using System.Text;
using QVPN.Core;

public static class SubscriptionTransportTests
{
    public static async Task RunAsync(Func<string, Action, Task> test)
    {
        await test("Subscription keeps distinct flow and fingerprint variants of one endpoint", () =>
        {
            var nodes = Subscription.Parse(string.Join('\n',
                Link("xtls-rprx-vision", "chrome"), Link("", "chrome"),
                Link("xtls-rprx-vision", "firefox"), Link("xtls-rprx-vision-udp443", "chrome")));
            Check(nodes.Count == 4 && nodes.Select(n => n.Id).Distinct().Count() == 4);
            Check(nodes.Select(n => (n.Flow, n.Fingerprint)).SequenceEqual(new[]
            {
                ("xtls-rprx-vision", "chrome"), ("", "chrome"),
                ("xtls-rprx-vision", "firefox"), ("xtls-rprx-vision-udp443", "chrome")
            }));
        });
        await test("Subscription presentation and parameter order do not duplicate a transport", () =>
        {
            var first = Link("xtls-rprx-vision", "chrome", "First location");
            var same = Link("xtls-rprx-vision", "chrome", "Renamed location");
            int question = same.IndexOf('?'), fragment = same.IndexOf('#');
            same = same[..(question + 1)] + string.Join('&', same[(question + 1)..fragment].Split('&').Reverse()) + same[fragment..];
            var nodes = Subscription.Parse(first + "\n" + same);
            Check(nodes.Count == 1 && nodes[0].Name == "First location");
            Check(Subscription.Parse(same).Single().Id == nodes[0].Id);
        });
        await test("Vision UDP443 is preserved in plain and encoded subscriptions and Xray", () =>
        {
            string link = Link("xtls-rprx-vision-udp443", "chrome");
            foreach (string text in new[] { link, Convert.ToBase64String(Encoding.UTF8.GetBytes(link)) })
            {
                var node = Subscription.Parse(text).Single();
                Check(node.Flow == "xtls-rprx-vision-udp443");
                var user = XrayConfigBuilder.Build(node)["outbounds"]![0]!["settings"]!["vnext"]![0]!["users"]![0]!;
                Check(user["flow"]!.GetValue<string>() == node.Flow);
            }
        });
        await test("Subscription accepts only the exact supported flow names", () =>
        {
            foreach (string flow in new[] { "xtls-rprx-vision-udp", "xtls-rprx-vision-udp443-extra", "XTLS-rprx-vision-udp443", "xtls-rprx-vision\n" })
            {
                try { Subscription.Parse(Link(flow, "chrome")); }
                catch (InvalidDataException) { continue; }
                throw new InvalidOperationException("Unsupported subscription flow was accepted.");
            }
        });
    }

    private static string Link(string flow, string fingerprint, string name = "Synthetic location")
    {
        string uuid = new Guid(Enumerable.Range(1, 16).Select(i => (byte)i).ToArray()).ToString();
        string key = Convert.ToBase64String(Enumerable.Range(1, 32).Select(i => (byte)i).ToArray()).TrimEnd('=').Replace('+', '-').Replace('/', '_');
        return $"vless://{uuid}@8.8.8.8:443?security=reality&type=tcp&encryption=none&pbk={key}&sid=abcd&sni=example.com&fp={fingerprint}&flow={Uri.EscapeDataString(flow)}#{Uri.EscapeDataString(name)}";
    }

    private static void Check(bool condition)
    {
        if (!condition) throw new InvalidOperationException("Subscription transport regression.");
    }
}