hometown/app/helpers/jsonld_helper.rb

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# frozen_string_literal: true
module JsonLdHelper
def equals_or_includes?(haystack, needle)
haystack.is_a?(Array) ? haystack.include?(needle) : haystack == needle
end
def equals_or_includes_any?(haystack, needles)
needles.any? { |needle| equals_or_includes?(haystack, needle) }
end
def first_of_value(value)
value.is_a?(Array) ? value.first : value
end
# The url attribute can be a string, an array of strings, or an array of objects.
# The objects could include a mimeType. Not-included mimeType means it's text/html.
def url_to_href(value, preferred_type = nil)
single_value = if value.is_a?(Array) && !value.first.is_a?(String)
value.find { |link| preferred_type.nil? || ((link['mimeType'].presence || 'text/html') == preferred_type) }
elsif value.is_a?(Array)
value.first
else
value
end
if single_value.nil? || single_value.is_a?(String)
single_value
else
single_value['href']
end
end
def as_array(value)
value.is_a?(Array) ? value : [value]
end
def value_or_id(value)
value.is_a?(String) || value.nil? ? value : value['id']
end
def supported_context?(json)
!json.nil? && equals_or_includes?(json['@context'], ActivityPub::TagManager::CONTEXT)
end
def unsupported_uri_scheme?(uri)
!uri.start_with?('http://', 'https://')
end
def canonicalize(json)
graph = RDF::Graph.new << JSON::LD::API.toRdf(json, documentLoader: method(:load_jsonld_context))
graph.dump(:normalize)
end
def fetch_resource(uri, id, on_behalf_of = nil)
unless id
json = fetch_resource_without_id_validation(uri, on_behalf_of)
return unless json
uri = json['id']
end
json = fetch_resource_without_id_validation(uri, on_behalf_of)
json.present? && json['id'] == uri ? json : nil
end
def fetch_resource_without_id_validation(uri, on_behalf_of = nil)
build_request(uri, on_behalf_of).perform do |response|
return body_to_json(response.body_with_limit) if response.code == 200
end
# If request failed, retry without doing it on behalf of a user
build_request(uri).perform do |response|
response.code == 200 ? body_to_json(response.body_with_limit) : nil
end
end
def body_to_json(body, compare_id: nil)
json = body.is_a?(String) ? Oj.load(body, mode: :strict) : body
return if compare_id.present? && json['id'] != compare_id
json
rescue Oj::ParseError
nil
end
def merge_context(context, new_context)
if context.is_a?(Array)
context << new_context
else
[context, new_context]
end
end
private
def build_request(uri, on_behalf_of = nil)
request = Request.new(:get, uri)
request.on_behalf_of(on_behalf_of) if on_behalf_of
request.add_headers('Accept' => 'application/activity+json, application/ld+json')
request
end
def load_jsonld_context(url, _options = {}, &_block)
json = Rails.cache.fetch("jsonld:context:#{url}", expires_in: 30.days, raw: true) do
request = Request.new(:get, url)
request.add_headers('Accept' => 'application/ld+json')
request.perform do |res|
raise JSON::LD::JsonLdError::LoadingDocumentFailed unless res.code == 200 && res.mime_type == 'application/ld+json'
res.body_with_limit
end
end
doc = JSON::LD::API::RemoteDocument.new(url, json)
block_given? ? yield(doc) : doc
end
end