feat: referal spec on registration

db/models/users.py

@@ -1,3 +1,5 @@
+import secrets
+import string
 from typing import TYPE_CHECKING
 
 from sqlalchemy import BIGINT, INTEGER, REAL, TEXT, VARCHAR, ForeignKey
@@ -9,6 +11,11 @@ if TYPE_CHECKING:
     from db.models import Order, Session, Subscription
 
 
+def generate_ref_code(length: int = 8):
+    alphabet = string.ascii_letters + string.digits
+    return "".join(secrets.choice(alphabet) for _ in range(length))
+
+
 class User(Base):
     __tablename__ = "users"
 
@@ -19,6 +26,9 @@ class User(Base):
     hashed_password: Mapped[str] = mapped_column(VARCHAR(255), nullable=True)
     telegram_id: Mapped[int] = mapped_column(BIGINT, unique=True, nullable=True)
     referal_id: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=True)
+    referal_code: Mapped[str] = mapped_column(
+        TEXT, nullable=False, unique=True, default=generate_ref_code
+    )
 
     balance: Mapped[float] = mapped_column(REAL, nullable=False, default=0)