using System.Buffers;
using System.Security.Claims;
using AyCode.Core;
using AyCode.Core.Extensions;
using AyCode.Core.Helpers;
using AyCode.Core.Loggers;
using AyCode.Core.Serializers.Binaries;
using AyCode.Core.Serializers.Jsons;
using AyCode.Models.Server.DynamicMethods;
using AyCode.Services.SignalRs;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Configuration;

namespace AyCode.Services.Server.SignalRs;

public abstract class AcWebSignalRHubBase<TSignalRTags, TLogger>(IConfiguration configuration, TLogger logger)
    : Hub<IAcSignalRHubItemServer>, IAcSignalRHubServer where TSignalRTags : AcSignalRTags where TLogger : AcLoggerBase
{
    protected readonly List<AcDynamicMethodCallModel<SignalRAttribute>> DynamicMethodCallModels = [];
    protected TLogger Logger = logger;
    protected IConfiguration Configuration = configuration;

    protected AcSerializerOptions SerializerOptions = new AcBinarySerializerOptions();

    /// <summary>
    /// Enable diagnostic logging for binary serialization debugging.
    /// Set to true to log hex dumps of serialized response data.
    /// </summary>
    public static bool EnableBinaryDiagnostics { get; set; } = false;

    #region Connection Lifecycle

    public override async Task OnConnectedAsync()
    {
        Logger.Debug($"Server OnConnectedAsync; ConnectionId: {GetConnectionId()}; UserIdentifier: {GetUserIdentifier()}");
        LogContextUserNameAndId();
        await base.OnConnectedAsync();
    }

    public override async Task OnDisconnectedAsync(Exception? exception)
    {
        var connectionId = GetConnectionId();
        var userIdentifier = GetUserIdentifier();
        
        if (exception == null)
            Logger.Debug($"Server OnDisconnectedAsync; ConnectionId: {connectionId}; UserIdentifier: {userIdentifier}");
        else
            Logger.Error($"Server OnDisconnectedAsync; ConnectionId: {connectionId}; UserIdentifier: {userIdentifier}", exception);

        LogContextUserNameAndId();
        await base.OnDisconnectedAsync(exception);
    }

    #endregion

    #region Message Processing

    public virtual Task OnReceiveMessage(int messageTag, byte[]? messageBytes, int? requestId)
    {
        return ProcessOnReceiveMessage(messageTag, messageBytes, requestId, null);
    }

    protected virtual async Task ProcessOnReceiveMessage(int messageTag, byte[]? message, int? requestId, Func<string, Task>? notFoundCallback)
    {
        var tagName = ConstHelper.NameByValue<TSignalRTags>(messageTag);

        if (message is { Length: 0 })
        {
            Logger.Warning($"message.Length == 0! Server OnReceiveMessage; requestId: {requestId}; ConnectionId: {GetConnectionId()}; {tagName}");
        }
        else
        {
            Logger.Debug($"[{message?.Length:N0}b] Server OnReceiveMessage; requestId: {requestId}; ConnectionId: {GetConnectionId()}; {tagName}");
        }

        try
        {
            if (AcDomain.IsDeveloperVersion) LogContextUserNameAndId();

            if (TryFindAndInvokeMethod(messageTag, message, tagName, out var responseData))
            {
                var responseMessage = CreateResponseMessage(messageTag, SignalResponseStatus.Success, responseData);
                
                if (Logger.LogLevel <= LogLevel.Debug)
                {
                    var responseSize = GetResponseSize(responseMessage);
                    Logger.Debug($"[{responseSize / 1024}kb] responseData serialized ({SerializerOptions.SerializerType})");
                }

                // Log binary diagnostics if enabled
                if (EnableBinaryDiagnostics && responseMessage is SignalResponseDataMessage dataMsg && dataMsg.ResponseData != null)
                {
                    LogResponseDataDiagnostics(messageTag, tagName, requestId, dataMsg.ResponseData);
                }

                await ResponseToCaller(messageTag, responseMessage, requestId);
                return;
            }
            
            Logger.Warning($"Not found dynamic method for the tag! {tagName}");
            notFoundCallback?.Invoke(tagName);
        }
        catch (Exception ex)
        {
            Logger.Error($"Server OnReceiveMessage; {ex.Message}; {tagName}", ex);
        }

        await ResponseToCaller(messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Error, null), requestId);
    }

