class Vernier::Output::FilenameFilter

def call(filename)
  if filename.match?(gem_regex)
    gem_match_regex =~ filename
    "gem:#$1-#$2:#$3"
  elsif filename.start_with?(pwd)
    filename.delete_prefix(pwd)
  elsif filename.start_with?(rubylibdir)
    path = filename.delete_prefix(rubylibdir)
    "rubylib:#{RUBY_VERSION}:#{path}"
  else
    filename
  end
end

def initialize
  @pwd = "#{Dir.pwd}/"
  @gem_regex = %r{\A#{Regexp.union(Gem.path)}/gems/}
  @gem_match_regex = %r{\A#{Regexp.union(Gem.path)}/gems/([a-zA-Z](?:[a-zA-Z0-9\.\_]|-[a-zA-Z])*)-([0-9][0-9A-Za-z\-_\.]*)/(.*)\z}
  @rubylibdir = "#{RbConfig::CONFIG["rubylibdir"]}/"
end