Class: CanvasLinkMigrator::LinkParser

Inherits:
Object
  • Object
show all
Defined in:
lib/canvas_link_migrator/link_parser.rb

Constant Summary collapse

REFERENCE_KEYWORDS = 
%w[CANVAS_COURSE_REFERENCE CANVAS_OBJECT_REFERENCE WIKI_REFERENCE IMS_CC_FILEBASE IMS-CC-FILEBASE].freeze
"LINK.PLACEHOLDER"
KNOWN_REFERENCE_TYPES = 
%w[
  announcements
  appointment_participants
  assignment_groups
  assignments
  attachments
  calendar_events
  context_external_tools
  context_module_tags
  context_modules
  course_paces
  created_learning_outcomes
  discussion_entries
  discussion_topics
  external_feeds
  grading_standards
  groups
  learning_outcome_groups
  learning_outcome_links
  learning_outcomes
  linked_learning_outcomes
  media_attachments_iframe
  modules
  pages
  quizzes
  rubrics
  wiki
  wiki_pages
].freeze
CONTAINER_TYPES = 
%w[div p body].freeze
%w[rel href src srcset data value longdesc data-download-url].freeze
RCE_MEDIA_TYPES = 
%w[audio video].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(migration_query_service) ⇒ LinkParser

Returns a new instance of LinkParser.



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# File 'lib/canvas_link_migrator/link_parser.rb', line 62

def initialize(migration_query_service)
  @migration_query_service = migration_query_service
  reset!
end

Instance Attribute Details

#migration_query_service ⇒ Object (readonly)

Returns the value of attribute migration_query_service.



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# File 'lib/canvas_link_migrator/link_parser.rb', line 60

def migration_query_service
  @migration_query_service
end

#unresolved_link_map ⇒ Object (readonly)

Returns the value of attribute unresolved_link_map.



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# File 'lib/canvas_link_migrator/link_parser.rb', line 60

def unresolved_link_map
  @unresolved_link_map
end

Instance Method Details



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# File 'lib/canvas_link_migrator/link_parser.rb', line 71

def add_unresolved_link(link, item_type, mig_id, field)
  key = { type: item_type, migration_id: mig_id }
  @unresolved_link_map[key] ||= {}
  @unresolved_link_map[key][field] ||= []
  @unresolved_link_map[key][field] << link
end

#convert(html, item_type, mig_id, field, remove_outer_nodes_if_one_child: nil) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 82

def convert(html, item_type, mig_id, field, remove_outer_nodes_if_one_child: nil)
  mig_id = mig_id.to_s
  doc = Nokogiri::HTML5.fragment(html || "", max_tree_depth: 10_000)

  # Replace source tags with iframes
  doc.search("source[data-media-type],source[data-media-id]").each do |source|
    next unless RCE_MEDIA_TYPES.include?(source.parent.name)

    media_node = source.parent
    media_node.name = "iframe"
    media_node["src"] = source["src"]
    source.remove
  end

  # Replace old style media anchor tags with iframes
  doc.search("a[id*='media_comment_']").each do |media_node|
    next unless media_node["class"].match('instructure_inline_media_comment')

    media_node.name = "iframe"
    # smallest accepted size for iframe since we don't have the size available for these
    media_node["style"] = "width: 320px; height: 240px; display: inline-block;"
    media_node["title"] = media_node.text
    media_node.child&.remove
    media_type = media_node["class"].match(/(audio|video)/)&.[](1)
    media_node["data-media-type"] = media_type if media_type
    media_node["src"] = media_node["href"]
    media_node.delete("href")
    media_node["allowfullscreen"] = "allowfullscreen"
    media_node["allow"] = "fullscreen"
    media_node["data-media-id"] = media_node["id"].sub("media_comment_", "")
  end

  doc.search("*").each do |node|
    LINK_ATTRS.each do |attr|
      convert_link(node, attr, item_type, mig_id, field)
    end
  end

  if remove_outer_nodes_if_one_child
    while doc.children.size == 1 && doc.child.child
      break unless CONTAINER_TYPES.member?(doc.child.name) && doc.child.attributes.blank?

