From a368dfa7b52066c0c5423f898823be18091cae84 Mon Sep 17 00:00:00 2001
From: Sam Germain <sam.germain@usask.ca>
Date: Wed, 7 Jul 2021 21:04:38 -0600
Subject: [PATCH] Changed InterestMode enum implementation

---
 freqtrade/enums/interestmode.py     | 28 +++++++++++-----------------
 freqtrade/persistence/migrations.py |  6 ++++--
 freqtrade/persistence/models.py     |  4 +---
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/freqtrade/enums/interestmode.py b/freqtrade/enums/interestmode.py
index c95f4731f..f35573f1f 100644
--- a/freqtrade/enums/interestmode.py
+++ b/freqtrade/enums/interestmode.py
@@ -1,30 +1,24 @@
 from enum import Enum, auto
 from decimal import Decimal
+from freqtrade.exceptions import OperationalException
 
 one = Decimal(1.0)
 four = Decimal(4.0)
 twenty_four = Decimal(24.0)
 
 
-class FunctionProxy:
-    """Allow to mask a function as an Object."""
+class InterestMode(Enum):
 
-    def __init__(self, function):
-        self.function = function
+    HOURSPERDAY = "HOURSPERDAY"
+    HOURSPER4 = "HOURSPER4"  # Hours per 4 hour segment
 
     def __call__(self, *args, **kwargs):
-        return self.function(*args, **kwargs)
 
+        borrowed, rate, hours = kwargs["borrowed"], kwargs["rate"], kwargs["hours"]
 
-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))
-    )
+        if self.name == "HOURSPERDAY":
+            return borrowed * rate * max(hours, one)/twenty_four
+        elif self.name == "HOURSPER4":
+            return borrowed * rate * (1 + max(0, (hours-four)/four))
+        else:
+            raise OperationalException(f"Leverage not available on this exchange with freqtrade")
diff --git a/freqtrade/persistence/migrations.py b/freqtrade/persistence/migrations.py
index 69ffc544e..b7c969945 100644
--- a/freqtrade/persistence/migrations.py
+++ b/freqtrade/persistence/migrations.py
@@ -52,6 +52,7 @@ def migrate_trades_table(decl_base, inspector, engine, table_back_name: str, col
     interest_rate = get_column_def(cols, 'interest_rate', '0.0')
     liquidation_price = get_column_def(cols, 'liquidation_price', 'null')
     is_short = get_column_def(cols, 'is_short', 'False')
+    interest_mode = get_column_def(cols, 'interest_mode', 'null')
     # If ticker-interval existed use that, else null.
     if has_column(cols, 'ticker_interval'):
         timeframe = get_column_def(cols, 'timeframe', 'ticker_interval')
@@ -88,7 +89,7 @@ def migrate_trades_table(decl_base, inspector, engine, table_back_name: str, col
             stoploss_order_id, stoploss_last_update,
             max_rate, min_rate, sell_reason, sell_order_status, strategy,
             timeframe, open_trade_value, close_profit_abs,
-            leverage, interest_rate, liquidation_price, is_short
+            leverage, interest_rate, liquidation_price, is_short, interest_mode
             )
         select id, lower(exchange),
             case
@@ -113,7 +114,8 @@ def migrate_trades_table(decl_base, inspector, engine, table_back_name: str, col
             {strategy} strategy, {timeframe} timeframe,
             {open_trade_value} open_trade_value, {close_profit_abs} close_profit_abs,
             {leverage} leverage, {interest_rate} interest_rate,
-            {liquidation_price} liquidation_price, {is_short} is_short
+            {liquidation_price} liquidation_price, {is_short} is_short,
+            {interest_mode} interest_mode
             from {table_back_name}
             """))
 
diff --git a/freqtrade/persistence/models.py b/freqtrade/persistence/models.py
index b9c1b89a8..9aa340fdc 100644
--- a/freqtrade/persistence/models.py
+++ b/freqtrade/persistence/models.py
@@ -612,8 +612,6 @@ class LocalTrade():
         # If nothing was borrowed
         if self.has_no_leverage:
             return zero
-        elif not self.interest_mode:
-            raise OperationalException(f"Leverage not available on {self.exchange} using freqtrade")
 
         open_date = self.open_date.replace(tzinfo=None)
         now = (self.close_date or datetime.now(timezone.utc)).replace(tzinfo=None)
@@ -624,7 +622,7 @@ class LocalTrade():
         rate = Decimal(interest_rate or self.interest_rate)
         borrowed = Decimal(self.borrowed)
 
-        return self.interest_mode.value(borrowed, rate, hours)
+        return self.interest_mode(borrowed=borrowed, rate=rate, hours=hours)
 
     def calc_close_trade_value(self, rate: Optional[float] = None,
                                fee: Optional[float] = None,