add brew-bundle-dir contributed command

Closes Homebrew/homebrew#27258.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Contributions/cmd/brew-bundle-dir.rb

@@ -0,0 +1,80 @@
+#!/usr/bin/env ruby
+
+# program name.
+NAME = "bundle-dir"
+
+# defaults.
+PREFIX_DEFAULT = "~/.brews.d"
+
+# effective prefix directory.
+PREFIX = File.expand_path(ENV["BUNDLE_DIR"] || PREFIX_DEFAULT)
+
+# validate prefix directory exists and is readable.
+odie "'#{PREFIX}' does not exist, is not a directory, or is not readable." unless File.readable?(PREFIX) && File.directory?(PREFIX)
+
+# list all available brewfiles in PREFIX.
+def list
+  Dir["#{PREFIX}/**/*.brewfile"].select do |brewfile|
+    File.readable?(brewfile)
+  end
+end
+
+# edit/open all available brewfiles in PREFIX.
+def edit
+  odie "environment variable EDITOR is not set." unless ENV["EDITOR"].length > 0
+  system "$EDITOR #{list().join(' ')}"
+end
+
+# count number of `brew * install` lines across all found brewfiles.
+def count
+  system "echo #{list().join(' ')} | xargs cat | grep -vE '^[#]' | grep -vE '^$' | wc -l | awk '{ print $NR }'"
+end
+
+# print a usage message.
+def usage
+  <<-USAGE
+Usage: brew #{NAME}
+
+  Options:
+
+   -c, --count  Count of formula found in all brewfiles found in PREFIX.
+   -e, --edit   Edit/open all brewfiles found in PREFIX.
+   -l, --list   List all brewfiles found in PREFIX.
+   -h, --help   Display help information.
+  USAGE
+end
+
+# command.
+command = ARGV.first
+
+# help.
+if ["--help", "-h"].include? command
+  puts usage ; exit 0
+end
+
+# list.
+if ["--list", "-l"].include? command
+  puts list ; exit 0
+end
+
+# edit.
+if ["--edit", "-e"].include? command
+  edit ; exit 0
+end
+
+# count.
+if ["--count", "-c"].include? command
+  count ; exit 0
+end
+
+# unknown option.
+if !command.nil? && command.length > 0
+  puts "#{usage}"
+  puts "\n"
+  odie "Unknown option: #{command}"
+end
+
+# main.
+list().each do |brewfile|
+  system "brew bundle #{brewfile}"
+end