pfm/PostFundManagement.Application/Interceptors/AuditInterceptor.cs

using PostFundManagement.Application.Services.Shared;
using PostFundManagement.Domain.Attributes;

namespace PostFundManagement.Application.Interceptors;

public sealed class AuditInterceptor(AuditService auditService, IHttpContextAccessor httpContextAccessor) : IAsyncInterceptor
{
    public void InterceptSynchronous(IInvocation invocation) => invocation.Proceed();

    public void InterceptAsynchronous(IInvocation invocation) =>
        invocation.ReturnValue = InternalInterceptAsynchronous(invocation);

    public void InterceptAsynchronous<TResult>(IInvocation invocation) =>
        invocation.ReturnValue = InternalInterceptAsynchronous<TResult>(invocation);

    private static async Task InternalInterceptAsynchronous(IInvocation invocation)
    {
        invocation.Proceed();

        var task = (Task)invocation.ReturnValue;

        await task.ConfigureAwait(false);
    }

    private async Task<TResult> InternalInterceptAsynchronous<TResult>(IInvocation invocation)
    {
        invocation.Proceed();

        var task = (Task<TResult>)invocation.ReturnValue;
        var resultObj = await task.ConfigureAwait(false);

        var method = invocation.MethodInvocationTarget ?? invocation.Method;
        var auditAttr = method.GetCustomAttribute<AuditAttribute>()
                     ?? invocation.Method.GetCustomAttribute<AuditAttribute>();

        if (auditAttr == null) return resultObj;

        if (resultObj is IResultBase result && result.IsSuccess)
        {
            try
            {
                var action = ResolveActionName(method.Name);
                var entityName = ResolveEntityName(method, resultObj, invocation.Arguments);
                var entityId = ResolveEntityId(resultObj, invocation.Arguments);
                var changes = BuildPayloadSummary(invocation.Method.GetParameters(), invocation.Arguments);
                var performedBy = ResolveUserId();

                await auditService.LogActionAsync(
                    entityId: entityId,
                    entityName: entityName,
                    action: action,
                    changes: changes,
                    performedBy: performedBy).ConfigureAwait(false);
            }
            catch { /* eat all exceptions, don't interrupt program flow */ }
        }

        return resultObj;
    }

    private static string ResolveActionName(string methodName) =>
        methodName.EndsWith("Async", StringComparison.Ordinal)
            ? methodName[..^5]
            : methodName;

    private static string ResolveEntityName(MethodInfo method, object? resultObj, object[] args)
    {
        var returnType = method.ReturnType;

        Type? innerType = null;

        if (returnType.IsGenericType)
        {
            var genericDef = returnType.GetGenericTypeDefinition();

            if (genericDef == typeof(Task<>) || genericDef == typeof(Task<>))
                innerType = returnType.GetGenericArguments()[0];
        }

        if (innerType != null && innerType.IsGenericType && typeof(IResultBase).IsAssignableFrom(innerType))
        {
            var valueType = innerType.GetGenericArguments().FirstOrDefault();

            if (valueType != null && valueType != typeof(bool) && valueType != typeof(int) && valueType != typeof(string))
                return valueType.Name;
        }

        foreach (var arg in args)
        {
            if (arg == null || arg is CancellationToken or IFormFile) continue;

            var argTypeName = arg.GetType().Name;

            if (argTypeName.EndsWith("Request", StringComparison.Ordinal))
            {
                var trimmed = argTypeName[..^7];

                return trimmed.Replace("Create", "").Replace("Update", "");
            }
        }

        return ResolveActionName(method.Name);
    }

    private static string ResolveEntityId(object? resultObj, object[] args)
    {
        if (resultObj != null)
        {
            var valueProp = resultObj.GetType().GetProperty("Value");
            if (valueProp != null)
            {
                var value = valueProp.GetValue(resultObj);
                if (value != null)
                {
                    var idProp = value.GetType().GetProperty("Id") ?? value.GetType().GetProperty("id");
                    if (idProp != null)
                    {
                        var idVal = idProp.GetValue(value);
                        if (idVal != null) return idVal.ToString()!;
                    }
                }
            }
        }

        foreach (var arg in args)
        {
            if (arg is long or int or Guid or string)
                return arg.ToString()!;

            if (arg != null && arg is not CancellationToken and not IFormFile)
            {
                var idProp = arg.GetType().GetProperty("Id") ?? arg.GetType().GetProperty("id");

                if (idProp != null)
                {
                    var idVal = idProp.GetValue(arg);

                    if (idVal != null) return idVal.ToString()!;
                }
            }
        }

        return "N/A";
    }

    private static string[] BuildPayloadSummary(ParameterInfo[] parameters, object[] args)
    {
        var entries = new List<string>();

        for (var i = 0; i < parameters.Length; i++)
        {
            var param = parameters[i];
            var arg = args[i];

            if (param.ParameterType == typeof(CancellationToken))
                continue;

            if (arg == null)
            {
                entries.Add($"{param.Name}: null");

                continue;
            }

            if (arg is IFormFile file)
            {
                entries.Add($"{param.Name}: [File] Name='{file.FileName}', Size={file.Length} bytes, Type='{file.ContentType}'");

                continue;
            }

            if (arg is IEnumerable<IFormFile> files)
            {
                var fileSummaries = files.Select(f => $"'{f.FileName}' ({f.Length} bytes)");

                entries.Add($"{param.Name}: [Files] count={fileSummaries.Count()} [{string.Join(", ", fileSummaries)}]");

                continue;
            }

            if (arg is Stream stream)
            {
                entries.Add($"{param.Name}: [Stream] Length={(stream.CanSeek ? stream.Length : -1)} bytes");

                continue;
            }

            try
            {
                var json = JsonSerializer.Serialize(arg);

                entries.Add($"{param.Name}: {json}");
            }
            catch
            {
                entries.Add($"{param.Name}: [Unserializable]");
            }
        }

        return [.. entries];
    }

    private Guid ResolveUserId()
    {
        var user = httpContextAccessor.HttpContext?.User;

        var sub = user?.FindFirst(ClaimTypes.NameIdentifier)?.Value ?? user?.FindFirst("sub")?.Value;

        return Guid.TryParse(sub, out var guid) ? guid : Guid.Empty;
    }
}