82 lines
2.0 KiB
Ruby
82 lines
2.0 KiB
Ruby
# frozen_string_literal: true
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module RetrieveTitle
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CRAWL_TIMEOUT = 1
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def self.crawl(url)
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fetch_title(url)
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rescue Exception
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# If there was a connection error, do nothing
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end
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def self.extract_title(html, encoding = nil)
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title = nil
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if doc = Nokogiri::HTML5(html, nil, encoding)
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title = doc.at('title')&.inner_text
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# A horrible hack - YouTube uses `document.title` to populate the title
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# for some reason. For any other site than YouTube this wouldn't be worth it.
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if title == "YouTube" && html =~ /document\.title *= *"(.*)";/
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title = Regexp.last_match[1].sub(/ - YouTube$/, '')
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end
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if !title && node = doc.at('meta[property="og:title"]')
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title = node['content']
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end
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end
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if title.present?
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title.gsub!(/\n/, ' ')
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title.gsub!(/ +/, ' ')
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title.strip!
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return title
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end
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nil
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end
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private
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def self.max_chunk_size(uri)
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# Amazon and YouTube leave the title until very late. Exceptions are bad
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# but these are large sites.
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return 500 if uri.host =~ /amazon\.(com|ca|co\.uk|es|fr|de|it|com\.au|com\.br|cn|in|co\.jp|com\.mx)$/
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return 300 if uri.host =~ /youtube\.com$/ || uri.host =~ /youtu.be/
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# default is 10k
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10
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end
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# Fetch the beginning of a HTML document at a url
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def self.fetch_title(url)
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fd = FinalDestination.new(url, timeout: CRAWL_TIMEOUT)
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current = nil
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title = nil
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encoding = nil
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fd.get do |_response, chunk, uri|
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if current
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current << chunk
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else
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current = chunk
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end
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if !encoding && content_type = _response['content-type']&.strip&.downcase
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if content_type =~ /charset="?([a-z0-9_-]+)"?/
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encoding = Regexp.last_match(1)
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if !Encoding.list.map(&:name).map(&:downcase).include?(encoding)
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encoding = nil
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end
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end
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end
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max_size = max_chunk_size(uri) * 1024
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title = extract_title(current, encoding)
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throw :done if title || max_size < current.length
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end
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title
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end
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end
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