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# frozen_string_literal: true
class Trends::Links < Trends::Base
PREFIX = 'trending_links'
self.default_options = {
threshold: 5,
review_threshold: 3,
max_score_cooldown: 2.days.freeze,
max_score_halflife: 8.hours.freeze,
decay_threshold: 1,
}
class Query < Trends::Query
def filtered_for!(account)
@account = account
self
end
def filtered_for(account)
clone.filtered_for!(account)
end
def to_arel
scope = PreviewCard.joins(:trend).reorder(score: :desc)
scope = scope.reorder(language_order_clause.desc, score: :desc) if preferred_languages.present?
scope = scope.merge(PreviewCardTrend.allowed) if @allowed
scope = scope.offset(@offset) if @offset.present?
scope = scope.limit(@limit) if @limit.present?
scope
end
private
def language_order_clause
Arel::Nodes::Case.new.when(PreviewCardTrend.arel_table[:language].in(preferred_languages)).then(1).else(0)
end
def preferred_languages
if @account&.chosen_languages.present?
@account.chosen_languages
else
@locale
end
end
end
def register(status, at_time = Time.now.utc)
original_status = status.proper
return unless (original_status.public_visibility? && status.public_visibility?) &&
!(original_status.account.silenced? || status.account.silenced?) &&
!(original_status.spoiler_text? || original_status.sensitive?)
original_status.preview_cards.each do |preview_card|
add(preview_card, status.account_id, at_time) if preview_card.appropriate_for_trends?
end
end
def add(preview_card, account_id, at_time = Time.now.utc)
preview_card.history.add(account_id, at_time)
record_used_id(preview_card.id, at_time)
end
def query
Query.new(key_prefix, klass)
end
def refresh(at_time = Time.now.utc)
preview_cards = PreviewCard.where(id: (recently_used_ids(at_time) + PreviewCardTrend.pluck(:preview_card_id)).uniq)
calculate_scores(preview_cards, at_time)
end
def request_review
PreviewCardTrend.pluck('distinct language').flat_map do |language|
score_at_threshold = PreviewCardTrend.where(language: language, allowed: true).order(rank: :desc).where('rank <= ?', options[:review_threshold]).first&.score || 0
preview_card_trends = PreviewCardTrend.where(language: language, allowed: false).joins(:preview_card)
preview_card_trends.filter_map do |trend|
preview_card = trend.preview_card
next unless trend.score > score_at_threshold && !preview_card.trendable? && preview_card.requires_review_notification?
if preview_card.provider.nil?
preview_card.provider = PreviewCardProvider.create(domain: preview_card.domain, requested_review_at: Time.now.utc)
else
preview_card.provider.touch(:requested_review_at)
end
preview_card
end
end
end
protected
def key_prefix
PREFIX
end
def klass
PreviewCard
end
private
def calculate_scores(preview_cards, at_time)
items = preview_cards.map do |preview_card|
expected = preview_card.history.get(at_time - 1.day).accounts.to_f
expected = 1.0 if expected.zero?
observed = preview_card.history.get(at_time).accounts.to_f
max_time = preview_card.max_score_at
max_score = preview_card.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
preview_card.update_columns(max_score: max_score, max_score_at: max_time)
end
decaying_score = if max_score.zero? || !valid_locale?(preview_card.language)
0
else
max_score * (0.5**((at_time.to_f - max_time.to_f) / options[:max_score_halflife].to_f))
end
[decaying_score, preview_card]
end
to_insert = items.filter { |(score, _)| score >= options[:decay_threshold] }
to_delete = items.filter { |(score, _)| score < options[:decay_threshold] }
PreviewCardTrend.transaction do
PreviewCardTrend.upsert_all(to_insert.map { |(score, preview_card)| { preview_card_id: preview_card.id, score: score, language: preview_card.language, allowed: preview_card.trendable? || false } }, unique_by: :preview_card_id) if to_insert.any?
PreviewCardTrend.where(preview_card_id: to_delete.map { |(_, preview_card)| preview_card.id }).delete_all if to_delete.any?
PreviewCardTrend.connection.exec_update('UPDATE preview_card_trends SET rank = t0.calculated_rank FROM (SELECT id, row_number() OVER w AS calculated_rank FROM preview_card_trends WINDOW w AS (PARTITION BY language ORDER BY score DESC)) t0 WHERE preview_card_trends.id = t0.id')
end
end
end
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