using Microsoft.AspNetCore.SignalR;
using System.Globalization;
using Microsoft.EntityFrameworkCore;
using System.Text.Json;
using RadicadeServer.DB;
using RadicadeServer.Extensions;
using RadicadeServer.RecNet.Accounts;
using RadicadeServer.RecNet.Auth;
using RadicadeServer.RecNet.Enums.Messages;
using RadicadeServer.RecNet.Messages;
using RadicadeServer.RecNet.Notifications;
using RadicadeServer.RecNet.Rooms;
using RadicadeServer.Utils;

namespace RadicadeServer.API.Notifications
{
	public static class Notify
	{
		public static IDbContextFactory<RecDBContext> DbFactory = null!;
		public static IHubContext<NotifyHub> Context = null!;
		public static List<HubClient> Clients = new List<HubClient>();

		private static readonly System.Collections.Concurrent.ConcurrentDictionary<string, HubCallerContext> _contexts = new();

		public static void RegisterContext(HubCallerContext context)
		{
			_contexts[context.ConnectionId] = context;
		}

		public static void ForgetContext(string connectionId)
		{
			_contexts.TryRemove(connectionId, out _);
		}





		public static readonly object ClientsLock = new();

		public static HubClient? GetClient(long accountId)
		{
			lock (ClientsLock)
				return Clients.FirstOrDefault(n => n.AccountId == accountId);
		}

		public static HubClient? GetConnectionClient(string connectionId)
		{
			lock (ClientsLock)
				return Clients.FirstOrDefault(n => n.ConnectionId == connectionId);
		}

		public static int ConnectedConnectionCount
		{
			get { lock (ClientsLock) return Clients.Count; }
		}

		public static List<long> ConnectedAccountIds()
		{
			lock (ClientsLock)
				return Clients.Select(n => n.AccountId).Distinct().ToList();
		}

		public static List<HubClient> SnapshotClients()
		{
			lock (ClientsLock)
			{
				return Clients.ToList();
			}
		}

		public static async Task SendMessage(long TargetId, Message msg, string? idFormOverride = null,
			Action<Message>? prepareWithId = null)
		{
			if (DbFactory == null)
			{
				return;
			}

			await using var ctx = await DbFactory.CreateDbContextAsync();

			msg.SentTime = DateTime.UtcNow;
			msg.ToPlayerId = TargetId;

			var originalId = msg.Id;
			await ctx.Database.CreateExecutionStrategy().ExecuteAsync(async () =>
			{
				await using var attempt = await DbFactory.CreateDbContextAsync();
				msg.Id = originalId;
				await using var transaction = prepareWithId != null && attempt.Database.IsRelational()
					? await attempt.Database.BeginTransactionAsync() : null;
				await attempt.Messages.AddAsync(msg);
				await attempt.SaveChangesAsync();
				if (prepareWithId != null)
				{
					prepareWithId(msg);
					await attempt.SaveChangesAsync();
				}
				if (transaction != null) await transaction.CommitAsync();
			});

			List<HubClient> clients;
			lock (ClientsLock)
				clients = Notify.Clients.Where(n => n.AccountId == TargetId).ToList();

			var notif = new Notification { Id = NotificationType.MessageReceived, Msg = msg };

			if (clients.Count == 0)
			{
				return;
			}

			foreach (var client in clients)
				await SendToConnection(client.ConnectionId, notif, idFormOverride);
		}

		public static async Task<int> SendUntilGoneAsync(long accountId, Notification message, TimeSpan window, TimeSpan interval, Notification? alternate = null)
		{
			if (window <= TimeSpan.Zero) window = TimeSpan.FromSeconds(8);
			if (interval <= TimeSpan.Zero) interval = TimeSpan.FromSeconds(1);

			var deadline = DateTime.UtcNow + window;
			var pushes = 0;

			while (true)
			{
				List<HubClient> clients;
				lock (ClientsLock)
					clients = Clients.Where(n => n.AccountId == accountId).ToList();

				if (clients.Count == 0)
				{
					return pushes;
				}

				pushes++;

				var frame = alternate != null && pushes % 2 == 0 ? alternate : message;
				foreach (var client in clients)
					await SendToConnection(client.ConnectionId, frame);

				if (DateTime.UtcNow >= deadline)
				{
					return pushes;
				}

				await Task.Delay(interval);
			}
		}

		private static string PayloadProbe(Notification frame)
		{
			try
			{
				if (frame.Msg == null) return "null";
				if (frame.Msg is string s) return s.Length == 0 ? "empty string" : "string";
				return frame.Msg.GetType().Name switch
				{
					"JsonElement" => "object",
					_ => frame.Msg.GetType().Name
				};
			}
			catch { return "unknown"; }
		}

		public static Notification EmptyObjectPayload(NotificationType id)
			=> new() { Id = id, Msg = JsonDocument.Parse("{}").RootElement.Clone() };

		public static Notification EmptyObjectPayload(string id)
			=> new() { Id = id, Msg = JsonDocument.Parse("{}").RootElement.Clone() };

