discourse/lib/post_action_creator.rb

# frozen_string_literal: true

class PostActionCreator
  class CreateResult < PostActionResult
    attr_accessor :post_action, :reviewable, :reviewable_score
  end

  # Shortcut methods for easier invocation
  class << self
    def create(
      created_by,
      post,
      action_key,
      message: nil,
      created_at: nil,
      reason: nil,
      silent: false
    )
      new(
        created_by,
        post,
        PostActionType.types[action_key],
        message: message,
        created_at: created_at,
        reason: reason,
        silent: silent,
      ).perform
    end

    %i[like off_topic spam inappropriate].each do |action|
      define_method(action) do |created_by, post, silent = false|
        create(created_by, post, action, silent: silent)
      end
    end
    %i[notify_moderators notify_user illegal].each do |action|
      define_method(action) do |created_by, post, message = nil|
        create(created_by, post, action, message: message)
      end
    end
  end

  def initialize(
    created_by,
    post,
    post_action_type_id,
    is_warning: false,
    message: nil,
    take_action: false,
    flag_topic: false,
    created_at: nil,
    queue_for_review: false,
    reason: nil,
    silent: false
  )
    @created_by = created_by
    @created_at = created_at || Time.zone.now

    @post = post
    @post_action_type_id = post_action_type_id
    @post_action_name = PostActionType.types[@post_action_type_id]

    @is_warning = is_warning
    @take_action = take_action && guardian.is_staff?

    @message = message
    @flag_topic = flag_topic
    @meta_post = nil

    @reason = reason
    @queue_for_review = queue_for_review

    @reason = "queued_by_staff" if reason.nil? && @queue_for_review

    @silent = silent
  end

  def post_can_act?
    guardian.post_can_act?(
      @post,
      @post_action_name,
      opts: {
        is_warning: @is_warning,
        taken_actions: taken_actions,
      },
    )
  end

  def taken_actions
    return @taken_actions if defined?(@taken_actions)
    @taken_actions = PostAction.counts_for([@post].compact, @created_by)[@post&.id]
  end

  def perform
    result = CreateResult.new

    if !post_can_act? || (@queue_for_review && !guardian.is_staff?)
      result.forbidden = true

      if taken_actions&.keys&.include?(PostActionType.types[@post_action_name])
        result.add_error(I18n.t("action_already_performed"))
      else
        result.add_error(I18n.t("invalid_access"))
      end
      return result
    end

    PostAction.limit_action!(@created_by, @post, @post_action_type_id)

    reviewable = Reviewable.includes(:reviewable_scores).find_by(target: @post)

    if reviewable && flagging_post? && cannot_flag_again?(reviewable)
      result.add_error(I18n.t("reviewables.already_handled"))
      return result
    end

    # create meta topic / post if needed
    if @message.present? &&
         %i[notify_moderators notify_user spam illegal].include?(@post_action_name)
      creator = create_message_creator
      # We need to check if the creator exists because it's possible `create_message_creator` returns nil
      # in the event that a `post_action_notify_user_handler` evaluated to false, haulting the post creation.
      if creator
        post = creator.create
        if creator.errors.present?
          result.add_errors_from(creator)
          return result
        end
        @meta_post = post
      end
    end

    begin
      post_action = create_post_action

      if post_action.blank? || post_action.errors.present?
        result.add_errors_from(post_action)
      else
        create_reviewable(result)
        enforce_rules
        UserActionManager.post_action_created(post_action)
        PostActionNotifier.post_action_created(post_action) if !@silent
        notify_subscribers

        # agree with other flags
        if @take_action && reviewable = @post.reviewable_flag
          result.reviewable.perform(@created_by, :agree_and_keep)
          post_action.try(:update_counters)
        end

        result.success = true
        result.post_action = post_action
      end
    rescue ActiveRecord::RecordNotUnique
      # If the user already performed this action, it's probably due to a different browser tab
      # or non-debounced clicking. We can ignore.
      result.success = true
      result.post_action =
        PostAction.find_by(
          user: @created_by,
          post: @post,
          post_action_type_id: @post_action_type_id,
        )
    end

    result
  end

  private

  def flagging_post?
    PostActionType.notify_flag_type_ids.include?(@post_action_type_id)
  end

  def cannot_flag_again?(reviewable)
    return false if @post_action_type_id == PostActionType.types[:notify_moderators]
    flag_type_already_used =
      reviewable.reviewable_scores.any? do |rs|
        rs.reviewable_score_type == @post_action_type_id && !rs.pending?
      end
    not_edited_since_last_review =
      @post.last_version_at.blank? || reviewable.updated_at > @post.last_version_at
    handled_recently =
      reviewable.updated_at > SiteSetting.cooldown_hours_until_reflag.to_i.hours.ago

    flag_type_already_used && not_edited_since_last_review && handled_recently
  end

  def notify_subscribers
    if @post_action_name == :like
      @post.publish_change_to_clients! :liked,
                                       {
                                         likes_count: @post.like_count + 1,
                                         user_id: @created_by.id,
                                       }
    elsif self.class.notify_types.include?(@post_action_name)
      @post.publish_change_to_clients! :acted
    end
  end

  def self.notify_types
    @notify_types ||= PostActionType.notify_flag_types.keys
  end

  def enforce_rules
    auto_close_if_threshold_reached
    auto_hide_if_needed
    SpamRule::AutoSilence.new(@post.user, @post).perform
  end

  def auto_close_if_threshold_reached
    return if topic.nil? || topic.closed?
    return unless topic.auto_close_threshold_reached?

