using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text.Json;
using System.Text.Json.Nodes;
using System.Threading;
using System.Threading.Tasks;

namespace CommonwealthOnline.Host.Services;

// Speaks the server's token-authenticated admin protocol on 127.0.0.1:AdminPort:
// read .admin-token, send {..,"adminToken"}\n, read one newline-terminated JSON reply.
public sealed class AdminClient
{
    private const int MaxResponseBytes = 1_000_000;

    private readonly int _port;
    private readonly string _tokenPath;

    public AdminClient(int adminPort, string tokenPath)
    {
        _port = adminPort;
        _tokenPath = tokenPath;
    }

    public async Task<JsonObject?> SendAsync(JsonObject request, CancellationToken ct = default)
    {
        var token = (await File.ReadAllTextAsync(_tokenPath, ct).ConfigureAwait(false)).Trim();
        var authenticated = (JsonObject)request.DeepClone();
        authenticated["adminToken"] = token;
        var payload = JsonSerializer.SerializeToUtf8Bytes(authenticated);

        using var client = new TcpClient();
        await client.ConnectAsync(IPAddress.Loopback, _port, ct).ConfigureAwait(false);
        var stream = client.GetStream();
        await stream.WriteAsync(payload, ct).ConfigureAwait(false);
        await stream.WriteAsync(new byte[] { (byte)'\n' }, ct).ConfigureAwait(false);

        using var buffer = new MemoryStream();
        var one = new byte[1];
        while (buffer.Length < MaxResponseBytes)
        {
            var read = await stream.ReadAsync(one, ct).ConfigureAwait(false);
            if (read == 0 || one[0] == (byte)'\n')
            {
                break;
            }

            buffer.WriteByte(one[0]);
        }

        return JsonNode.Parse(buffer.ToArray()) as JsonObject;
    }

    public Task<JsonObject?> StatusAsync(CancellationToken ct = default) =>
        SendAsync(new JsonObject { ["cmd"] = "status" }, ct);

    public Task<JsonObject?> ClientsAsync(CancellationToken ct = default) =>
        SendAsync(new JsonObject { ["cmd"] = "clients" }, ct);

    public Task<JsonObject?> KickAsync(uint playerId, string reason, CancellationToken ct = default) =>
        SendAsync(new JsonObject { ["cmd"] = "kick", ["playerId"] = playerId, ["reason"] = reason }, ct);

    public Task<JsonObject?> BanAsync(uint playerId, string reason, CancellationToken ct = default) =>
        SendAsync(new JsonObject { ["cmd"] = "ban", ["playerId"] = playerId, ["reason"] = reason }, ct);
}