		public static void SendReliably(long accountId, Notification message, TimeSpan window, TimeSpan interval, Notification? alternate = null)
		{
			_ = Task.Run(async () =>
			{
				try { await SendUntilGoneAsync(accountId, message, window, interval, alternate); }
				catch (Exception) { }
			});
		}

		public static int DisconnectAccount(long accountId, string reason)
		{
			List<string> connectionIds;
			lock (ClientsLock)
				connectionIds = Clients.Where(n => n.AccountId == accountId).Select(n => n.ConnectionId).ToList();

			var closed = 0;
			foreach (var connectionId in connectionIds)
			{
				if (!_contexts.TryRemove(connectionId, out var context)) continue;

				try
				{
					context.Abort();
					closed++;
				}
				catch (Exception)
				{
				}
			}

			return closed;
		}

		public static async Task SendNotify(long AccountId, Notification Message)
		{
			List<HubClient> clients;
			lock (ClientsLock)
				clients = Notify.Clients.Where(n => n.AccountId == AccountId).ToList();

			if (clients.Count == 0)
			{
				return;
			}







			foreach (var client in clients)
				await SendToConnection(client.ConnectionId, Message);
		}







		public static async Task SendSelfAccountUpdate(long accountId)
		{
			if (DbFactory == null)
			{
				return;
			}

			await using var ctx = await DbFactory.CreateDbContextAsync();

			var profile = await ctx.Profiles.FirstOrDefaultAsync(x => x.accountId == accountId);
			if (profile == null) return;

			var plrData = await ctx.Players.FirstOrDefaultAsync(x => x.AccountId == accountId);
			if (plrData == null) return;

			await SendNotify(accountId, new Notification
			{
				Id = "SelfAccountUpdate",
				Msg = PlayerUtils.BuildSelfAccount(profile, plrData)
			});
		}

		public static async Task<Presence?> BuildSelfPresenceAsync(RecDBContext ctx, long accountId)
		{
			var realPresence = await ctx.Presences.FirstOrDefaultAsync(x => x.playerId == accountId);
			if (realPresence == null) return null;

			RoomInstance? roomInstance = realPresence.roomInstance is > 0
				? await ctx.RoomInstances.FirstOrDefaultAsync(x => x.roomInstanceId == realPresence.roomInstance)
				: null;

			return await Presence.CreateAsync(ctx, realPresence, roomInstance);
		}

		public static async Task SendGlobalNotify(Notification Message)
		{






			if (Notify.Context == null)
			{
				return;
			}
			await Notify.Context.Clients.All.SendAsync("Notification", Message.ToJson());
		}




		private static async Task SendToConnection(string connectionId, Notification Message, string? idFormOverride = null)
		{
			if (Notify.Context == null)
			{
				return;
			}
			await Notify.Context.Clients.Client(connectionId).SendAsync("Notification",
				idFormOverride == null ? Message.ToJson() : EnvelopeWithIdForm(Message, idFormOverride));

		}

		public static string EnvelopeWithIdForm(Notification message, string idJson)
			=> $"{{\"Id\":{idJson},\"Msg\":{message.Msg?.ToJson() ?? "null"}}}";

		public static string IdFormJson(string? form, NotificationType type)
		{
			var number = Convert.ToInt64(type, CultureInfo.InvariantCulture)
				.ToString(CultureInfo.InvariantCulture);

			return (form ?? "string").Trim().ToLowerInvariant() switch
			{
				"number" => number,
				"name" => JsonSerializer.Serialize(type.ToString()),
				_ => JsonSerializer.Serialize(number),
			};
		}

		public static async Task<string> ReplayStoredCoachMessageAsync(long accountId, string? form)
		{
			if (DbFactory == null) return "no database configured";

			await using var ctx = await DbFactory.CreateDbContextAsync();

			var stored = await ctx.Messages
				.Where(m => m.ToPlayerId == accountId && m.Type == MessageType.CoachMessage)
				.OrderByDescending(m => m.Id)
				.FirstOrDefaultAsync();

			if (stored == null)
				return $"account {accountId} has no stored coach message - send one from the admin panel first, then replay it.";

			List<HubClient> clients;
			lock (ClientsLock)
				clients = Notify.Clients.Where(n => n.AccountId == accountId).ToList();

			if (clients.Count == 0)
				return $"account {accountId} has {connectedClause()} but no notify hub connection; nothing to push to. " +
					"Check the [NotifyHub] connect line in server-console.log.";

			var notif = new Notification { Id = NotificationType.MessageReceived, Msg = stored };
			var idJson = IdFormJson(form, NotificationType.MessageReceived);

			foreach (var client in clients)
				await SendToConnection(client.ConnectionId, notif, idJson);

			var wire = EnvelopeWithIdForm(notif, idJson);

			return $"replayed stored coach message {stored.Id} to account {accountId} on {clients.Count} connection(s).\n" +
				$"Id token on the wire: {idJson}\n" +
				$"envelope: {wire}\n" +
				ExpectedClientReaction(idJson, NotificationType.MessageReceived);
		}

