import json

USER_FILE = "./data/users.json"

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

def save_users(data):
    with open(USER_FILE, "w") as f:
        json.dump(data, f)

def update_user(user_id, username, fullname):
    has_changes = False
    users = load_users()
    user = users.get(str(user_id), {})
    
    if user.get("username", "") != username:
        has_changes = True
        user["username"] = username
    if user.get("fullname", "") != fullname:
        has_changes = True
        user["fullname"] = fullname
    if not user.get("role"):
        has_changes = True
        user["role"] = "guest"
    
    if has_changes:
        users[str(user_id)] = user
        save_users(users)


def get_role(user_id):
    return load_users().get(str(user_id), {}).get("role", "guest")

def get_username(user_id):
    return load_users().get(str(user_id), {}).get("username", None)

def get_fullname(user_id):
    return load_users().get(str(user_id), {}).get("fullname", None)

def set_credentials(user_id, username, password):
    users = load_users()
    user = users.get(str(user_id), {})
    user["credentials"] = {"username": username, "password": password}
    users[str(user_id)] = user
    save_users(users)

def get_credentials(user_id):
    return load_users().get(str(user_id), {}).get("credentials")

def get_grantor_credentials(user_id, gate):
    from access_control import load_access
    access = load_access().get(str(user_id), {})
    entry = access.get(gate) or access.get("all")
    if not entry:
        return None
    grantor_id = entry.get("grantor")
    return get_credentials(grantor_id)

def get_admins():
    return [uid for uid, u in load_users().items() if u.get("role") == "admin"]