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module SocialHelper
# The club's name is a proper noun and identical in both locales.
OG_SITE_NAME = "Chaos Computer Club".freeze
# Facebook's og:locale wants a language_TERRITORY tag, not a bare
# language code. Anything not listed falls back to the default locale's
# tag rather than emitting something no consumer recognises.
OG_LOCALES = { :de => "de_DE", :en => "en_GB" }.freeze
OG_DEFAULT_IMAGE = "/images/social_default.png".freeze
# Previews render unpublished drafts behind nothing but a token in the
# URL, so these controllers emit no social metadata at all.
PREVIEW_CONTROLLERS = %w[shared_previews pages].freeze
# Search result pages are the classic noindex case. Previews join them
# for the reason above.
NOINDEX_CONTROLLERS = (PREVIEW_CONTROLLERS + %w[search]).freeze
# og:image must be an absolute URL with a scheme; a path is ignored.
# request.base_url rather than a routing helper, so default_url_options
# cannot inject a locale prefix into a static asset path.
def og_absolute_url(path)
"#{request.base_url}#{path}"
end
def social_meta?
!PREVIEW_CONTROLLERS.include?(controller_name)
end
def robots_directive
return nil unless NOINDEX_CONTROLLERS.include?(controller_name)
# nofollow on previews as well, so a crawler that reaches one does not
# walk out of it into whatever the draft links to. Search pages omit it,
# since following result links is the one useful thing a crawler can do
# there.
PREVIEW_CONTROLLERS.include?(controller_name) ? "noindex, nofollow" : "noindex"
end
# The headline asset's card if it has one, else the site default.
# has_variant?
#
# The query suffix defeats indefinite crawler caching: FileAttachment
# deliberately keeps public URLs stable across a file replacement, so
# without it Facebook would serve the superseded card forever.
def og_image_url
asset = @page&.persisted? ? @page.headline_asset : nil
if asset&.has_variant?(:og)
og_absolute_url("#{asset.upload.url(:og)}?v=#{asset.upload_updated_at.to_i}")
else
og_absolute_url(OG_DEFAULT_IMAGE)
end
end
# Both files are exactly 1200x630, so these are constants either way.
def og_image_width
FileAttachment::OG_WIDTH
end
def og_image_height
FileAttachment::OG_HEIGHT
end
def og_image_alt
asset = @page&.persisted? ? @page.headline_asset : nil
asset&.has_variant?(:og) ? asset.name.to_s : OG_SITE_NAME
end
def og_title
@page&.title.presence || OG_SITE_NAME
end
# Public controllers are deliberately not pinned to the default locale,
# so Globalize follows I18n.locale here and the abstract arrives in the
# language being served. Abstracts hold markup, hence strip_tags.
def og_description
text = strip_tags(@page&.abstract.to_s).squish
return truncate(text, :length => 200, :separator => " ") if text.present?
t("layouts.social_meta.site_description")
end
# A rendered page is a piece of content; the aggregate views (search,
# tags, gallery) have no @page and are the site itself.
def og_type
@page&.persisted? ? "article" : "website"
end
def og_published_time
@page&.published_at&.iso8601
end
# request.path rather than a routing helper: it is already the locale's
# own canonical form -- unprefixed for German, /en/ for English -- and
# dropping the query string is what makes it canonical.
def og_canonical_url
og_absolute_url(request.path)
end
def og_locale
OG_LOCALES.fetch((@page&.effective_lang || I18n.locale).to_sym,
OG_LOCALES[I18n.default_locale.to_sym])
end
# Only locales in which this page genuinely has a translation, so a
# crawler is not told about a variant that would fall back.
def og_locale_alternates
return [] unless @page
(@page.translated_locales.map(&:to_sym) - [og_locale_key]).filter_map do |locale|
OG_LOCALES[locale]
end
end
private
def og_locale_key
(@page&.effective_lang || I18n.locale).to_sym
end
end
|
