mime_thing.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'cgi'
require 'pp'
require 'mime/types'

def mime_type(file)
  case
    when file =~ /\.jpg/ then 'image/jpg'
    when file =~ /\.gif$/ then 'image/gif'
    when file =~ /\.png$/ then 'image/png'
    else 'application/octet-stream'
  end
end

CRLF = "\r\n"
def build_multipart_bodies(*files)
  boundary = Time.now.to_i.to_s(16)
  body = ""
  files.each do |file|
    esc_key = CGI.escape("media[]")
    body << "--#{boundary}#{CRLF}"
    if file.respond_to?(:read)
      body << "Content-Disposition: form-data; name=\"#{esc_key}\"; filename=\"#{File.basename(file.path)}\"#{CRLF}"
      body << "Content-Type: #{MIME::Types.type_for(file.path).to_s}#{CRLF*2}"
      body << file.read
    else
      body << "Content-Disposition: form-data; name=\"#{esc_key}\"#{CRLF*2}#{file}"
    end
    body << CRLF
  end
  body << "--#{boundary}--#{CRLF*2}"
  {
    :body => body,
    :headers => {"Content-Type" => "multipart/form-data; boundary=#{boundary}"}
  }
end

f = File.open("tiny.jpg")
pp multipart