class ActiveSupport::Messages::Metadata

def as_json(options = {})
  { _rails: { message: @message, exp: @expires_at, pur: @purpose } }
end

def decode(message)
  ::Base64.strict_decode64(message)
end

def encode(message)
  ::Base64.strict_encode64(message)
end

def extract_metadata(message)
  data = JSON.decode(message) rescue nil
  if data.is_a?(Hash) && data.key?("_rails")
    new(decode(data["_rails"]["message"]), data["_rails"]["exp"], data["_rails"]["pur"])
  else
    new(message)
  end
end

def fresh?
  @expires_at.nil? || Time.now.utc < @expires_at
end

def initialize(message, expires_at = nil, purpose = nil)
  @message, @purpose = message, purpose
  @expires_at = expires_at.is_a?(String) ? parse_expires_at(expires_at) : expires_at
end

def match?(purpose)
  @purpose.to_s == purpose.to_s
end

def parse_expires_at(expires_at)
  if ActiveSupport.use_standard_json_time_format
    Time.iso8601(expires_at)
  else
    Time.parse(expires_at)
  end
end

def pick_expiry(expires_at, expires_in)
  if expires_at
    expires_at.utc.iso8601(3)
  elsif expires_in
    Time.now.utc.advance(seconds: expires_in).iso8601(3)
  end
end

def verify(message, purpose)
  extract_metadata(message).verify(purpose)
end

def verify(purpose)
  @message if match?(purpose) && fresh?
end

def wrap(message, expires_at: nil, expires_in: nil, purpose: nil)
  if expires_at || expires_in || purpose
    JSON.encode new(encode(message), pick_expiry(expires_at, expires_in), purpose)
  else
    message
  end
end