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/postNewQueryState.ts

@@ -0,0 +1,58 @@
+const POST_NEW_REVIEW_PATH_PREFIX = '/posts/new?urls='
+const MAX_POST_NEW_REVIEW_TARGET_BYTES = 6_144
+
+const textEncoder = new TextEncoder ()
+
+
+const rawUrlsParam = (search: string): string | null => {
+  const query = search.startsWith ('?') ? search.slice (1) : search
+  if (query === '')
+    return null
+
+  for (const segment of query.split ('&'))
+    {
+      if (segment === 'urls')
+        return ''
+      if (segment.startsWith ('urls='))
+        return segment.slice ('urls='.length)
+    }
+
+  return null
+}
+
+
+export const buildPostNewReviewPath = (urls: string[]): string =>
+    `${ POST_NEW_REVIEW_PATH_PREFIX }${ urls.map (url => encodeURIComponent (url)).join ('+') }`
+
+
+export const postNewReviewPathByteLength = (urls: string[]): number =>
+    textEncoder.encode (buildPostNewReviewPath (urls)).byteLength
+
+
+export const isPostNewReviewPathWithinLimit = (urls: string[]): boolean =>
+    postNewReviewPathByteLength (urls) < MAX_POST_NEW_REVIEW_TARGET_BYTES
+
+
+export const parsePostNewReviewUrls = (search: string): string[] => {
+  const raw = rawUrlsParam (search)
+  if (raw == null)
+    return []
+
+  return raw
+      .split ('+')
+      .filter (segment => segment !== '')
+      .map (segment => {
+        try
+        {
+          return decodeURIComponent (segment)
+        }
+        catch
+        {
+          return segment
+        }
+      })
+}
+
+
+export const hasPostNewReviewState = (search: string): boolean =>
+    rawUrlsParam (search) != null