class SitemapEntriesController < ApplicationController
  PAGE_SIZE = 1_000
  RESOURCES = [
      'posts', 'tags', 'deerjikists', 'materials',
      'descriptions', 'tag_groups', 'theatres'].freeze

  def index
    locale = resolve_locale!
    resources = RESOURCES.map { |resource| { resource:, count: entries(resource, locale).count } }
    render json: { resources:, page_size: PAGE_SIZE }
  end

  def show
    locale = resolve_locale!
    resource = params[:resource]
    return head :not_found unless RESOURCES.include?(resource)

    page = Integer(params.fetch(:page, '1'), exception: false)
    return head :bad_request unless page && page.positive?

    scope = entries(resource, locale)
    return head :not_found if page > [(scope.count.to_f / PAGE_SIZE).ceil, 1].max

    ids = scope.order(:id).offset((page - 1) * PAGE_SIZE).limit(PAGE_SIZE).pluck(:id)
    render json: { ids: }
  end

  private

  def entries resource, locale
    named_tags = TagName.where(language_code: locale.language_code, primary_flg: true)
        .select(:tag_id)
    case resource
    when 'posts'
      Post.all
    when 'tags'
      Tag.where(id: named_tags)
    when 'deerjikists'
      Tag.where(id: named_tags).where(id: Deerjikist.select(:tag_id))
    when 'materials'
      Material.all
    when 'descriptions'
      TagDescription.where(language_code: locale.language_code, tag_id: named_tags)
          .where.not(body: [nil, ''])
          .where(TagDescriptionVersion
              .where('tag_description_versions.tag_id = tag_descriptions.tag_id')
              .where('tag_description_versions.language_code = tag_descriptions.language_code')
              .where('tag_description_versions.version_no = tag_descriptions.version_no')
              .arel.exists)
    when 'tag_groups'
      TagGroup.joins(:versions)
          .where('tag_group_versions.version_no = tag_groups.version_no')
    when 'theatres'
      Theatre.kept
    end
  end
end