파일 다운로드 스케쥴링 및 진행률 표시 기능 구현

src/lib/modules/file/download.ts

@@ -0,0 +1,84 @@
+import axios from "axios";
+import { limitFunction } from "p-limit";
+import { writable, type Writable } from "svelte/store";
+import { decryptData } from "$lib/modules/crypto";
+import { fileDownloadStatusStore, type FileDownloadStatus } from "$lib/stores";
+
+const requestFileDownload = limitFunction(
+  async (status: Writable<FileDownloadStatus>, id: number) => {
+    status.update((value) => {
+      value.status = "downloading";
+      return value;
+    });
+
+    const res = await axios.get(`/api/file/${id}/download`, {
+      responseType: "arraybuffer",
+      onDownloadProgress: ({ progress, rate, estimated }) => {
+        status.update((value) => {
+          value.progress = progress;
+          value.rate = rate;
+          value.estimated = estimated;
+          return value;
+        });
+      },
+    });
+    const fileEncrypted: ArrayBuffer = res.data;
+
+    status.update((value) => {
+      value.status = "decryption-pending";
+      return value;
+    });
+    return fileEncrypted;
+  },
+  { concurrency: 1 },
+);
+
+const decryptFile = limitFunction(
+  async (
+    status: Writable<FileDownloadStatus>,
+    fileEncrypted: ArrayBuffer,
+    fileEncryptedIv: string,
+    dataKey: CryptoKey,
+  ) => {
+    status.update((value) => {
+      value.status = "decrypting";
+      return value;
+    });
+
+    const fileBuffer = await decryptData(fileEncrypted, fileEncryptedIv, dataKey);
+
+    status.update((value) => {
+      value.status = "decrypted";
+      value.result = fileBuffer;
+      return value;
+    });
+    return fileBuffer;
+  },
+  { concurrency: 4 },
+);
+
+export const downloadFile = async (id: number, fileEncryptedIv: string, dataKey: CryptoKey) => {
+  const status = writable<FileDownloadStatus>({
+    id,
+    status: "download-pending",
+  });
+  fileDownloadStatusStore.update((value) => {
+    value.push(status);
+    return value;
+  });
+
+  try {
+    return await decryptFile(
+      status,
+      await requestFileDownload(status, id),
+      fileEncryptedIv,
+      dataKey,
+    );
+  } catch (e) {
+    status.update((value) => {
+      value.status = "error";
+      return value;
+    });
+    throw e;
+  }
+};

src/lib/modules/file/index.ts

@@ -1,2 +1,3 @@
 export * from "./cache";
+export * from "./download";
 export * from "./upload";

src/lib/modules/file/upload.ts

@@ -120,7 +120,7 @@ const encryptFile = limitFunction(
   { concurrency: 4 },
 );
 
-const uploadFileInternal = limitFunction(
+const requestFileUpload = limitFunction(
   async (status: Writable<FileUploadStatus>, form: FormData) => {
     status.update((value) => {
       value.status = "uploading";
@@ -209,7 +209,7 @@ export const uploadFile = async (
     );
     form.set("content", new Blob([fileEncrypted.ciphertext]));
 
-    await uploadFileInternal(status, form);
+    await requestFileUpload(status, form);
     return true;
   } catch (e) {
     status.update((value) => {

src/lib/stores/file.ts

@@ -15,4 +15,22 @@ export interface FileUploadStatus {
   estimated?: number;
 }
 
+export interface FileDownloadStatus {
+  id: number;
+  status:
+    | "download-pending"
+    | "downloading"
+    | "decryption-pending"
+    | "decrypting"
+    | "decrypted"
+    | "canceled"
+    | "error";
+  progress?: number;
+  rate?: number;
+  estimated?: number;
+  result?: ArrayBuffer;
+}
+
 export const fileUploadStatusStore = writable<Writable<FileUploadStatus>[]>([]);
+
+export const fileDownloadStatusStore = writable<Writable<FileDownloadStatus>[]>([]);