show cask info on browser

Library/Homebrew/cask/cmd/info.rb

@@ -18,14 +18,38 @@ module Cask
 
       def self.parser
         super do
-          flag "--json=",
-               description: "Output information in JSON format."
+          flag   "--json=",
+                 description: "Output information in JSON format."
+          switch "--github",
+                 description: "Open the GitHub source page for <Cask> in a browser. "
+        end
+      end
+
+      def github_info(cask)
+        sourcefile_path = cask.sourcefile_path
+        dir = cask.tap.path
+        path = sourcefile_path.relative_path_from(dir)
+        remote = cask.tap.remote
+        github_remote_path(remote, path)
+      end
+
+      def github_remote_path(remote, path)
+        if remote =~ %r{^(?:https?://|git(?:@|://))github\.com[:/](.+)/(.+?)(?:\.git)?$}
+          "https://github.com/#{Regexp.last_match(1)}/#{Regexp.last_match(2)}/blob/HEAD/#{path}"
+        else
+          "#{remote}/#{path}"
         end
       end
 
       def run
         if args.json == "v1"
           puts JSON.generate(casks.map(&:to_h))
+        elsif args.github?
+          raise CaskUnspecifiedError if args.no_named?
+
+          args.named.to_formulae_and_casks.map do |cask|
+            exec_browser(github_info(cask))
+          end
         else
           casks.each_with_index do |cask, i|
             puts unless i.zero?

Library/Homebrew/cmd/info.rb

@@ -86,7 +86,7 @@ module Homebrew
     elsif args.github?
       raise FormulaUnspecifiedError if args.no_named?
 
-      exec_browser(*args.named.to_formulae.map { |f| github_info(f) })
+      exec_browser(*args.named.to_formulae_and_casks.map { |f| github_info(f) })
     else
       print_info(args: args)
     end
@@ -148,7 +148,11 @@ module Homebrew
   def github_info(f)
     if f.tap
       if remote = f.tap.remote
-        path = f.path.relative_path_from(f.tap.path)
+        path = if f.class.superclass == Formula
+          f.path.relative_path_from(f.tap.path)
+        elsif f.is_a?(Cask::Cask)
+          f.sourcefile_path.relative_path_from(f.tap.path)
+        end
         github_remote_path(remote, path)
       else
         f.path