canvas-lms/lib/text_helper.rb

# encoding: UTF-8
#
# By Henrik Nyh <http://henrik.nyh.se> 2008-01-30.
# Free to modify and redistribute with credit.

# modified by Dave Nolan <http://textgoeshere.org.uk> 2008-02-06
# Ellipsis appended to text of last HTML node
# Ellipsis inserted after final word break

# modified by Mark Dickson <mark@sitesteaders.com> 2008-12-18
# Option to truncate to last full word
# Option to include a 'more' link
# Check for nil last child

# Copied from http://pastie.textmate.org/342485,
# based on http://henrik.nyh.se/2008/01/rails-truncate-html-helper

require 'nokogiri'
require 'rdiscount'

module TextHelper
  def force_zone(time)
    (time.in_time_zone(@time_zone || Time.zone) rescue nil) || time
  end

  def self.date_string(start_date, *args)
    return nil unless start_date
    start_date = start_date.in_time_zone.beginning_of_day
    style = args.last.is_a?(Symbol) ? args.pop : :normal
    end_date = args.pop
    end_date = end_date.in_time_zone.beginning_of_day if end_date
    start_date_display = Utils::DatePresenter.new(start_date).as_string(style)
    if end_date.nil? || start_date == end_date
      start_date_display
    else
      I18n.t('time.ranges.different_days', "%{start_date_and_time} to %{end_date_and_time}",
        :start_date_and_time => start_date_display,
        :end_date_and_time => Utils::DatePresenter.new(end_date).as_string(style)
      )
    end
  end

  def date_string(*args)
    TextHelper.date_string(*args)
  end

  def time_string(start_time, end_time=nil, zone=nil)
    presenter = Utils::TimePresenter.new(start_time, zone)
    presenter.as_string(display_as_range: end_time)
  end

  def datetime_span(*args)
    string = datetime_string(*args)
    if string && !string.empty? && args[0]
      "<span class='zone_cached_datetime' title='#{args[0].iso8601 rescue ""}'>#{string}</span>"
    else
      nil
    end
  end

  def datetime_string(start_datetime, datetime_type=:event, end_datetime=nil, shorten_midnight=false, zone=nil)
    zone ||= ::Time.zone
    presenter = Utils::DatetimeRangePresenter.new(start_datetime, end_datetime, datetime_type, zone)
    presenter.as_string(shorten_midnight: shorten_midnight)
  end

  def time_ago_in_words_with_ago(time)
    I18n.t('#time.with_ago', '%{time} ago', :time => (time_ago_in_words time rescue ''))
  end

  # more precise than distance_of_time_in_words, and takes a number of seconds,
  # rather than two times. also assumes durations on the scale of hours or
  # less, so doesn't bother with days, months, or years
  def readable_duration(seconds)
    # keys stolen from ActionView::Helpers::DateHelper#distance_of_time_in_words
    case seconds
    when  0...60
      I18n.t('datetime.distance_in_words.x_seconds',
        { :one => "1 second", :other => "%{count} seconds" },
        :count => seconds.round)
    when 60...3600
      I18n.t('datetime.distance_in_words.x_minutes',
        { :one => "1 minute", :other => "%{count} minutes" },
        :count => (seconds / 60.0).round)
    else
      I18n.t('datetime.distance_in_words.about_x_hours',
        { :one => "about 1 hour", :other => "about %{count} hours" },
        :count => (seconds / 3600.0).round)
    end
  end

  def truncate_html(input, options={})
    doc = Nokogiri::HTML(input)
    options[:max_length] ||= 250
    num_words = options[:num_words] || (options[:max_length] / 5) || 30
    truncate_string = options[:ellipsis] || I18n.t('lib.text_helper.ellipsis', '...')
    truncate_string += options[:link] if options[:link]
    truncate_elem = Nokogiri::HTML("<span>" + truncate_string + "</span>").at("span")

    current = doc.children.first
    count = 0

    while true
      # we found a text node
      if current.is_a?(Nokogiri::XML::Text)
        count += current.text.split.length
        # we reached our limit, let's get outta here!
        break if count > num_words
        previous = current
      end

      if current.children.length > 0
        # this node has children, can't be a text node,
        # lets descend and look for text nodes
        current = current.children.first
      elsif !current.next.nil?
        #this has no children, but has a sibling, let's check it out
        current = current.next
      else
        # we are the last child, we need to ascend until we are
        # either done or find a sibling to continue on to
        n = current
        while !n.is_a?(Nokogiri::HTML::Document) and n.parent.next.nil?
          n = n.parent
        end

