1 files changed, 68 insertions, 30 deletions

diff --git a/app/models/trends/links.rb b/app/models/trends/links.rb
index 604894cd6..8808b3ab6 100644
--- a/app/models/trends/links.rb
+++ b/app/models/trends/links.rb
@@ -11,6 +11,40 @@ class Trends::Links < Trends::Base
     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
 
@@ -28,24 +62,33 @@ class Trends::Links < Trends::Base
     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) + currently_trending_ids(false, -1)).uniq)
+    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
-    preview_cards = PreviewCard.where(id: currently_trending_ids(false, -1))
+    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_cards.filter_map do |preview_card|
-      next unless would_be_trending?(preview_card.id) && !preview_card.trendable? && preview_card.requires_review_notification?
+      preview_card_trends.filter_map do |trend|
+        preview_card = trend.preview_card
 
-      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
+        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
+        preview_card
+      end
     end
   end
 
@@ -62,10 +105,7 @@ class Trends::Links < Trends::Base
   private
 
   def calculate_scores(preview_cards, at_time)
-    global_items = []
-    locale_items = Hash.new { |h, key| h[key] = [] }
-
-    preview_cards.each do |preview_card|
+    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
@@ -89,26 +129,24 @@ class Trends::Links < Trends::Base
         preview_card.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]
+      decaying_score = begin
+        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
+      end
 
-      global_items << { score: decaying_score, item:  preview_card }
-      locale_items[preview_card.language] << { score: decaying_score, item: preview_card } if valid_locale?(preview_card.language)
+      [decaying_score, preview_card]
     end
 
-    replace_items('', global_items)
+    to_insert = items.filter { |(score, _)| score >= options[:decay_threshold] }
+    to_delete = items.filter { |(score, _)| score < options[:decay_threshold] }
 
-    Trends.available_locales.each do |locale|
-      replace_items(":#{locale}", locale_items[locale])
+    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
-
-  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