class Addressable::URI

def self.heuristic_parse(uri, hints={})
  # If we were given nil, return nil.
  return nil unless uri
  # If a URI object is passed, just return itself.
  return uri.dup if uri.kind_of?(self)
  # If a URI object of the Ruby standard library variety is passed,
  # convert it to a string, then parse the string.
  # We do the check this way because we don't want to accidentally
  # cause a missing constant exception to be thrown.
  if uri.class.name =~ /^URI\b/
    uri = uri.to_s
  end
  unless uri.respond_to?(:to_str)
    raise TypeError, "Can't convert #{uri.class} into String."
  end
  # Otherwise, convert to a String
  uri = uri.to_str.dup.strip
  hints = {
    :scheme => "http"
  }.merge(hints)
  case uri
  when /^http:\//i
    uri.sub!(/^http:\/+/i, "http://")
  when /^https:\//i
    uri.sub!(/^https:\/+/i, "https://")
  when /^feed:\/+http:\//i
    uri.sub!(/^feed:\/+http:\/+/i, "feed:http://")
  when /^feed:\//i
    uri.sub!(/^feed:\/+/i, "feed://")
  when %r[^file:/{4}]i
    uri.sub!(%r[^file:/+]i, "file:////")
  when %r[^file://localhost/]i
    uri.sub!(%r[^file://localhost/+]i, "file:///")
  when %r[^file:/+]i
    uri.sub!(%r[^file:/+]i, "file:///")
  when /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/
    uri.sub!(/^/, hints[:scheme] + "://")
  when /\A\d+\..*:\d+\z/
    uri = "#{hints[:scheme]}://#{uri}"
  end
  match = uri.match(URIREGEX)
  fragments = match.captures
  authority = fragments[3]
  if authority && authority.length > 0
    new_authority = authority.tr("\\", "/").gsub(" ", "%20")
    # NOTE: We want offset 4, not 3!
    offset = match.offset(4)
    uri = uri.dup
    uri[offset[0]...offset[1]] = new_authority
  end
  parsed = self.parse(uri)
  if parsed.scheme =~ /^[^\/?#\.]+\.[^\/?#]+$/
    parsed = self.parse(hints[:scheme] + "://" + uri)
  end
  if parsed.path.include?(".")
    if parsed.path[/\b@\b/]
      parsed.scheme = "mailto" unless parsed.scheme
    elsif new_host = parsed.path[/^([^\/]+\.[^\/]*)/, 1]
      parsed.defer_validation do
        new_path = parsed.path.sub(
          Regexp.new("^" + Regexp.escape(new_host)), EMPTY_STR)
        parsed.host = new_host
        parsed.path = new_path
        parsed.scheme = hints[:scheme] unless parsed.scheme
      end
    end
  end
  return parsed
end