ministryofjustice/peoplefinder

require "csv"

module CsvPublisher
  class UserBehaviorReport
    extend SingleForwardable

    attr_reader :file, :query, :dataset

    FILE_EXTENSION = "csv".freeze

    def initialize
      @file = self.class.default_file_path
      @query = UserBehaviorQuery.new
    end

    def publish!
      @dataset = query.data
      write! if dataset.present?
    end
    def_single_delegator :new, :publish!, :publish!

    class << self
      def report_name
        name.demodulize.underscore
      end

      def default_file_path
        FileUtils.mkdir_p tmp_dir
        tmp_dir.join(default_file_name)
      end

    private

      def tmp_dir
        @tmp_dir ||= Rails.root.join("tmp/reports")
      end

      # e.g. peoplefinder_staging_user_behavior_report
      def default_file_name
        "#{Rails.application.class.module_parent_name.underscore}_#{(ENV['ENV'] || Rails.env).downcase}_#{report_name}.#{FILE_EXTENSION}"
      end
    end

  private

    def csv_header
      dataset.first.keys
    end

    def csv_record(record_hash)
      csv_record = []
      record_hash.each_value do |value|
        csv_record += [value]
      end
      csv_record
    end

    def save!(file)
      content = File.read(file)
      Report.where(name: self.class.report_name).delete_all
      Report.create(name: self.class.report_name, content:, extension: FILE_EXTENSION, mime_type: "text/csv") # rubocop:disable Rails/SaveBang
    end

    def write!
      CSV.open(file, "w", write_headers: true, headers: csv_header) do |csv|
        dataset.each do |rec|
          csv << csv_record(rec)
        end
      end
      save!(file)
    end
  end
end