Initial commit: Quantum Terminal — Free & Open Source Trading Platform

backend/data_manager/fetchers/base_fetcher.py

@@ -0,0 +1,54 @@
+"""
+BaseFetcher — abstract interface for data source adapters.
+
+Every fetcher (MT5, DXFeed, futures bridge, CSV import) implements this.
+"""
+
+from abc import ABC, abstractmethod
+from datetime import datetime
+from typing import Optional
+import pandas as pd
+
+
+class BaseFetcher(ABC):
+    """
+    Abstract data fetcher interface.
+
+    Implementations must return DataFrames with:
+      - DatetimeIndex named 'time' (UTC)
+      - Lowercase column names: open, high, low, close, tick_volume, spread, real_volume
+    """
+
+    name: str = "base"  # Override in subclass
+
+    @abstractmethod
+    def fetch_bars(
+        self,
+        symbol: str,
+        timeframe: str,
+        date_from: datetime,
+        date_to: datetime,
+    ) -> Optional[pd.DataFrame]:
+        """
+        Fetch OHLCV bars for the given symbol/timeframe/date range.
+        Returns None on failure.
+        """
+        ...
+
+    @abstractmethod
+    def fetch_bars_n(
+        self,
+        symbol: str,
+        timeframe: str,
+        n_bars: int,
+    ) -> Optional[pd.DataFrame]:
+        """
+        Fetch the most recent N bars.
+        Returns None on failure.
+        """
+        ...
+
+    @abstractmethod
+    def is_available(self) -> bool:
+        """Check if this data source is currently reachable."""
+        ...