require 'cgi'
require 'mime/types'

# Takes a hash of string and file parameters and returns a string of text
# formatted to be sent as a multipart form post.
#
# Author:: Cody Brimhall <mailto:cbrimhall@ucdavis.edu>
# Created:: 22 Feb 2008
module Itrp
  module Multipart
    VERSION = "1.0.0" unless const_defined?(:VERSION)

    # Formats a given hash as a multipart form post
    # If a hash value responds to :string or :read messages, then it is
    # interpreted as a file and processed accordingly; otherwise, it is assumed
    # to be a string
    class Post
      # We have to pretend like we're a web browser...
      USERAGENT = "Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en-us) AppleWebKit/523.10.6 (KHTML, like Gecko) Version/3.0.4 Safari/523.10.6" unless const_defined?(:USERAGENT)
      BOUNDARY = "0123456789ABLEWASIEREISAWELBA9876543210" unless const_defined?(:BOUNDARY)
      CONTENT_TYPE = "multipart/form-data; boundary=#{ BOUNDARY }" unless const_defined?(:CONTENT_TYPE)
      HEADER = { "Content-Type" => CONTENT_TYPE, "User-Agent" => USERAGENT } unless const_defined?(:HEADER)

      def self.prepare_query(params)
        fp = []

        params.each do |k, v|
          if v.respond_to?(:path) && v.respond_to?(:read)
            fp.push(FileParam.new(k, v.path, v.read))
          else
            fp.push(StringParam.new(k, v))
          end
        end

        # Assemble the request body using the special multipart format
        query = fp.map{ |p| "--#{BOUNDARY}\r\n#{p.to_multipart}" }.join  + "--#{BOUNDARY}--"
        return query, HEADER
      end
    end

    private

    # Formats a basic string key/value pair for inclusion with a multipart post
    class StringParam
      attr_accessor :k, :v

      def initialize(k, v)
        @k = k
        @v = v
      end

      def to_multipart
        return %(Content-Disposition: form-data; name="#{CGI::escape(k.to_s)}"\r\n\r\n#{v}\r\n)
      end
    end

    # Formats the contents of a file or string for inclusion with a multipart
    # form post
    class FileParam
      attr_accessor :k, :filename, :content

      def initialize(k, filename, content)
        @k = k
        @filename = filename
        @content = content
      end

      def to_multipart
        # If we can tell the possible mime-type from the filename, use the first in the list; otherwise, use "application/octet-stream"
        mime_type = MIME::Types.type_for(filename)[0] || MIME::Types["application/octet-stream"][0]
        return %(Content-Disposition: form-data; name="#{CGI::escape(k.to_s)}"; filename="#{filename}"\r\nContent-Type: #{ mime_type.simplified }\r\n\r\n#{ content }\r\n)
      end
    end
  end
end