    /// <summary>
    /// Reads a VarUInt from byte array at given position.
    /// </summary>
    private static (uint value, int bytesRead) ReadVarUIntFromBytes(byte[] data, int startPos)
    {
        uint value = 0;
        var shift = 0;
        var bytesRead = 0;
        
        while (startPos + bytesRead < data.Length)
        {
            var b = data[startPos + bytesRead];
            bytesRead++;
            value |= (uint)(b & 0x7F) << shift;
            if ((b & 0x80) == 0)
                break;
            shift += 7;
            if (shift > 35)
                break;
        }
        
        return (value, bytesRead);
    }

    /// <summary>
    /// Logs type information about the response data before serialization.
    /// </summary>
    private void LogResponseDataTypeInfo(object responseData)
    {
        try
        {
            var type = responseData.GetType();
            Logger.Info($"=== SERVER RESPONSE TYPE INFO (BEFORE SERIALIZE) ===");
            Logger.Info($"Runtime Type: {type.Name}");
            Logger.Info($"FullName: {type.FullName}");
            Logger.Info($"Namespace: {type.Namespace}");
            Logger.Info($"Assembly: {type.Assembly.GetName().Name} v{type.Assembly.GetName().Version}");
            Logger.Info($"AssemblyQualifiedName: {type.AssemblyQualifiedName}");
            Logger.Info($"Assembly Location: {type.Assembly.Location}");
            
            // For collections, log element type info
            if (type.IsGenericType)
            {
                var genericArgs = type.GetGenericArguments();
                Logger.Info($"Generic Arguments: [{string.Join(", ", genericArgs.Select(t => t.FullName))}]");
                
                if (genericArgs.Length == 1)
                {
                    var elementType = genericArgs[0];
                    Logger.Info($"--- ELEMENT TYPE INFO ---");
                    Logger.Info($"Element Type: {elementType.Name}");
                    Logger.Info($"Element FullName: {elementType.FullName}");
                    Logger.Info($"Element Namespace: {elementType.Namespace}");
                    Logger.Info($"Element Assembly: {elementType.Assembly.GetName().Name} v{elementType.Assembly.GetName().Version}");
                    Logger.Info($"Element AssemblyQualifiedName: {elementType.AssemblyQualifiedName}");
                    Logger.Info($"Element Assembly Location: {elementType.Assembly.Location}");
                    Logger.Info($"Element BaseType: {elementType.BaseType?.FullName ?? "null"}");
                    
                    // Log inheritance chain
                    var baseType = elementType.BaseType;
                    var inheritanceChain = new List<string>();
                    while (baseType != null && baseType != typeof(object))
                    {
                        inheritanceChain.Add($"{baseType.Name} ({baseType.Assembly.GetName().Name})");
                        baseType = baseType.BaseType;
                    }
                    if (inheritanceChain.Count > 0)
                    {
                        Logger.Info($"Element Inheritance: {string.Join(" -> ", inheritanceChain)}");
                    }
                    
                    LogTypePropertiesServer(elementType, "Element");
                }
            }
            else
            {
                Logger.Info($"BaseType: {type.BaseType?.FullName ?? "null"}");
                LogTypePropertiesServer(type, "Response");
            }
        }
        catch (Exception ex)
        {
            Logger.Warning($"Failed to log response type info: {ex.Message}");
        }
    }

    /// <summary>
    /// Logs all properties of a type with their declaring types.
    /// </summary>
    private void LogTypePropertiesServer(Type type, string prefix)
    {
        var props = type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance)
            .Where(p => p.CanRead && p.GetIndexParameters().Length == 0)
            .ToArray();
        
        // Log in declaration order (not alphabetically)
        Logger.Info($"{prefix} Property Count: {props.Length}");
        for (var i = 0; i < props.Length; i++)
        {
            var p = props[i];
            var declaringType = p.DeclaringType?.Name ?? "?";
            var declaringAssembly = p.DeclaringType?.Assembly.GetName().Name ?? "?";
            Logger.Info($"  {prefix}[{i}]: {p.Name} : {p.PropertyType.Name} (declared in {declaringType} @ {declaringAssembly})");
        }
    }

    /// <summary>
    /// Logs diagnostic information about the ResponseData binary for debugging serialization issues.
    /// </summary>
    private void LogResponseDataDiagnostics(int messageTag, string tagName, int? requestId, byte[] responseData)
    {
        try
        {
            Logger.Info($"=== SERVER RESPONSE DATA DIAGNOSTICS (AFTER SERIALIZE) ===");
            Logger.Info($"Tag: {messageTag} ({tagName}); RequestId: {requestId}; ResponseData.Length: {responseData.Length}");
            Logger.Info($"HEX (first 500 bytes): {Convert.ToHexString(responseData.AsSpan(0, Math.Min(500, responseData.Length)))}");
            
            if (responseData.Length >= 3)
            {
                var version = responseData[0];
                var marker = responseData[1];
                Logger.Info($"Version: {version}; Marker: 0x{marker:X2}");
                
                if ((marker & 0x10) != 0)
                {
                    // Read property count as VarUInt
                    var pos = 2;
                    var (propCount, bytesRead) = ReadVarUIntFromBytes(responseData, pos);
                    pos += bytesRead;
                    
