require 'csv'
require 'activerecord-import'
require 'zip'

module CanvasSync
  module Processors
    class ProvisioningReportProcessor
      # Used by the {CanvasSync::Importers::BulkImporter bulk importer}. The keys are
      # CSV columns and the values are the database columns.
      USERS_CSV_MAPPING = {
        canvas_user_id: :canvas_user_id,
        user_id: :sis_id,
        email: :email,
        first_name: :first_name,
        last_name: :last_name,
        status: :status,
        login_id: :login_id
      }

      COURSES_CSV_MAPPING = {
        canvas_course_id: :canvas_course_id,
        course_id: :sis_id,
        short_name: :short_name,
        long_name: :long_name,
        canvas_account_id: :canvas_account_id,
        canvas_term_id: :canvas_term_id,
        term_id: :term_sis_id,
        start_date: :start_date,
        end_date: :end_date,
        status: :status
      }

      ENROLLMENTS_CSV_MAPPING = {
        canvas_enrollment_id: :canvas_enrollment_id,
        canvas_course_id: :canvas_course_id,
        course_id: :course_sis_id,
        canvas_user_id: :canvas_user_id,
        user_id: :user_sis_id,
        role: :role,
        role_id: :role_id,
        canvas_section_id: :canvas_section_id,
        section_id: :section_sis_id,
        status: :status,
        base_role_type: :base_role_type
      }

      SECTIONS_CSV_MAPPING = {
        canvas_section_id: :canvas_section_id,
        section_id: :sis_id,
        canvas_course_id: :canvas_course_id,
        name: :name,
        status: :status,
        start_date: :start_date,
        end_date: :end_date
      }

      # Processes a provisioning report using the bulk importer.
      #
      # options must contain a models key. If there is only one model
      # Canvas downloads the single report directly as a CSV. If it's
      # more than one model Canvas downloads a ZIP file, so we have to
      # extract that and iterate through it for processing.
      #
      # @param report_file_path [String]
      # @param options [Hash]
      def self.process(report_file_path, options)
        if options[:models].length == 1
          send("process_#{options[:models][0]}", report_file_path)
        else
          unzipped_file_path = extract(report_file_path)
          Dir[unzipped_file_path + "/*.csv"].each do |file_path|
            model_name = file_path.split("/").last.split(".").first
            send("process_#{model_name}", file_path)
          end
        end
      end

      private

      def self.extract(file_path)
        unzipped_file_path = "#{file_path}_unzipped"

        Zip::File.open(file_path) do |zip_file|
          zip_file.each do |f|
            f_path = File.join(unzipped_file_path, f.name)
            FileUtils.mkdir_p(File.dirname(f_path))
            zip_file.extract(f, f_path) unless File.exist?(f_path)
          end
        end

        unzipped_file_path
      end

      def self.process_users(report_file_path)
        CanvasSync::Importers::BulkImporter.import(
          report_file_path,
          USERS_CSV_MAPPING,
          User,
          :canvas_user_id,
          true)
      end

      def self.process_courses(report_file_path)
        CanvasSync::Importers::BulkImporter.import(report_file_path, COURSES_CSV_MAPPING, Course, :canvas_course_id)
      end

      def self.process_enrollments(report_file_path)
        CanvasSync::Importers::BulkImporter.import(
          report_file_path,
          ENROLLMENTS_CSV_MAPPING,
          Enrollment,
          :canvas_enrollment_id,
          true)
      end

      def self.process_sections(report_file_path)
        CanvasSync::Importers::BulkImporter.import(report_file_path, SECTIONS_CSV_MAPPING, Section, :canvas_section_id)
      end
    end
  end
end