add models.py

models.py

@@ -0,0 +1,56 @@
+"""
+Placeholder module for future data models.
+
+The current assignment does not require any persistent or structured data, but the
+project layout follows a typical Python package structure.  The ``models``
+module is kept minimal to satisfy the requirement of having at least four
+files and to demonstrate how one might extend the project later.
+"""
+
+from __future__ import annotations
+
+# ---------------------------------------------------------------------------
+# Example data class – not used directly in the streaming demo but shows
+# how a model could be defined for future extensions.
+# ---------------------------------------------------------------------------
+from dataclasses import dataclass, field
+from typing import Dict, List
+
+@dataclass
+class ProductPrice:
+    """Represents a price entry for a product in a specific city."""
+
+    product: str
+    city: str
+    price: float
+    currency: str = "rubles"
+
+    def __post_init__(self) -> None:
+        if self.price < 0:
+            raise ValueError("Price cannot be negative")
+
+# ---------------------------------------------------------------------------
+# Repository pattern – a very small in‑memory store.
+# ---------------------------------------------------------------------------
+class PriceRepository:
+    """Simple repository that holds :class:`ProductPrice` objects."""
+
+    def __init__(self) -> None:
+        self._store: Dict[tuple[str, str], ProductPrice] = {}
+
+    def add(self, entry: ProductPrice) -> None:
+        key = (entry.product.lower(), entry.city.lower())
+        self._store[key] = entry
+
+    def get(self, product: str, city: str) -> ProductPrice | None:
+        return self._store.get((product.lower(), city.lower()))
+
+# ---------------------------------------------------------------------------
+# Example usage – not executed in the main script but demonstrates API.
+# ---------------------------------------------------------------------------
+if __name__ == "__main__":  # pragma: no cover
+    repo = PriceRepository()
+    repo.add(ProductPrice("milk", "kazan", 89))
+    print(repo.get("Milk", "KAZAN"))
+
+# End of models.py