"""
Common dependencies for routers.
"""


from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer

from ..config import Config, Settings
from ..db import Device, User, UserCapabilityType

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl=f"{Settings._.api_v1_prefix}/user/authenticate"
)


class Responses:
    """
    Just a namespace.

    Describes API response status codes.
    """

    OK = {
        "content": None,
    }
    INSTALLED = {
        "description": "kiwi-vpn already installed",
        "content": None,
    }
    NOT_INSTALLED = {
        "description": "kiwi-vpn not installed",
        "content": None,
    }
    NEEDS_USER = {
        "description": "Must be logged in",
        "content": None,
    }
    NEEDS_ADMIN = {
        "description": "Must be admin",
        "content": None,
    }
    NEEDS_REQUESTED_USER = {
        "description": "Must be the requested user",
        "content": None,
    }
    ENTRY_EXISTS = {
        "description": "Entry exists in database",
        "content": None,
    }
    ENTRY_DOESNT_EXIST = {
        "description": "Entry does not exist in database",
        "content": None,
    }
    CANT_TARGET_SELF = {
        "description": "Operation can't target yourself",
        "content": None,
    }


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    current_config: Config | None = Depends(Config.load),
) -> User | None:
    """
    Get the currently logged-in user from the database.
    """

    # can't connect to an unconfigured database
    if current_config is None:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST)

    username = await current_config.jwt.decode_token(token)

    return User.get(username)


async def get_current_user_if_exists(
    current_user: User | None = Depends(get_current_user),
) -> User:
    """
    Get the currently logged-in user if it exists.
    """

    # fail if not requested by a user
    if current_user is None:
        # don't use error 404 here: possible user enumeration
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN)

    return current_user


async def get_current_user_if_admin(
    current_user: User = Depends(get_current_user_if_exists),
) -> User:
    """
    Fail if the currently logged-in user is not an admin.
    """

    if not current_user.can(UserCapabilityType.admin):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN)

    return current_user


async def get_user_by_name(
    user_name: str,
    current_user: User = Depends(get_current_user_if_exists),
) -> User:
    """
    Get a user by name.

    Works if a) the currently logged-in user is an admin,
    or b) if it is the requested user.
    """

    # check if current user is admin
    if current_user.can(UserCapabilityType.admin):
        # fail if requested user doesn't exist
        if (user := User.get(user_name)) is None:
            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND)

    # check if current user is requested user
    elif current_user.name == user_name:
        pass

    # current user is neither admin nor the requested user
    else:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN)

    return user


async def get_device_by_id(
    device_id: int,
    current_config: Config | None = Depends(Config.load),
) -> Device | None:

    # can't connect to an unconfigured database
    if current_config is None:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST)

    return Device.get(device_id)


async def get_device_by_id_if_editable(
    device: Device | None = Depends(get_device_by_id),
    current_user: User = Depends(get_current_user_if_exists),
) -> Device:

    # fail if device doesn't exist
    if device is None:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND)

    # fail if device is not owned by current user
    if not current_user.owns(device):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN)

    return device