from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from pydantic import BaseModel, ConfigDict, EmailStr
from typing import List, Optional
from datetime import datetime
import uuid

from app.core.database import get_db
from app.core.security import security
from app.models.user import User, UserRole
from app.api import deps 

router = APIRouter()

# ===================================
# PYDANTIC SCHEMAS
# ===================================

class UserCreate(BaseModel):
    """Schema para crear usuario - NO incluye tenant_id (se asigna automáticamente)"""
    email: EmailStr
    first_name: str
    last_name: str
    role: UserRole
    password: str
    language: str = "es"
    timezone: str = "UTC"
    notifications_email: bool = True
    
class UserUpdate(BaseModel):
    """Schema para actualizar usuario"""
    email: Optional[EmailStr] = None
    first_name: Optional[str] = None
    last_name: Optional[str] = None
    role: Optional[UserRole] = None
    is_active: Optional[bool] = None
    password: Optional[str] = None
    language: Optional[str] = None
    timezone: Optional[str] = None
    notifications_email: Optional[bool] = None

class UserResponse(BaseModel):
    """Schema de respuesta - incluye todos los campos públicos"""
    id: uuid.UUID
    tenant_id: uuid.UUID
    email: EmailStr
    first_name: str
    last_name: str
    avatar_url: Optional[str] = None
    role: UserRole
    is_active: bool
    email_verified: bool
    last_login: Optional[datetime] = None
    language: str
    timezone: str
    notifications_email: bool
    totp_enabled: bool
    created_at: datetime
    updated_at: datetime
    
    model_config = ConfigDict(from_attributes=True)


# ===================================
# ENDPOINTS
# ===================================

@router.get("/", response_model=List[UserResponse])
async def read_users(
    skip: int = 0, 
    limit: int = 100,
    role: Optional[UserRole] = None,
    is_active: Optional[bool] = None,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Listar usuarios del tenant del usuario actual.
    
    ✅ Implementa multi-tenancy: solo muestra usuarios del tenant del usuario.
    
    Filtros opcionales:
    - role: filtrar por rol
    - is_active: filtrar por estado activo
    """
    # ✅ CORREGIDO: Filtrar por tenant_id
    query = select(User).where(User.tenant_id == current_user.tenant_id)
    
    # Aplicar filtros opcionales
    if role:
        query = query.where(User.role == role)
    if is_active is not None:
        query = query.where(User.is_active == is_active)
    
    query = query.offset(skip).limit(limit).order_by(User.created_at.desc())
    
    result = await db.execute(query)
    return result.scalars().all()


@router.post("/", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def create_user(
    user: UserCreate, 
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Crear nuevo usuario en el tenant del usuario actual.
    
    ✅ Implementa multi-tenancy: asigna automáticamente tenant_id del usuario.
    
    Restricciones:
    - Solo ADMIN, SUPPORT_MANAGER y CLIENT_ADMIN pueden crear usuarios
    - El email debe ser único dentro del tenant
    """
    # Verificar permisos
    if not current_user.can_manage_users:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have permission to create users"
        )
    
    # Verificar si el email ya existe en el tenant
    query = select(User).where(
        User.email == user.email,
        User.tenant_id == current_user.tenant_id
    )
    result = await db.execute(query)
    if result.scalar_one_or_none():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered in this tenant"
        )
    
    # Preparar datos del usuario
    user_data = user.model_dump(exclude={"password"})
    password_hash = security.hash_password(user.password)
    
    # ✅ CORREGIDO: Asignar tenant_id del usuario actual
    db_user = User(
        **user_data,
        password_hash=password_hash,
        tenant_id=current_user.tenant_id  # ✅ Multi-tenancy automático
    )
    
    db.add(db_user)
    await db.commit()
    await db.refresh(db_user)
    return db_user


@router.get("/{user_id}", response_model=UserResponse)
async def read_user(
    user_id: uuid.UUID,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Obtener un usuario específico del tenant.
    
