Move get_sell_rate to exchange class

freqtrade/exchange/exchange.py

@@ -88,6 +88,10 @@ class Exchange:
 
         # Cache for 10 minutes ...
         self._fetch_tickers_cache: TTLCache = TTLCache(maxsize=1, ttl=60 * 10)
+        # Cache values for 1800 to avoid frequent polling of the exchange for prices
+        # Caching only applies to RPC methods, so prices for open trades are still
+        # refreshed once every iteration.
+        self._sell_rate_cache: TTLCache = TTLCache(maxsize=100, ttl=1800)
         self._buy_rate_cache: TTLCache = TTLCache(maxsize=100, ttl=1800)
 
         # Holds candles
@@ -912,6 +916,15 @@ class Exchange:
         except ccxt.BaseError as e:
             raise OperationalException(e) from e
 
+    def _order_book_gen(self, pair: str, side: str, order_book_max: int = 1,
+                        order_book_min: int = 1):
+        """
+        Helper generator to query orderbook in loop (used for early sell-order placing)
+        """
+        order_book = self.fetch_l2_order_book(pair, order_book_max)
+        for i in range(order_book_min, order_book_max + 1):
+            yield order_book[side][i - 1][0]
+
     def get_buy_rate(self, pair: str, refresh: bool) -> float:
         """
         Calculates bid target between current ask price and last price
@@ -958,6 +971,46 @@ class Exchange:
 
         return used_rate
 
+    def get_sell_rate(self, pair: str, refresh: bool) -> float:
+        """
+        Get sell rate - either using ticker bid or first bid based on orderbook
+        or remain static in any other case since it's not updating.
+        :param pair: Pair to get rate for
+        :param refresh: allow cached data
+        :return: Bid rate
+        :raises PricingError if price could not be determined.
+        """
+        if not refresh:
+            rate = self._sell_rate_cache.get(pair)
+            # Check if cache has been invalidated
+            if rate:
+                logger.debug(f"Using cached sell rate for {pair}.")
+                return rate
+
+        ask_strategy = self._config.get('ask_strategy', {})
+        if ask_strategy.get('use_order_book', False):
+            # This code is only used for notifications, selling uses the generator directly
+            logger.info(
+                f"Getting price from order book {ask_strategy['price_side'].capitalize()} side."
+            )
+            try:
+                rate = next(self._order_book_gen(pair, f"{ask_strategy['price_side']}s"))
+            except (IndexError, KeyError) as e:
+                logger.warning("Sell Price at location from orderbook could not be determined.")
+                raise PricingError from e
+        else:
+            ticker = self.fetch_ticker(pair)
+            ticker_rate = ticker[ask_strategy['price_side']]
+            if ticker['last'] and ticker_rate < ticker['last']:
+                balance = ask_strategy.get('bid_last_balance', 0.0)
+                ticker_rate = ticker_rate - balance * (ticker_rate - ticker['last'])
+            rate = ticker_rate
+
+        if rate is None:
+            raise PricingError(f"Sell-Rate for {pair} was empty.")
+        self._sell_rate_cache[pair] = rate
+        return rate
+
     # Fee handling
 
     @retrier