      doc = doc.child
    end
  end

  doc.inner_html
rescue Nokogiri::SyntaxError
  ""
end

#convert_link(node, attr, item_type, mig_id, field) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 133

def convert_link(node, attr, item_type, mig_id, field)
  return unless node[attr].present?

  if attr == "value" &&
     !(node[attr] =~ /IMS(?:-|_)CC(?:-|_)FILEBASE/ || node[attr].include?("CANVAS_COURSE_REFERENCE"))
    return
  end

  url = node[attr].dup
  REFERENCE_KEYWORDS.each do |ref|
    url.gsub!("%24#{ref}%24", "$#{ref}$")
  end

  result = parse_url(url, node, attr)
  handle_parsed_url(url, result, node, attr, item_type, mig_id, field)
end

#handle_parsed_url(url, result, node, attr, item_type, mig_id, field) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 150

def handle_parsed_url(url, result, node, attr, item_type, mig_id, field)
  if result[:resolved]
    # resolved, just replace and carry on
    handle_resolved_link(url, result, node, attr)
  else
    handle_unresolved_link(url, result, node, attr, item_type, mig_id, field)
  end
end

#handle_resolved_link(url, result, node, attr) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 183

def handle_resolved_link(url, result, node, attr)
  new_url = result[:new_url] || url
  unless CanvasLinkMigrator.relative_url?(new_url)
    # perform configured substitutions
    if (processed_url = @migration_query_service.process_domain_substitutions(new_url))
      new_url = processed_url
    end
    # relative-ize absolute links outside the course but inside our domain
    # (analogous to what is done in Api#process_incoming_html_content)
    begin
      uri = URI.parse(new_url)
       = @migration_query_service.context_hosts.map { |h| h.split(":").first }
      if .include?(uri.host)
        uri.scheme = uri.host = uri.port = nil
        new_url = uri.to_s
      end
    rescue URI::InvalidURIError, URI::InvalidComponentError
      nil
    end
  end
  node[attr] = new_url
end

#handle_unresolved_link(url, result, node, attr, item_type, mig_id, field) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 159

def handle_unresolved_link(url, result, node, attr, item_type, mig_id, field)
  result.delete(:resolved)
  if result[:link_type] == :media_object
    # because we may actually change the media comment node itself
    # (rather than just replacing a value), we're going to
    # replace the entire node with a placeholder
    result[:old_value] = node ? node.to_xml : result[:rel_path]

    result[:placeholder] = placeholder(result[:old_value])
    placeholder_node = Nokogiri::HTML5.fragment(result[:placeholder])

    node.replace(placeholder_node) if node
  else
    result[:old_value] = node ? node[attr] : url
    result[:placeholder] = placeholder(result[:old_value])
    # replace the inner html of an anchor tag if it matches the href
    if node && node.name == "a" && attr == "href" && node["href"] == node.inner_html.delete("\n").strip
      node.inner_html = result[:placeholder]
    end
    node[attr] = result[:placeholder] if node
  end
  add_unresolved_link(result, item_type, mig_id, field)
end

#media_params(type) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 214

def media_params(type)
  "?type=#{type}&embedded=true"
end

#parse_single_url(url, link_type = nil) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 218

def parse_single_url(url, link_type = nil)
  parse_url(url, nil, nil, link_type)
end

#parse_url(url, node, attr, link_type = nil) ⇒ Object

returns a hash with resolution status and data to hold onto if unresolved



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# File 'lib/canvas_link_migrator/link_parser.rb', line 222

