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# frozen_string_literal: true
class Trends::Tags < Trends::Base
PREFIX = 'trending_tags'
self.default_options = {
threshold: 5,
review_threshold: 3,
max_score_cooldown: 2.days.freeze,
max_score_halflife: 4.hours.freeze,
decay_threshold: 1,
}
def register(status, at_time = Time.now.utc)
return unless !status.reblog? && status.public_visibility? && !status.account.silenced?
status.tags.each do |tag|
add(tag, status.account_id, at_time) if tag.usable?
end
end
def add(tag, account_id, at_time = Time.now.utc)
tag.history.add(account_id, at_time)
record_used_id(tag.id, at_time)
end
def refresh(at_time = Time.now.utc)
tags = Tag.where(id: (recently_used_ids(at_time) + currently_trending_ids(false, -1)).uniq)
calculate_scores(tags, at_time)
end
def request_review
tags = Tag.where(id: currently_trending_ids(false, -1))
tags.filter_map do |tag|
next unless would_be_trending?(tag.id) && !tag.trendable? && tag.requires_review_notification?
tag.touch(:requested_review_at)
tag
end
end
protected
def key_prefix
PREFIX
end
def klass
Tag
end
private
def calculate_scores(tags, at_time)
items = []
tags.each do |tag|
expected = tag.history.get(at_time - 1.day).accounts.to_f
expected = 1.0 if expected.zero?
observed = tag.history.get(at_time).accounts.to_f
max_time = tag.max_score_at
max_score = tag.max_score
max_score = 0 if max_time.nil? || max_time < (at_time - options[:max_score_cooldown])
score = if expected > observed || observed < options[:threshold]
0
else
((observed - expected)**2) / expected
end
if score > max_score
max_score = score
max_time = at_time
# Not interested in triggering any callbacks for this
tag.update_columns(max_score: max_score, max_score_at: max_time)
end
decaying_score = max_score * (0.5**((at_time.to_f - max_time.to_f) / options[:max_score_halflife].to_f))
next unless decaying_score >= options[:decay_threshold]
items << { score: decaying_score, item: tag }
end
replace_items('', items)
end
def filter_for_allowed_items(items)
items.select { |item| item[:item].trendable? }
end
def would_be_trending?(id)
score(id) > score_at_rank(options[:review_threshold] - 1)
end
end
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