		private static string connectedClause()
		{
			var accounts = ConnectedAccountIds();
			return accounts.Count == 0
				? "no notify hub connections at all"
				: $"{accounts.Count} account(s) connected ({string.Join(", ", accounts)})";
		}

		private static string ExpectedClientReaction(string idJson, NotificationType type)
		{
			var number = Convert.ToInt64(type, CultureInfo.InvariantCulture).ToString(CultureInfo.InvariantCulture);
			if (idJson == number)
				return "expected: the client logs a hub-frame parse failure and handles nothing - this is NOT a fix.";
			if (idJson.Trim('"') == type.ToString())
				return "expected: the client parses the frame, finds no handler under that name, and silently ignores it.";
			return $"expected: the client handles it as {type} ({number}) - the message appears on the watch without a relog.";
		}

		public static string WireId(object? id)
		{
			try { return JsonSerializer.Serialize(id); }
			catch { return id?.ToString() ?? "null"; }
		}

				public static async Task SendAccountUpdate(long accountId)
		{
			if (DbFactory == null) return;

			await using var ctx = await DbFactory.CreateDbContextAsync();
			var profile = await ctx.Profiles.FirstOrDefaultAsync(x => x.accountId == accountId);
			if (profile == null) return;

			await SendNotify(accountId, new Notification { Id = "AccountUpdate", Msg = profile });
			await UpdateSubscriptions(accountId, Notifs.SubscriptionUpdateProfile, profile);
			await SendSelfAccountUpdate(accountId);
		}

		public static Task UpdateEveryone(long playerId) => UpdateSubscriptions(playerId);

		public static async Task UpdateSubscriptions(long playerId)
		{
			if (DbFactory == null) return;

			var subscribers = GetSubscriberConnections(playerId);
			if (subscribers.Count == 0) return;

			var factory = DbFactory;
			await Task.WhenAll(subscribers.Select(async subscriber =>
			{
				try
				{
					await using var ctx = await factory.CreateDbContextAsync();
					await SendStatusTo(ctx, playerId, subscriber);
				}
				catch (Exception)
				{
				}
			}));
		}

		public static async Task UpdateSubscriptionsForClient(string connectionId)
		{
			if (DbFactory == null) return;

			var client = GetConnectionClient(connectionId);
			if (client == null) return;

			long[] subscriptions;
			lock (client.SubscriptionsLock)
				subscriptions = client.HasSubscriptions ? client.Subscriptions.Distinct().ToArray() : Array.Empty<long>();

			if (subscriptions.Length == 0) return;

			await using var ctx = await DbFactory.CreateDbContextAsync();
			foreach (var playerId in subscriptions)
				await SendStatusTo(ctx, playerId, client);
		}

		public static async Task UpdateSubscriptions(long playerId, object id, object message)
		{
			var subscribers = GetSubscriberConnections(playerId);
			var wireId = id is Notifs.SubscriptionUpdateProfile
				? "AccountUpdate"
				: id;
			var notification = new Notification { Id = wireId, Msg = message };
			if (notification.Id is "AccountUpdate")
				await UpdateSubscriptions(playerId);

			foreach (var subscriber in subscribers)
				await SendToConnection(subscriber.ConnectionId, notification);
		}

		public static async Task SendToSubscribers(long playerId, Notification message)
		{
			foreach (var subscriber in GetSubscriberConnections(playerId))
				await SendToConnection(subscriber.ConnectionId, message);
		}

		private static List<HubClient> GetSubscriberConnections(long playerId)
		{
			return SnapshotClients().Where(client =>
			{
				lock (client.SubscriptionsLock)
					return client.HasSubscriptions && client.Subscriptions.Contains(playerId);
			}).ToList();
		}

		private static async Task SendStatusTo(RecDBContext ctx, long fromPlayerId, HubClient recipient)
		{
			var realPresence = await ctx.Presences.FirstOrDefaultAsync(x => x.playerId == fromPlayerId);
			if (realPresence == null) return;

			RoomInstance? roomInstance = realPresence.roomInstance is > 0
				? await ctx.RoomInstances.FirstOrDefaultAsync(x => x.roomInstanceId == realPresence.roomInstance)
				: null;
			roomInstance = await RoomUtils.ForViewerAsync(roomInstance, recipient.AccountId);

			if (roomInstance != null)
			{
				roomInstance = roomInstance.Copy();
				roomInstance.photonRegion = string.Empty;
				roomInstance.photonRoomId = string.Empty;
				roomInstance.dataBlob = string.Empty;
				roomInstance.roomCode = string.Empty;
			}

			var playerPresence = await Presence.CreateAsync(ctx, realPresence, roomInstance);
			playerPresence.ForViewer(recipient.AccountId);
			await SendToConnection(recipient.ConnectionId, new Notification
			{
				Id = "PresenceUpdate",
				Msg = playerPresence
			});
		}
	}
}