feat(currencies): add automatic exchange rate fetching

Closes #123

app/apps/currencies/forms.py

@@ -1,3 +1,4 @@
+from crispy_bootstrap5.bootstrap5 import Switch
 from crispy_forms.bootstrap import FormActions
 from crispy_forms.helper import FormHelper
 from crispy_forms.layout import Layout
@@ -9,7 +10,7 @@ from apps.common.widgets.crispy.submit import NoClassSubmit
 from apps.common.widgets.datepicker import AirDateTimePickerInput
 from apps.common.widgets.decimal import ArbitraryDecimalDisplayNumberInput
 from apps.common.widgets.tom_select import TomSelect
-from apps.currencies.models import Currency, ExchangeRate
+from apps.currencies.models import Currency, ExchangeRate, ExchangeRateService
 
 
 class CurrencyForm(forms.ModelForm):
@@ -99,3 +100,50 @@ class ExchangeRateForm(forms.ModelForm):
                     ),
                 ),
             )
+
+
+class ExchangeRateServiceForm(forms.ModelForm):
+    class Meta:
+        model = ExchangeRateService
+        fields = [
+            "name",
+            "service_type",
+            "is_active",
+            "api_key",
+            "fetch_interval_hours",
+            "target_currencies",
+            "target_accounts",
+        ]
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.helper = FormHelper()
+        self.helper.form_tag = False
+        self.helper.form_method = "post"
+        self.helper.layout = Layout(
+            "name",
+            "service_type",
+            Switch("is_active"),
+            "api_key",
+            "fetch_interval_hours",
+            "target_currencies",
+            "target_accounts",
+        )
+
+        if self.instance and self.instance.pk:
+            self.helper.layout.append(
+                FormActions(
+                    NoClassSubmit(
+                        "submit", _("Update"), css_class="btn btn-outline-primary w-100"
+                    ),
+                ),
+            )
+        else:
+            self.helper.layout.append(
+                FormActions(
+                    NoClassSubmit(
+                        "submit", _("Add"), css_class="btn btn-outline-primary w-100"
+                    ),
+                ),
+            )