Module: Shared::PurlDeprecation

Extended by:
ActiveSupport::Concern
Included in:
AnatomicalPart
Defined in:
app/models/concerns/shared/purl_deprecation.rb

Instance Method Summary collapse

Instance Method Details

#head_follow(url, limit: 10) ⇒ Object (private) 



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# File 'app/models/concerns/shared/purl_deprecation.rb', line 68

def head_follow(url, limit: 10)
  raise 'too many redirects' if limit <= 0

  uri = URI.parse(url)
  path = uri.request_uri.presence || '/'
  response = ::Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == 'https') { |http| http.head(path) }

  if response.is_a?(Net::HTTPRedirection) && (location = response['location']).present?
    return head_follow(location, limit: limit - 1)
  end
  [response, url]
end

#looks_obsolete_landing?(url) ⇒ Boolean (private)

Very light heuristic to avoid full HTML parsing: only for obo PURLs, fetch and scan a small chunk for “obsolete/deprecated”.

Returns:

  • (Boolean) 


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# File 'app/models/concerns/shared/purl_deprecation.rb', line 83

def looks_obsolete_landing?(url)
  uri = URI.parse(url)
  return false unless uri.host =~ /obolibrary|purl\.obolibrary\.org/i

  req_path = uri.request_uri.presence || '/'
  body = ''
  ::Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == 'https') do |http|
    http.request_get(req_path, { 'Range' => 'bytes=0-4096' }) do |r|
      body = r.body.to_s
    end
  end
  body.match?(/obsolete|deprecated|superseded/i)
rescue
  false
end

#purl_value ⇒ Object

Override in the including class if the attribute name differs.



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# File 'app/models/concerns/shared/purl_deprecation.rb', line 16

def purl_value
  respond_to?(:uri) ? uri : nil
end

#sv_purl_not_deprecated ⇒ Object

HEAD the PURL, follow a few redirects, and flag common “deprecated” cases.



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# File 'app/models/concerns/shared/purl_deprecation.rb', line 21

def sv_purl_not_deprecated
  url = purl_value
  return if url.blank?

  response, final_url = head_follow(url)

  code = response&.code.to_i
  deprecated = false
  message = nil

  case code
  when 410 # Gone – common for retired PURLs
    deprecated = true
    message = 'responds 410 (Gone)'
  when 301, 302, 303, 307, 308
    # Heuristics: a lot of obo PURLs redirect to replacement/obsolete pages
    if final_url&.match?(/obsolete|deprecated|replaced|superseded/i)
      deprecated = true
      message = "redirects to '#{final_url}' which looks deprecated/obsolete"
    end
  when 404
    deprecated = true
    message = 'responds 404 (Not Found)'
  else
    # Some servers return 200 OK to an “obsolete term” landing page.
    # Do a very lightweight GET only when code is 200 and host looks like OBO.
    if code == 200 && URI(url).host =~ /purl\.obolibrary\.org/i
      if looks_obsolete_landing?(final_url || url)
        deprecated = true
        message = 'lands on a page that looks like an obsolete/deprecated term'
      end
    end
  end

  if deprecated
    soft_validations.add(
      :uri,
      "PURL #{message}.",
    )
  end
rescue => e
  # Don't hard-fail SV on network hiccups
  soft_validations.add(:uri, "PURL check could not be completed (#{e.class}: #{e.message}).")
end