                    Logger.Info($"Header property count: {propCount}");
                    
                    for (var i = 0; i < (int)propCount && pos < responseData.Length; i++)
                    {
                        // Read string length as VarUInt
                        var (strLen, strLenBytes) = ReadVarUIntFromBytes(responseData, pos);
                        pos += strLenBytes;
                        
                        if (pos + (int)strLen <= responseData.Length)
                        {
                            var propName = System.Text.Encoding.UTF8.GetString(responseData, pos, (int)strLen);
                            pos += (int)strLen;
                            Logger.Info($"  Header[{i}]: '{propName}'");
                        }
                        else
                        {
                            Logger.Info($"  Header[{i}]: <truncated at pos {pos}>");
                            break;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Logger.Warning($"Failed to log response data diagnostics: {ex.Message}");
        }
    }

    /// <summary>
    /// Creates a response message using the configured serializer.
    /// </summary>
    protected virtual ISignalRMessage CreateResponseMessage(int messageTag, SignalResponseStatus status, object? responseData)
    {
        return new SignalResponseDataMessage(messageTag, status, responseData, SerializerOptions);
    }

    /// <summary>
    /// Gets the size of the response data for logging purposes.
    /// </summary>
    private static int GetResponseSize(ISignalRMessage responseMessage)
    {
        return responseMessage is SignalResponseDataMessage dataMsg ? dataMsg.ResponseData?.Length ?? 0 : 0;
    }

    /// <summary>
    /// Finds and invokes the method registered for the given message tag.
    /// </summary>
    private bool TryFindAndInvokeMethod(int messageTag, byte[]? message, string tagName, out object? responseData)
    {
        responseData = null;

        foreach (var methodsByDeclaringObject in DynamicMethodCallModels)
        {
            if (!methodsByDeclaringObject.MethodsByMessageTag.TryGetValue(messageTag, out var methodInfoModel)) 
                continue;

            var methodName = $"{methodsByDeclaringObject.InstanceObject.GetType().Name}.{methodInfoModel.MethodInfo.Name}";
            var paramValues = DeserializeParameters(message, methodInfoModel, tagName, methodName);

            if (paramValues == null)
                Logger.Debug($"Found dynamic method for the tag! method: {methodName}(); {tagName}");
            else
                Logger.Debug($"Found dynamic method for the tag! method: {methodName}({string.Join(", ", methodInfoModel.ParamInfos.Select(x => x.Name))}); {tagName}");

            responseData = methodInfoModel.MethodInfo.InvokeMethod(methodsByDeclaringObject.InstanceObject, paramValues);

            // Log type information if diagnostics enabled
            if (EnableBinaryDiagnostics && responseData != null)
            {
                LogResponseDataTypeInfo(responseData);
            }

            if (methodInfoModel.Attribute.SendToOtherClientType != SendToClientType.None)
                SendMessageToOthers(methodInfoModel.Attribute.SendToOtherClientTag, responseData).Forget();

            return true;
        }

        return false;
    }

    /// <summary>
    /// Deserializes parameters from the message based on method signature.
    /// Uses Binary serialization for message wrapper.
    /// </summary>
    private static object[]? DeserializeParameters(byte[]? message, AcMethodInfoModel<SignalRAttribute> methodInfoModel, string tagName, string methodName)
    {
        if (methodInfoModel.ParamInfos is not { Length: > 0 })
            return null;

        if (message is null or { Length: 0 })
            throw new ArgumentException($"Message is null or empty but method '{methodName}' requires {methodInfoModel.ParamInfos.Length} parameter(s); {tagName}");

        var paramValues = new object[methodInfoModel.ParamInfos.Length];
        var firstParamType = methodInfoModel.ParamInfos[0].ParameterType;

        // First, try to deserialize as SignalPostJsonMessage to get raw PostDataJson
        var msgBase = SignalRSerializationHelper.DeserializeFromBinary<SignalPostJsonMessage>(message);
        if (msgBase?.PostDataJson == null || string.IsNullOrEmpty(msgBase.PostDataJson))
        {
            throw new ArgumentException($"Failed to deserialize message for method '{methodName}'; {tagName}");
        }

        var json = msgBase.PostDataJson;

