from typing import Any, List

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from app import crud, models, schemas
from app.api import deps

router = APIRouter()


@router.get("/", response_model=List[schemas.User])
def read_users(
    db: Session = Depends(deps.get_db),
    skip: int = 0,
    limit: int = 100,
    current_user: models.User = Depends(deps.get_current_admin_user),
) -> Any:
    """
    Retrieve users. Admin only.
    """
    users = crud.user.get_all(db, skip=skip, limit=limit)
    return users


@router.post("/", response_model=schemas.User)
def create_user(
    *,
    db: Session = Depends(deps.get_db),
    user_in: schemas.UserCreate,
    current_user: models.User = Depends(deps.get_current_admin_user),
) -> Any:
    """
    Create new user. Admin only.
    """
    user = crud.user.get_by_email(db, email=user_in.email)
    if user:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Email already registered",
        )
    
    user = crud.user.get_by_username(db, username=user_in.username)
    if user:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Username already registered",
        )
    
    user = crud.user.create(db, obj_in=user_in)
    return user


@router.get("/{user_id}", response_model=schemas.User)
def read_user(
    user_id: str,
    current_user: models.User = Depends(deps.get_current_active_user),
    db: Session = Depends(deps.get_db),
) -> Any:
    """
    Get a specific user by id.
    """
    user = crud.user.get_by_id(db, user_id=user_id)
    if user == current_user:
        return user
    if not crud.user.is_admin(current_user):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions to access this resource",
        )
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found",
        )
    return user


@router.put("/{user_id}", response_model=schemas.User)
def update_user(
    *,
    db: Session = Depends(deps.get_db),
    user_id: str,
    user_in: schemas.UserUpdate,
    current_user: models.User = Depends(deps.get_current_active_user),
) -> Any:
    """
    Update a user.
    """
    user = crud.user.get_by_id(db, user_id=user_id)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found",
        )
    
    # Check permissions
    if user.id != current_user.id and not crud.user.is_admin(current_user):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions to perform this action",
        )
    
    # Prevent non-admin users from changing their role
    if user_in.role is not None and user_in.role != user.role and not crud.user.is_admin(current_user):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions to change the role",
        )
    
    # If updating email, check it's not already taken
    if user_in.email is not None and user_in.email != user.email:
        existing_user = crud.user.get_by_email(db, email=user_in.email)
        if existing_user:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Email already registered",
            )
    
    # If updating username, check it's not already taken
    if user_in.username is not None and user_in.username != user.username:
        existing_user = crud.user.get_by_username(db, username=user_in.username)
        if existing_user:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Username already registered",
            )
    
    user = crud.user.update(db, db_obj=user, obj_in=user_in)
    return user


@router.delete("/{user_id}", response_model=schemas.User)
def delete_user(
    *,
    db: Session = Depends(deps.get_db),
    user_id: str,
    current_user: models.User = Depends(deps.get_current_admin_user),
) -> Any:
    """
    Delete a user. Admin only.
    """
    user = crud.user.get_by_id(db, user_id=user_id)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="User not found",
        )
    
    # Prevent admins from deleting themselves
    if user.id == current_user.id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Users cannot delete their own account",
        )
    
    user = crud.user.delete(db, user_id=user_id)
    return user