findIndex(
+          item => item.attachment.path === state.selectedAttachmentPath
+        ) || 0
+      : 0
+);
+
+export const getMedia = createSelector(
+  getLightboxState,
+  (state): Array<MediaItemType> => (state.isShowingLightbox ? state.media : [])
+);