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

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 is 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-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
