using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using VOL.Core.Configuration;

namespace VOL.Core.Utilities
{
    /// <summary>
    /// IOT签名
    /// </summary>
    public static class IOTSignatureHelper
    {
        private static readonly string SecretKey = AppSetting.IOTConfig.SecretKey;
        private static readonly TimeSpan ValidDuration = TimeSpan.FromMinutes(AppSetting.IOTConfig.ExpirationDate); // 签名有效期

        public static string GenerateSignature(string data, long timestamp)
        {
            string message = $"{data}:{timestamp}";
            using (var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(SecretKey)))
            {
                var hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(message));
                return Convert.ToBase64String(hash);
            }
        }

        public static bool ValidateSignature(string data, long timestamp, string signature)
        {
            if (Math.Abs((DateTimeOffset.UtcNow.ToUnixTimeSeconds() - timestamp)) > ValidDuration.TotalSeconds)
            {
                return false; // 时间戳过期
            }

            var generatedSignature = GenerateSignature(data, timestamp);
            return generatedSignature == signature;
        }
    }
}