C# License Validation with Avalex (.NET / WPF)

using System;
using System.Net.Http;
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json.Serialization;
using System.Threading.Tasks;

public class AvalexLicenseClient
{
    private static readonly HttpClient client = new HttpClient();
    private const string ApiUrl = "http://localhost:8080/licenses/validate";
    private const string ProductId = "prod_enterprise_2026";

    public class ValidateRequest
    {
        [JsonPropertyName("licenseId")]
        public string LicenseId { get; set; }
        [JsonPropertyName("productId")]
        public string ProductId { get; set; }
        [JsonPropertyName("hwid")]
        public string Hwid { get; set; }
    }

    public class ValidateResponse
    {
        [JsonPropertyName("valid")]
        public bool Valid { get; set; }
    }

    public static string GetHwid()
    {
        string raw = Environment.MachineName + Environment.UserName + Environment.ProcessorCount;
        using var sha256 = SHA256.Create();
        byte[] bytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(raw));
        return BitConverter.ToString(bytes).Replace("-", "").Substring(0, 32);
    }

    public static async Task<bool> ValidateAsync(string licenseId)
    {
        var requestObj = new ValidateRequest
        {
            LicenseId = licenseId,
            ProductId = ProductId,
            Hwid = GetHwid()
        };
        try
        {
            var response = await client.PostAsJsonAsync(ApiUrl, requestObj);
            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadFromJsonAsync<ValidateResponse>();
                return result?.Valid ?? false;
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[Avalex Error] {ex.Message}");
        }
        return false;
    }
}