From 2c49efbe67bbf2b82c0d08e85d047ebc96c65479 Mon Sep 17 00:00:00 2001
From: Sam Dudley <samuel.dudley@digital.trade.gov.uk>
Date: Mon, 25 Nov 2024 16:47:39 +0000
Subject: [PATCH] add contextvar magic small js optimisation

---
 core/utils/generic_helpers.py   | 10 ++++++++++
 forecast/views/edit_forecast.py |  4 ++--
 front_end/src/Util.js           |  5 +++--
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/core/utils/generic_helpers.py b/core/utils/generic_helpers.py
index 1c6564d21..0fa165cf9 100644
--- a/core/utils/generic_helpers.py
+++ b/core/utils/generic_helpers.py
@@ -1,4 +1,5 @@
 import datetime
+from contextvars import ContextVar
 
 from django.contrib.admin.models import CHANGE, LogEntry
 from django.contrib.contenttypes.models import ContentType
@@ -6,7 +7,14 @@
 from core.models import FinancialYear
 
 
+_current_financial_year = ContextVar("current_financial_year", default=None)
+
+
 def get_current_financial_year():
+    # FIXME: decide if to include this
+    if var := _current_financial_year.get():
+        return var
+
     y = FinancialYear.objects.filter(current=True)
     if y:
         current_financial_year = y.last().financial_year
@@ -27,6 +35,8 @@ def get_current_financial_year():
             # calendar year
             current_financial_year -= 1
 
+    _current_financial_year.set(current_financial_year)
+
     return current_financial_year
 
 
diff --git a/forecast/views/edit_forecast.py b/forecast/views/edit_forecast.py
index 0a1c8f1cf..4954c5d02 100644
--- a/forecast/views/edit_forecast.py
+++ b/forecast/views/edit_forecast.py
@@ -471,7 +471,7 @@ class EditForecastView(
     def class_name(self):
         return "wide-table"
 
-    # FIXME: might be risky
+    # FIXME: Triple check this is safe
     @cached_property
     def cost_centre_details(self):
         cost_centre = CostCentre.objects.select_related("directorate__group").get(
@@ -532,7 +532,7 @@ def get_payroll_forecast_report(self):
 
         return data
 
-    @property
+    @cached_property
     def future_year_display(self):
         if self._future_year_display is None:
             current_year = get_current_financial_year()
diff --git a/front_end/src/Util.js b/front_end/src/Util.js
index ee0510407..7aeb4deda 100644
--- a/front_end/src/Util.js
+++ b/front_end/src/Util.js
@@ -32,10 +32,11 @@ function getCookie(name) {
     return cookieValue;
 }
 
+const NumberFormat = new Intl.NumberFormat('en-GB'); 
+
 export const formatValue = (value) => {
-    let nfObject = new Intl.NumberFormat('en-GB'); 
     let pounds = Math.round(value)
-    return nfObject.format(pounds); 
+    return NumberFormat.format(pounds); 
 }
 
 /**