discourse/lib/topic_query.rb

# frozen_string_literal: true

#
# Helps us find topics.
# Returns a TopicList object containing the topics found.
#

class TopicQuery
  include PrivateMessageLists

  PG_MAX_INT ||= 2_147_483_647
  DEFAULT_PER_PAGE_COUNT ||= 30

  def self.validators
    @validators ||=
      begin
        int = lambda { |x| Integer === x || (String === x && x.match?(/\A-?[0-9]+\z/)) }
        zero_up_to_max_int = lambda { |x| int.call(x) && x.to_i.between?(0, PG_MAX_INT) }
        array_or_string = lambda { |x| Array === x || String === x }

        {
          max_posts: zero_up_to_max_int,
          min_posts: zero_up_to_max_int,
          page: zero_up_to_max_int,
          tags: array_or_string,
        }
      end
  end

  def self.validate?(option, value)
    if fn = validators[option.to_sym]
      fn.call(value)
    else
      true
    end
  end

  def self.public_valid_options
    # For these to work in Ember, add them to `controllers/discovery-sortable.js`
    @public_valid_options ||= %i[
      page
      before
      bumped_before
      topic_ids
      category
      order
      ascending
      min_posts
      max_posts
      status
      filter
      state
      search
      q
      f
      group_name
      tags
      match_all_tags
      no_subcategories
      no_tags
      exclude_tag
    ]
  end

  def self.valid_options
    @valid_options ||=
      public_valid_options +
        %i[
          except_topic_ids
          limit
          page
          per_page
          visible
          guardian
          no_definitions
          destination_category_id
          include_all_pms
          include_pms
        ]
  end

  # Maps `order` to a columns in `topics`
  SORTABLE_MAPPING = {
    "likes" => "like_count",
    "op_likes" => "op_likes",
    "views" => "views",
    "posts" => "posts_count",
    "activity" => "bumped_at",
    "posters" => "participant_count",
    "category" => "category_id",
    "created" => "created_at",
  }

  cattr_accessor :results_filter_callbacks
  self.results_filter_callbacks = []

  attr_accessor :options, :user, :guardian

  def self.add_custom_filter(key, &blk)
    @custom_filters ||= {}
    valid_options << key
    public_valid_options << key
    @custom_filters[key] = blk
  end

  def self.remove_custom_filter(key)
    @custom_filters.delete(key)
    public_valid_options.delete(key)
    valid_options.delete(key)
    @custom_filters = nil if @custom_filters.length == 0
  end

  def self.apply_custom_filters(results, topic_query)
    if @custom_filters
      @custom_filters.each { |key, filter| results = filter.call(results, topic_query) }
    end
    results
  end

  def initialize(user = nil, options = {})
    options.assert_valid_keys(TopicQuery.valid_options)
    @options = options.dup
    @user = user
    @guardian = options[:guardian] || Guardian.new(@user)
  end

  def joined_topic_user(list = nil)
    (list || Topic).joins(
      "LEFT OUTER JOIN topic_users AS tu ON (topics.id = tu.topic_id AND tu.user_id = #{@user.id.to_i})",
    )
  end

  def get_pm_params(topic)
    if topic.private_message?
      my_group_ids =
        topic
          .topic_allowed_groups
          .joins(
            "
          LEFT JOIN group_users gu
          ON topic_allowed_groups.group_id = gu.group_id
          AND gu.user_id = #{@user.id.to_i}
        ",
          )
          .where("gu.group_id IS NOT NULL")
          .pluck(:group_id)

      target_group_ids = topic.topic_allowed_groups.pluck(:group_id)

      target_users = topic.topic_allowed_users

      if my_group_ids.present?
        # strip out users in groups you already belong to
        target_users =
          target_users.joins(
            "LEFT JOIN group_users gu ON gu.user_id = topic_allowed_users.user_id AND #{DB.sql_fragment("gu.group_id IN (?)", my_group_ids)}",
          ).where("gu.group_id IS NULL")
      end

      target_user_ids =
        target_users.where("NOT topic_allowed_users.user_id = ?", @user.id).pluck(:user_id)

      {
        topic: topic,
        my_group_ids: my_group_ids,
        target_group_ids: target_group_ids,
        target_user_ids: target_user_ids,
      }
    end
  end

  def list_related_for(topic, pm_params: nil)
    return if !topic.private_message?
    return if @user.blank?

    return if !@user.in_any_groups?(SiteSetting.personal_message_enabled_groups_map)

    builder = SuggestedTopicsBuilder.new(topic)
    pm_params = pm_params || get_pm_params(topic)

    if pm_params[:my_group_ids].present?
      builder.add_results(
        related_messages_group(
          pm_params.merge(
            count: [6, builder.results_left].max,
            exclude: builder.excluded_topic_ids,
          ),
        ),
      )
    else
      builder.add_results(
        related_messages_user(
          pm_params.merge(
            count: [6, builder.results_left].max,
            exclude: builder.excluded_topic_ids,
          ),
        ),
      )
    end

    params = { unordered: true }
    params[:preload_posters] = true
    create_list(:suggested, params, builder.results)
  end

