広場投稿追加画面の刷新 (#399) (#413)

Reviewed-on: #413
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

frontend/src/lib/postImportStorage.ts

@@ -0,0 +1,94 @@
+import type { StorageErrorHandler } from '@/lib/postImportTypes'
+
+const SOURCE_DRAFT_KEY = 'post-import-source-draft'
+
+
+const readStorage = (
+    key:       string,
+    onError?:  StorageErrorHandler,
+): string | null => {
+  if (typeof window === 'undefined')
+    return null
+
+  try
+  {
+    return sessionStorage.getItem (key)
+  }
+  catch
+  {
+    onError?.('保存済みデータを読み込めませんでした．')
+    return null
+  }
+}
+
+
+const writeStorage = (
+    key:       string,
+    value:     string,
+    onError?:  StorageErrorHandler,
+): boolean => {
+  if (typeof window === 'undefined')
+    return false
+
+  try
+  {
+    sessionStorage.setItem (key, value)
+    return true
+  }
+  catch
+  {
+    onError?.('ブラウザへ保存できませんでした．')
+    return false
+  }
+}
+
+
+const removeStorage = (
+    key:       string,
+    onError?:  StorageErrorHandler,
+) => {
+  if (typeof window === 'undefined')
+    return
+
+  try
+  {
+    sessionStorage.removeItem (key)
+  }
+  catch
+  {
+    onError?.('保存済みデータを削除できませんでした．')
+  }
+}
+
+
+export const loadPostImportSourceDraft = (
+    onError?: StorageErrorHandler,
+): { source: string } => {
+  const raw = readStorage (SOURCE_DRAFT_KEY, onError)
+  if (raw == null)
+    return { source: '' }
+
+  try
+  {
+    const value = JSON.parse (raw) as { source?: string }
+    return { source: typeof value.source === 'string' ? value.source : '' }
+  }
+  catch
+  {
+    return { source: '' }
+  }
+}
+
+
+export const savePostImportSourceDraft = (
+    source:    string,
+    onError?:  StorageErrorHandler,
+): boolean =>
+    writeStorage (SOURCE_DRAFT_KEY, JSON.stringify ({ source }), onError)
+
+
+export const clearPostImportSourceDraft = (
+    onError?: StorageErrorHandler,
+) => {
+  removeStorage (SOURCE_DRAFT_KEY, onError)
+}