    # the threshold has been reached, we will close the topic waiting for intervention
    topic.update_status(
      "closed",
      true,
      Discourse.system_user,
      message:
        I18n.t("temporarily_closed_due_to_flags", count: SiteSetting.num_hours_to_close_topic),
    )

    topic.set_or_create_timer(
      TopicTimer.types[:open],
      SiteSetting.num_hours_to_close_topic,
      by_user: Discourse.system_user,
    )
  end

  def auto_hide_if_needed
    return if @post.hidden?
    return if !@created_by.staff? && @post.user&.staff?

    not_auto_action_flag_type = !PostActionType.auto_action_flag_types.include?(@post_action_name)
    return if not_auto_action_flag_type && !@queue_for_review

    if @queue_for_review
      @post.topic.update_status("visible", false, @created_by) if @post.is_first_post?

      @post.hide!(
        @post_action_type_id,
        Post.hidden_reasons[:flag_threshold_reached],
        custom_message: :queued_by_staff,
      )
      return
    end

    if trusted_spam_flagger?
      @post.hide!(@post_action_type_id, Post.hidden_reasons[:flagged_by_tl3_user])
      return
    end

    score = ReviewableFlaggedPost.find_by(target: @post)&.score || 0
    if score >= Reviewable.score_required_to_hide_post || @take_action
      @post.hide!(@post_action_type_id)
    end
  end

  # Special case: If you have TL3 and the user is TL0, and the flag is spam,
  # hide it immediately.
  def trusted_spam_flagger?
    SiteSetting.high_trust_flaggers_auto_hide_posts && @post_action_name == :spam &&
      @created_by.has_trust_level?(TrustLevel[3]) && @post.user&.trust_level == TrustLevel[0]
  end

  def create_post_action
    @targets_topic = !!(@post.topic.reload.posts_count != 1 if @flag_topic && @post.topic)

    where_attrs = {
      post_id: @post.id,
      user_id: @created_by.id,
      post_action_type_id: @post_action_type_id,
    }

    action_attrs = {
      staff_took_action: @take_action,
      related_post_id: @meta_post&.id,
      targets_topic: @targets_topic,
      created_at: @created_at,
    }

    # First try to revive a trashed record
    post_action = PostAction.where(where_attrs).with_deleted.where("deleted_at IS NOT NULL").first

    if post_action
      post_action.recover!
      action_attrs.each { |attr, val| post_action.public_send("#{attr}=", val) }
      post_action.save
    else
      post_action = PostAction.create(where_attrs.merge(action_attrs))
      if post_action && post_action.errors.count == 0
        BadgeGranter.queue_badge_grant(Badge::Trigger::PostAction, post_action: post_action)
      end
    end

    if post_action
      case @post_action_type_id
      when *PostActionType.notify_flag_type_ids
        DiscourseEvent.trigger(:flag_created, post_action, self)
      when PostActionType.types[:like]
        DiscourseEvent.trigger(:like_created, post_action, self)
      end
    end

    if @post_action_type_id == PostActionType.types[:like]
      GivenDailyLike.increment_for(@created_by.id)
    end

    post_action
  rescue ActiveRecord::RecordNotUnique
    # can happen despite being .create
    PostAction.where(where_attrs).first
  end

  def create_message_creator
    title =
      I18n.t(
        "post_action_types.#{@post_action_name}.email_title",
        title: @post.topic.title,
        locale: SiteSetting.default_locale,
      )

    body =
      I18n.t(
        "post_action_types.#{@post_action_name}.email_body",
        message: @message,
        link: "#{Discourse.base_url}#{@post.url}",
        locale: SiteSetting.default_locale,
      )

    create_args = {
      archetype: Archetype.private_message,
      is_warning: @is_warning,
      title: title.truncate(SiteSetting.max_topic_title_length, separator: /\s/),
      raw: body,
    }

    if %i[notify_moderators spam illegal].include?(@post_action_name)
      create_args[:subtype] = TopicSubtype.notify_moderators
      create_args[:target_group_names] = [Group[:moderators].name]

      if SiteSetting.enable_category_group_moderation? &&
           @post.topic&.category&.reviewable_by_group_id?
        create_args[:target_group_names] << @post.topic.category.reviewable_by_group.name
      end
    else
      create_args[:subtype] = TopicSubtype.notify_user

      if @post_action_name == :notify_user
        create_args[:target_usernames] = @post.user.username

        # Evaluate DiscoursePluginRegistry.post_action_notify_user_handlers.
        # If any return false, return early from this method
        handler_values =
          DiscoursePluginRegistry.post_action_notify_user_handlers.map do |handler|
            handler.call(@created_by, @post, @message)
          end
        return if handler_values.any? { |value| value == false }
      elsif @post_action_name != :notify_moderators
        # this is a hack to allow a PM with no recipients, we should think through
        # a cleaner technique, a PM with myself is valid for flagging
        "x"
      end
    end

    PostCreator.new(@created_by, create_args)
  end

  def create_reviewable(result)
    return unless flagging_post?
    return if @post.user_id.to_i < 0

    result.reviewable =
      ReviewableFlaggedPost.needs_review!(
        created_by: @created_by,
        target: @post,
        topic: @post.topic,
        reviewable_by_moderator: true,
        potential_spam: @post_action_type_id == PostActionType.types[:spam],
        payload: {
          targets_topic: @targets_topic,
        },
      )

    result.reviewable_score =
      result.reviewable.add_score(
        @created_by,
        @post_action_type_id,
        created_at: @created_at,
        take_action: @take_action,
        meta_topic_id: @meta_post&.topic_id,
        reason: @reason,
        force_review: trusted_spam_flagger?,
      )
  end

  def guardian
    @guardian ||= Guardian.new(@created_by)
  end

  def topic
    @post.topic
  end
end