Plausible Analytics

VoidCat/Model/Extensions.cs

@@ -236,4 +236,7 @@ public static class Extensions
 
     public static bool HasVirusScanner(this VoidSettings settings)
         => settings.VirusScanner?.ClamAV != default || settings.VirusScanner?.VirusTotal != default;
+
+    public static bool HasPlausible(this VoidSettings settings)
+        => settings.PlausibleAnalytics?.Endpoint != null;
 }

VoidCat/Model/VoidSettings.cs

@@ -90,6 +90,11 @@ namespace VoidCat.Model
         /// Select which store to use for files storage, if not set "local-disk" will be used
         /// </summary>
         public string DefaultFileStore { get; init; } = "local-disk";
+        
+        /// <summary>
+        /// Plausible Analytics endpoint url
+        /// </summary>
+        public PlausibleSettings? PlausibleAnalytics { get; init; }
     }
 
     public sealed class TorSettings
@@ -158,4 +163,10 @@ namespace VoidCat.Model
         public Uri? Url { get; init; }
         public string? EgressQuery { get; init; }
     }
+
+    public sealed class PlausibleSettings
+    {
+        public Uri? Endpoint { get; init; }
+        public string? Domain { get; init; }
+    }
 }

VoidCat/Program.cs

@@ -2,6 +2,7 @@ using Newtonsoft.Json;
 using Prometheus;
 using VoidCat;
 using VoidCat.Model;
+using VoidCat.Services.Analytics;
 using VoidCat.Services.Migrations;
 
 JsonConvert.DefaultSettings = () => VoidStartup.ConfigJsonSettings(new());
@@ -90,6 +91,7 @@ if (mode.HasFlag(RunModes.Webserver))
 
     app.UseHealthChecks("/healthz");
 
+    app.UseMiddleware<AnalyticsMiddleware>();
     app.UseEndpoints(ep =>
     {
         ep.MapControllers();

VoidCat/Services/Abstractions/IWebAnalyticsCollector.cs

@@ -0,0 +1,6 @@
+namespace VoidCat.Services.Abstractions;
+
+public interface IWebAnalyticsCollector
+{
+    Task TrackPageView(HttpContext context);
+}

VoidCat/Services/Analytics/AnalyticsMiddleware.cs

@@ -0,0 +1,32 @@
+using VoidCat.Services.Abstractions;
+
+namespace VoidCat.Services.Analytics;
+
+public class AnalyticsMiddleware : IMiddleware
+{
+    private readonly ILogger<AnalyticsMiddleware> _logger;
+    private readonly IEnumerable<IWebAnalyticsCollector> _collectors;
+
+    public AnalyticsMiddleware(IEnumerable<IWebAnalyticsCollector> collectors, ILogger<AnalyticsMiddleware> logger)
+    {
+        _collectors = collectors;
+        _logger = logger;
+    }
+
+    public async Task InvokeAsync(HttpContext context, RequestDelegate next)
+    {
+        foreach (var collector in _collectors)
+        {
+            try
+            {
+                await collector.TrackPageView(context);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to track page view");
+            }
+        }
+
+        await next(context);
+    }
+}

VoidCat/Services/Analytics/AnalyticsStartup.cs

@@ -0,0 +1,21 @@
+using VoidCat.Model;
+using VoidCat.Services.Abstractions;
+
+namespace VoidCat.Services.Analytics;
+
+public static class AnalyticsStartup
+{
+    /// <summary>
+    /// Add services needed to collect analytics
+    /// </summary>
+    /// <param name="services"></param>
+    /// <param name="settings"></param>
+    public static void AddAnalytics(this IServiceCollection services, VoidSettings settings)
+    {
+        services.AddTransient<AnalyticsMiddleware>();
+        if (settings.HasPlausible())
+        {
+            services.AddTransient<IWebAnalyticsCollector, PlausibleAnalytics>();
+        }
+    }
+}

VoidCat/Services/Analytics/PlausibleAnalytics.cs

@@ -0,0 +1,71 @@
+using System.Text;
+using Newtonsoft.Json;
+using VoidCat.Model;
+using VoidCat.Services.Abstractions;
+
+namespace VoidCat.Services.Analytics;
+
+public class PlausibleAnalytics : IWebAnalyticsCollector
+{
+    private readonly HttpClient _client;
+    private readonly string _domain;
+
+    public PlausibleAnalytics(HttpClient client, VoidSettings settings)
+    {
+        _client = client;
+        _client.BaseAddress = settings.PlausibleAnalytics!.Endpoint!;
+        _domain = settings.PlausibleAnalytics!.Domain!;
+    }
+
+    public async Task TrackPageView(HttpContext context)
+    {
+        var request = new HttpRequestMessage(HttpMethod.Post, "/api/event");
+        request.Headers.Add("user-agent", context.Request.Headers.UserAgent.First());
+        request.Headers.Add("x-forwarded-for",
+            context.Request.Headers.TryGetValue("x-forwarded-for", out var xff) ? xff.First() : null);
+
+        var ub = new UriBuilder("http:", context.Request.Host.Host, context.Request.Host.Port ?? 80,
+            context.Request.Path)
+        {
+            Query = context.Request.QueryString.Value
+        };
+
+        var ev = new EventObj(_domain, ub.Uri)
+        {
+            Referrer =
+                context.Request.Headers.Referer.Any()
+                    ? new Uri(context.Request.Headers.Referer.FirstOrDefault()!)
+                    : null
+        };
+        request.Content = new ByteArrayContent(Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(ev)));
+        request.Content.Headers.ContentType = new("application/json");
+
+        var rsp = await _client.SendAsync(request);
+        if (!rsp.IsSuccessStatusCode)
+        {
+            throw new Exception(
+                $"Invalid plausible analytics response {rsp.StatusCode} {await rsp.Content.ReadAsStringAsync()}");
+        }
+    }
+
+    internal class EventObj
+    {
+        public EventObj(string domain, Uri url)
+        {
+            Domain = domain;
+            Url = url;
+        }
+
+        [JsonProperty("name")] public string Name { get; init; } = "pageview";
+
+        [JsonProperty("domain")] public string Domain { get; init; }
+
+        [JsonProperty("url")] public Uri Url { get; init; }
+
+        [JsonProperty("screen_width")] public int? ScreenWidth { get; init; }
+
+        [JsonProperty("referrer")] public Uri? Referrer { get; init; }
+
+        [JsonProperty("props")] public object? Props { get; init; }
+    }
+}

VoidCat/VoidStartup.cs

@@ -12,6 +12,7 @@ using StackExchange.Redis;
 using VoidCat.Model;
 using VoidCat.Services;
 using VoidCat.Services.Abstractions;
+using VoidCat.Services.Analytics;
 using VoidCat.Services.Background;
 using VoidCat.Services.Captcha;
 using VoidCat.Services.Files;
@@ -150,6 +151,7 @@ public static class VoidStartup
         });
 
         services.AddTransient<RazorPartialToStringRenderer>();
+        services.AddAnalytics(voidSettings);
     }
 
     public static void AddBackgroundServices(this IServiceCollection services, VoidSettings voidSettings)