"""General utilities for S23DR 2026."""

import numpy as np
import os
from typing import Optional


def set_seed(seed=42):
    import random
    random.seed(seed)
    np.random.seed(seed)
    try:
        import torch
        torch.manual_seed(seed)
        if torch.cuda.is_available():
            torch.cuda.manual_seed_all(seed)
    except ImportError:
        pass


def get_hf_token():
    return os.environ.get("HF_TOKEN") or os.environ.get("HUGGING_FACE_HUB_TOKEN")


def setup_hf_auth():
    token = get_hf_token()
    if token:
        from huggingface_hub import login
        login(token=token, add_to_git_credential=False)
        return True
    return False


def empty_solution():
    return np.zeros((2, 3)), [(0, 1)], [6]


def validate_solution(vertices, edges):
    if vertices is None or edges is None:
        return False
    if len(vertices) < 2 or len(edges) < 1:
        return False
    max_idx = len(vertices) - 1
    for a, b in edges:
        if a < 0 or b < 0 or a > max_idx or b > max_idx or a == b:
            return False
    return True


def format_time(seconds):
    if seconds < 60:
        return f"{seconds:.1f}s"
    elif seconds < 3600:
        return f"{seconds/60:.1f}m"
    else:
        return f"{seconds/3600:.1f}h"