class Faraday::Request::Multipart

def call(env)
  match_content_type(env) do |params|
    env.request.boundary ||= unique_boundary
    env.request_headers[CONTENT_TYPE] += "; boundary=#{env.request.boundary}"
    env.body = create_multipart(env, params)
  end
  @app.call env
end

def create_multipart(env, params)
  boundary = env.request.boundary
  parts = process_params(params) do |key, value|
    Faraday::Parts::Part.new(boundary, key, value)
  end
  parts << Faraday::Parts::EpiloguePart.new(boundary)
  body = Faraday::CompositeReadIO.new(parts)
  env.request_headers[Faraday::Env::ContentLength] = body.length.to_s
  return body
end

def has_multipart?(obj)
  # string is an enum in 1.8, returning list of itself
  if obj.respond_to?(:each) && !obj.is_a?(String)
    (obj.respond_to?(:values) ? obj.values : obj).each do |val|
      return true if (val.respond_to?(:content_type) || has_multipart?(val))
    end
  end
  false
end

def process_params(params, prefix = nil, pieces = nil, &block)
  params.inject(pieces || []) do |all, (key, value)|
    key = "#{prefix}[#{key}]" if prefix
    case value
    when Array
      values = value.inject([]) { |a,v| a << [nil, v] }
      process_params(values, key, all, &block)
    when Hash
      process_params(value, key, all, &block)
    else
      all << block.call(key, value)
    end
  end
end

def process_request?(env)
  type = request_type(env)
  env.body.respond_to?(:each_key) and !env.body.empty? and (
    (type.empty? and has_multipart?(env.body)) or
    type == self.class.mime_type
  )
end

def unique_boundary
  "#{DEFAULT_BOUNDARY_PREFIX}-#{SecureRandom.hex}"
end