from pydantic import BaseModel, ConfigDict, Field, model_validator
from datetime import datetime


class TaskAssignmentCreate(BaseModel):
    model_config = ConfigDict(extra="forbid")

    user_ids: list[int] = Field(min_length=1, max_length=20)


class TaskAssignmentResponse(BaseModel):
    id: int
    task_id: int
    user_id: int
    assigned_by: int
    user_name: str | None = None
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)

    @model_validator(mode="before")
    @classmethod
    def resolve_user_name(cls, data):  # type: ignore[override]
        """Populate user_name from eagerly loaded user relationship."""
        if hasattr(data, "user") and data.user is not None:
            if not getattr(data, "user_name", None):
                data = dict(
                    id=data.id,
                    task_id=data.task_id,
                    user_id=data.user_id,
                    assigned_by=data.assigned_by,
                    user_name=data.user.username,
                    created_at=data.created_at,
                )
        return data