discourse/app/controllers/reviewables_controller.rb

class ReviewablesController < ApplicationController
  requires_login

  PER_PAGE = 10

  before_action :version_required, only: [:update, :perform]

  def index
    min_score = params[:min_score].nil? ? SiteSetting.min_score_default_visibility : params[:min_score].to_f
    offset = params[:offset].to_i

    if params[:type].present?
      raise Discourse::InvalidParameter.new(:type) unless Reviewable.valid_type?(params[:type])
    end

    status = (params[:status] || 'pending').to_sym
    raise Discourse::InvalidParameter.new(:status) unless allowed_statuses.include?(status)

    topic_id = params[:topic_id] ? params[:topic_id].to_i : nil
    category_id = params[:category_id] ? params[:category_id].to_i : nil

    filters = {
      status: status,
      category_id: category_id,
      topic_id: topic_id,
      min_score: min_score,
      username: params[:username],
      type: params[:type]
    }

    total_rows = Reviewable.list_for(current_user, filters).count
    reviewables = Reviewable.list_for(current_user, filters.merge(limit: PER_PAGE, offset: offset)).to_a

    # This is a bit awkward, but ActiveModel serializers doesn't seem to serialize STI. Note `hash`
    # is mutated by the serializer and contains the side loaded records which must be merged in the end.
    hash = {}
    json = {
      reviewables: reviewables.map! do |r|
        result = r.serializer.new(r, root: nil, hash: hash, scope: guardian).as_json
        hash[:bundled_actions].uniq!
        (hash['actions'] || []).uniq!
        result
      end,
      meta: filters.merge(
        total_rows_reviewables: total_rows, types: meta_types, reviewable_types: Reviewable.types
      )
    }
    if (offset + PER_PAGE) < total_rows
      json[:meta][:load_more_reviewables] = review_path(filters.merge(offset: offset + PER_PAGE))
    end
    json.merge!(hash)

    render_json_dump(json, rest_serializer: true)
  end

  def topics
    topic_ids = Set.new

    stats = {}
    unique_users = {}

    # topics isn't indexed on `reviewable_score` and doesn't know what the current user can see,
    # so let's query from the inside out.
    Reviewable.viewable_by(current_user).pending.each do |r|
      topic_ids << r.topic_id

      meta = stats[r.topic_id] ||= { count: 0, unique_users: 0 }
      users = unique_users[r.topic_id] ||= Set.new

      r.reviewable_scores.each do |rs|
        users << rs.user_id
        meta[:count] += 1
      end
      meta[:unique_users] = users.size
    end

    topics = Topic.where(id: topic_ids).order('reviewable_score DESC')
    render_serialized(topics, ReviewableTopicSerializer, root: 'reviewable_topics', stats: stats)
  end

  def show
    reviewable = find_reviewable

    render_serialized(
      reviewable,
      reviewable.serializer,
      rest_serializer: true,
      root: 'reviewable',
      meta: {
        types: meta_types
      }
    )
  end

  def update
    reviewable = find_reviewable
    editable = reviewable.editable_for(guardian)
    raise Discourse::InvalidAccess.new unless editable.present?

    # Validate parameters are all editable
    edit_params = params[:reviewable] || {}
    edit_params.each do |name, value|
      if value.is_a?(ActionController::Parameters)
        value.each do |pay_name, pay_value|
          raise Discourse::InvalidAccess.new unless editable.has?("#{name}.#{pay_name}")
        end
      else
        raise Discourse::InvalidAccess.new unless editable.has?(name)
      end
    end

    begin
      if reviewable.update_fields(edit_params, current_user, version: params[:version].to_i)
        result = edit_params.merge(version: reviewable.version)
        render json: result
      else
        render_json_error(reviewable.errors)
      end
    rescue Reviewable::UpdateConflict
      return render_json_error(I18n.t('reviewables.conflict'), status: 409)
    end
  end

  def perform
    args = { version: params[:version].to_i }

    begin
      result = find_reviewable.perform(current_user, params[:action_id].to_sym, args)
    rescue Reviewable::InvalidAction => e
      # Consider InvalidAction an InvalidAccess
      raise Discourse::InvalidAccess.new(e.message)
    rescue Reviewable::UpdateConflict
      return render_json_error(I18n.t('reviewables.conflict'), status: 409)
    end

    if result.success?
      render_serialized(result, ReviewablePerformResultSerializer)
    else
      render_json_error(result)
    end
  end

protected

  def find_reviewable
    reviewable = Reviewable.viewable_by(current_user).where(id: params[:reviewable_id]).first
    raise Discourse::NotFound.new if reviewable.blank?
    reviewable
  end

  def allowed_statuses
    @allowed_statuses ||= (%i[reviewed all] + Reviewable.statuses.keys)
  end

  def version_required
    if params[:version].blank?
      render_json_error(I18n.t('reviewables.missing_version'), status: 422)
    end
  end

  def meta_types
    {
      created_by: 'user',
      target_created_by: 'user'
    }
  end

end