  # Return a list of suggested topics for a topic
  # The include_random param was added so plugins can generate a suggested topics list without the random topics
  def list_suggested_for(topic, pm_params: nil, include_random: true)
    # Don't suggest messages unless we have a user, and private messages are
    # enabled.
    if topic.private_message? &&
         (@user.blank? || !@user.in_any_groups?(SiteSetting.personal_message_enabled_groups_map))
      return
    end

    builder = SuggestedTopicsBuilder.new(topic)

    pm_params = pm_params || get_pm_params(topic)

    if DiscoursePluginRegistry.list_suggested_for_providers.any?
      DiscoursePluginRegistry.list_suggested_for_providers.each do |provider|
        suggested = provider.call(topic, pm_params, self)
        builder.add_results(suggested[:result]) if suggested && !suggested[:result].blank?
      end
    end

    # When logged in we start with different results
    if @user
      if topic.private_message?
        unless builder.full?
          builder.add_results(new_messages(pm_params.merge(count: builder.results_left)))
        end

        unless builder.full?
          builder.add_results(unread_messages(pm_params.merge(count: builder.results_left)))
        end
      else
        builder.add_results(
          unread_results(
            topic: topic,
            per_page: builder.results_left,
            max_age: SiteSetting.suggested_topics_unread_max_days_old,
          ),
          :high,
        )

        unless builder.full?
          builder.add_results(new_results(topic: topic, per_page: builder.category_results_left))
        end
      end
    end

    if !topic.private_message?
      if include_random && !builder.full?
        builder.add_results(
          random_suggested(topic, builder.results_left, builder.excluded_topic_ids),
        )
      end
    end

    params = { unordered: true }
    params[:preload_posters] = true if topic.private_message?
    create_list(:suggested, params, builder.results)
  end

  # The latest view of topics
  def list_latest
    create_list(:latest, {}, latest_results)
  end

  def list_filter
    topics_filter =
      TopicsFilter.new(
        guardian: @guardian,
        scope: latest_results(include_muted: false, skip_ordering: true),
      )

    results = topics_filter.filter_from_query_string(@options[:q])

    if !topics_filter.topic_notification_levels.include?(NotificationLevels.all[:muted])
      results = remove_muted_topics(results, @user)
    end

    results = apply_ordering(results) if results.order_values.empty?

    create_list(:filter, {}, results)
  end

  def list_read
    create_list(:read, unordered: true) do |topics|
      topics.where("tu.last_visited_at IS NOT NULL").order("tu.last_visited_at DESC")
    end
  end

  def list_new
    if @user&.new_new_view_enabled?
      create_list(:new, { unordered: true }, new_and_unread_results)
    else
      create_list(:new, { unordered: true }, new_results)
    end
  end

  def list_unread
    create_list(:unread, { unordered: true }, unread_results)
  end

  def list_unseen
    create_list(:unseen, { unordered: true }, unseen_results)
  end

  def list_posted
    create_list(:posted) { |l| l.where("tu.posted") }
  end

  def list_bookmarks
    create_list(:bookmarks) { |l| l.where("tu.bookmarked") }
  end

  def list_top_for(period)
    score_column = TopTopic.score_column_for_period(period)
    create_list(:top, unordered: true) do |topics|
      topics = remove_muted_categories(topics, @user)
      topics = topics.joins(:top_topic).where("top_topics.#{score_column} > 0")
      if period == :yearly && @user.try(:trust_level) == TrustLevel[0]
        topics.order(<<~SQL)
          CASE WHEN (
             COALESCE(topics.pinned_at, '1900-01-01') > COALESCE(tu.cleared_pinned_at, '1900-01-01')
          ) THEN 0 ELSE 1 END,
          top_topics.#{score_column} DESC,
          topics.bumped_at DESC
        SQL
      else
        topics.order(<<~SQL)
          COALESCE(top_topics.#{score_column}, 0) DESC, topics.bumped_at DESC
        SQL
      end
    end
  end

  def list_topics_by(user)
    @options[:filtered_to_user] = user.id
    create_list(:user_topics) { |topics| topics.where(user_id: user.id) }
  end

  def list_group_topics(group)
    list =
      default_results.where(
        "
      topics.user_id IN (
        SELECT user_id FROM group_users gu WHERE gu.group_id = ?
      )
    ",
        group.id.to_i,
      )

