using System.Collections.Generic;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace WIDESEAWCS_Tasks.SocketServer
{
    public partial class TcpSocketServer
    {
        public IReadOnlyList<string> GetClientIds()
        {
            lock (_syncRoot)
            {
                return _clients.Keys.ToList();
            }
        }

        public string? GetClientIdByDevice(string deviceId)
        {
            lock (_syncRoot)
            {
                return _deviceBindings.TryGetValue(deviceId, out var cid) ? cid : null;
            }
        }

        public Task<bool> SendToDeviceAsync(string deviceId, string message)
        {
            var clientId = GetClientIdByDevice(deviceId);
            if (clientId == null) return Task.FromResult(false);
            return SendToClientAsync(clientId, message);
        }

        public async Task<bool> SendToClientAsync(string clientId, string message)
        {
            TcpClient? client;
            SemaphoreSlim? sem = null;
            Encoding? enc = null;
            lock (_syncRoot)
            {
                _clients.TryGetValue(clientId, out client);
                _clientLocks.TryGetValue(clientId, out sem);
                _clientEncodings.TryGetValue(clientId, out enc);
            }

            if (client == null || !client.Connected)
            {
                return false;
            }

            enc ??= _textEncoding;

            if (sem != null) await sem.WaitAsync();
            try
            {
                var ns = client.GetStream();
                var data = enc.GetBytes((message ?? string.Empty) + "\n");
                await ns.WriteAsync(data, 0, data.Length);
            }
            finally
            {
                if (sem != null) sem.Release();
            }
            return true;
        }

        public async Task BroadcastAsync(string message)
        {
            List<TcpClient> clients;
            lock (_syncRoot)
            {
                clients = _clients.Values.ToList();
            }

            await Task.WhenAll(clients.Select(c => Task.Run(async () =>
            {
                try { await SendAsync(c, message); } catch { }
            })));
        }

        public static async Task SendAsync(TcpClient client, string message)
        {
            if (client == null || !client.Connected)
            {
                return;
            }

            NetworkStream stream = client.GetStream();
            var data = Encoding.UTF8.GetBytes((message ?? string.Empty) + "\n");
            await stream.WriteAsync(data, 0, data.Length);
        }
    }
}