From 8c251aae7ff61fab5c2d8e44df8e2fc67e3addf2 Mon Sep 17 00:00:00 2001
From: Nulo <git@nulo.in>
Date: Sun, 10 Dec 2023 17:52:54 -0300
Subject: [PATCH] WIP: un intento de evitar streamsaver si es posible
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no me genera mucha confianza este código pero era para prevenir usar streamsaver cuando no lo necesitamos con un hack en el servidor si está disponible
---
 frontend/src/lib/fetch.ts | 69 ++++++++++++++++++++++++++-------------
 1 file changed, 47 insertions(+), 22 deletions(-)

diff --git a/frontend/src/lib/fetch.ts b/frontend/src/lib/fetch.ts
index ae2f5b0..729af21 100644
--- a/frontend/src/lib/fetch.ts
+++ b/frontend/src/lib/fetch.ts
@@ -1,4 +1,3 @@
-import streamSaver from "streamsaver";
 import { zData, type Distribution, zError, zDumpMetadata } from "common/schema";
 
 export async function downloadFile(
@@ -7,36 +6,62 @@ export async function downloadFile(
   dist: Distribution,
 ) {
   if (!dist.downloadURL) throw new Error("no downloadURL");
-  const outputS = streamSaver.createWriteStream(
-    dist.downloadURL.slice(dist.downloadURL.lastIndexOf("/") + 1),
-  );
-  const res = await fetchGzipped(
-    `${dataPath}/${datasetId}/${dist.identifier}/${
-      dist.fileName || dist.identifier
-    }.gz`,
-  );
-  await res.body!.pipeTo(outputS);
+  const downloadURL = `${dataPath}/${datasetId}/${dist.identifier}/${
+    dist.fileName || dist.identifier
+  }.gz`;
+
+  const localGzip = async () => {
+    const streamSaver = await import("streamsaver");
+    const outputS = streamSaver.createWriteStream(
+      dist.downloadURL!.slice(dist.downloadURL!.lastIndexOf("/") + 1),
+    );
+    const res = await fetchGzipped(downloadURL);
+    await res.body!.pipeTo(outputS);
+  };
+
+  if (navigator.userAgent.indexOf("Firefox") != -1) {
+    // firefox, por alguna razón inexplicable, no entiende el `content-encoding`
+    // cuando se intenta descargar un archivo. lo ignora y guarda el archivo
+    // comprimido. entonces tenemos que usar el hack de streamsaver. prefiero
+    // usarlo solo en firefox porque anda medio mal o no anda en otros navegadores.
+    await localGzip();
+  } else {
+    const infoRes = await fetch(downloadURL);
+    await infoRes.body?.cancel();
+    if (infoRes.headers.get("Content-Type") === "application/gzip-hack") {
+      // server tiene el hack de gzip=true activado, genial
+      location.href = `${downloadURL}?gzip=true`;
+    } else {
+      await localGzip();
+    }
+  }
 }
 
 async function fetchGzipped(url: string): Promise<Response> {
-  let res = await fetch(url);
+  let res = await fetch(`${url}?gzip=true`);
   if (res.status === 404 && url.endsWith(".gz")) {
     // probar cargando el archivo no comprimido
     res = await fetch(url.slice(0, url.length - ".gz".length));
     return res;
   }
-  let DecStream;
-  if ("DecompressionStream" in window) DecStream = window.DecompressionStream;
-  else {
-    const { makeDecompressionStream } = await import(
-      "compression-streams-polyfill/ponyfill"
-    );
-    DecStream = makeDecompressionStream(TransformStream);
+  if (res.headers.get("Content-Type") === "application/gzip-hack") {
+    // server tiene el hack de gzip=true activado, genial
+    return res;
+  } else {
+    // server no tiene el hack, usamos DecompressionStream
+    let DecStream;
+    if ("DecompressionStream" in window) DecStream = window.DecompressionStream;
+    else {
+      const { makeDecompressionStream } = await import(
+        "compression-streams-polyfill/ponyfill"
+      );
+      DecStream = makeDecompressionStream(TransformStream);
+    }
+    const ds = new DecStream("gzip");
+    const decompressedStream = res.body!.pipeThrough(ds);
+    const resD = new Response(decompressedStream);
+    return resD;
   }
-  const ds = new DecStream("gzip");
-  const decompressedStream = res.body!.pipeThrough(ds);
-  const resD = new Response(decompressedStream);
-  return resD;
 }
 let cachedGzippedJson = new Map<string, { date: Date; data: unknown }>();