    create_list(:group_topics, {}, list)
  end

  def list_category_topic_ids(category)
    query = default_results(category: category.id)
    pinned_ids =
      query
        .where("topics.pinned_at IS NOT NULL AND topics.category_id = ?", category.id)
        .limit(nil)
        .order("pinned_at DESC")
        .pluck(:id)
    non_pinned_ids =
      query.where("topics.pinned_at IS NULL OR topics.category_id <> ?", category.id).pluck(:id)
    (pinned_ids + non_pinned_ids)
  end

  def list_new_in_category(category)
    create_list(:new_in_category, unordered: true, category: category.id) do |list|
      list.by_newest.first(25)
    end
  end

  def self.new_filter(list, treat_as_new_topic_start_date: nil, treat_as_new_topic_clause_sql: nil)
    if treat_as_new_topic_start_date
      list =
        list.where("topics.created_at >= :created_at", created_at: treat_as_new_topic_start_date)
    else
      list = list.where("topics.created_at >= #{treat_as_new_topic_clause_sql}")
    end

    list.where("tu.last_read_post_number IS NULL").where(
      "COALESCE(tu.notification_level, :tracking) >= :tracking",
      tracking: TopicUser.notification_levels[:tracking],
    )
  end

  def self.unread_filter(list, whisperer: false)
    col_name = whisperer ? "highest_staff_post_number" : "highest_post_number"

    list.where("tu.last_read_post_number < topics.#{col_name}").where(
      "COALESCE(tu.notification_level, :regular) >= :tracking",
      regular: TopicUser.notification_levels[:regular],
      tracking: TopicUser.notification_levels[:tracking],
    )
  end

  # Any changes here will need to be reflected in `lib/topic-list-tracked-filter.js` for the `isTrackedTopic` function on
  # the client side. The `f=tracked` query param is not heavily used so we do not want to be querying for a topic's
  # tracked status by default. Instead, the client will handle the filtering when the `f=tracked` query params is present.
  def self.tracked_filter(list, user_id)
    tracked_category_ids_sql = <<~SQL
    SELECT cd.category_id FROM category_users cd
    WHERE cd.user_id = :user_id AND cd.notification_level >= :tracking
    SQL

    has_sub_sub_categories = SiteSetting.max_category_nesting == 3

    sql = +<<~SQL
      topics.category_id IN (
        SELECT
          c.id
        FROM categories c
        #{has_sub_sub_categories ? "LEFT JOIN categories parent_categories ON parent_categories.id = c.parent_category_id" : ""}
        WHERE (c.id IN (#{tracked_category_ids_sql}))
        OR c.parent_category_id IN (#{tracked_category_ids_sql})
        #{has_sub_sub_categories ? "OR (parent_categories.id IS NOT NULL AND parent_categories.parent_category_id IN (#{tracked_category_ids_sql}))" : ""}
      )
    SQL

    sql << <<~SQL if SiteSetting.tagging_enabled
        OR topics.id IN (
          SELECT tt.topic_id FROM topic_tags tt WHERE tt.tag_id IN (
            SELECT tu.tag_id
            FROM tag_users tu
            WHERE tu.user_id = :user_id AND tu.notification_level >= :tracking
          )
        )
      SQL

    list.where(sql, user_id: user_id, tracking: NotificationLevels.all[:tracking])
  end

  def prioritize_pinned_topics(topics, options)
    pinned_clause =
      if options[:category_id]
        +"topics.category_id = #{options[:category_id].to_i} AND"
      else
        +"pinned_globally AND "
      end

    pinned_clause << " pinned_at IS NOT NULL "

    if @user
      pinned_clause << " AND (topics.pinned_at > tu.cleared_pinned_at OR tu.cleared_pinned_at IS NULL)"
    end

    unpinned_topics = topics.where("NOT ( #{pinned_clause} )")
    pinned_topics = topics.dup.offset(nil).where(pinned_clause).reorder(pinned_at: :desc)

    per_page = options[:per_page] || per_page_setting
    limit = per_page unless options[:limit] == false
    page = options[:page].to_i

    if page == 0
      (pinned_topics + unpinned_topics)[0...limit] if limit
    else
      offset = (page * per_page) - pinned_topics.length
      offset = 0 if offset <= 0
      unpinned_topics.offset(offset).to_a
    end
  end

  def create_list(filter, options = {}, topics = nil)
    options[:filter] ||= filter
    topics ||= default_results(options)
    topics = yield(topics) if block_given?
    topics =
      DiscoursePluginRegistry.apply_modifier(:topic_query_create_list_topics, topics, options, self)

    options = options.merge(@options)
    if %w[activity default].include?(options[:order] || "activity") && !options[:unordered] &&
         filter != :private_messages
      topics = prioritize_pinned_topics(topics, options)
    end

    topics = topics.to_a

    if options[:preload_posters]
      user_ids = []
      topics.each do |ft|
        user_ids << ft.user_id << ft.last_post_user_id << ft.featured_user_ids <<
          ft.allowed_user_ids
      end

      user_lookup = UserLookup.new(user_ids)

