Added basic currency exchange data

server/foxbank_server/apis/__init__.py

@@ -5,6 +5,7 @@ from .accounts import bp as acc_bp
 from .login import bp as login_bp
 from .transactions import bp as transactions_bp
 from .notifications import bp as notifications_bp
+from .forex import bp as forex_bp
 
 class ApiWithErr(Api):
     def handle_http_exception(self, error):
@@ -31,3 +32,4 @@ def init_apis(app: Flask):
     api.register_blueprint(acc_bp, url_prefix='/accounts')
     api.register_blueprint(transactions_bp, url_prefix='/transactions')
     api.register_blueprint(notifications_bp, url_prefix='/notifications')
+    api.register_blueprint(forex_bp, url_prefix='/forex')

server/foxbank_server/apis/forex.py

@@ -0,0 +1,26 @@
+from flask.views import MethodView
+from flask_smorest import Blueprint
+from marshmallow import Schema, fields
+
+from ..db_utils import get_forex_rate
+from .. import returns
+
+bp = Blueprint('forex', __name__, description='Foreign Exchange information')
+
+class GetExchangeResult(returns.SuccessSchema):
+    rate = fields.Float(optional=True)
+
+@bp.get('/<from_currency>/<to_currency>')
+@bp.response(422, returns.ErrorSchema, description='Invalid currency')
+@bp.response(200, GetExchangeResult)
+def get_exchange(from_currency: str, to_currency: str):
+    """Get exchange rate between two currencies"""
+    if from_currency == to_currency:
+        rate = 1
+    else:
+        rate = get_forex_rate(from_currency, to_currency)
+
+    if rate is None:
+        return returns.abort(returns.invalid_argument('currency'))
+
+    return returns.success(rate=rate)

server/foxbank_server/db_utils.py

@@ -306,5 +306,32 @@ class Module(ModuleType):
         )
         self.db.commit()
 
+    @get_db
+    def get_forex_rate(self, from_currency: str, to_currency: str) -> float | None:
+        cur = self.db.cursor()
+
+        if from_currency == 'RON' or to_currency == 'RON':
+            currency_pairs = [(from_currency, to_currency)]
+        else:
+            currency_pairs = [(from_currency, 'RON'), ('RON', to_currency)]
+
+        amount = 1.0
+        for currency_pair in currency_pairs:
+            to_select = 'to_ron'
+            if currency_pair[0] == 'RON':
+                to_select = 'from_ron'
+            cur.execute(
+                f'select {to_select} from exchange where currency = ?',
+                (currency_pair[1] if currency_pair[0] == 'RON' else currency_pair[0],),
+            )
+            rate = cur.fetchone()
+            if rate is None:
+                amount = None
+                break
+            rate = rate[0]
+            amount *= rate
+
+        return amount
+
 
 sys.modules[__name__] = Module(__name__)

server/init.sql

@@ -60,6 +60,13 @@ create table users_notifications (
 	foreign key (notification_id) references notifications (id)
 );
 
+create table exchange (
+	id integer primary key autoincrement,
+	currency text not null,
+	to_ron real not null,
+	from_ron real not null
+);
+
 create view V_account_balance as
 select 
 	accounts_transactions.account_id as "account_id",