Moved interest calculation to an enum

freqtrade/enums/__init__.py

@@ -1,5 +1,6 @@
 # flake8: noqa: F401
 from freqtrade.enums.backteststate import BacktestState
+from freqtrade.enums.interestmode import InterestMode
 from freqtrade.enums.rpcmessagetype import RPCMessageType
 from freqtrade.enums.runmode import NON_UTIL_MODES, OPTIMIZE_MODES, TRADING_MODES, RunMode
 from freqtrade.enums.selltype import SellType

freqtrade/enums/interestmode.py

@@ -0,0 +1,30 @@
+from enum import Enum, auto
+from decimal import Decimal
+
+one = Decimal(1.0)
+four = Decimal(4.0)
+twenty_four = Decimal(24.0)
+
+
+class FunctionProxy:
+    """Allow to mask a function as an Object."""
+
+    def __init__(self, function):
+        self.function = function
+
+    def __call__(self, *args, **kwargs):
+        return self.function(*args, **kwargs)
+
+
+class InterestMode(Enum):
+    """Equations to calculate interest"""
+
+    # Interest_rate is per day, minimum time of 1 hour
+    HOURSPERDAY = FunctionProxy(
+        lambda borrowed, rate, hours: borrowed * rate * max(hours, one)/twenty_four
+    )
+
+    # Interest_rate is per 4 hours, minimum time of 4 hours
+    HOURSPER4 = FunctionProxy(
+        lambda borrowed, rate, hours: borrowed * rate * (1 + max(0, (hours-four)/four))
+    )