      # memoize for loop so we don't keep looking these up
      translations = TopicPostersSummary.translations

      topics.each do |t|
        t.posters = t.posters_summary(user_lookup: user_lookup, translations: translations)
      end
    end

    topics.each do |t|
      t.allowed_user_ids = filter == :private_messages ? t.allowed_users.map { |u| u.id } : []
    end

    list = TopicList.new(filter, @user, topics, options.merge(@options))
    list.per_page = options[:per_page] || per_page_setting
    list
  end

  def latest_results(options = {})
    result = default_results(options)
    result = remove_muted(result, @user, options)
    result = apply_shared_drafts(result, get_category_id(options[:category]), options)

    # plugins can remove topics here:
    self.class.results_filter_callbacks.each do |filter_callback|
      result = filter_callback.call(:latest, result, @user, options)
    end

    result
  end

  def unseen_results(options = {})
    result = default_results(options)
    result = unseen_filter(result, @user.first_seen_at, @user.whisperer?) if @user
    result = remove_muted(result, @user, options)
    result = apply_shared_drafts(result, get_category_id(options[:category]), options)

    # plugins can remove topics here:
    self.class.results_filter_callbacks.each do |filter_callback|
      result = filter_callback.call(:latest, result, @user, options)
    end

    result
  end

  def unread_results(options = {})
    result =
      TopicQuery.unread_filter(
        default_results(options.reverse_merge(unordered: true)),
        whisperer: @user&.whisperer?,
      ).order("CASE WHEN topics.user_id = tu.user_id THEN 1 ELSE 2 END")

    result = apply_max_age_limit(result, options)

    self.class.results_filter_callbacks.each do |filter_callback|
      result = filter_callback.call(:unread, result, @user, options)
    end

    suggested_ordering(result, options)
  end

  def new_results(options = {})
    # TODO does this make sense or should it be ordered on created_at
    #  it is ordering on bumped_at now
    result =
      TopicQuery.new_filter(
        default_results(options.reverse_merge(unordered: true)),
        treat_as_new_topic_start_date: @user.user_option.treat_as_new_topic_start_date,
      )
    result = remove_muted(result, @user, options)
    result = remove_dismissed(result, @user)

    self.class.results_filter_callbacks.each do |filter_callback|
      result = filter_callback.call(:new, result, @user, options)
    end

    suggested_ordering(result, options)
  end

  def new_and_unread_results(options = {})
    base = default_results(options.reverse_merge(unordered: true))

    new_results =
      TopicQuery.new_filter(
        base,
        treat_as_new_topic_start_date: @user.user_option.treat_as_new_topic_start_date,
      )
    new_results = remove_muted(new_results, @user, options)
    new_results = remove_dismissed(new_results, @user)

    unread_results =
      apply_max_age_limit(TopicQuery.unread_filter(base, whisperer: @user&.whisperer?), options)

    base.joins_values.concat(new_results.joins_values, unread_results.joins_values)
    base.joins_values.uniq!
    results = base.merge(new_results.or(unread_results))

    results = results.order("CASE WHEN topics.user_id = tu.user_id THEN 1 ELSE 2 END")
    suggested_ordering(results, options)
  end

  protected

  def per_page_setting
    DEFAULT_PER_PAGE_COUNT
  end

  def apply_shared_drafts(result, category_id, options)
    # PERF: avoid any penalty if there are no shared drafts enabled
    # on some sites the cost can be high eg: gearbox
    return result if SiteSetting.shared_drafts_category == ""

    drafts_category_id = SiteSetting.shared_drafts_category.to_i
    viewing_shared = category_id && category_id == drafts_category_id

    if guardian.can_see_shared_draft?
      if options[:destination_category_id]
        destination_category_id = get_category_id(options[:destination_category_id])
        topic_ids = SharedDraft.where(category_id: destination_category_id).pluck(:topic_id)

        return result.where(id: topic_ids)
      end

      return result.includes(:shared_draft).references(:shared_draft) if viewing_shared
    elsif viewing_shared
      return(
        result.joins("LEFT OUTER JOIN shared_drafts sd ON sd.topic_id = topics.id").where(
          "sd.id IS NULL",
        )
      )
    end

    result.where("topics.category_id != ?", drafts_category_id)
  end

  def apply_ordering(result, options = {})
    sort_column = SORTABLE_MAPPING[options[:order]] || "default"
    sort_dir = (options[:ascending] == "true") ? "ASC" : "DESC"

