Added story preview and confirmation dialogs to send story

ts/hooks/useConfirmDiscard.tsx

@@ -0,0 +1,33 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React, { useState } from 'react';
+
+import type { PropsType } from '../components/ConfirmDiscardDialog';
+
+import { ConfirmDiscardDialog } from '../components/ConfirmDiscardDialog';
+import type { LocalizerType } from '../types/Util';
+
+export function useConfirmDiscard(
+  i18n: LocalizerType
+): [JSX.Element | null, (condition: boolean, callback: () => void) => void] {
+  const [props, setProps] = useState<Omit<PropsType, 'i18n'> | null>(null);
+  const confirmElement = props ? (
+    <ConfirmDiscardDialog i18n={i18n} {...props} />
+  ) : null;
+
+  function confirmDiscardIf(condition: boolean, callback: () => void) {
+    if (condition) {
+      setProps({
+        onClose() {
+          setProps(null);
+        },
+        onDiscard: callback,
+      });
+    } else {
+      callback();
+    }
+  }
+
+  return [confirmElement, confirmDiscardIf];
+}