class Aws::Rest::Request::Headers

def apply(http_req, params)
  @rules.shape.members.each do |name, ref|
    value = params[name]
    next if value.nil?
    case ref.location
    when 'header' then apply_header_value(http_req.headers, ref, value)
    when 'headers' then apply_header_map(http_req.headers, ref, value)
    end
  end
end

def apply_header_map(headers, ref, values)
  prefix = ref.location_name || ''
  values.each_pair do |name, value|
    headers["#{prefix}#{name}"] = value.to_s
  end
end

def apply_header_value(headers, ref, value)
  value = apply_json_trait(value) if ref['jsonvalue']
  case ref.shape
  when TimestampShape then headers[ref.location_name] = timestamp(ref, value)
  when ListShape then list(headers, ref, value)
  else headers[ref.location_name] = value.to_s
  end
end

def apply_json_trait(value)
  Base64.strict_encode64(value)
end

def escape_header_list_string(s)
  (s.include?('"') || s.include?(",")) ? "\"#{s.gsub('"', '\"')}\"" : s
end

def initialize(rules)
  @rules = rules
end

def list(headers, ref, value)
  return if !value || value.empty?
  headers[ref.location_name] = value
    .compact
    .map { |s| escape_header_list_string(s.to_s) }
    .join(",")
end

def timestamp(ref, value)
  case ref['timestampFormat'] || ref.shape['timestampFormat']
  when 'unixTimestamp' then value.to_i
  when 'iso8601' then value.utc.iso8601
  else
    # header default to rfc822
    value.utc.httpdate
  end
end