refactor: Improve type safety in download and file routes by updating type annotations

src/app/api/download-part/[file_id]/[part_index]/route.ts

@@ -1,4 +1,4 @@
-import { NextResponse } from 'next/server';
+import { NextResponse, NextRequest } from 'next/server';
 import pool from '@/lib/db';
 import { RowDataPacket } from 'mysql2/promise';
 
@@ -6,15 +6,20 @@ interface FilePart extends RowDataPacket {
   discord_message_id: string | null;
 }
 
+interface RouteContext {
+  params: {
+    file_id: string;
+    part_index: string;
+  };
+}
+
 if (!process.env.DISCORD_BOT_TOKEN || !process.env.DISCORD_CHANNEL_ID) {
   throw new Error('Discord bot token or channel ID is not configured');
 }
 
-export async function GET(request: Request, { params }: { params: { file_id: string; part_index: string; } }) {
+export async function GET(request: NextRequest, context: { params: Record<string, string | string[]> }) {
   try {
-    const params = await context.params;
-    const file_id = params.file_id as string;
-    const part_index = params.part_index as string;
+    const { file_id, part_index } = params;
 
     // NOTE: In a real-world scenario, you MUST validate if the user has permission to download this part.
     // This would involve checking the download_token against the hash in the `files` table.

src/app/api/file/[file_id]/route.ts

@@ -1,11 +1,24 @@
-import { NextResponse } from 'next/server';
+import { NextResponse, NextRequest } from 'next/server';
 import pool from '@/lib/db';
 import bcrypt from 'bcrypt';
+import { RowDataPacket } from 'mysql2/promise';
 
-export async function GET(request: Request, context: any) {
+interface FileData extends RowDataPacket {
+  filename: string;
+  size: number;
+  num_parts: number;
+  expires_at: Date | null;
+  token_hash: string;
+}
+
+interface FilePartMetadata extends RowDataPacket {
+  part_index: number;
+  size: number;
+}
+
+export async function GET(request: NextRequest, { params }: { params: { file_id: string; } }) {
   try {
-    const params = await context.params;
-    const file_id = params.file_id as string;
+    const file_id = params.file_id;
     const { searchParams } = new URL(request.url);
     const token = searchParams.get('token');
 
@@ -16,8 +29,8 @@ export async function GET(request: Request, context: any) {
     const connection = await pool.getConnection();
     try {
       // 1. Fetch file metadata and token hash
-      const [fileRows]: any[] = await connection.query('SELECT * FROM files WHERE id = ? AND deleted = 0', [file_id]);
-      const file = fileRows[0];
+      const [fileRows]: [RowDataPacket[], unknown] = await connection.query('SELECT * FROM files WHERE id = ? AND deleted = 0', [file_id]);
+      const file = fileRows[0] as FileData;
 
       if (!file) {
         return NextResponse.json({ error: 'File not found' }, { status: 404 });
@@ -35,7 +48,7 @@ export async function GET(request: Request, context: any) {
       }
 
       // 4. Fetch file parts
-      const [partsRows]: any[] = await connection.query(
+      const [partsRows]: [RowDataPacket[], unknown] = await connection.query(
         'SELECT part_index, size FROM file_parts WHERE file_id = ? ORDER BY part_index ASC',
         [file_id]
       );
@@ -45,7 +58,7 @@ export async function GET(request: Request, context: any) {
         filename: file.filename,
         size: file.size,
         num_parts: file.num_parts,
-        parts: partsRows,
+        parts: partsRows[0] as FilePartMetadata[],
       };
 
       return NextResponse.json(response);

src/app/download/[file_id]/page.tsx

@@ -3,6 +3,11 @@
 import { useEffect, useState, useRef } from 'react';
 import { useParams, useSearchParams } from 'next/navigation';
 
+interface MetadataPart {
+  part_index: number;
+  size: number;
+}
+
 // Helper to convert Base64 string back to ArrayBuffer
 function base64ToBuffer(base64: string) {
     const binary_string = window.atob(base64.replace(/-/g, '+').replace(/_/g, '/'));
@@ -106,7 +111,7 @@ export default function DownloadPage() {
                 setDownloadState('downloading');
                 const encryptedParts = new Array(metadata.num_parts);
 
-                const downloadPromises = metadata.parts.map(async (part: any) => {
+                const downloadPromises = metadata.parts.map(async (part: MetadataPart) => {
                     const response = await fetchWithRetry(`/api/download-part/${file_id}/${part.part_index}`);
                     const buffer = await response.arrayBuffer();
                     encryptedParts[part.part_index] = { index: part.part_index, data: buffer };
@@ -127,7 +132,7 @@ export default function DownloadPage() {
                     ['decrypt']
                 );
 
-                const decryptPromises = encryptedParts.map(async (part) => {
+                const decryptPromises = encryptedParts.map(async (part: { index: number; data: ArrayBuffer }) => {
                     const iv = part.data.slice(0, 12);
                     const data = part.data.slice(12);
                     const decrypted = await window.crypto.subtle.decrypt({ name: 'AES-GCM', iv }, fileKey, data);