def parse_url(url, node, attr, link_type = nil)
  if url =~ /wiki_page_migration_id=(.*)/
    unresolved(:wiki_page, migration_id: $1)
  elsif url =~ /discussion_topic_migration_id=(.*)/
    unresolved(:discussion_topic, migration_id: $1)
  elsif url =~ %r{\$CANVAS_COURSE_REFERENCE\$/modules/items/([^?]*)(\?.*)?}
    unresolved(:module_item, migration_id: $1, query: $2)
  elsif url =~ %r{\$CANVAS_COURSE_REFERENCE\$/file_ref/([^/?#]+)(.*)}
    in_media_iframe = node && (attr == "src" && %w[iframe source].include?(node.name) && (node["data-media-id"] || node["data-media-type"]))
    rest = (in_media_iframe && node) ? media_params(node["data-media-type"]) : $2
    unresolved(:file_ref,
               migration_id: $1,
               rest: rest,
               in_media_iframe: in_media_iframe,
               target_blank: node && node['target'] == "_blank" && node.name == "a" && attr == "href"
    )
  elsif url =~ %r{(?:\$CANVAS_OBJECT_REFERENCE\$|\$WIKI_REFERENCE\$)/([^/]*)/([^?]*)(\?.*)?}
    if KNOWN_REFERENCE_TYPES.include?($1)
      unresolved(:object, type: $1, migration_id: $2, query: $3)
    else
      # If the `type` is not known, there's something amiss...
      @migration_query_service.report_link_parse_warning($1)
      resolved(url)
    end
  elsif url =~ %r{\$CANVAS_COURSE_REFERENCE\$/(.*)}
    resolved("#{@migration_query_service.context_path}/#{$1}")
  elsif url =~ %r{\$IMS(?:-|_)CC(?:-|_)FILEBASE\$/(.*)}
    rel_path = URI::DEFAULT_PARSER.unescape($1)

    if (attr == "href" && node && node["class"]&.include?("instructure_inline_media_comment")) ||
       (attr == "src" && node && %w[iframe source].include?(node.name) && (node["data-media-id"] || node["data-media-type"])) ||
      link_type == :media_object
      unresolved(:media_object, rel_path: rel_path)
    else
      unresolved(:file, rel_path: rel_path)
    end
  elsif (attr == "src" && node && %w[iframe source].include?(node.name) && (node["data-media-id"] || node["data-media-type"])) ||
    link_type == :media_object
    # media_objects_iframe course copy reference without an attachment id, change to media_attachments_iframe
    rel_path =  node ? node["src"] : url
    unresolved(:media_object, rel_path: rel_path)
  elsif (@migration_query_service.supports_embedded_images && attr == "src" && (info_match = url.match(%r{\Adata:(?<mime_type>[-\w]+/[-\w+.]+)?;base64,(?<image>.*)}m))) ||
    link_type == :image
    result = @migration_query_service.link_embedded_image(info_match)
    if result[:resolved]
      resolved(result[:url])
    else
      unresolved(:file, rel_path: result[:url])
    end
  elsif # rubocop:disable Lint/DuplicateBranch
        # Equation image, leave it alone
        (attr == "src" && node && node["class"] && node["class"].include?("equation_image")) || # rubocop:disable Layout/ConditionPosition
        # The file is in the context of an AQ, leave the link alone
        url =~ %r{\A/assessment_questions/\d+/files/\d+} ||
        # This points to a specific file already, leave it alone
        url =~ %r{\A/courses/\d+/files/\d+} ||
        !@migration_query_service.fix_relative_urls? ||
        # It's just a link to an anchor, leave it alone
        url.start_with?("#")
    resolved
  elsif CanvasLinkMigrator.relative_url?(url)
    unresolved(:file, rel_path: URI::DEFAULT_PARSER.unescape(url))
  else # rubocop:disable Lint/DuplicateBranch
    resolved
  end
end

#placeholder(old_value) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 78

def placeholder(old_value)
  "#{LINK_PLACEHOLDER}_#{Digest::MD5.hexdigest(old_value)}"
end

#reset! ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 67

def reset!
  @unresolved_link_map = {}
end

#resolved(new_url = nil) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 210

def resolved(new_url = nil)
  { resolved: true, new_url: new_url}
end

#unresolved(type, data = {}) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_parser.rb', line 206

def unresolved(type, data = {})
  { resolved: false, link_type: type }.merge(data)
end