파일 업로드 스케쥴링 구현

암호화는 동시에 최대 4개까지, 업로드는 1개까지 가능하도록 설정했습니다.

src/lib/modules/file/cache.ts

@@ -0,0 +1,50 @@
+import {
+  getFileCacheIndex as getFileCacheIndexFromIndexedDB,
+  storeFileCacheIndex,
+  deleteFileCacheIndex,
+  type FileCacheIndex,
+} from "$lib/indexedDB";
+import { readFile, writeFile, deleteFile } from "$lib/modules/opfs";
+
+const fileCacheIndex = new Map<number, FileCacheIndex>();
+
+export const prepareFileCache = async () => {
+  for (const cache of await getFileCacheIndexFromIndexedDB()) {
+    fileCacheIndex.set(cache.fileId, cache);
+  }
+};
+
+export const getFileCacheIndex = () => {
+  return Array.from(fileCacheIndex.values());
+};
+
+export const getFileCache = async (fileId: number) => {
+  const cacheIndex = fileCacheIndex.get(fileId);
+  if (!cacheIndex) return null;
+
+  cacheIndex.lastRetrievedAt = new Date();
+  storeFileCacheIndex(cacheIndex); // Intended
+  return await readFile(`/cache/${fileId}`);
+};
+
+export const storeFileCache = async (fileId: number, fileBuffer: ArrayBuffer) => {
+  const now = new Date();
+  await writeFile(`/cache/${fileId}`, fileBuffer);
+
+  const cacheIndex: FileCacheIndex = {
+    fileId,
+    cachedAt: now,
+    lastRetrievedAt: now,
+    size: fileBuffer.byteLength,
+  };
+  fileCacheIndex.set(fileId, cacheIndex);
+  await storeFileCacheIndex(cacheIndex);
+};
+
+export const deleteFileCache = async (fileId: number) => {
+  if (!fileCacheIndex.has(fileId)) return;
+
+  fileCacheIndex.delete(fileId);
+  await deleteFile(`/cache/${fileId}`);
+  await deleteFileCacheIndex(fileId);
+};