    # If we are sorting in the default order desc, we should consider including pinned
    # topics. Otherwise, just use bumped_at.
    if sort_column == "default"
      if sort_dir == "DESC"
        # If something requires a custom order, for example "unread" which sorts the least read
        # to the top, do nothing
        return result if options[:unordered]
      end
      sort_column = "bumped_at"
    end

    # If we are sorting by category, actually use the name
    if sort_column == "category_id"
      # TODO forces a table scan, slow
      return result.references(:categories).order(<<~SQL)
        CASE WHEN categories.id = #{SiteSetting.uncategorized_category_id.to_i} THEN '' ELSE categories.name END #{sort_dir}
      SQL
    end

    if sort_column == "op_likes"
      return(
        result.includes(:first_post).order(
          "(SELECT like_count FROM posts p3 WHERE p3.topic_id = topics.id AND p3.post_number = 1) #{sort_dir}",
        )
      )
    end

    if sort_column.start_with?("custom_fields")
      field = sort_column.split(".")[1]
      return(
        result.order(
          "(SELECT CASE WHEN EXISTS (SELECT true FROM topic_custom_fields tcf WHERE tcf.topic_id::integer = topics.id::integer AND tcf.name = '#{field}') THEN (SELECT value::integer FROM topic_custom_fields tcf WHERE tcf.topic_id::integer = topics.id::integer AND tcf.name = '#{field}') ELSE 0 END) #{sort_dir}",
        )
      )
    end

    result.order("topics.#{sort_column} #{sort_dir}")
  end

  def get_category_id(category_id_or_slug)
    return nil unless category_id_or_slug.present?
    category_id = category_id_or_slug.to_i

    if category_id == 0
      category_id = Category.where(slug: category_id_or_slug, parent_category_id: nil).pick(:id)
    end

    category_id
  end

  # Create results based on a bunch of default options
  def default_results(options = {})
    options.reverse_merge!(@options)
    options.reverse_merge!(per_page: per_page_setting) unless options[:limit] == false

    # Whether to include unlisted (visible = false) topics
    viewing_own_topics = @user && @user.id == options[:filtered_to_user]

    if options[:visible].nil?
      options[:visible] = true if @user.nil? || @user.regular?
      options[:visible] = false if @guardian.can_see_unlisted_topics? || viewing_own_topics
    end

    # Start with a list of all topics
    result = Topic.includes(:category)

    if @user
      result =
        result.joins(
          "LEFT OUTER JOIN topic_users AS tu ON (topics.id = tu.topic_id AND tu.user_id = #{@user.id.to_i})",
        ).references("tu")
    end

    category_id = get_category_id(options[:category])
    @options[:category_id] = category_id
    if category_id
      if options[:no_subcategories]
        result = result.where("topics.category_id = ?", category_id)
      else
        result = result.where("topics.category_id IN (?)", Category.subcategory_ids(category_id))
        if !SiteSetting.show_category_definitions_in_topic_lists
          result =
            result.where(
              "categories.topic_id IS DISTINCT FROM topics.id OR topics.category_id = ?",
              category_id,
            )
        end
      end
      result = result.references(:categories)

      if !@options[:order]
        filter = (options[:filter] || options[:f])
        # category default sort order
        sort_order, sort_ascending =
          Category.where(id: category_id).pick(:sort_order, :sort_ascending)
        if sort_order && (filter.blank? || %i[latest unseen].include?(filter))
          options[:order] = sort_order
          options[:ascending] = !!sort_ascending ? "true" : "false"
        else
          options[:order] = "default"
          options[:ascending] = "false"
        end
      end
    end

    if SiteSetting.tagging_enabled
      result = result.includes(:tags)
      result = filter_by_tags(result)
    end

    result = apply_ordering(result, options) if !options[:skip_ordering]

    all_listable_topics =
      @guardian.filter_allowed_categories(
        Topic.unscoped.listable_topics,
        category_id_column: "categories.id",
      )

    if options[:include_pms] || options[:include_all_pms]
      all_pm_topics =
        if options[:include_all_pms] && @guardian.is_admin?
          Topic.unscoped.private_messages
        else
          Topic.unscoped.private_messages_for_user(@user)
        end
      result = result.merge(all_listable_topics.or(all_pm_topics))
    else
      result = result.merge(all_listable_topics)
    end

    # Don't include the category topics if excluded
    if options[:no_definitions]
      result = result.where("COALESCE(categories.topic_id, 0) <> topics.id")
    end

    result = result.limit(options[:per_page]) unless options[:limit] == false
    result = result.visible if options[:visible]
    result =
      result.where.not(topics: { id: options[:except_topic_ids] }).references(:topics) if options[
      :except_topic_ids
    ]

    if options[:page]
      offset = options[:page].to_i * options[:per_page]
      result = result.offset(offset) if offset > 0
    end

    if options[:topic_ids]
      result = result.where("topics.id in (?)", options[:topic_ids]).references(:topics)
    end

    if search = options[:search].presence
      result =
        result.where(
          "topics.id in (select pp.topic_id from post_search_data pd join posts pp on pp.id = pd.post_id where pd.search_data @@ #{Search.ts_query(term: search.to_s)})",
        )
    end

