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