grafx 2.8.3174,71

Casks/g/grafx.rb

@@ -1,17 +1,38 @@
 cask "grafx" do
-  version "2.8.3104,67"
-  sha256 "c637e21fcdbd5f3ee77e12c3d637b21f22cceedc2d7082f18e874685f9346cf6"
+  version "2.8.3174,71"
+  sha256 "b0207e50bddf10e289d03ba2dd52e7fe1c5c5ee32293cc2441eb9e0aac536891"
 
   url "https://pulkomandy.tk/projects/GrafX#{version.major}/downloads/#{version.csv.second}"
   name "GrafX2"
   desc "256 colour painting program"
   homepage "https://pulkomandy.tk/projects/GrafX#{version.major}"
 
+  # Upstream lists a number of files for macOS on the download page
+  # (https://pulkomandy.tk/projects/GrafX2/downloads) but it's not clear which
+  # variant we should use. The homepage links to grafx2.eu as the "Main website"
+  # and its download page links to a specific download for macOS, so we check
+  # that instead. The full version isn't listed on the page, so we have to check
+  # the filename in the `Content-Disposition` header of the download response.
+  # NOTE: The grafx2.eu download page uses an iframe from grafx2.chez.com for
+  # the page content, so we're checking the iframe URL.
   livecheck do
-    url "https://pulkomandy.tk/projects/GrafX2/downloads"
-    regex(%r{href=.*?/downloads/(\d+)[\s'">]+Grafx2\.app-x86_64-sdl2-v?(\d+(?:\.\d+)+)\.zip}im)
+    url "http://grafx2.chez.com/index.php?static3/downloads"
+    regex(%r{Mac\s*OS.*?href=.*?/projects/GrafX#{version.major}/downloads/(\d+)/?["' >]}im)
     strategy :page_match do |page, regex|
-      page.scan(regex).map { |match| "#{match[1]},#{match[0]}" }
+      # Match the ID for the macOS download
+      download_id = page.scan(regex).flatten.max_by { |v| Version.new(v) }
+      next unless download_id
+
+      # Fetch the headers for the download URL
+      download_headers = Homebrew::Livecheck::Strategy.page_headers("https://pulkomandy.tk/projects/GrafX#{version.major}/downloads/#{download_id}")
+      next if download_headers.blank?
+
+      # Match the version from the filename in the `Content-Disposition` header
+      merged_headers = download_headers.reduce(&:merge)
+      version = merged_headers["content-disposition"]&.[](/Grafx\d+\.app.*?v?(\d+(?:\.\d+)+)/i, 1)
+      next unless version
+
+      "#{version},#{download_id}"
     end
   end