feat: billing for groups of deals

models/billing.py

@@ -5,8 +5,9 @@ from sqlalchemy import ForeignKey
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from models import BaseModel
+
 if TYPE_CHECKING:
-    from models import Deal
+    from models import Deal, DealGroup
 
 
 class DealBillRequest(BaseModel):
@@ -23,3 +24,19 @@ class DealBillRequest(BaseModel):
 
     pdf_url: Mapped[str] = mapped_column(nullable=True)
     invoice_number: Mapped[str] = mapped_column(nullable=True)
+
+
+class GroupBillRequest(BaseModel):
+    __tablename__ = 'group_bill_requests'
+
+    group_id: Mapped[int] = mapped_column(ForeignKey('deal_groups.id'),
+                                          nullable=False,
+                                          primary_key=True,
+                                          unique=True)
+    group: Mapped['DealGroup'] = relationship(back_populates='bill_request')
+
+    created_at: Mapped[datetime.datetime] = mapped_column(nullable=False)
+    paid: Mapped[bool] = mapped_column(nullable=False, default=False)
+
+    pdf_url: Mapped[str] = mapped_column(nullable=True)
+    invoice_number: Mapped[str] = mapped_column(nullable=True)

models/deal_group.py

@@ -4,6 +4,7 @@ from sqlalchemy import ForeignKey, Table, Column
 from sqlalchemy.orm import mapped_column, Mapped, relationship
 
 from models import BaseModel
+from models import GroupBillRequest
 
 if TYPE_CHECKING:
     from models import Deal
@@ -24,6 +25,10 @@ class DealGroup(BaseModel):
         back_populates='group',
         secondary='deal_relations'
     )
+    bill_request: Mapped[Optional['GroupBillRequest']] = relationship(
+        back_populates='group',
+        lazy='joined'
+    )
 
 
 deal_relations = Table(