grokify / mime-builder-ruby

require 'mime/types'

module MIMEBuilder

  class Filepath

    attr_accessor :mime

    attr_accessor :filepath

    # {:base64_encode bool, :content_type string, :content_id_disable bool}

    def initialize(filepath, opts={})

      if opts.key?(:base64_encode) && opts[:base64_encode]

        @base64_encode = true

      else

        @base64_encode = false

      end

      @mime = create_mime(filepath, opts[:content_id_disable])

      @mime.headers.set(

        'Content-Type',

        get_file_content_type(filepath, opts[:content_type])

      )

      set_attachment_content_disposition(opts[:is_attachment])

    end

    def create_mime(filepath, content_id_disable)

      bytes = read_file_bytes(filepath)

      mime = nil

      if @base64_encode

        mime = MIME::Text.new(Base64.encode64(bytes))

        mime.headers.set('Content-Transfer-Encoding', 'base64')

      else

        mime = MIME::Application.new(bytes)

      end

      mime.headers.delete('Content-Id') if content_id_disable

      return mime

    end

    def read_file_bytes(filepath=nil)

      unless File.file?(filepath.to_s)

        raise "File \"#{filepath.to_s}\" does not exist or cannot be read"

      end

      file_bytes = File.open(filepath, 'rb:BINARY') { |f| f.read }

      return file_bytes

    end

    def get_file_content_type(filepath=nil, content_type=nil)

      if content_type.is_a?(String) && content_type =~ %r{^[^/\s]+/[^/\s]+}

        return content_type

      end

      return MIME::Types.type_for(filepath).first.content_type \

        || 'application/octet-stream'

    end

    def get_attachment_content_disposition(filepath=nil)

      filename = File.basename(filepath.to_s)

      if filename.is_a?(String) && filename.length > 0

        return "attachment; filename=\"#{filename}\""

      end

      return 'attachment'

    end

  end

end