feat(tools:currency-converter): show 1:1 rates for all available currencies

app/apps/mini_tools/utils/exchange_rate_map.py

@@ -0,0 +1,85 @@
+from typing import Dict
+
+from django.db.models import Func, F, Value
+from django.db.models.functions import Extract
+from django.utils import timezone
+
+from apps.currencies.models import ExchangeRate
+
+
+def get_currency_exchange_map(date=None) -> Dict[str, dict]:
+    """
+    Creates a nested dictionary of exchange rates and currency information.
+
+    Returns:
+    {
+        'BTC': {
+            'decimal_places': 8,
+            'prefix': '₿',
+            'suffix': '',
+            'rates': {'USD': Decimal('34000.00'), 'EUR': Decimal('31000.00')}
+        },
+        'USD': {
+            'decimal_places': 2,
+            'prefix': '$',
+            'suffix': '',
+            'rates': {'BTC': Decimal('0.0000294'), 'EUR': Decimal('0.91')}
+        },
+        ...
+    }
+    """
+    if date is None:
+        date = timezone.localtime(timezone.now())
+
+    # Get all exchange rates for the closest date
+    exchange_rates = (
+        ExchangeRate.objects.select_related(
+            "from_currency", "to_currency"
+        )  # Optimize currency queries
+        .annotate(
+            date_diff=Func(Extract(F("date") - Value(date), "epoch"), function="ABS"),
+            effective_rate=F("rate"),
+        )
+        .order_by("from_currency", "to_currency", "date_diff")
+        .distinct("from_currency", "to_currency")
+    )
+
+    # Initialize the result dictionary
+    rate_map = {}
+
+    # Build the exchange rate mapping with currency info
+    for rate in exchange_rates:
+        # Add from_currency info if not exists
+        if rate.from_currency.name not in rate_map:
+            rate_map[rate.from_currency.name] = {
+                "decimal_places": rate.from_currency.decimal_places,
+                "prefix": rate.from_currency.prefix,
+                "suffix": rate.from_currency.suffix,
+                "rates": {},
+            }
+
+        # Add to_currency info if not exists
+        if rate.to_currency.name not in rate_map:
+            rate_map[rate.to_currency.name] = {
+                "decimal_places": rate.to_currency.decimal_places,
+                "prefix": rate.to_currency.prefix,
+                "suffix": rate.to_currency.suffix,
+                "rates": {},
+            }
+
+        # Add direct rate
+        rate_map[rate.from_currency.name]["rates"][rate.to_currency.name] = {
+            "rate": rate.rate,
+            "decimal_places": rate.to_currency.decimal_places,
+            "prefix": rate.to_currency.prefix,
+            "suffix": rate.to_currency.suffix,
+        }
+        # Add inverse rate
+        rate_map[rate.to_currency.name]["rates"][rate.from_currency.name] = {
+            "rate": 1 / rate.rate,
+            "decimal_places": rate.from_currency.decimal_places,
+            "prefix": rate.from_currency.prefix,
+            "suffix": rate.from_currency.suffix,
+        }
+
+    return rate_map

app/apps/mini_tools/views.py

@@ -5,6 +5,7 @@ from apps.common.widgets.decimal import convert_to_decimal
 from apps.currencies.models import Currency
 from apps.currencies.utils.convert import convert
 from apps.mini_tools.forms import CurrencyConverterForm
+from apps.mini_tools.utils.exchange_rate_map import get_currency_exchange_map
 
 
 @login_required
@@ -14,11 +15,13 @@ def unit_price_calculator(request):
 
 @login_required
 def currency_converter(request):
+    rate_map = get_currency_exchange_map()
+
     form = CurrencyConverterForm()
     return render(
         request,
         "mini_tools/currency_converter/currency_converter.html",
-        context={"form": form},
+        context={"form": form, "rate_map": rate_map},
     )