        // Check if it's an IdMessage format (contains "Ids" property)
        if (json.Contains("\"Ids\""))
        {
            // Parse as IdMessage - each Id is a JSON string for a parameter
            var idMessage = json.JsonTo<IdMessage>();
            if (idMessage?.Ids != null && idMessage.Ids.Count > 0)
            {
                for (var i = 0; i < idMessage.Ids.Count && i < methodInfoModel.ParamInfos.Length; i++)
                {
                    var paramType = methodInfoModel.ParamInfos[i].ParameterType;
                    paramValues[i] = AcJsonDeserializer.Deserialize(idMessage.Ids[i], paramType)!;
                }
                return paramValues;
            }
        }

        // Single complex object - deserialize directly from PostDataJson
        paramValues[0] = json.JsonTo(firstParamType)!;
        return paramValues;
    }

    /// <summary>
    /// Determines if a type should use IdMessage format.
    /// </summary>
    private static bool IsPrimitiveOrStringOrEnum(Type type)
    {
        return type == typeof(string) || type.IsEnum || type.IsValueType || type == typeof(DateTime);
    }

    #endregion

    #region Response Methods

    protected virtual Task ResponseToCallerWithContent(int messageTag, object? content)
        => ResponseToCaller(messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Success, content), null);

    protected virtual Task ResponseToCaller(int messageTag, ISignalRMessage message, int? requestId)
        => SendMessageToClient(Clients.Caller, messageTag, message, requestId);

    protected virtual Task SendMessageToUserIdWithContent(string userId, int messageTag, object? content)
        => SendMessageToUserIdInternal(userId, messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Success, content), null);

    protected virtual Task SendMessageToUserIdInternal(string userId, int messageTag, ISignalRMessage message, int? requestId)
        => SendMessageToClient(Clients.User(userId), messageTag, message, requestId);

    protected virtual Task SendMessageToConnectionIdWithContent(string connectionId, int messageTag, object? content)
        => SendMessageToConnectionIdInternal(connectionId, messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Success, content), null);

    protected virtual Task SendMessageToConnectionIdInternal(string connectionId, int messageTag, ISignalRMessage message, int? requestId)
        => SendMessageToClient(Clients.Client(connectionId), messageTag, message, requestId);

    protected virtual Task SendMessageToOthers(int messageTag, object? content)
        => SendMessageToClient(Clients.Others, messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Success, content), null);

    protected virtual Task SendMessageToAll(int messageTag, object? content)
        => SendMessageToClient(Clients.All, messageTag, CreateResponseMessage(messageTag, SignalResponseStatus.Success, content), null);
    
    /// <summary>
    /// Sends message to client using Binary serialization.
    /// </summary>
    protected virtual async Task SendMessageToClient(IAcSignalRHubItemServer sendTo, int messageTag, ISignalRMessage message, int? requestId = null)
    {
        var responseBytes = SignalRSerializationHelper.SerializeToBinary(message);

        var tagName = ConstHelper.NameByValue<TSignalRTags>(messageTag);
        
        Logger.Debug($"[{responseBytes.Length / 1024}kb] Server sending message to client; requestId: {requestId}; Aborted: {IsConnectionAborted()}; ConnectionId: {GetConnectionId()}; {tagName}");

        await sendTo.OnReceiveMessage(messageTag, responseBytes, requestId);

        Logger.Debug($"Server sent message to client; requestId: {requestId}; ConnectionId: {GetConnectionId()}; {tagName}");
    }

    #endregion

    #region Context Accessor Methods

    protected virtual string GetConnectionId() => Context.ConnectionId;
    protected virtual bool IsConnectionAborted() => Context.ConnectionAborted.IsCancellationRequested;
    protected virtual string? GetUserIdentifier() => Context.UserIdentifier;
    protected virtual ClaimsPrincipal? GetUser() => Context.User;

    #endregion

    #region Logging

    protected virtual void LogContextUserNameAndId()
    {
        var user = GetUser();
        if (user == null) return;

        var userName = user.Identity?.Name;
        Guid.TryParse(user.FindFirstValue(ClaimTypes.NameIdentifier), out var userId);

        if (AcDomain.IsDeveloperVersion) 
            Logger.WarningConditional($"SignalR.Context; userName: {userName}; userId: {userId}");
        else 
            Logger.Debug($"SignalR.Context; userName: {userName}; userId: {userId}");
    }

    #endregion
}