from datetime import datetime, timezone

from src.models import Status, Role, Credential, Grant, User
from src.repository import UsersRepository


class UsersService:

    def __init__(self, users_repository: UsersRepository):
        self._users_repository = users_repository

    def add_user(self, uid: str) -> User:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            user = User(uid)
            self._users_repository.save(uid, user)
        return user

    def get_user(self, uid: str) -> User:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            raise Exception("User not found")
        return user

    def get_role(self, uid: str) -> Role:
        return self.get_user(uid).role

    def get_credentials(self, uid: str, gate_key: str) -> Credential | None:
        user = self._users_repository.get_by_uid(uid)
        if user.role in (Role.ADMIN, Role.MEMBER):
            creds = user.credentials
            if not creds:
                raise Exception("Please set your credentials with `/setcredentials` first")
        elif user.role == Role.GUEST and self.can_open_gate(uid, gate_key):
            grantor = self.get_grantor(user, gate_key)
            if not grantor:
                raise Exception("No valid grantor available.")
            creds = grantor.credentials
            if not creds:
                raise Exception("No valid grantor credentials available.")
            self.update_grant_last_used(uid, gate_key)
            # try:
            #     await context.bot.send_message(chat_id=grantor, text=f"Guest {uid} opened {gate_name}")
            # except Exception as e:
            #     print(f"Failed to notify {grantor} that guest {uid} opened {gate_name}: {e}")
        else:
            raise Exception("Access denied.")

    def set_credentials(self, uid: str, credentials: Credential) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if user:
            user.credentials = credentials
            self._users_repository.save(uid, user)
            return True
        return False

    def can_open_gate(self, uid: str, gate_key: str) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if not user or user.status != Status.ENABLED:
            return False
        if user.role == Role.ADMIN or user.role == Role.MEMBER:
            return True
        grant = user.grants.get(gate_key)
        if not grant or grant.status != Status.ENABLED:
            return False
        if grant.expires_at <= datetime.now(timezone.utc):
            return False
        return True

    def has_grants(self, uid: str) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if not user or user.status != Status.ENABLED:
            return False
        if user.role == Role.ADMIN or user.role == Role.MEMBER:
            return True
        return any(grant.status == Status.ENABLED and grant.expires_at > datetime.now(timezone.utc) for grant in
                   user.grants.values())

    def get_grantor(self, user: User, gate: str) -> User | None:
        grant = user.grants.get(gate)
        return self._users_repository.get_by_uid(grant.grantor) if grant else None

    def get_admins(self) -> list[str]:
        return [user.uid for user in self._users_repository.get_all() if user.role == Role.ADMIN]

    def grant_access(self, uid: str, gate: str, expires_at: datetime, grantor_id: str) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            return False
        user.grants[gate] = Grant(grantor_id, expires_at)
        self._users_repository.save(uid, user)
        return True

    def revoke_access(self, uid: str, gate: str) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            return False
        if gate in user.grants:
            del user.grants[gate]
            self._users_repository.save(uid, user)
            return True
        return False

    def update_grant_last_used(self, uid: str, gate_key: str) -> bool:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            return False
        grant = user.grants.get(gate_key)
        if not grant:
            return False
        grant.last_used_at = datetime.now(timezone.utc)
        self._users_repository.save(uid, user)
        return True

    def get_granted_gates(self, uid: str) -> list[str]:
        user = self._users_repository.get_by_uid(uid)
        if not user:
            return []
        if user.role == Role.ADMIN or user.role == Role.MEMBER:
            return ['all']
        if 'all' in user.grants and user.grants['all'].status == Status.ENABLED and user.grants[
            'all'].expires_at > datetime.now(timezone.utc):
            return ['all']
        return [gate for gate, grant in user.grants.items() if
                grant.status == Status.ENABLED and grant.expires_at > datetime.now(timezone.utc)]