from typing import Optional
from datetime import datetime
from pydantic import BaseModel, Field, model_validator

class ReservationBaseDTO(BaseModel):
    classroom_id: int = Field(..., description="ID del aula asignada")
    commission_id: int = Field(..., description="ID de la comisión académica")
    user_id: int = Field(..., description="ID del docente responsable")
    start_time: datetime = Field(..., description="Fecha y hora de inicio")
    end_time: datetime = Field(..., description="Fecha y hora de finalización")
    purpose: str = Field(default="Clase regular", max_length=500, description="Motivo o título de la reserva")
    expected_attendees: int = Field(default=20, ge=1, description="Cantidad estimada de asistentes")
    shift: Optional[str] = Field(default=None, max_length=30, description="Turno (Mañana, Tarde, Vespertino, Noche)")
    virtual_link: Optional[str] = Field(default=None, max_length=500, description="Enlace a sala virtual (Meet/Zoom)")
    notes: Optional[str] = Field(default=None, description="Observaciones adicionales")
    status: Optional[str] = Field(default="PENDING", description="Estado de la reserva")

    @model_validator(mode='after')
    def validate_time_range(self):
        if self.end_time <= self.start_time:
            raise ValueError("La hora de finalización debe ser posterior a la hora de inicio.")
        return self

class ReservationCreateDTO(ReservationBaseDTO):
    allow_co_teaching_exception: Optional[bool] = Field(default=False, description="Excepción justificada si hay co-docencia")

class ReservationUpdateDTO(BaseModel):
    classroom_id: Optional[int] = None
    start_time: Optional[datetime] = None
    end_time: Optional[datetime] = None
    purpose: Optional[str] = None
    expected_attendees: Optional[int] = None
    shift: Optional[str] = None
    virtual_link: Optional[str] = None
    notes: Optional[str] = None
    status: Optional[str] = None
    allow_co_teaching_exception: Optional[bool] = False

class ReservationResponseDTO(ReservationBaseDTO):
    id: int
    created_at: Optional[datetime] = None

    class Config:
        from_attributes = True