# frozen_string_literal: true

require 'google/apis/drive_v3'

module Lcms
  module Engine
    class LessonsGdocBundler
      PDF_LINKS_KEYS = { full: 'gdoc_full', tm: 'gdoc_tm', sm: 'gdoc_sm' }.freeze

      def initialize(unit)
        @unit = unit
      end

      def bundle
        return if unit.children.empty?

        # ensure root folder exists
        root_id = drive_service.create_folder root_folder

        unit_folder = drive_service.create_folder dirname(unit), root_id

        unit.children.includes(:documents).each do |resource|
          next unless resource.document?

          build_lesson_folder resource, unit_folder
        end

        # return (and save somewhere the unit bundle url)
        "https://drive.google.com/open?id=#{unit_folder}"
      rescue Google::Apis::TransmissionError => e
        Rails.logger.error "Failed to bundle unit: #{unit.slug}, #{e.message}"
      end

      private

      attr_reader :unit

      def build_lesson_folder(resource, unit_folder)
        document = resource.document
        # create lesson bundle folder
        lesson_bundle = drive_service.create_folder dirname(resource), unit_folder

        # copy files from gdoc_full
        full_folder = drive_id document.links[PDF_LINKS_KEYS[:full]]
        return unless full_folder

        drive_service.copy_files full_folder, lesson_bundle

        # materials
        %i(tm sm).each do |mtype|
          build_materials_folder document, lesson_bundle, mtype
        end
      rescue Google::Apis::ServerError => e
        Rails.logger.error "Failed to build lesson folder for #{resource.id}, #{e.message}"
      end

      def build_materials_folder(document, lesson_bundle, type)
        folder = drive_id document.links[PDF_LINKS_KEYS[type]]
        return unless folder

        name = type == :sm ? 'Student Materials' : 'Teacher Materials'
        materials_bundle = drive_service.create_folder name, lesson_bundle
        drive_service.copy_files folder, materials_bundle
      rescue Google::Apis::ServerError => e
        Rails.logger.error "Failed to build materials folder: #{document&.resource&.id} #{type}, #{e.message}"
      end

      def dirname(res)
        subject = res.subject.casecmp('math').zero? ? 'Math' : 'ELA'
        Breadcrumbs.new(res).short_pieces[1..].unshift(subject).join('-')
      end

      def drive_id(url)
        return unless url

        url.match(%r{drive\.google\.com/open\?id=([^/]+)})&.[](1)
      end

      def drive_service
        @drive_service ||= Google::DriveService.build(nil, gdoc_folder: root_folder)
      end

      def root_folder
        @root_folder ||= ENV['BUNDLES_ROOT_FOLDER'].presence || "unit-bundles-#{Rails.env}"
      end
    end
  end
end