파일 캐시 추가

src/lib/modules/opfs.ts

@@ -0,0 +1,53 @@
+let rootHandle: FileSystemDirectoryHandle | null = null;
+
+export const prepareOpfs = async () => {
+  rootHandle = await navigator.storage.getDirectory();
+};
+
+const getFileHandle = async (path: string, create = true) => {
+  if (!rootHandle) {
+    throw new Error("OPFS not prepared");
+  } else if (path[0] !== "/") {
+    throw new Error("Path must be absolute");
+  }
+
+  const parts = path.split("/");
+  if (parts.length <= 1) {
+    throw new Error("Invalid path");
+  }
+
+  try {
+    let directoryHandle: FileSystemDirectoryHandle = rootHandle;
+
+    for (const part of parts.slice(0, -1)) {
+      if (!part) continue;
+      directoryHandle = await directoryHandle.getDirectoryHandle(part, { create });
+    }
+
+    return directoryHandle.getFileHandle(parts[parts.length - 1]!, { create });
+  } catch (e) {
+    if (e instanceof DOMException && e.name === "NotFoundError") {
+      return null;
+    }
+    throw e;
+  }
+};
+
+export const readFileFromOpfs = async (path: string) => {
+  const fileHandle = await getFileHandle(path, false);
+  if (!fileHandle) return null;
+
+  const file = await fileHandle.getFile();
+  return await file.arrayBuffer();
+};
+
+export const writeFileToOpfs = async (path: string, data: ArrayBuffer) => {
+  const fileHandle = await getFileHandle(path);
+  const writable = await fileHandle!.createWritable();
+
+  try {
+    await writable.write(data);
+  } finally {
+    await writable.close();
+  }
+};