Implemented system overview

Moonlight.ApiServer/Services/ApplicationService.cs

@@ -0,0 +1,95 @@
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using MoonCore.Attributes;
+
+namespace Moonlight.ApiServer.Services;
+
+[Singleton]
+public class ApplicationService
+{
+    private ILogger<ApplicationService> Logger;
+    private readonly IHost Host;
+
+    public ApplicationService(ILogger<ApplicationService> logger, IHost host)
+    {
+        Logger = logger;
+        Host = host;
+    }
+
+    public Task<string> GetOsName()
+    {
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+        {
+            // Windows platform detected
+            var osVersion = Environment.OSVersion.Version;
+            return Task.FromResult($"Windows {osVersion.Major}.{osVersion.Minor}.{osVersion.Build}");
+        }
+
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+        {
+            var releaseRaw = File
+                .ReadAllLines("/etc/os-release")
+                .FirstOrDefault(x => x.StartsWith("PRETTY_NAME="));
+
+            if (string.IsNullOrEmpty(releaseRaw))
+                return Task.FromResult("Linux (unknown release)");
+
+            var release = releaseRaw
+                .Replace("PRETTY_NAME=", "")
+                .Replace("\"", "");
+                
+            if(string.IsNullOrEmpty(release))
+                return Task.FromResult("Linux (unknown release)");
+
+            return Task.FromResult(release);
+        }
+
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+        {
+            // macOS platform detected
+            var osVersion = Environment.OSVersion.Version;
+            return Task.FromResult($"macOS {osVersion.Major}.{osVersion.Minor}.{osVersion.Build}");
+        }
+
+        // Unknown platform
+        return Task.FromResult("N/A");
+    }
+    
+    public Task<long> GetMemoryUsage()
+    {
+        var process = Process.GetCurrentProcess();
+        var bytes = process.PrivateMemorySize64;
+        return Task.FromResult(bytes);
+    }
+    
+    public Task<TimeSpan> GetUptime()
+    {
+        var process = Process.GetCurrentProcess();
+        var uptime = DateTime.Now - process.StartTime;
+        return Task.FromResult(uptime);
+    }
+
+    public Task<int> GetCpuUsage()
+    {
+        var process = Process.GetCurrentProcess();
+        var cpuTime = process.TotalProcessorTime;
+        var wallClockTime = DateTime.UtcNow - process.StartTime.ToUniversalTime();
+        
+        var cpuUsage = (int)(100.0 * cpuTime.TotalMilliseconds / wallClockTime.TotalMilliseconds / Environment.ProcessorCount);
+        
+        return Task.FromResult(cpuUsage);
+    }
+
+    public Task Shutdown()
+    {
+        Logger.LogCritical("Restart of api server has been requested");
+
+        Task.Run(async () =>
+        {
+            await Task.Delay(TimeSpan.FromSeconds(1));
+            await Host.StopAsync(CancellationToken.None);
+        });
+        
+        return Task.CompletedTask;
+    }
+}