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 29

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 25

def migration_id_converter
  @migration_id_converter
end

Instance Method Details

#attachment_path_id_lookup_lower ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 43

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 156

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

#media_attachment_iframe_url(file_id, media_type = nil) ⇒ Object 



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

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

#media_iframe_url(media_id, media_type = nil) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 216

def media_iframe_url(media_id, media_type = nil)
  url = "/media_objects_iframe/#{media_id}"
  url += "?type=#{media_type}" if media_type.present?
  url
end

#missing_relative_file_url(rel_path) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 151

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) ⇒ Object

finds the :new_value to use to replace the placeholder



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

def resolve_link!(link)
  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 = @migration_id_converter.convert_attachment_migration_id(migration_id)
      if att_id
        link[:new_value] = "#{context_path}/files/#{att_id}/preview"
      end
    elsif type == "media_attachments_iframe"
      att_id = @migration_id_converter.convert_attachment_migration_id(migration_id)
      link[:new_value] = att_id ? "/media_attachments_iframe/#{att_id}#{link[:query]}" : link[:old_value]
    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]
    node = Nokogiri::HTML5.fragment(link[:old_value]).children.first
    new_url = resolve_media_comment_data(node, rel_path, link[:media_attachment])
    new_url ||= resolve_relative_file_url(rel_path)

    unless new_url
      new_url ||= missing_relative_file_url(rel_path)
      link[:missing_url] = new_url
    end
    if ["iframe", "source"].include?(node.name)
      node["src"] = new_url
    else
      node["href"] = new_url
    end
    link[:new_value] = node.to_s
  when :file
    rel_path = link[:rel_path]
    new_url = resolve_relative_file_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 = @migration_id_converter.convert_attachment_migration_id(link[:migration_id])
    if file_id
      rest = link[:rest].presence || "/preview"

      # 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
      if rest.include?("icon_maker_icon=1")
        link[:new_value] = "/files/#{file_id}#{rest}"
      elsif link[:in_media_iframe] && link[:media_attachment]
        link[:new_value] = "/media_attachments_iframe/#{file_id}#{rest}"
      else
        link[:new_value] = "#{context_path}/files/#{file_id}#{rest}"
        link[:new_value] = "/media_objects_iframe?mediahref=#{link[:new_value]}" if link[:in_media_iframe]
      end
    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 33

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_comment_data(node, rel_path, media_attachment) ⇒ Object 



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# File 'lib/canvas_link_migrator/link_resolver.rb', line 228

def resolve_media_comment_data(node, rel_path, media_attachment)
  if (file = find_file_in_context(rel_path[/^[^?]+/])) # strip query string for this search
    media_id = file.try(:media_object)&.media_id || file["media_entry_id"]
    if media_id && media_id != "maybe"
      if ["iframe", "source"].include?(node.name)
        node["data-media-id"] = media_id
        if media_attachment
          return media_attachment_iframe_url(file["id"], node["data-media-type"])
        else
          return media_iframe_url(media_id, node["data-media-type"])
        end
      else
        node["id"] = "media_comment_#{media_id}"
        return "/media_objects/#{media_id}"
      end
    end
  end

  if node["id"] && node["id"] =~ /\Amedia_comment_(.+)\z/
    "/media_objects/#{$1}"
  elsif node["data-media-id"].present?
    media_iframe_url(node["data-media-id"], node["data-media-type"])
  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 139

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 174

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 185

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 = []
      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 += "?#{qs.join("&")}" if qs.present?
    end
    rel_path_parts.shift
  end
  new_url
end