Serilog example for logging

examples/Cli/Logging/Infrastructure/LogInterceptor.cs

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+using Logging.Commands;
+using Serilog.Core;
+using Spectre.Console.Cli;
+
+namespace Logging
+{
+    public class LogInterceptor : ICommandInterceptor
+    {
+        public static readonly LoggingLevelSwitch LogLevel = new();
+
+        public void Intercept(CommandContext context, CommandSettings settings)
+        {
+            if (settings is LogCommandSettings logSettings)
+            {
+                LoggingEnricher.Path = logSettings.LogFile ?? "application.log";
+                LogLevel.MinimumLevel = logSettings.LogLevel;
+            }
+        }
+    }
+}

examples/Cli/Logging/Infrastructure/LoggingEnricher.cs

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+using Serilog.Core;
+using Serilog.Events;
+
+namespace Logging
+{
+    internal class LoggingEnricher : ILogEventEnricher
+    {
+        private string _cachedLogFilePath;
+        private LogEventProperty _cachedLogFilePathProperty;
+
+        // this path and level will be set by the LogInterceptor.cs after parsing the settings
+        public static string Path = string.Empty;
+
+        public const string LogFilePathPropertyName = "LogFilePath";
+
+        public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
+        {
+            // the settings might not have a path or we might not be within a command in which case
+            // we won't have the setting so a default value for the log file will be required
+            LogEventProperty logFilePathProperty;
+
+            if (_cachedLogFilePathProperty != null && Path.Equals(_cachedLogFilePath))
+            {
+                // Path hasn't changed, so let's use the cached property
+                logFilePathProperty = _cachedLogFilePathProperty;
+            }
+            else
+            {
+                // We've got a new path for the log. Let's create a new property
+                // and cache it for future log events to use
+                _cachedLogFilePath = Path;
+                _cachedLogFilePathProperty = logFilePathProperty = propertyFactory.CreateProperty(LogFilePathPropertyName, Path);
+            }
+
+            logEvent.AddPropertyIfAbsent(logFilePathProperty);
+        }
+    }
+}

examples/Cli/Logging/Infrastructure/TypeRegistrar.cs

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+using System;
+using Microsoft.Extensions.DependencyInjection;
+using Spectre.Console.Cli;
+
+namespace Logging
+{
+    public sealed class TypeRegistrar : ITypeRegistrar
+    {
+        private readonly IServiceCollection _builder;
+
+        public TypeRegistrar(IServiceCollection builder)
+        {
+            _builder = builder;
+        }
+
+        public ITypeResolver Build()
+        {
+            return new TypeResolver(_builder.BuildServiceProvider());
+        }
+
+        public void Register(Type service, Type implementation)
+        {
+            _builder.AddSingleton(service, implementation);
+        }
+
+        public void RegisterInstance(Type service, object implementation)
+        {
+            _builder.AddSingleton(service, implementation);
+        }
+
+        public void RegisterLazy(Type service, Func<object> func)
+        {
+            if (func is null)
+            {
+                throw new ArgumentNullException(nameof(func));
+            }
+
+            _builder.AddSingleton(service, _ => func());
+        }
+    }
+}

examples/Cli/Logging/Infrastructure/TypeResolver.cs

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+using System;
+using Microsoft.Extensions.DependencyInjection;
+using Spectre.Console.Cli;
+
+namespace Logging
+{
+    public sealed class TypeResolver : ITypeResolver
+    {
+        private readonly IServiceProvider _provider;
+
+        public TypeResolver(IServiceProvider provider)
+        {
+            _provider = provider ?? throw new ArgumentNullException(nameof(provider));
+        }
+
+        public object Resolve(Type type)
+        {
+            return _provider.GetRequiredService(type);
+        }
+    }
+}