Remove report dependency on report controller

The ReportsController was referencing the report and the report was
referencing the controller. It's unlikely that this circular dependency
created a memory leak but it's generally a bad design. And we need to
make the reporting independent of the controller to isolate it in a
background job.

app/controllers/admin/reports_controller.rb

@@ -31,7 +31,7 @@ module Admin
     private
 
     def export_report
-      send_data @report.render_as(report_format, controller: self), filename: report_filename
+      send_data @report.render_as(report_format), filename: report_filename
     end
 
     def render_report

lib/reporting/report_renderer.rb

@@ -38,30 +38,29 @@ module Reporting
       @report.rows.map(&:to_h).as_json
     end
 
-    def render_as(target_format, controller: nil)
+    def render_as(target_format)
       unless target_format.to_sym.in?(REPORT_FORMATS)
         raise ActionController::BadRequest, "report_format should be in #{REPORT_FORMATS}"
       end
 
-      public_send("to_#{target_format}", controller)
+      public_send("to_#{target_format}")
     end
 
-    def to_csv(_context_controller = nil)
+    def to_csv
       SpreadsheetArchitect.to_csv(headers: table_headers, data: table_rows)
     end
 
-    def to_xlsx(_context_controller = nil)
+    def to_xlsx
       SpreadsheetArchitect.to_xlsx(spreadsheets_options)
     end
 
-    def to_pdf(context_controller)
-      WickedPdf.new.pdf_from_string(
-        context_controller.render_to_string(
-          template: 'admin/reports/_table',
-          layout: 'pdf',
-          locals: { report: @report }
-        )
+    def to_pdf
+      html = ApplicationController.render(
+        template: "admin/reports/_table",
+        layout: "pdf",
+        locals: { report: @report }
       )
+      WickedPdf.new.pdf_from_string(html)
     end
 
     private