사소한 리팩토링

src/routes/(fullscreen)/settings/thumbnail/service.svelte.ts

@@ -0,0 +1,170 @@
+import { limitFunction } from "p-limit";
+import { get, writable, type Writable } from "svelte/store";
+import { encryptData } from "$lib/modules/crypto";
+import { storeFileThumbnailCache } from "$lib/modules/file";
+import type { FileInfo } from "$lib/modules/filesystem";
+import { generateThumbnail as doGenerateThumbnail } from "$lib/modules/thumbnail";
+import type { FileThumbnailUploadRequest } from "$lib/server/schemas";
+import { requestFileDownload } from "$lib/services/file";
+
+export type GenerationStatus =
+  | "queued"
+  | "generation-pending"
+  | "generating"
+  | "upload-pending"
+  | "uploading"
+  | "uploaded"
+  | "error";
+
+interface File {
+  id: number;
+  info: Writable<FileInfo | null>;
+  status?: Writable<GenerationStatus>;
+}
+
+const workingFiles = new Map<number, Writable<GenerationStatus>>();
+
+let queue: (() => void)[] = [];
+let memoryUsage = 0;
+const MEMORY_LIMIT = 100 * 1024 * 1024; // 100 MiB
+
+export const persistentStates = $state({
+  files: [] as File[],
+});
+
+export const getGenerationStatus = (fileId: number) => {
+  return workingFiles.get(fileId);
+};
+
+const generateThumbnail = limitFunction(
+  async (
+    status: Writable<GenerationStatus>,
+    fileBuffer: ArrayBuffer,
+    fileType: string,
+    dataKey: CryptoKey,
+  ) => {
+    status.set("generating");
+
+    const thumbnail = await doGenerateThumbnail(fileBuffer, fileType);
+    if (!thumbnail) {
+      status.set("error");
+      return null;
+    }
+
+    const thumbnailBuffer = await thumbnail.arrayBuffer();
+    const thumbnailEncrypted = await encryptData(thumbnailBuffer, dataKey);
+    status.set("upload-pending");
+    return { plaintext: thumbnailBuffer, ...thumbnailEncrypted };
+  },
+  { concurrency: 4 },
+);
+
+const requestThumbnailUpload = limitFunction(
+  async (
+    status: Writable<GenerationStatus>,
+    fileId: number,
+    dataKeyVersion: Date,
+    thumbnail: { plaintext: ArrayBuffer; ciphertext: ArrayBuffer; iv: string },
+  ) => {
+    status.set("uploading");
+
+    const form = new FormData();
+    form.set(
+      "metadata",
+      JSON.stringify({
+        dekVersion: dataKeyVersion.toISOString(),
+        contentIv: thumbnail.iv,
+      } satisfies FileThumbnailUploadRequest),
+    );
+    form.set("content", new Blob([thumbnail.ciphertext]));
+
+    const res = await fetch(`/api/file/${fileId}/thumbnail/upload`, { method: "POST", body: form });
+    if (!res.ok) return false;
+
+    status.set("uploaded");
+    workingFiles.delete(fileId);
+    persistentStates.files = persistentStates.files.filter(({ id }) => id != fileId);
+
+    storeFileThumbnailCache(fileId, thumbnail.plaintext); // Intended
+    return true;
+  },
+  { concurrency: 4 },
+);
+
+const enqueue = async (
+  status: Writable<GenerationStatus> | undefined,
+  fileInfo: FileInfo,
+  priority = false,
+) => {
+  if (status) {
+    status.set("queued");
+  } else {
+    status = writable("queued");
+    workingFiles.set(fileInfo.id, status);
+    persistentStates.files = persistentStates.files.map((file) =>
+      file.id === fileInfo.id ? { ...file, status } : file,
+    );
+  }
+
+  let resolver;
+  const promise = new Promise((resolve) => {
+    resolver = resolve;
+  });
+
+  if (priority) {
+    queue = [() => resolver!(), ...queue];
+  } else {
+    queue.push(resolver!);
+  }
+
+  await promise;
+};
+
+export const requestThumbnailGeneration = async (fileInfo: FileInfo) => {
+  let status = workingFiles.get(fileInfo.id);
+  if (status && get(status) !== "error") return;
+
+  if (workingFiles.values().some((status) => get(status) !== "error")) {
+    await enqueue(status, fileInfo);
+  }
+  while (memoryUsage >= MEMORY_LIMIT) {
+    await enqueue(status, fileInfo, true);
+  }
+
+  if (status) {
+    status.set("generation-pending");
+  } else {
+    status = writable("generation-pending");
+    workingFiles.set(fileInfo.id, status);
+    persistentStates.files = persistentStates.files.map((file) =>
+      file.id === fileInfo.id ? { ...file, status } : file,
+    );
+  }
+
+  let fileSize = 0;
+  try {
+    const file = await requestFileDownload(fileInfo.id, fileInfo.contentIv!, fileInfo.dataKey!);
+    fileSize = file.byteLength;
+
+    memoryUsage += fileSize;
+    if (memoryUsage < MEMORY_LIMIT) {
+      queue.shift()?.();
+    }
+
+    const thumbnail = await generateThumbnail(
+      status,
+      file,
+      fileInfo.contentType,
+      fileInfo.dataKey!,
+    );
+    if (!thumbnail) return;
+    if (!(await requestThumbnailUpload(status, fileInfo.id, fileInfo.dataKeyVersion!, thumbnail))) {
+      status.set("error");
+    }
+  } catch {
+    status.set("error");
+  } finally {
+    memoryUsage -= fileSize;
+    queue.shift()?.();
+  }
+};