    ✅ Implementa multi-tenancy: solo permite acceso a usuarios del propio tenant.
    """
    query = select(User).where(
        User.id == user_id,
        User.tenant_id == current_user.tenant_id  # ✅ Seguridad multi-tenant
    )
    result = await db.execute(query)
    user = result.scalar_one_or_none()
    
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    return user


@router.put("/{user_id}", response_model=UserResponse)
async def update_user(
    user_id: uuid.UUID,
    user_update: UserUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Actualizar usuario del tenant.
    
    ✅ Implementa multi-tenancy: solo permite actualizar usuarios del propio tenant.
    
    Restricciones:
    - Solo ADMIN, SUPPORT_MANAGER y CLIENT_ADMIN pueden actualizar usuarios
    - No se puede cambiar el tenant_id
    """
    # Verificar permisos
    if not current_user.can_manage_users:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have permission to update users"
        )
    
    # Buscar usuario
    query = select(User).where(
        User.id == user_id,
        User.tenant_id == current_user.tenant_id
    )
    result = await db.execute(query)
    db_user = result.scalar_one_or_none()
    
    if not db_user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    # Verificar email único si se está cambiando
    update_data = user_update.model_dump(exclude_unset=True)
    if "email" in update_data and update_data["email"] != db_user.email:
        email_query = select(User).where(
            User.email == update_data["email"],
            User.tenant_id == current_user.tenant_id,
            User.id != user_id
        )
        email_result = await db.execute(email_query)
        if email_result.scalar_one_or_none():
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Email already in use by another user"
            )
    
    # Actualizar campos
    for field, value in update_data.items():
        if field == "password":
            # Hash the new password
            db_user.password_hash = security.hash_password(value)
        else:
            setattr(db_user, field, value)
    
    await db.commit()
    await db.refresh(db_user)
    return db_user


@router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_user(
    user_id: uuid.UUID,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Desactivar usuario del tenant (soft delete).
    
    ✅ Implementa multi-tenancy: solo permite desactivar usuarios del propio tenant.
    
    Restricciones:
    - Solo ADMIN puede eliminar usuarios
    - No se puede eliminar a sí mismo
    - No se puede eliminar el último ADMIN del tenant
    """
    # Verificar permisos - solo ADMIN puede eliminar
    if current_user.role != UserRole.ADMIN:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Only admins can delete users"
        )
    
    # No se puede eliminar a sí mismo
    if user_id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="You cannot delete yourself"
        )
    
    # Buscar usuario
    query = select(User).where(
        User.id == user_id,
        User.tenant_id == current_user.tenant_id
    )
    result = await db.execute(query)
    db_user = result.scalar_one_or_none()
    
    if not db_user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    # Verificar que no sea el último admin del tenant
    if db_user.role == UserRole.ADMIN:
        admin_query = select(User).where(
            User.tenant_id == current_user.tenant_id,
            User.role == UserRole.ADMIN,
            User.is_active == True,
            User.id != user_id
        )
        admin_result = await db.execute(admin_query)
        active_admins = admin_result.scalars().all()
        
        if len(active_admins) == 0:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Cannot delete the last active admin of the tenant"
            )
    
    # Soft delete
    db_user.is_active = False
    await db.commit()
    return None


@router.patch("/{user_id}/activate", response_model=UserResponse)
async def activate_user(
    user_id: uuid.UUID,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(deps.get_current_user)
):
    """
    Reactivar usuario desactivado.
    
    ✅ Implementa multi-tenancy: solo permite reactivar usuarios del propio tenant.
    """
    # Verificar permisos
    if not current_user.can_manage_users:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="You don't have permission to activate users"
        )
    
    # Buscar usuario
    query = select(User).where(
        User.id == user_id,
        User.tenant_id == current_user.tenant_id
    )
    result = await db.execute(query)
    db_user = result.scalar_one_or_none()
    
    if not db_user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found"
        )
    
    db_user.is_active = True
    await db.commit()
    await db.refresh(db_user)
    return db_user