class Faraday::Request::Multipart

def call(env)
  match_content_type(env) do |params|
    env[:request] ||= {}
    env[:request][:boundary] ||= DEFAULT_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]['Content-Length'] = body.length.to_s
  return body
end

def has_multipart?(body)
  body.values.each do |val|
    if val.respond_to?(:content_type)
      return true
    elsif val.respond_to?(:values)
      return true if 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