class Mail::ContentTypeField

def attempt_to_clean
  # Sanitize the value, handle special cases
  Mail::ContentTypeElement.new(sanitize(value))
rescue Mail::Field::ParseError
  # All else fails, just get the MIME media type
  Mail::ContentTypeElement.new(get_mime_type(value))
end

def decoded
  p = "; #{parameters.decoded}" if parameters && parameters.length > 0
  "#{content_type}#{p}"
end

def default
  decoded
end

def element
  @element ||=
    begin
      Mail::ContentTypeElement.new(value)
    rescue Mail::Field::ParseError
      attempt_to_clean
    end
end

def encoded
  p = ";\r\n\s#{parameters.encoded}" if parameters && parameters.length > 0
  "#{name}: #{content_type}#{p}\r\n"
end

def filename
  @filename ||= parameters['filename'] || parameters['name']
end

def generate_boundary
  "--==_mimepart_#{Mail.random_tag}"
end

def get_mime_type(val)
  case val
  when /^([\w\-]+)\/([\w\-]+);.+$/i
    "#{$1}/#{$2}"
  else
    'text/plain'
  end
end

def initialize(value = nil, charset = nil)
  if value.is_a? Array
    @main_type = value[0]
    @sub_type = value[1]
    @parameters = ParameterHash.new.merge!(value.last)
  else
    @main_type = nil
    @sub_type = nil
    value = value.to_s
  end
  super ensure_filename_quoted(value), charset
end

def main_type
  @main_type ||= element.main_type
end

def method_missing(name, *args, &block)
  if name.to_s =~ /(\w+)=/
    self.parameters[$1] = args.first
    @value = "#{content_type}; #{stringify(parameters)}"
  else
    super
  end
end

def parameters
  unless defined? @parameters
    @parameters = ParameterHash.new
    element.parameters.each { |p| @parameters.merge!(p) }
  end
  @parameters
end

def sanitize(val)
  # TODO: check if there are cases where whitespace is not a separator
  val = val.
    gsub(/\s*=\s*/,'='). # remove whitespaces around equal sign
    gsub(/[; ]+/, '; '). #use '; ' as a separator (or EOL)
    gsub(/;\s*$/,'') #remove trailing to keep examples below
  if val =~ /((boundary|name|filename)=(\S*))/i
    val = "#{$`.downcase}#{$2}=#{$3}#{$'.downcase}"
  else
    val.downcase!
  end
  case
  when val.chomp =~ /^\s*([\w\-]+)\/([\w\-]+)\s*;\s?(ISO[\w\-]+)$/i
    # Microsoft helper:
    # Handles 'type/subtype;ISO-8559-1'
    "#{$1}/#{$2}; charset=#{Utilities.quote_atom($3)}"
  when val.chomp =~ /^text;?$/i
    # Handles 'text;' and 'text'
    "text/plain;"
  when val.chomp =~ /^(\w+);\s(.*)$/i
    # Handles 'text; <parameters>'
    "text/plain; #{$2}"
  when val =~ /([\w\-]+\/[\w\-]+);\scharset="charset="(\w+)""/i
    # Handles text/html; charset="charset="GB2312""
    "#{$1}; charset=#{Utilities.quote_atom($2)}"
  when val =~ /([\w\-]+\/[\w\-]+);\s+(.*)/i
    type = $1
    # Handles misquoted param values
    # e.g: application/octet-stream; name=archiveshelp1[1].htm
    # and: audio/x-midi;\r\n\sname=Part .exe
    params = $2.to_s.split(/\s+/)
    params = params.map { |i| i.to_s.chomp.strip }
    params = params.map { |i| i.split(/\s*\=\s*/, 2) }
    params = params.map { |i| "#{i[0]}=#{Utilities.dquote(i[1].to_s.gsub(/;$/,""))}" }.join('; ')
    "#{type}; #{params}"
  when val =~ /^\s*$/
    'text/plain'
  else
    val
  end
end

def singular?
  true
end

def string
  "#{main_type}/#{sub_type}"
end

def stringify(params)
  params.map { |k,v| "#{k}=#{Encodings.param_encode(v)}" }.join("; ")
end

def sub_type
  @sub_type ||= element.sub_type
end

def value
  if @value.is_a? Array
    "#{@main_type}/#{@sub_type}; #{stringify(parameters)}"
  else
    @value
  end
end

def with_boundary(type)
  new "#{type}; boundary=#{generate_boundary}"
end