Added HTTP range support

src/index.ts

@@ -80,9 +80,48 @@ app.get("/api/data/:id", async (req, res)=>{
             const head = Buffer.concat(head_chunks);
             detectBufferMime(head).then((mime)=>{
                 res.contentType(mime);
-                res.write(head);
-                stream.pipe(res);
-                stream.resume();
+                res.header("Accept-Ranges", "bytes");
+                const range = req.range(dl.received);
+                if (range)
+                {
+                    if (typeof(range) == "number")
+                        return res.status(400).send({error:"Invalid range"});
+
+                    const r = range[0]!;
+                    r.end += 1;
+
+                    res.status(206);
+                    res.header("Content-Range", `bytes ${r.start}-${r.end-1}/${dl.received}`);
+                    res.header("Content-Length", String(r.end - r.start));
+                    if (r.start < head.length)
+                        res.write(head.slice(r.start, r.end));
+
+                    if ((r.end-r.start) - head.length <= 0)
+                        return res.end();
+
+                    let start = r.start-head.length;
+                    let end = r.end-head.length;
+                    stream.on("data", (chunk)=>{
+                        if (start < chunk.length)
+                            res.write(chunk.slice(Math.max(0, start), end));
+                        start -= chunk.length;
+                        end -= chunk.length;
+                        if (end <= 0)
+                        {
+                            res.end();
+                            stream.pause();
+                            stream.destroy();
+                        }
+                    });
+                    stream.resume();
+                }
+                else
+                {
+                    res.header("Content-Length", String(dl.received));
+                    res.write(head);
+                    stream.pipe(res);
+                    stream.resume();
+                }
             });
         }
     }