import json
from datetime import datetime, timezone

ACCESS_FILE = "./data/access.json"

def load_access():
    try:
        with open(ACCESS_FILE, "r") as f:
            return json.load(f)
    except FileNotFoundError:
        return {}

def save_access(data):
    with open(ACCESS_FILE, "w") as f:
        json.dump(data, f)

def get_grantor(user_id, gate):
    access = load_access().get(str(user_id), {})
    entry = access.get(gate) or access.get("all")
    return entry.get("grantor", "")

def can_open_gate(user_id, gate):
    access = load_access().get(str(user_id), {})
    entry = access.get(gate) or access.get("all")
    if not entry or entry["type"] != "timed":
        return False
    if datetime.now(timezone.utc) < datetime.fromisoformat(entry["expires_at"].replace("Z", "+00:00")):
        return True
    return False

def grant_access(user_id, gate, expires_at, grantor_id):
    access = load_access()
    user_access = access.get(str(user_id), {})
    user_access[gate] = {
        "type": "timed",
        "expires_at": expires_at,
        "grantor": grantor_id
    }
    access[str(user_id)] = user_access
    save_access(access)