    # NOTE protect against SYM attack can be removed with Ruby 2.2
    #
    state = options[:state]
    if @user && state && TopicUser.notification_levels.keys.map(&:to_s).include?(state)
      level = TopicUser.notification_levels[state.to_sym]
      result =
        result.where(
          "topics.id IN (
                                SELECT topic_id
                                FROM topic_users
                                WHERE user_id = ? AND
                                      notification_level = ?)",
          @user.id,
          level,
        )
    end

    if before = options[:before]
      if (before = before.to_i) > 0
        result = result.where("topics.created_at < ?", before.to_i.days.ago)
      end
    end

    if bumped_before = options[:bumped_before]
      if (bumped_before = bumped_before.to_i) > 0
        result = result.where("topics.bumped_at < ?", bumped_before.to_i.days.ago)
      end
    end

    if status = options[:status]
      result =
        TopicsFilter.new(scope: result, guardian: @guardian).filter_status(
          status: options[:status],
          category_id: options[:category],
        )
    end

    if (filter = (options[:filter] || options[:f])) && @user
      action = (PostActionType.types[:like] if filter == "liked")
      if action
        result =
          result.where(
            "topics.id IN (SELECT pp.topic_id
                              FROM post_actions pa
                              JOIN posts pp ON pp.id = pa.post_id
                              WHERE pa.user_id = :user_id AND
                                    pa.post_action_type_id = :action AND
                                    pa.deleted_at IS NULL
                           )",
            user_id: @user.id,
            action: action,
          )
      end

      result = TopicQuery.tracked_filter(result, @user.id) if filter == "tracked"
    end

    result = result.where("topics.posts_count <= ?", options[:max_posts]) if options[
      :max_posts
    ].present?
    result = result.where("topics.posts_count >= ?", options[:min_posts]) if options[
      :min_posts
    ].present?

    result = TopicQuery.apply_custom_filters(result, self)

    result
  end

  def remove_muted(list, user, options)
    if options && (options[:include_muted].nil? || options[:include_muted]) &&
         options[:state] != "muted"
      list = remove_muted_topics(list, user)
    end

    list = remove_muted_categories(list, user, exclude: options[:category])
    TopicQuery.remove_muted_tags(list, user, options)
  end

  def remove_muted_topics(list, user)
    if user
      list =
        list.where(
          "COALESCE(tu.notification_level,1) > :muted",
          muted: TopicUser.notification_levels[:muted],
        )
    end

    list
  end

  def remove_muted_categories(list, user, opts = nil)
    category_id = get_category_id(opts[:exclude]) if opts

    if user
      list =
        list
          .references("cu")
          .joins(
            "LEFT JOIN category_users ON category_users.category_id = topics.category_id AND category_users.user_id = #{user.id}",
          )
          .where(
            "topics.category_id = :category_id
                OR
                (COALESCE(category_users.notification_level, :default) <> :muted AND (topics.category_id IS NULL OR topics.category_id NOT IN(:indirectly_muted_category_ids)))
                OR tu.notification_level > :regular",
            category_id: category_id || -1,
            default: CategoryUser.default_notification_level,
            indirectly_muted_category_ids:
              CategoryUser.indirectly_muted_category_ids(user).presence || [-1],
            muted: CategoryUser.notification_levels[:muted],
            regular: TopicUser.notification_levels[:regular],
          )
    elsif SiteSetting.mute_all_categories_by_default
      category_ids = [
        SiteSetting.default_categories_watching.split("|"),
        SiteSetting.default_categories_tracking.split("|"),
        SiteSetting.default_categories_watching_first_post.split("|"),
        SiteSetting.default_categories_normal.split("|"),
      ].flatten.map(&:to_i)
      category_ids << category_id if category_id.present? && category_ids.exclude?(category_id)

      list = list.where("categories.id IN (?)", category_ids) if category_ids.present?
    else
      category_ids = SiteSetting.default_categories_muted.split("|").map(&:to_i)
      category_ids -= [category_id] if category_id.present? && category_ids.include?(category_id)

      list = list.where("categories.id NOT IN (?)", category_ids) if category_ids.present?
    end

    list
  end

  def self.remove_muted_tags(list, user, opts = {})
    if !SiteSetting.tagging_enabled || SiteSetting.remove_muted_tags_from_latest == "never"
      return list
    end

    muted_tag_ids = []

    if user.present?
      muted_tag_ids = TagUser.lookup(user, :muted).pluck(:tag_id)
    else
      muted_tag_names = SiteSetting.default_tags_muted.split("|")

      muted_tag_ids = Tag.where(name: muted_tag_names).pluck(:id) if muted_tag_names.present?
    end

    return list if muted_tag_ids.blank?

