Class: CanvasLinkMigrator::LinkResolver

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(migration_id_converter) ⇒ LinkResolver

Returns a new instance of LinkResolver.



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 30

def initialize(migration_id_converter)
  @migration_id_converter = migration_id_converter
end

Instance Attribute Details

#migration_id_converter ⇒ Object

Returns the value of attribute migration_id_converter.



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 26

def migration_id_converter
  @migration_id_converter
end

Instance Method Details

#add_verifier_to_query(url, uuid) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 48

def add_verifier_to_query(url, uuid)
  parsed_url = Addressable::URI.parse(url)
  parsed_url.query_values = (parsed_url.query_values || {}).merge("verifier" => uuid)
  parsed_url.to_s
rescue Addressable::InvalidURIError
  url
end

#attachment_path_id_lookup_lower ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 44

def attachment_path_id_lookup_lower
  @attachment_path_id_lookup_lower ||= attachment_path_id_lookup&.transform_keys(&:downcase)
end

#find_file_in_context(rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 176

def find_file_in_context(rel_path)
  mig_id = nil
  # This is for backward-compatibility: canvas attachment filenames are escaped
  # with '+' for spaces and older exports have files with that instead of %20
  alt_rel_path = rel_path.tr("+", " ")
  if attachment_path_id_lookup
    mig_id ||= attachment_path_id_lookup[rel_path]
    mig_id ||= attachment_path_id_lookup[alt_rel_path]
  end
  if !mig_id && attachment_path_id_lookup_lower
    mig_id ||= attachment_path_id_lookup_lower[rel_path.downcase]
    mig_id ||= attachment_path_id_lookup_lower[alt_rel_path.downcase]
  end

  # This md5 comparison is here to handle faulty cartridges with the migration_id equivalent of an empty string
  mig_id && mig_id != "gd41d8cd98f00b204e9800998ecf8427e" && @migration_id_converter.lookup_attachment_by_migration_id(mig_id)
end

#is_relative_user_url(rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 268

def is_relative_user_url(rel_path)
  rel_path.start_with?("/users/")
end

#media_attachment_iframe_url(file_id, uuid = nil, media_type = nil) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 238

def media_attachment_iframe_url(file_id, uuid = nil, media_type = nil)
  url = "/media_attachments_iframe/#{file_id}?embedded=true"
  url += "&type=#{media_type}" if media_type.present?
  url += "&verifier=#{uuid}" if uuid.present?
  url
end

#missing_relative_file_url(rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 171

def missing_relative_file_url(rel_path)
  # the rel_path should already be escaped
  File.join(URI::DEFAULT_PARSER.escape("#{context_path}/file_contents/#{@migration_id_converter.root_folder_name}"), rel_path.gsub(" ", "%20"))
end

#resolve_link!(link, preset_type = false) ⇒ Object

finds the :new_value to use to replace the placeholder



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 57

def resolve_link!(link, preset_type = false)
  link[:link_type] = preset_type if preset_type
  case link[:link_type]
  when :wiki_page
    if (linked_wiki_url = @migration_id_converter.convert_wiki_page_migration_id_to_slug(link[:migration_id]))
      link[:new_value] = "#{context_path}/pages/#{linked_wiki_url}#{link[:query]}"
    end
  when :discussion_topic
    if (linked_topic_id = @migration_id_converter.convert_discussion_topic_migration_id(link[:migration_id]))
      link[:new_value] = "#{context_path}/discussion_topics/#{linked_topic_id}#{link[:query]}"
    end
  when :module_item
    if (tag_id = @migration_id_converter.convert_context_module_tag_migration_id(link[:migration_id]))
      link[:new_value] = "#{context_path}/modules/items/#{tag_id}#{link[:query]}"
    end
  when :object
    type = link[:type]
    migration_id = link[:migration_id]

    type_for_url = type
    type = "context_modules" if type == "modules"
    type = "pages" if type == "wiki"
    if type == "pages"
      query = resolve_module_item_query(nil, link[:query])
      linked_wiki_url = @migration_id_converter.convert_wiki_page_migration_id_to_slug(migration_id) || migration_id
      link[:new_value] = "#{context_path}/pages/#{linked_wiki_url}#{query}"
    elsif type == "attachments"
      att_id, uuid = @migration_id_converter.convert_attachment_migration_id(migration_id)
      if att_id
        new_url = "#{context_path}/files/#{att_id}/preview"
        new_url = add_verifier_to_query(new_url, uuid) if uuid
        link[:new_value] = new_url
      end
    elsif type == "media_attachments_iframe"
      att_id, uuid = @migration_id_converter.convert_attachment_migration_id(migration_id)
      new_url = att_id ? "/media_attachments_iframe/#{att_id}#{link[:query]}" : link[:old_value]
      new_url = add_verifier_to_query(new_url, uuid) if uuid
      link[:new_value] = new_url
    else
      object_id = @migration_id_converter.convert_migration_id(type, migration_id)
      if object_id
        query = resolve_module_item_query(nil, link[:query])
        link[:new_value] = "#{context_path}/#{type_for_url}/#{object_id}#{query}"
      end
    end
  when :media_object
    # because we actually might change the node itself
    # this part is a little trickier
    # tl;dr we've replaced the entire node with the placeholder
    # see LinkParser for details
    rel_path = link[:rel_path] || link[:old_value]
    node = Nokogiri::HTML5.fragment(link[:old_value]).children.first
    new_url = resolve_media_data(node, rel_path)
    new_url ||= resolve_relative_file_url(rel_path)

