From 7169d1ba2745ed4cb71338120be493d7540096d8 Mon Sep 17 00:00:00 2001
From: Edward Betts <edward@4angle.com>
Date: Sun, 4 Aug 2024 11:44:44 +0800
Subject: [PATCH] Improve support for adding a new currency

---
 agenda/fx.py          | 14 +++++++++++---
 templates/macros.html |  2 +-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/agenda/fx.py b/agenda/fx.py
index efd4d7d..0e22711 100644
--- a/agenda/fx.py
+++ b/agenda/fx.py
@@ -44,10 +44,16 @@ async def get_gbpusd(config: flask.config.Config) -> Decimal:
     return typing.cast(Decimal, 1 / data["quotes"]["USDGBP"])
 
 
-def read_cached_rates(filename: str, currencies: list[str]) -> dict[str, Decimal]:
+def read_cached_rates(
+    filename: str | None, currencies: list[str]
+) -> dict[str, Decimal]:
     """Read FX rates from cache."""
+    if filename is None:
+        return {}
+
     with open(filename) as file:
         data = json.load(file, parse_float=Decimal)
+
     return {
         cur: Decimal(data["quotes"][f"GBP{cur}"])
         for cur in currencies
@@ -69,7 +75,9 @@ def get_rates(config: flask.config.Config) -> dict[str, Decimal]:
     currency_string = ",".join(sorted(currencies))
     file_suffix = f"{currency_string}_to_GBP.json"
     existing_data = os.listdir(fx_dir)
-    existing_files = [f for f in existing_data if f.endswith(file_suffix)]
+    existing_files = [f for f in existing_data if f.endswith(".json")]
+
+    full_path: str | None = None
 
     if existing_files:
         recent_filename = max(existing_files)
@@ -77,7 +85,7 @@ def get_rates(config: flask.config.Config) -> dict[str, Decimal]:
         delta = now - recent
 
         full_path = os.path.join(fx_dir, recent_filename)
-        if delta < timedelta(hours=12):
+        if not recent_filename.endswith(file_suffix) or delta < timedelta(hours=12):
             return read_cached_rates(full_path, currencies)
 
     url = "http://api.exchangerate.host/live"
diff --git a/templates/macros.html b/templates/macros.html
index ae77489..a01925b 100644
--- a/templates/macros.html
+++ b/templates/macros.html
@@ -38,7 +38,7 @@
   <div class="grid-item text-end">
     {% if item.price and item.currency %}
       <span class="badge bg-info text-nowrap">{{ "{:,d}".format(item.price | int) }} {{ item.currency }}</span>
-      {% if item.currency != "GBP" %}
+      {% if item.currency != "GBP" and item.currency in fx_rate %}
         <span class="badge bg-info text-nowrap">{{ "{:,.2f}".format(item.price / fx_rate[item.currency]) }} GBP</span>
       {% endif %}
     {% elif item.free %}