import time
from typing import List

from constants import FOUR_HOURS


class SessionTracker:
    def __init__(self) -> None:
        self.session_timestamp_map = dict()

    def update_session(self, session_id: str):
        self.session_timestamp_map[session_id] = time.time()

    def delete_session(self, session_id: str):
        if session_id in self.session_timestamp_map:
            del self.session_timestamp_map[session_id]

    def delete_inactive_sessions(self) -> List[str]:
        now = time.time()
        sessions_to_delete = [
            sid
            for sid, last_t in self.session_timestamp_map.items()
            if now - last_t > FOUR_HOURS
        ]

        for session_id in sessions_to_delete:
            del self.session_timestamp_map[session_id]

        return sessions_to_delete

    def delete_oldest_session(self) -> str | None:
        if len(self.session_timestamp_map) == 0:
            return None
        oldest_session_id = min(self.session_timestamp_map.items(), key=lambda x: x[1])[
            0
        ]
        self.delete_session(oldest_session_id)
        return oldest_session_id