    # if viewing the topic list for a muted tag, show all the topics
    if !opts[:no_tags] && opts[:tags].present?
      if TagUser
           .lookup(user, :muted)
           .joins(:tag)
           .where("lower(tags.name) = ?", opts[:tags].first.downcase)
           .exists?
        return list
      end
    end

    if SiteSetting.remove_muted_tags_from_latest == "always"
      list =
        list.where(
          "
        NOT EXISTS(
          SELECT 1
            FROM topic_tags tt
           WHERE tt.tag_id IN (:tag_ids)
             AND tt.topic_id = topics.id)",
          tag_ids: muted_tag_ids,
        )
    else
      list =
        list.where(
          "
        EXISTS (
          SELECT 1
            FROM topic_tags tt
           WHERE tt.tag_id NOT IN (:tag_ids)
             AND tt.topic_id = topics.id
        ) OR NOT EXISTS (SELECT 1 FROM topic_tags tt WHERE tt.topic_id = topics.id)",
          tag_ids: muted_tag_ids,
        )
    end
  end

  def remove_dismissed(list, user)
    if user
      list.joins(<<~SQL).where("dismissed_topic_users.id IS NULL")
        LEFT JOIN dismissed_topic_users
        ON dismissed_topic_users.topic_id = topics.id
        AND dismissed_topic_users.user_id = #{user.id.to_i}
        SQL
    else
      list
    end
  end

  def new_messages(params)
    TopicQuery.new_filter(
      messages_for_groups_or_user(params[:my_group_ids]),
      treat_as_new_topic_start_date: Time.at(SiteSetting.min_new_topics_time).to_datetime,
    ).limit(params[:count])
  end

  def unread_messages(params)
    query =
      TopicQuery.unread_filter(
        messages_for_groups_or_user(params[:my_group_ids]),
        whisperer: @user.whisperer?,
      )

    first_unread_pm_at =
      if params[:my_group_ids].present?
        GroupUser.where(user_id: @user.id, group_id: params[:my_group_ids]).minimum(
          :first_unread_pm_at,
        )
      else
        UserStat.where(user_id: @user.id).pick(:first_unread_pm_at)
      end

    query = query.where("topics.updated_at >= ?", first_unread_pm_at) if first_unread_pm_at
    query = query.limit(params[:count]) if params[:count]
    query
  end

  def related_messages_user(params)
    messages = messages_for_user.limit(params[:count])
    messages = allowed_messages(messages, params)
  end

  def related_messages_group(params)
    messages = messages_for_groups_or_user(params[:my_group_ids]).limit(params[:count])
    messages = allowed_messages(messages, params)
  end

  def allowed_messages(messages, params)
    user_ids = (params[:target_user_ids] || [])
    group_ids = ((params[:target_group_ids] - params[:my_group_ids]) || [])

    if user_ids.present?
      messages =
        messages.joins(
          "
          LEFT JOIN topic_allowed_users ta2
          ON topics.id = ta2.topic_id
          AND #{DB.sql_fragment("ta2.user_id IN (?)", user_ids)}
        ",
        )
    end

    if group_ids.present?
      messages =
        messages.joins(
          "
          LEFT JOIN topic_allowed_groups tg2
          ON topics.id = tg2.topic_id
          AND #{DB.sql_fragment("tg2.group_id IN (?)", group_ids)}
        ",
        )
    end

    messages =
      if user_ids.present? && group_ids.present?
        messages.where("ta2.topic_id IS NOT NULL OR tg2.topic_id IS NOT NULL")
      elsif user_ids.present?
        messages.where("ta2.topic_id IS NOT NULL")
      elsif group_ids.present?
        messages.where("tg2.topic_id IS NOT NULL")
      end
  end

  def messages_for_groups_or_user(group_ids)
    if group_ids.present?
      base_messages.joins(
        "
          LEFT JOIN (
            SELECT * FROM topic_allowed_groups _tg
            LEFT JOIN group_users gu
            ON gu.user_id = #{@user.id.to_i}
            AND gu.group_id = _tg.group_id
            WHERE #{DB.sql_fragment("gu.group_id IN (?)", group_ids)}
          ) tg ON topics.id = tg.topic_id
        ",
      ).where("tg.topic_id IS NOT NULL")
    else
      messages_for_user
    end
  end

  def messages_for_user
    base_messages.joins(
      "
        LEFT JOIN topic_allowed_users ta
        ON topics.id = ta.topic_id
        AND ta.user_id = #{@user.id.to_i}
      ",
    ).where("ta.topic_id IS NOT NULL")
  end

