From e1217493b3966cabbb4f738f545723a569afaee2 Mon Sep 17 00:00:00 2001
From: Michael Stramel <stramel@users.noreply.github.com>
Date: Wed, 3 Jun 2020 15:18:01 -0500
Subject: [PATCH] Enable compression on dev server responses (#419)

---
 package-lock.json   | 14 ++++++++++++++
 package.json        |  2 ++
 src/commands/dev.ts | 38 ++++++++++++++++++++++++++++++++++----
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index d5f6bf8979..86450ad5c1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2159,6 +2159,12 @@
       "resolved": "https://registry.npmjs.org/@types/color-name/-/color-name-1.1.1.tgz",
       "integrity": "sha512-rr+OQyAjxze7GgWrSaJwydHStIhHq2lvY3BOC2Mj7KnzI7XK0Uw1TOOdI9lDoajEbSWLiYgoo4f1R51erQfhPQ=="
     },
+    "@types/compressible": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@types/compressible/-/compressible-2.0.0.tgz",
+      "integrity": "sha512-ioFCyNkga3vWcvLowx1qO+/4D0jw8JYpjoIC2b6NzQ7zk7A03Sw/KEsDuRtKqtAo2/GOhbyWQYuPVsg8h/ACcA==",
+      "dev": true
+    },
     "@types/es-module-lexer": {
       "version": "0.3.0",
       "resolved": "https://registry.npmjs.org/@types/es-module-lexer/-/es-module-lexer-0.3.0.tgz",
@@ -3884,6 +3890,14 @@
       "integrity": "sha1-ZF/ErfWLcrZJ1crmUTVhnbJv8UM=",
       "dev": true
     },
+    "compressible": {
+      "version": "2.0.18",
+      "resolved": "https://registry.npmjs.org/compressible/-/compressible-2.0.18.tgz",
+      "integrity": "sha512-AF3r7P5dWxL8MxyITRMlORQNaOA2IkAFaTr4k7BUumjPtRpGDTZpl0Pb1XCO6JeDCBdp126Cgs9sMxqSjgYyRg==",
+      "requires": {
+        "mime-db": ">= 1.43.0 < 2"
+      }
+    },
     "concat-map": {
       "version": "0.0.1",
       "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
diff --git a/package.json b/package.json
index 706278a25f..45d1bb8cfc 100644
--- a/package.json
+++ b/package.json
@@ -59,6 +59,7 @@
     "cachedir": "^2.3.0",
     "chalk": "^4.0.0",
     "chokidar": "^3.4.0",
+    "compressible": "^2.0.18",
     "cosmiconfig": "^6.0.0",
     "css-modules-loader-core": "^1.1.0",
     "deepmerge": "^4.2.2",
@@ -100,6 +101,7 @@
     "@pika/plugin-ts-standard-pkg": "^0.9.1",
     "@types/babel__traverse": "^7.0.7",
     "@types/cacache": "^12.0.1",
+    "@types/compressible": "^2.0.0",
     "@types/es-module-lexer": "^0.3.0",
     "@types/http-proxy": "^1.17.4",
     "@types/mkdirp": "^1.0.0",
diff --git a/src/commands/dev.ts b/src/commands/dev.ts
index 29c8f19a69..60fd393a42 100644
--- a/src/commands/dev.ts
+++ b/src/commands/dev.ts
@@ -27,6 +27,8 @@
 import cacache from 'cacache';
 import chalk from 'chalk';
 import chokidar from 'chokidar';
+import isCompressible from 'compressible'
+import detectPort from 'detect-port';
 import etag from 'etag';
 import {EventEmitter} from 'events';
 import execa from 'execa';
@@ -37,9 +39,10 @@ import mime from 'mime-types';
 import npmRunPath from 'npm-run-path';
 import os from 'os';
 import path from 'path';
-import url from 'url';
 import onProcessExit from 'signal-exit';
-import detectPort from 'detect-port';
+import stream from 'stream'
+import url from 'url';
+import zlib from 'zlib';
 import {BuildScript, SnowpackPluginBuildResult} from '../config';
 import {EsmHmrEngine} from '../hmr-server-engine';
 import {scanCodeImportsExports, transformEsmImports} from '../rewrite-imports';
@@ -101,19 +104,46 @@ const sendFile = (
   ext = '.html',
 ) => {
   const ETag = etag(body);
-  const headers = {
+  const headers: Record<string, string> = {
     'Content-Type': mime.contentType(ext) || 'application/octet-stream',
     'Access-Control-Allow-Origin': '*',
     ETag,
+    Vary: 'Accept-Encoding'
   };
 
   if (req.headers['if-none-match'] === ETag) {
     res.writeHead(304, headers);
+    res.end()
+    return
+  }
+
+  let acceptEncoding = (req.headers['accept-encoding'] as string) || ''
+  if (req.headers["cache-control"]?.includes('no-transform') || ['HEAD', 'OPTIONS'].includes(req.method!) || !isCompressible(mime.contentType(ext))) {
+    acceptEncoding = ''
+  }
+
+  function onError(err) {
+    if (err) {
+      res.end()
+      console.error(
+        chalk.red(
+          `  ✘ An error occurred while compressing ${chalk.bold(req.url)}`,
+        ),
+        err
+      );
+    }
+  }
+
+  const raw = stream.Readable.from([body])
+  if (/\bgzip\b/.test(acceptEncoding)) {
+    headers['Content-Encoding'] = 'gzip'
+    res.writeHead(200, headers)
+    stream.pipeline(raw, zlib.createGzip(), res, onError)
   } else {
     res.writeHead(200, headers);
     res.write(body, getEncodingType(ext));
+    res.end()
   }
-  res.end();
 };
 
 const sendError = (res, status) => {