v1 review pass: fixed some minor bugs

api/routes/files.ts

@@ -15,20 +15,62 @@ router.get("/:dumpId", async (ctx) => {
   const dump = getDump(dumpId);
 
   if (dump.kind !== "file" || !dump.fileMime || !dump.fileName) {
-    throw new APIException(APIErrorCode.NOT_FOUND, 404, "No file for this dump");
+    throw new APIException(
+      APIErrorCode.NOT_FOUND,
+      404,
+      "No file for this dump",
+    );
   }
 
+  const path = `api/uploads/${dumpId}`;
+
+  let data: Uint8Array;
   try {
-    const data = await Deno.readFile(`api/uploads/${dumpId}`);
-    ctx.response.headers.set("Content-Type", dump.fileMime);
-    ctx.response.headers.set(
-      "Content-Disposition",
-      `inline; filename="${dump.fileName}"`,
-    );
-    ctx.response.body = data;
+    data = await Deno.readFile(path);
   } catch {
     throw new APIException(APIErrorCode.NOT_FOUND, 404, "File not found");
   }
+
+  const total = data.byteLength;
+  ctx.response.headers.set("Content-Type", dump.fileMime);
+  ctx.response.headers.set(
+    "Content-Disposition",
+    `inline; filename="${dump.fileName}"`,
+  );
+  ctx.response.headers.set("Accept-Ranges", "bytes");
+
+  const rangeHeader = ctx.request.headers.get("Range");
+
+  if (rangeHeader) {
+    const match = rangeHeader.match(/^bytes=(\d*)-(\d*)$/);
+    if (!match) {
+      ctx.response.status = 416;
+      ctx.response.headers.set("Content-Range", `bytes */${total}`);
+      return;
+    }
+
+    const start = match[1]
+      ? parseInt(match[1], 10)
+      : total - parseInt(match[2], 10);
+    const end = match[2]
+      ? Math.min(parseInt(match[2], 10), total - 1)
+      : total - 1;
+
+    if (start > end || start >= total) {
+      ctx.response.status = 416;
+      ctx.response.headers.set("Content-Range", `bytes */${total}`);
+      return;
+    }
+
+    const chunk = data.subarray(start, end + 1);
+    ctx.response.status = 206;
+    ctx.response.headers.set("Content-Range", `bytes ${start}-${end}/${total}`);
+    ctx.response.headers.set("Content-Length", String(chunk.byteLength));
+    ctx.response.body = chunk;
+  } else {
+    ctx.response.headers.set("Content-Length", String(total));
+    ctx.response.body = data;
+  }
 });
 
 export default router;