    unless new_url
      new_url = rel_path.include?("#{context_path}/file_contents") ? rel_path : missing_relative_file_url(rel_path)
      link[:missing_url] = new_url
    end
    if %w[iframe source].include?(node.name)
      node["src"] = new_url
    else
      node["href"] = new_url
    end
    link[:new_value] = node.name === 'text' ? new_url : node.to_s
  when :file
    rel_path = link[:rel_path] || link[:old_value]
    new_url = resolve_relative_file_url(rel_path)
    # leave user urls alone
    new_url ||= rel_path if is_relative_user_url(rel_path)
    unless new_url
      new_url = missing_relative_file_url(rel_path)
      link[:missing_url] = new_url
    end
    link[:new_value] = new_url
  when :file_ref
    file_id, uuid = @migration_id_converter.convert_attachment_migration_id(link[:migration_id])
    if file_id
      rest = link[:rest].presence
      rest ||= "/preview" unless link[:target_blank]

      # Icon Maker files should not have the course
      # context prepended to the URL. This prevents
      # redirects to non cross-origin friendly urls
      # during a file fetch
      new_url = if rest&.include?("icon_maker_icon=1")
                  "/files/#{file_id}#{rest}"
                elsif link[:in_media_iframe]
                  "/media_attachments_iframe/#{file_id}#{rest}"
                else
                  "#{context_path}/files/#{file_id}#{rest}"
                end
      new_url = add_verifier_to_query(new_url, uuid) if uuid
      link[:new_value] = new_url
    else
      link[:missing_url] = link[:old_value].partition("$CANVAS_COURSE_REFERENCE$").last
    end
  else
    raise "unrecognized link_type (#{link[:link_type]}) in unresolved link"
  end
end

#resolve_links!(link_map) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 34

def resolve_links!(link_map)
  link_map.each_value do |field_links|
    field_links.each_value do |links|
      links.each do |link|
        resolve_link!(link)
      end
    end
  end
end

#resolve_media_data(node, rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 245

def resolve_media_data(node, rel_path)
  if rel_path && (file = find_file_in_context(rel_path[/^[^?]+/])) # strip query string for this search
    media_id = file["media_entry_id"]
    node["data-media-id"] = media_id # safe to delete?
    media_attachment_iframe_url(file["id"], file["uuid"], node["data-media-type"])
  elsif rel_path&.match(/\/media_attachments_iframe\/\d+/)
    # media attachment from another course or something
    rel_path
  elsif node["data-media-id"] && (file_id, uuid = @migration_id_converter.convert_attachment_media_id(node["data-media-id"]))
    file_id ? media_attachment_iframe_url(file_id, uuid, node["data-media-type"]) : nil
  elsif (identifier = rel_path.match(/media_objects(?:_iframe)?\/([^?.]+)/)) && (file_id, uuid = @migration_id_converter.convert_attachment_media_id(identifier.[](1)))
    file_id ? media_attachment_iframe_url(file_id, uuid, node["data-media-type"]) : nil
  elsif node.name == "text" && rel_path[/^[^?]+/] && (mig_id = rel_path[/^[^?]+/].match(/[^\/]+$/)[0])
    file = @migration_id_converter.lookup_attachment_by_migration_id(mig_id)
    media_attachment_iframe_url(file["id"], file["uuid"])
  else
    node.delete("class")
    node.delete("id")
    node.delete("style")
    nil
  end
end

#resolve_module_item_query(_context, query) ⇒ Object 



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

def resolve_module_item_query(_context, query)
  return query unless query&.include?("module_item_id=")

  original_param = query.sub("?", "").split("&").detect { |p| p.include?("module_item_id=") }
  mig_id = original_param.split("=").last
  tag_id = @migration_id_converter.convert_context_module_tag_migration_id(mig_id)
  return query unless tag_id

  new_param = "module_item_id=#{tag_id}"
  query.sub(original_param, new_param)
end

#resolve_relative_file_url(rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 194

def resolve_relative_file_url(rel_path)
  split = rel_path.split("?")
  qs = split.pop if split.length > 1
  path = split.join("?")

  # since we can't be sure whether a ? is part of a filename or query string, try it both ways
  new_url = resolve_relative_file_url_with_qs(path, qs)
  new_url ||= resolve_relative_file_url_with_qs(rel_path, "") if qs.present?
  new_url
end

#resolve_relative_file_url_with_qs(rel_path, qs) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 205

def resolve_relative_file_url_with_qs(rel_path, qs)
  new_url = nil
  rel_path_parts = Pathname.new(rel_path).each_filename.to_a

  # e.g. start with "a/b/c.txt" then try "b/c.txt" then try "c.txt"
  while new_url.nil? && !rel_path_parts.empty?
    sub_path = File.join(rel_path_parts)
    if (file = find_file_in_context(sub_path))
      new_url = "#{context_path}/files/#{file["id"]}"
      # support other params in the query string, that were exported from the
      # original path components and query string. see
      # CCHelper::file_query_string
      params = Rack::Utils.parse_nested_query(qs.presence || "")
      qs = []
      qs << "verifier=#{file["uuid"]}" if file["uuid"].present?
      new_action = ""
      params.each do |k, v|
        case k
        when /canvas_qs_(.*)/
          qs << "#{Rack::Utils.escape($1)}=#{Rack::Utils.escape(v)}"
        when /canvas_(.*)/
          new_action += "/#{$1}"
        end
      end
      new_url += new_action.presence || "/preview"
      new_url.chomp!("/")
      new_url += "?#{qs.join("&")}" if qs.present?
    end
    rel_path_parts.shift
  end
  new_url
end