require_relative '../base'
require_relative 'support/database'
require_relative 'support/indexer'
require_relative 'support/settings'

module ImportScripts::Mbox
  class Importer < ImportScripts::Base
    # @param settings [ImportScripts::Mbox::Settings]
    def initialize(settings)
      @settings = settings
      super()

      @database = Database.new(@settings.data_dir, @settings.batch_size)
    end

    def change_site_settings
      super

      SiteSetting.enable_staged_users = true
    end

    protected

    def execute
      index_messages
      import_categories
      import_users
      import_posts
    end

    def index_messages
      puts '', 'creating index'
      indexer = Indexer.new(@database, @settings)
      indexer.execute
    end

    def import_categories
      puts '', 'creating categories'
      rows = @database.fetch_categories

      create_categories(rows) do |row|
        {
          id: row['name'],
          name: row['name']
        }
      end
    end

    def import_users
      puts '', 'creating users'
      total_count = @database.count_users
      last_email = ''

      batches do |offset|
        rows, last_email = @database.fetch_users(last_email)
        break if rows.empty?

        next if all_records_exist?(:users, rows.map { |row| row['email'] })

        create_users(rows, total: total_count, offset: offset) do |row|
          {
            id: row['email'],
            email: row['email'],
            name: row['name'],
            trust_level: @settings.trust_level,
            staged: true,
            created_at: to_time(row['date_of_first_message'])
          }
        end
      end
    end

    def batches
      super(@settings.batch_size)
    end

    def import_posts
      puts '', 'creating topics and posts'
      total_count = @database.count_messages
      last_row_id = 0

      batches do |offset|
        rows, last_row_id = @database.fetch_messages(last_row_id)
        break if rows.empty?

        next if all_records_exist?(:posts, rows.map { |row| row['msg_id'] })

        create_posts(rows, total: total_count, offset: offset) do |row|
          if row['in_reply_to'].blank?
            map_first_post(row)
          else
            map_reply(row)
          end
        end
      end
    end

    def map_post(row)
      user_id = user_id_from_imported_user_id(row['from_email']) || Discourse::SYSTEM_USER_ID
      body = row['body'] || ''
      body << map_attachments(row['raw_message'], user_id) if row['attachment_count'].positive?
      body << Email::Receiver.elided_html(row['elided']) if row['elided'].present?

      {
        id: row['msg_id'],
        user_id: user_id,
        created_at: to_time(row['email_date']),
        raw: body,
        raw_email: row['raw_message'],
        via_email: true,
        # cook_method: Post.cook_methods[:email] # this is slowing down the import by factor 4
      }
    end

    def map_first_post(row)
      mapped = map_post(row)
      mapped[:category] = category_id_from_imported_category_id(row['category'])
      mapped[:title] = row['subject'].strip[0...255]
      mapped
    end

    def map_reply(row)
      parent = @lookup.topic_lookup_from_imported_post_id(row['in_reply_to'])

      if parent.blank?
        puts "Parent message #{row['in_reply_to']} doesn't exist. Skipping #{row['msg_id']}: #{row['subject'][0..40]}"
        return nil
      end

      mapped = map_post(row)
      mapped[:topic_id] = parent[:topic_id]
      mapped
    end

    def map_attachments(raw_message, user_id)
      receiver = Email::Receiver.new(raw_message)
      attachment_markdown = ''

      receiver.attachments.each do |attachment|
        tmp = Tempfile.new(['discourse-email-attachment', File.extname(attachment.filename)])

        begin
          File.open(tmp.path, 'w+b') { |f| f.write attachment.body.decoded }
          upload = UploadCreator.new(tmp, attachment.filename).create_for(user_id)

          if upload && upload.errors.empty?
            attachment_markdown << "\n\n#{receiver.attachment_markdown(upload)}\n\n"
          end
        ensure
          tmp.try(:close!)
        end
      end

      attachment_markdown
    end

    def to_time(datetime)
      Time.zone.at(DateTime.iso8601(datetime)) if datetime
    end
  end
end