"""Simple API-key authentication decorator."""
import os
from functools import wraps
from flask import request, jsonify


def require_api_key(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        key = request.headers.get("X-API-Key") or request.args.get("api_key")
        expected = os.environ.get("API_KEY", "")
        if not expected:
            return jsonify({"error": "API key not configured on server"}), 500
        if key != expected:
            return jsonify({"error": "Unauthorized"}), 401
        return f(*args, **kwargs)
    return decorated