Add Splitwise clone backend

app/schemas.py

@@ -0,0 +1,62 @@
+from __future__ import annotations
+
+from decimal import Decimal
+from uuid import UUID
+
+from pydantic import BaseModel, Field, model_validator
+
+
+class ExpenseItemCreate(BaseModel):
+    description: str
+    amount: Decimal
+    participants: list[str]
+    shares: dict[str, float] | None = None
+
+    @model_validator(mode="after")
+    def validate_shares(self) -> ExpenseItemCreate:
+        if self.shares is not None:
+            if set(self.shares.keys()) != set(self.participants):
+                raise ValueError("shares keys must match participants exactly")
+            total = sum(self.shares.values())
+            if abs(total - 100.0) > 0.01:
+                raise ValueError(f"shares must sum to 100, got {total}")
+        if len(self.participants) != len(set(self.participants)):
+            raise ValueError("participants must be unique")
+        return self
+
+
+class ExpenseReportCreate(BaseModel):
+    title: str
+    items: list[ExpenseItemCreate]
+
+
+class ExpenseShareOut(BaseModel):
+    user_sub: str
+    user_name: str | None
+    percentage: float
+
+
+class ExpenseItemOut(BaseModel):
+    id: UUID
+    description: str
+    amount: Decimal
+    shares: list[ExpenseShareOut]
+
+
+class ExpenseReportOut(BaseModel):
+    id: UUID
+    title: str
+    creator_sub: str
+    creator_name: str | None
+    created_at: str
+    items: list[ExpenseItemOut]
+    participants: list[dict[str, str | None]]
+
+
+class ExpenseReportListOut(BaseModel):
+    reports: list[ExpenseReportOut]
+    total_count: int
+
+
+class ErrorResponse(BaseModel):
+    detail: str