using System.Net.WebSockets;
using DysonNetwork.Shared.Proto;
using DysonNetwork.Shared.Stream;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using NATS.Client.Core;
using NATS.Net;
using Swashbuckle.AspNetCore.Annotations;
using WebSocketPacket = DysonNetwork.Shared.Models.WebSocketPacket;

namespace DysonNetwork.Ring.Connection;

[ApiController]
public class WebSocketController(
    WebSocketService ws,
    ILogger<WebSocketContext> logger,
    INatsConnection nats
) : ControllerBase
{
    private static readonly List<string> AllowedDeviceAlternative = ["watch"];

    [Route("/ws")]
    [Authorize]
    [SwaggerIgnore]
    public async Task<ActionResult> TheGateway([FromQuery] string? deviceAlt)
    {
        if (string.IsNullOrWhiteSpace(deviceAlt))
            deviceAlt = null;
        if (deviceAlt is not null && !AllowedDeviceAlternative.Contains(deviceAlt))
            return BadRequest("Unsupported device alternative: " + deviceAlt);

        HttpContext.Items.TryGetValue("CurrentUser", out var currentUserValue);
        HttpContext.Items.TryGetValue("CurrentSession", out var currentSessionValue);
        if (
            currentUserValue is not Account currentUser
            || currentSessionValue is not AuthSession currentSession
        )
        {
            return Unauthorized();
        }

        var accountId = Guid.Parse(currentUser.Id!);
        var deviceId = currentSession.Challenge?.DeviceId ?? Guid.NewGuid().ToString();

        if (string.IsNullOrEmpty(deviceId))
            return BadRequest("Unable to get device ID from session.");
        if (deviceAlt is not null)
            deviceId = $"{deviceId}+{deviceAlt}";

        var webSocket = await HttpContext.WebSockets.AcceptWebSocketAsync(
            new WebSocketAcceptContext { KeepAliveInterval = TimeSpan.FromSeconds(60) }
        );
        var cts = new CancellationTokenSource();
        var connectionKey = (accountId, deviceId);

        if (!ws.TryAdd(connectionKey, webSocket, cts))
        {
            await webSocket.SendAsync(
                new ArraySegment<byte>(
                    new WebSocketPacket
                    {
                        Type = "error.dupe",
                        ErrorMessage = "Too many connections from the same device and account.",
                    }.ToBytes()
                ),
                WebSocketMessageType.Binary,
                true,
                CancellationToken.None
            );
            await webSocket.CloseAsync(
                WebSocketCloseStatus.PolicyViolation,
                "Too many connections from the same device and account.",
                CancellationToken.None
            );
            return new EmptyResult();
        }

        logger.LogDebug(
            $"Connection established with user @{currentUser.Name}#{currentUser.Id} and device #{deviceId}"
        );

        // Broadcast WebSocket connected event
        await nats.PublishAsync(
            WebSocketConnectedEvent.Type,
            GrpcTypeHelper
                .ConvertObjectToByteString(
                    new WebSocketConnectedEvent
                    {
                        AccountId = accountId,
                        DeviceId = deviceId,
                        IsOffline = false,
                    }
                )
                .ToByteArray(),
            cancellationToken: cts.Token
        );

        try
        {
            await _ConnectionEventLoop(deviceId, currentUser, webSocket, cts.Token);
        }
        catch (WebSocketException ex)
            when (ex.Message.Contains(
                    "The remote party closed the WebSocket connection without completing the close handshake"
                )
            )
        {
            logger.LogDebug(
                "WebSocket disconnected with user @{UserName}#{UserId} and device #{DeviceId} - client closed connection without proper handshake",
                currentUser.Name,
                currentUser.Id,
                deviceId
            );
        }
        catch (Exception ex)
        {
            logger.LogError(
                ex,
                "WebSocket disconnected with user @{UserName}#{UserId} and device #{DeviceId} unexpectedly",
                currentUser.Name,
                currentUser.Id,
                deviceId
            );
        }
        finally
        {
            ws.Disconnect(connectionKey);

            // Broadcast WebSocket disconnected event
            await nats.PublishAsync(
                WebSocketDisconnectedEvent.Type,
                GrpcTypeHelper
                    .ConvertObjectToByteString(
                        new WebSocketDisconnectedEvent
                        {
                            AccountId = accountId,
                            DeviceId = deviceId,
                            IsOffline = !WebSocketService.GetAccountIsConnected(accountId),
                        }
                    )
                    .ToByteArray(),
                cancellationToken: cts.Token
            );

            logger.LogDebug(
                $"Connection disconnected with user @{currentUser.Name}#{currentUser.Id} and device #{deviceId}"
            );
        }

        return new EmptyResult();
    }

    private async Task _ConnectionEventLoop(
        string deviceId,
        Account currentUser,
        WebSocket webSocket,
        CancellationToken cancellationToken
    )
    {
        var connectionKey = (AccountId: Guid.Parse(currentUser.Id), DeviceId: deviceId);

        var buffer = new byte[1024 * 4];
        try
        {
            while (true)
            {
                var receiveResult = await webSocket.ReceiveAsync(
                    new ArraySegment<byte>(buffer),
                    cancellationToken
                );

                if (receiveResult.CloseStatus.HasValue)
                    break;

                var packet = WebSocketPacket.FromBytes(buffer[..receiveResult.Count]);
                await ws.HandlePacket(currentUser, connectionKey.DeviceId, packet, webSocket);
            }
        }
        catch (OperationCanceledException)
        {
            if (
                webSocket.State != WebSocketState.Closed
                && webSocket.State != WebSocketState.Aborted
            )
            {
                ws.Disconnect(connectionKey);
            }
        }
    }
}