feat: add download functionality to ArchiveComponent with presigned URL support

src/blog/api.ts

@@ -6,6 +6,7 @@ import { apiRequest, apiPost } from '../utils/api';
 import { getS3Url } from './s3Config';
 import type {
   UploadPresignedURLResponse,
+  DownloadPresignedURLResponse,
   CreatePostResponse,
   ListPostsRequest,
   ListPostsResponse,
@@ -94,6 +95,21 @@ export async function uploadBlogFile(
   return { fileKey, url };
 }
 
+/**
+ * Get presigned URL for downloading a file
+ */
+export async function getDownloadPresignedURL(
+  fileKey: string,
+): Promise<DownloadPresignedURLResponse> {
+  const response = await apiPost(`${API_BASE}/file/download`, { fileKey });
+
+  if (!response.ok) {
+    throw new Error(`Failed to get download URL: ${response.statusText}`);
+  }
+
+  return response.json();
+}
+
 /**
  * Backwards-compatible image upload helper
  */

src/blog/nodes/ArchiveComponent.tsx

@@ -11,9 +11,10 @@ import {
   KEY_ESCAPE_COMMAND,
   SELECTION_CHANGE_COMMAND,
 } from 'lexical';
-import { useCallback, useEffect, useMemo, useRef } from 'react';
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 
-import { getS3Url } from '../s3Config';
+import { getDownloadPresignedURL } from '../api';
+import type { DownloadPresignedURLResponse } from '../types';
 
 function formatFileSize(bytes?: number): string | undefined {
   if (bytes === undefined) {
@@ -49,16 +50,25 @@ export default function ArchiveComponent({
   const [editor] = useLexicalComposerContext();
   const [isSelected, setSelected, clearSelection] = useLexicalNodeSelection(nodeKey);
   const containerRef = useRef<HTMLDivElement | null>(null);
-
-  const resolvedUrl = useMemo(() => {
-    if (fileKey) {
-      return getS3Url(fileKey);
-    }
-    return undefined;
-  }, [fileKey]);
+  const [downloadInfo, setDownloadInfo] = useState<DownloadPresignedURLResponse | null>(null);
+  const [isFetchingDownload, setIsFetchingDownload] = useState(false);
+  const [downloadError, setDownloadError] = useState<string | undefined>(undefined);
 
   const readableSize = useMemo(() => formatFileSize(fileSize), [fileSize]);
   const isUploading = uploadProgress !== undefined && uploadProgress < 100 && !uploadError;
+  const downloadButtonDisabled = !fileKey || isUploading || Boolean(uploadError) || isFetchingDownload;
+  const downloadButtonLabel = useMemo(() => {
+    if (!fileKey) {
+      return 'Preparing link...';
+    }
+    if (uploadError) {
+      return 'Unavailable';
+    }
+    if (isFetchingDownload) {
+      return 'Preparing...';
+    }
+    return 'Download';
+  }, [fileKey, isFetchingDownload, uploadError]);
 
   const handleEscape = useCallback(() => {
     if (!isSelected) {
@@ -111,6 +121,63 @@ export default function ArchiveComponent({
     );
   }, [editor, handleClick, handleEscape]);
 
+  useEffect(() => {
+    setDownloadInfo(null);
+    setDownloadError(undefined);
+    setIsFetchingDownload(false);
+  }, [fileKey]);
+
+  const triggerDownload = useCallback(
+    (url: string) => {
+      const link = document.createElement('a');
+      link.href = url;
+      link.download = fileName;
+      link.target = '_blank';
+      link.rel = 'noopener noreferrer';
+      document.body.appendChild(link);
+      link.click();
+      document.body.removeChild(link);
+    },
+    [fileName],
+  );
+
+  const handleDownload = useCallback(async () => {
+    if (!fileKey || isFetchingDownload) {
+      return;
+    }
+
+    try {
+      setIsFetchingDownload(true);
+      setDownloadError(undefined);
+
+      const isInfoValid = (info: DownloadPresignedURLResponse | null): boolean => {
+        if (!info) {
+          return false;
+        }
+        const expireAtMs = info.expireAt > 1_000_000_000_000 ? info.expireAt : info.expireAt * 1000;
+        return Date.now() < expireAtMs - 5_000;
+      };
+
+      let info = downloadInfo;
+      if (!isInfoValid(info)) {
+        info = await getDownloadPresignedURL(fileKey);
+        setDownloadInfo(info);
+      }
+
+      if (!info) {
+        throw new Error('Download link unavailable');
+      }
+
+      triggerDownload(info.url);
+    } catch (error) {
+      setDownloadError(
+        error instanceof Error ? error.message : 'Unable to prepare download link',
+      );
+    } finally {
+      setIsFetchingDownload(false);
+    }
+  }, [downloadInfo, fileKey, isFetchingDownload, triggerDownload]);
+
   const borderColor = uploadError
     ? 'rgba(244, 67, 54, 0.6)'
     : isSelected
@@ -136,19 +203,14 @@ export default function ArchiveComponent({
       <div className="editor-archive-details">
         <div className="editor-archive-title">{fileName}</div>
         <div className="editor-archive-meta">Archive{readableSize ? ` • ${readableSize}` : ''}</div>
-        {resolvedUrl ? (
-          <a
-            className="editor-archive-link"
-            href={resolvedUrl}
-            download={fileName}
-            target="_blank"
-            rel="noopener noreferrer"
+        <button
+          type="button"
+          className={`editor-archive-link${downloadButtonDisabled ? ' disabled' : ''}`}
+          onClick={handleDownload}
+          disabled={downloadButtonDisabled}
         >
-            Download
-          </a>
-        ) : (
-          <span className="editor-archive-link disabled">Preparing link...</span>
-        )}
+          {downloadButtonLabel}
+        </button>
         {isUploading && (
           <div className="editor-archive-progress">
             <div className="editor-archive-progress-bar">
@@ -165,6 +227,9 @@ export default function ArchiveComponent({
         {uploadError && (
           <div className="editor-archive-error">❌ {uploadError}</div>
         )}
+        {downloadError && (
+          <div className="editor-archive-error">❌ {downloadError}</div>
+        )}
       </div>
     </div>
   );

src/blog/types.ts

@@ -8,6 +8,11 @@ export interface UploadPresignedURLResponse {
   expireAt: number;
 }
 
+export interface DownloadPresignedURLResponse {
+  url: string;
+  expireAt: number;
+}
+
 export interface CreatePostResponse {
   postId: string;
 }