  def base_messages
    query =
      Topic.where("topics.archetype = ?", Archetype.private_message).joins(
        "LEFT JOIN topic_users tu ON topics.id = tu.topic_id AND tu.user_id = #{@user.id.to_i}",
      )

    query = query.includes(:tags) if SiteSetting.tagging_enabled
    query.order("topics.bumped_at DESC")
  end

  def random_suggested(topic, count, excluded_topic_ids = [])
    result = default_results(unordered: true, per_page: count).where(closed: false, archived: false)

    if SiteSetting.limit_suggested_to_category
      excluded_topic_ids += Category.where(id: topic.category_id).pluck(:id)
    else
      excluded_topic_ids += Category.topic_ids.to_a
    end
    result =
      result.where("topics.id NOT IN (?)", excluded_topic_ids) unless excluded_topic_ids.empty?

    result = remove_muted_categories(result, @user)
    result = remove_muted_topics(result, @user)

    # If we are in a category, prefer it for the random results
    if topic.category_id
      result =
        result.order("CASE WHEN topics.category_id = #{topic.category_id.to_i} THEN 0 ELSE 1 END")
    end

    # Best effort, it over selects, however if you have a high number
    # of muted categories there is tiny chance we will not select enough
    # in particular this can happen if current category is empty and tons
    # of muted, big edge case
    #
    # we over select in case cache is stale
    max = (count * 1.3).to_i
    ids = SiteSetting.limit_suggested_to_category ? [] : RandomTopicSelector.next(max)
    ids.concat(RandomTopicSelector.next(max, topic.category))

    result.where(id: ids.uniq)
  end

  def suggested_ordering(result, options)
    # Prefer unread in the same category
    if options[:topic] && options[:topic].category_id
      result =
        result.order(
          "CASE WHEN topics.category_id = #{options[:topic].category_id.to_i} THEN 0 ELSE 1 END",
        )
    end

    result.order("topics.bumped_at DESC")
  end

  private

  def unseen_filter(list, user_first_seen_at, whisperer)
    list = list.where("topics.bumped_at >= ?", user_first_seen_at)

    col_name = whisperer ? "highest_staff_post_number" : "highest_post_number"
    list.where("tu.last_read_post_number IS NULL OR tu.last_read_post_number < topics.#{col_name}")
  end

  def apply_max_age_limit(results, options)
    if @user
      # micro optimisation so we don't load up all of user stats which we do not need
      unread_at =
        DB.query_single("select first_unread_at from user_stats where user_id = ?", @user.id).first

      if max_age = options[:max_age]
        max_age_date = max_age.days.ago
        unread_at ||= max_age_date
        unread_at = unread_at > max_age_date ? unread_at : max_age_date
      end

      # perf note, in the past we tried doing this in a subquery but performance was
      # terrible, also tried with a join and it was bad
      results = results.where("topics.updated_at >= ?", unread_at)
    end
    results
  end

  def filter_by_tags(result)
    tags_arg = @options[:tags]

    if tags_arg && tags_arg.size > 0
      tags_arg = tags_arg.split if String === tags_arg
      tags_query = tags_arg[0].is_a?(String) ? Tag.where_name(tags_arg) : Tag.where(id: tags_arg)
      tags = tags_query.select(:id, :target_tag_id).map { |t| t.target_tag_id || t.id }.uniq

      if ActiveModel::Type::Boolean.new.cast(@options[:match_all_tags])
        # ALL of the given tags:
        if tags_arg.length == tags.length
          tags.each_with_index do |tag, index|
            sql_alias = ["t", index].join

            result =
              result.joins(
                "INNER JOIN topic_tags #{sql_alias} ON #{sql_alias}.topic_id = topics.id AND #{sql_alias}.tag_id = #{tag}",
              )
          end
        else
          result = result.none # don't return any results unless all tags exist in the database
        end
      else
        # ANY of the given tags:
        result = result.joins(:tags).where("tags.id in (?)", tags)
      end

      # TODO: this is very side-effecty and should be changed
      # It is done cause further up we expect normalized tags
      @options[:tags] = tags
    elsif @options[:no_tags]
      # the following will do: ("topics"."id" NOT IN (SELECT DISTINCT "topic_tags"."topic_id" FROM "topic_tags"))
      result = result.where.not(id: TopicTag.distinct.select(:topic_id))
    end

    if @options[:exclude_tag].present? &&
         !DiscourseTagging.hidden_tag_names(@guardian).include?(@options[:exclude_tag])
      result = result.where(<<~SQL, name: @options[:exclude_tag])
        topics.id NOT IN (
          SELECT topic_tags.topic_id
          FROM topic_tags
          INNER JOIN tags ON tags.id = topic_tags.tag_id
          WHERE tags.name = :name
        )
        SQL
    end

    result
  end
end