alenaPy · Blackwoodseller · Feb 26, 2019
diff --git a/calculator/__init__.py b/calculator/__init__.py
diff --git a/calculator/money_calculator.py b/calculator/money_calculator.py
@@ -0,0 +1,93 @@
+"""Simple money expressions calculator"""
+
+from functools import lru_cache
+import requests
+
+
+class CurrencyConverter(object):
+    """Currency rates provider"""
+
+    def __init__(self):
+        url = 'http://www.apilayer.net/api/live?' \
+              'access_key=f9c1e5189e29b2bdedcc4ac740653e17'
+        response = requests.get(url)
+        if response.status_code != 200:
+            raise Exception('Unexpected response {}'.format(response))
+
+        self.table = response.json()['quotes']
+
+    def get_rate_from_usd(self, to_cur):
+        """Returns rate from USD for to_cur currency"""
+        target_cur = to_cur.strip().upper()
+        if target_cur == 'USD':
+            return 1
+
+        rates = [rate for cur, rate in self.table.items()
+                 if cur[3:] == target_cur]
+        if not rates:
+            raise RuntimeError('Unknown currency {}'.format(target_cur))
+
+        return rates[0]
+
+    @lru_cache(maxsize=32)
+    def get_rate(self, from_cur, to_cur):
+        """Returns currency rate
+
+        :param from_cur: initial currency abbreviation
+        :param to_cur:  target currency abbreviation
+        """
+        initial_rate = self.get_rate_from_usd(from_cur)
+        target_rate = self.get_rate_from_usd(to_cur)
+
+        return target_rate / initial_rate
+
+
+class Money(object):
+    """Money class with currency converting functionality"""
+    converter = CurrencyConverter()
+    operation_currency = 'EUR'
+    default_currency = 'USD'
+
+    def __init__(self, amount, currency=None):
+        self.amount = amount
+        self.currency = currency or self.default_currency
+
+    def __str__(self):
+        return '{} {}'.format(self.amount, self.currency)
+
+    def __add__(self, money):
+        return Money(
+            self.converter.get_rate(
+                self.currency,
+                self.operation_currency) * self.amount + self.converter.
+            get_rate(money.currency,
+                     self.operation_currency) * money.amount,
+            self.operation_currency)
+
+    def __sub__(self, money):
+        return Money(
+            self.converter.get_rate(
+                self.currency,
+                self.operation_currency) * self.amount - self.converter.
+            get_rate(money.currency,
+                     self.operation_currency) * money.amount,
+            self.operation_currency)
+
+    def __neg__(self):
+        return Money(- self.converter.get_rate(
+            self.currency, self.operation_currency) * self.amount,
+            self.operation_currency)
+
+    def __mul__(self, money):
+        return Money(money * self.converter.get_rate(
+            self.currency, self.operation_currency) * self.amount,
+            self.operation_currency)
+
+    __rmul__ = __mul__
+
+
+if __name__ == '__main__':
+    x = Money(10, 'BYN')
+    y = Money(11)  # define your own default value, e.g. “USD”
+    z = Money(12.34, 'EUR')
+    print(z + 3.11 * x + y * 0.8)  # result in “EUR”
diff --git a/setup.py b/setup.py
@@ -0,0 +1,12 @@
+from distutils.core import setup
+
+
+setup(
+    name="calculator",
+    version="0.0.1",
+    author="Oleksii Potorzhynskyi",
+    author_email="oleksii_potorzhynskyi@epam.com",
+    url="http://www.epam.com",
+    description="Money expression calculator example",
+    packages=["calculator"],
+)