#--
# Copyright (c) 2007-2013 Nick Sieger.
# See the file README.txt included with the distribution for
# software license details.
#++

module Datadog
  module Vendor
    module Multipart
      module Post
        module Parts
          module Part
            def self.new(boundary, name, value, headers = {})
              headers ||= {} # avoid nil values
              if file?(value)
                FilePart.new(boundary, name, value, headers)
              else
                ParamPart.new(boundary, name, value, headers)
              end
            end

            def self.file?(value)
              value.respond_to?(:content_type) && value.respond_to?(:original_filename)
            end

            def length
              @part.length
            end

            def to_io
              @io
            end
          end

          # Represents a parametric part to be filled with given value.
          class ParamPart
            include Part

            # @param boundary [String]
            # @param name [#to_s]
            # @param value [String]
            # @param headers [Hash] Content-Type and Content-ID are used, if present.
            def initialize(boundary, name, value, headers = {})
              @part = build_part(boundary, name, value, headers)
              @io = StringIO.new(@part)
            end

            def length
              @part.bytesize
            end

            # @param boundary [String]
            # @param name [#to_s]
            # @param value [String]
            # @param headers [Hash] Content-Type is used, if present.
            def build_part(boundary, name, value, headers = {})
              part = ''
              part << "--#{boundary}\r\n"
              part << "Content-ID: #{headers["Content-ID"]}\r\n" if headers["Content-ID"]
              part << "Content-Disposition: form-data; name=\"#{name.to_s}\"\r\n"
              part << "Content-Type: #{headers["Content-Type"]}\r\n" if headers["Content-Type"]
              part << "\r\n"
              part << "#{value}\r\n"
            end
          end

          # Represents a part to be filled from file IO.
          class FilePart
            include Part

            attr_reader :length

            # @param boundary [String]
            # @param name [#to_s]
            # @param io [IO]
            # @param headers [Hash]
            def initialize(boundary, name, io, headers = {})
              file_length = io.respond_to?(:length) ?  io.length : File.size(io.local_path)
              @head = build_head(boundary, name, io.original_filename, io.content_type, file_length,
                                 io.respond_to?(:opts) ? io.opts.merge(headers) : headers)
              @foot = "\r\n"
              @length = @head.bytesize + file_length + @foot.length
              @io = CompositeReadIO.new(StringIO.new(@head), io, StringIO.new(@foot))
            end

            # @param boundary [String]
            # @param name [#to_s]
            # @param filename [String]
            # @param type [String]
            # @param content_len [Integer]
            # @param opts [Hash]
            def build_head(boundary, name, filename, type, content_len, opts = {})
              opts = opts.clone

              trans_encoding = opts.delete("Content-Transfer-Encoding") || "binary"
              content_disposition = opts.delete("Content-Disposition") || "form-data"

              part = ''
              part << "--#{boundary}\r\n"
              part << "Content-Disposition: #{content_disposition}; name=\"#{name.to_s}\"; filename=\"#{filename}\"\r\n"
              part << "Content-Length: #{content_len}\r\n"
              if content_id = opts.delete("Content-ID")
                part << "Content-ID: #{content_id}\r\n"
              end

              if opts["Content-Type"] != nil
                part <<  "Content-Type: " + opts["Content-Type"] + "\r\n"
              else
                part << "Content-Type: #{type}\r\n"
              end

              part << "Content-Transfer-Encoding: #{trans_encoding}\r\n"

              opts.each do |k, v|
                part << "#{k}: #{v}\r\n"
              end

              part << "\r\n"
            end
          end

          # Represents the epilogue or closing boundary.
          class EpiloguePart
            include Part

            def initialize(boundary)
              @part = "--#{boundary}--\r\n"
              @io = StringIO.new(@part)
            end
          end
        end
      end
    end
  end
end