steamPackages.steam: add update script

pkgs/games/steam/steam.nix

@@ -38,6 +38,8 @@ stdenv.mkDerivation (finalAttrs: {
     sed -e 's,/usr/bin/steam,steam,g' steam.desktop > $out/share/applications/steam.desktop
   '';
 
+  passthru.updateScript = ./update-bootstrap.py;
+
   meta = with lib; {
     description = "Digital distribution platform";
     longDescription = ''

pkgs/games/steam/update-bootstrap.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env nix-shell
+#!nix-shell --pure --keep NIX_PATH -i python3 -p git nix-update "python3.withPackages (ps: [ ps.beautifulsoup4 ps.requests ])"
+
+import sys
+import re
+import requests
+import subprocess
+from bs4 import BeautifulSoup
+
+VERSION_PATTERN = re.compile(r'^steam_(?P<ver>(\d+\.)+)tar.gz$')
+
+found_versions = []
+response = requests.get("https://repo.steampowered.com/steam/archive/stable/")
+soup = BeautifulSoup (response.text, "html.parser")
+for a in soup.find_all("a"):
+    href = a["href"]
+    if not href.endswith(".tar.gz"):
+        continue
+
+    match = VERSION_PATTERN.match(href)
+    if match is not None:
+        version = match.groupdict()["ver"][0:-1]
+        found_versions.append(version)
+
+if len(found_versions) == 0:
+    print("Failed to find available versions!", file=sys.stderr)
+    sys.exit(1)
+
+found_versions.sort()
+subprocess.run(["nix-update", "--version", found_versions[-1], "steamPackages.steam"])
+found_versions[0]