refactors

backend/models/exchange.py

@@ -0,0 +1,83 @@
+import uuid
+from datetime import UTC, datetime
+from typing import TYPE_CHECKING
+
+from sqlalchemy import DateTime, Enum, Float, ForeignKey, Integer
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from database import Base
+
+from .enums import BitcoinTransferMethod, ExchangeStatus, TradeDirection
+
+if TYPE_CHECKING:
+    from .user import User
+
+
+class Exchange(Base):
+    """Bitcoin exchange trades booked by users."""
+
+    __tablename__ = "exchanges"
+    # Note: No unique constraint on slot_start to allow cancelled bookings
+    # to be replaced. Application-level check in create_exchange ensures only
+    # one BOOKED trade per slot. For existing databases, manually drop the
+    # constraint: ALTER TABLE exchanges DROP CONSTRAINT IF EXISTS
+    # uq_exchange_slot_start;
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    public_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        nullable=False,
+        unique=True,
+        index=True,
+        default=uuid.uuid4,
+    )
+    user_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("users.id"), nullable=False, index=True
+    )
+    user: Mapped["User"] = relationship("User", foreign_keys=[user_id], lazy="joined")
+
+    # Slot timing
+    slot_start: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, index=True
+    )
+    slot_end: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+
+    # Trade details
+    direction: Mapped[TradeDirection] = mapped_column(
+        Enum(TradeDirection), nullable=False
+    )
+    bitcoin_transfer_method: Mapped[BitcoinTransferMethod] = mapped_column(
+        Enum(BitcoinTransferMethod),
+        nullable=False,
+        default=BitcoinTransferMethod.ONCHAIN,
+    )
+    eur_amount: Mapped[int] = mapped_column(Integer, nullable=False)  # EUR cents
+    sats_amount: Mapped[int] = mapped_column(Integer, nullable=False)  # Satoshis
+
+    # Price information (snapshot at booking time)
+    market_price_eur: Mapped[float] = mapped_column(
+        Float, nullable=False
+    )  # EUR per BTC
+    agreed_price_eur: Mapped[float] = mapped_column(
+        Float, nullable=False
+    )  # EUR per BTC with premium
+    premium_percentage: Mapped[int] = mapped_column(
+        Integer, nullable=False
+    )  # e.g. 5 for 5%
+
+    # Status
+    status: Mapped[ExchangeStatus] = mapped_column(
+        Enum(ExchangeStatus), nullable=False, default=ExchangeStatus.BOOKED
+    )
+
+    # Timestamps
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=lambda: datetime.now(UTC)
+    )
+    cancelled_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    completed_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )