Add --max-overdraft option

README.md

@@ -171,6 +171,10 @@ optional arguments:
   --cointracking-usd    Use this flag if you have configured cointracking
                         calculate prices in USD. Conversion from USD to SEK
                         will then be done by this script instead.
+  --max-overdraft MAX_OVERDRAFT
+                        The maximum overdraft to allow for each coin, at the
+                        event of an overdraft the coin balance will be set to
+                        zero.
 ```
 
 ### Example

report.py

@@ -29,6 +29,7 @@ def __str__(self):
 parser.add_argument('--rounding-report', help='Generate report of roundings done which can be pasted in Ovriga Upplysningar, the file will be put in the out folder.', action='store_true')
 parser.add_argument('--rounding-report-threshold', help='The number of percent difference required for an amount to be included in the report.', default='1')
 parser.add_argument('--cointracking-usd', help='Use this flag if you have configured cointracking calculate prices in USD. Conversion from USD to SEK will then be done by this script instead.', action='store_true')
+parser.add_argument('--max-overdraft', type=float, help='The maximum overdraft to allow for each coin, at the event of an overdraft the coin balance will be set to zero.', default=1e-9)
 opts = parser.parse_args()
 
 if not os.path.isdir(opts.out):
@@ -41,6 +42,7 @@ def __str__(self):
 tax_events = tax.compute_tax(trades,
                              datetime.datetime(year=opts.year,month=1,day=1,hour=0, minute=0),
                              datetime.datetime(year=opts.year,month=12,day=31,hour=23, minute=59),
+                             opts.max_overdraft,
                              exclude_groups=opts.exclude_groups if opts.exclude_groups else [],
                              coin_report_filename=os.path.join(opts.out, "coin_report.csv") if opts.coin_report else None
                              )

tax.py

@@ -9,10 +9,11 @@ def is_fiat(coin):
 
 
 class Coin:
-    def __init__(self, symbol):
+    def __init__(self, symbol, max_overdraft):
         self.symbol = symbol
         self.amount = 0.0
         self.cost_basis = 0.0
+        self.max_overdraft = max_overdraft
 
     def buy(self, amount:float, price:float):
         new_amount = self.amount + amount
@@ -21,7 +22,7 @@ def buy(self, amount:float, price:float):
 
     def sell(self, amount:float, price:float) -> TaxEvent:
         amount_left = self.amount - amount
-        if amount_left < -1e-9:
+        if amount_left < -self.max_overdraft:
             raise Exception(f"Not enough coins available for {self.symbol}, {self.amount} < {amount}.")
         if amount_left < 0.0:
             amount_left = 0.0
@@ -33,15 +34,15 @@ def sell(self, amount:float, price:float) -> TaxEvent:
         return tax_event
 
 
-def compute_tax(trades, from_date, to_date, native_currency='SEK', exclude_groups=[], coin_report_filename=None):
+def compute_tax(trades, from_date, to_date, max_overdraft, native_currency='SEK', exclude_groups=[], coin_report_filename=None):
     tax_events = []
     coins = {}
 
     def get_buy_coin(trade:Trade):
         if trade.buy_coin == native_currency:
             return None
         if trade.buy_coin not in coins:
-            coins[trade.buy_coin] = Coin(trade.buy_coin)
+            coins[trade.buy_coin] = Coin(trade.buy_coin, max_overdraft)
         return coins[trade.buy_coin]
 
     def get_sell_coin(trade:Trade):