feat: implement R2 audio file management and rate limiting enhancements

- Add R2 client setup and audio upload functionality in lib/r2.ts.
- Create audio file cleanup functions in lib/r2-cleanup.ts to delete voice files associated with videos, projects, and workspaces.
- Enhance rate limiting in lib/rate-limit.ts with new action-specific limits and improved IP validation.
- Introduce a unified rate limit check function that returns a 429 response when limits are exceeded.
- Update package.json to include the AWS SDK for S3.

app/api/upload/audio/[filename]/route.ts

@@ -0,0 +1,58 @@
+import { NextResponse } from 'next/server';
+import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
+import { GetObjectCommand } from '@aws-sdk/client-s3';
+
+// Only allow UUID filenames with safe extensions
+const SAFE_FILENAME = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z0-9]+$/i;
+
+export async function GET(
+  _request: Request,
+  { params }: { params: Promise<{ filename: string }> }
+) {
+  try {
+    const { filename } = await params;
+
+    // Validate filename to prevent path traversal
+    if (!SAFE_FILENAME.test(filename)) {
+      return NextResponse.json({ error: 'Invalid filename' }, { status: 400 });
+    }
+
+    const key = `voice/${filename}`;
+
+    const response = await r2Client.send(
+      new GetObjectCommand({
+        Bucket: R2_BUCKET_NAME,
+        Key: key,
+      })
+    );
+
+    if (!response.Body) {
+      return NextResponse.json({ error: 'File not found' }, { status: 404 });
+    }
+
+    const contentType = response.ContentType || 'audio/webm';
+    const contentLength = response.ContentLength;
+
+    // Stream the response body directly instead of buffering in memory
+    const stream = response.Body.transformToWebStream();
+
+    return new NextResponse(stream, {
+      status: 200,
+      headers: {
+        'Content-Type': contentType,
+        ...(contentLength ? { 'Content-Length': String(contentLength) } : {}),
+        'Cache-Control': 'public, max-age=31536000, immutable',
+      },
+    });
+  } catch (error: unknown) {
+    const errorName = error instanceof Error ? error.name : '';
+    if (errorName === 'NoSuchKey') {
+      return NextResponse.json({ error: 'File not found' }, { status: 404 });
+    }
+    console.error('Error serving audio:', error);
+    return NextResponse.json(
+      { error: 'Failed to retrieve audio' },
+      { status: 500 }
+    );
+  }
+}

app/api/upload/audio/route.ts

@@ -0,0 +1,76 @@
+import { NextResponse } from 'next/server';
+import { auth } from '@/lib/auth';
+import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
+import { PutObjectCommand } from '@aws-sdk/client-s3';
+import { randomUUID } from 'crypto';
+import { rateLimit } from '@/lib/rate-limit';
+
+const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10MB
+const ALLOWED_TYPES = ['audio/webm', 'audio/ogg', 'audio/mp4', 'audio/mpeg', 'audio/wav'];
+
+export async function POST(request: Request) {
+  try {
+    // Rate limit
+    const limited = await rateLimit(request, 'voice-upload');
+    if (limited) return limited;
+
+    // Require authentication
+    const session = await auth();
+    if (!session?.user?.id) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+    }
+
+    const formData = await request.formData();
+    const file = formData.get('audio') as File | null;
+
+    if (!file) {
+      return NextResponse.json({ error: 'No audio file provided' }, { status: 400 });
+    }
+
+    if (file.size > MAX_FILE_SIZE) {
+      return NextResponse.json(
+        { error: 'File too large. Maximum size is 10MB.' },
+        { status: 400 }
+      );
+    }
+
+    // Check content type
+    const contentType = file.type || 'audio/webm';
+    if (!ALLOWED_TYPES.includes(contentType)) {
+      return NextResponse.json(
+        { error: `Unsupported audio format: ${contentType}` },
+        { status: 400 }
+      );
+    }
+
+    // Generate unique filename
+    const ext = contentType.split('/')[1] || 'webm';
+    const filename = `${randomUUID()}.${ext}`;
+    const key = `voice/${filename}`;
+
+    // Convert to buffer
+    const arrayBuffer = await file.arrayBuffer();
+    const buffer = Buffer.from(arrayBuffer);
+
+    // Upload to R2
+    await r2Client.send(
+      new PutObjectCommand({
+        Bucket: R2_BUCKET_NAME,
+        Key: key,
+        Body: buffer,
+        ContentType: contentType,
+      })
+    );
+
+    // Return the URL through our proxy endpoint
+    const voiceUrl = `/api/upload/audio/${filename}`;
+
+    return NextResponse.json({ url: voiceUrl }, { status: 201 });
+  } catch (error) {
+    console.error('Error uploading audio:', error);
+    return NextResponse.json(
+      { error: 'Failed to upload audio' },
+      { status: 500 }
+    );
+  }
+}