        # we've reached the top and found no more text nodes, break
        if n.is_a?(Nokogiri::HTML::Document)
          break;
        else
          current = n.parent.next
        end
      end
    end

    if count >= num_words
      unless count == num_words
        new_content = current.text.split

        # If we're here, the last text node we counted eclipsed the number of words
        # that we want, so we need to cut down on words.  The easiest way to think about
        # this is that without this node we'd have fewer words than the limit, so all
        # the previous words plus a limited number of words from this node are needed.
        # We simply need to figure out how many words are needed and grab that many.
        # Then we need to -subtract- an index, because the first word would be index zero.

        # For example, given:
        # <p>Testing this HTML truncater.</p><p>To see if its working.</p>
        # Let's say I want 6 words.  The correct returned string would be:
        # <p>Testing this HTML truncater.</p><p>To see...</p>
        # All the words in both paragraphs = 9
        # The last paragraph is the one that breaks the limit.  How many words would we
        # have without it? 4.  But we want up to 6, so we might as well get that many.
        # 6 - 4 = 2, so we get 2 words from this node, but words #1-2 are indices #0-1, so
        # we subtract 1.  If this gives us -1, we want nothing from this node. So go back to
        # the previous node instead.
        index = num_words-(count-new_content.length)-1
        if index >= 0
          new_content = new_content[0..index]
          current.add_previous_sibling(truncate_elem)
          new_node = Nokogiri::XML::Text.new(new_content.join(' '), doc)
          truncate_elem.add_previous_sibling(new_node)
          current = truncate_elem
        else
          current = previous
          # why would we do this next line? it just ends up xml escaping stuff
          #current.content = current.content
          current.add_next_sibling(truncate_elem)
          current = truncate_elem
        end
      end

      # remove everything else
      while !current.is_a?(Nokogiri::HTML::Document)
        while !current.next.nil?
          current.next.remove
        end
        current = current.parent
      end
    end

    # now we grab the html and not the text.
    # we do first because nokogiri adds html and body tags
    # which we don't want
    res = doc.at_css('body').inner_html rescue nil
    res ||= doc.root.children.first.inner_html rescue ""
    res && res.html_safe
  end

  def self.make_subject_reply_to(subject)
    blank_re = I18n.t('#subject_reply_to', "Re: %{subject}", :subject => '')
    return subject if subject.starts_with?(blank_re)
    I18n.t('#subject_reply_to', "Re: %{subject}", :subject => subject)
  end

  class MarkdownSafeBuffer < String; end
  # use this to flag interpolated parameters as markdown-safe (see
  # mt below) so they get eval'ed rather than escaped, e.g.
  #  mt(:add_description, :example => markdown_safe('`1 + 1 = 2`'))
  def markdown_safe(string)
    MarkdownSafeBuffer.new(string)
  end

  def markdown_escape(string)
    return string if string.is_a?(MarkdownSafeBuffer)
    markdown_safe(string.gsub(/([\\`\*_\{\}\[\]\(\)\#\+\-\.!])/, '\\\\\1'))
  end

  # use this rather than t() if the translation contains trusted markdown
  def mt(*args)
    inlinify = :auto
    if args.last.is_a?(Hash)
      options = args.last
      inlinify = options.delete(:inlinify) if options.has_key?(:inlinify)
      options.each_pair do |key, value|
        next unless value.is_a?(String) && !value.is_a?(MarkdownSafeBuffer) && !value.is_a?(ActiveSupport::SafeBuffer)
        next if key == :wrapper
        options[key] = markdown_escape(value).gsub(/\s+/, ' ').strip
      end
    end
    translated = t(*args)
    markdown(translated, inlinify)
  end

  def markdown(string, inlinify = :auto)
    string = ERB::Util.h(string) unless string.html_safe?
    result = RDiscount.new(string).to_html.strip
    # Strip wrapping <p></p> if inlinify == :auto && they completely wrap the result && there are not multiple <p>'s
    result.gsub!(/<\/?p>/, '') if inlinify == :auto && result =~ /\A<p>.*<\/p>\z/m && !(result =~ /.*<p>.*<p>.*/m)
    result.strip.html_safe
  end
end