# ~*~ encoding: utf-8 ~*~

module Aladdin

  # Encapsulate sanitization options.
  # Adapted from
  # https://github.com/github/gollum/blob/master/lib/gollum/sanitization.rb
  class Sanitize < ::Sanitize

    # white-listed elements
    ELEMENTS = [
      'a', 'abbr', 'acronym', 'address', 'area', 'b', 'big',
      'blockquote', 'br', 'button', 'caption', 'center', 'cite',
      'code', 'col', 'colgroup', 'dd', 'del', 'dfn', 'dir',
      'div', 'dl', 'dt', 'em', 'fieldset', 'font', 'form', 'h1',
      'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', 'input',
      'ins', 'kbd', 'label', 'legend', 'li', 'map', 'menu',
      'ol', 'optgroup', 'option', 'p', 'pre', 'q', 's', 'samp',
      'select', 'small', 'span', 'strike', 'strong', 'sub',
      'sup', 'table', 'tbody', 'td', 'textarea', 'tfoot', 'th',
      'thead', 'tr', 'tt', 'u', 'ul', 'var'
    ].freeze

    # white-listed attributes
    ATTRIBUTES = {
      'a'   => ['href'],
      'img' => ['src'],
      :all  => ['abbr', 'accept', 'accept-charset',
                'accesskey', 'action', 'align', 'alt', 'axis',
                'border', 'cellpadding', 'cellspacing', 'char',
                'charoff', 'class', 'charset', 'checked', 'cite',
                'clear', 'cols', 'colspan', 'color',
                'compact', 'coords', 'datetime', 'dir',
                'disabled', 'enctype', 'for', 'frame',
                'headers', 'height', 'hreflang',
                'hspace', 'id', 'ismap', 'label', 'lang',
                'longdesc', 'maxlength', 'media', 'method',
                'multiple', 'name', 'nohref', 'noshade',
                'nowrap', 'prompt', 'readonly', 'rel', 'rev',
                'rows', 'rowspan', 'rules', 'scope',
                'selected', 'shape', 'size', 'span',
                'start', 'summary', 'tabindex', 'target',
                'title', 'type', 'usemap', 'valign', 'value',
                'vspace', 'width']
    }.freeze

    # white-listed protocols
    PROTOCOLS = {
      'a'   => {'href' => ['http', 'https', 'mailto', 'ftp', 'irc', 'apt', :relative]},
      'img' => {'src'  => ['http', 'https', :relative]}
    }.freeze

    # elements to remove (incl. contents)
    REMOVE_CONTENTS = [
      'script',
      'style'
    ].freeze

    # attributes to add to elements
    ADD_ATTRIBUTES = {
      'a' => {'rel' => 'nofollow'}
    }

    # Creates a new sanitizer with Aladdin's configuration.
    def initialize
      super config
    end

    private

    # Returns a configuration hash.
    def config
      { elements:         ELEMENTS.dup,
        attributes:       ATTRIBUTES.dup,
        protocols:        PROTOCOLS.dup,
        add_attributes:   ADD_ATTRIBUTES.dup,
        remove_contents:  REMOVE_CONTENTS.dup,
        allow_comments:   false
      }
    end

  end

end