class CountsExportsController < ApplicationController
  wrap_parameters false

  def prepare
    locale = resolve_locale!
    payload = request.request_parameters.merge(request.query_parameters)
    exporter = CountsExporter.new(payload, language_code: locale.language_code)
    session[:counts_export_owner] ||= SecureRandom.hex(32)
    token = CountsExportDownload.prepare(exporter, session[:counts_export_owner])
    response.headers['Cache-Control'] = 'private, no-store'
    render json: { token: }
  rescue ArgumentError, TypeError, KeyError, JSON::ParserError
    head :bad_request
  end

  def download
    file = CountsExportDownload.find(params[:token], session[:counts_export_owner])
    return head :not_found unless file

    response.headers['Cache-Control'] = 'private, no-store'
    send_file file.fetch('path'),
              filename: "counts-#{ file.fetch('resource') }.#{ file.fetch('format') }",
              type: file['format'] == 'json' ? 'application/json' : 'text/csv',
              disposition: 'attachment'
  end

  def index
    locale = resolve_locale!
    payload = request.request_parameters.except('authenticity_token')
        .merge(request.query_parameters)
    exporter = CountsExporter.new(payload,
                                  language_code: locale.language_code)
    response.headers['Content-Type'] = exporter.format == 'json' ?
        'application/json; charset=utf-8' : 'text/csv; charset=utf-8'
    response.headers['Content-Disposition'] =
        "attachment; filename=\"counts-#{ exporter.resource }.#{ exporter.format }\""
    response.headers['Cache-Control'] = 'private, no-store'
    response.headers['X-Accel-Buffering'] = 'no'
    # Rack::ETag otherwise materialises the response to calculate a digest.
    response.headers['Last-Modified'] = Time.current.httpdate
    self.response_body = exporter.body
  rescue ArgumentError, TypeError, KeyError, JSON::ParserError
    head :bad_request
  end
end