chore(shared): add shared notification infrastructure

source/Nuke.Build.Shared/Notifications.cs

@@ -0,0 +1,96 @@
+// Copyright 2023 Maintainers of NUKE.
+// Distributed under the MIT License.
+// https://github.com/nuke-build/nuke/blob/master/LICENSE
+
+using System;
+using System.Linq;
+using System.Net.Http;
+using System.Text.Json;
+using System.Threading.Tasks;
+using JetBrains.Annotations;
+using Nuke.Common;
+using Nuke.Common.IO;
+using Nuke.Common.Utilities;
+
+namespace Nuke.Build.Shared;
+
+internal record Notification(string Title, string Text, Link[] Links)
+{
+    public string Title { get; } = Title;
+    public string Text { get; } = Text;
+    public Link[] Links { get; } = Links;
+}
+
+internal record Link(string Text, string Url)
+{
+    public string Text { get; } = Text;
+    public string Url { get; } = Url;
+}
+
+[PublicAPI]
+internal class NotificationFetcher
+{
+    private const string NotificationEndpoint = "https://nuke.build/notifications.json";
+    private const string UtmMedium = "development";
+
+    private readonly AbsolutePath _notificationDirectory = Constants.GlobalNukeDirectory / "received-notifications";
+    private readonly string _utmSource;
+
+    public NotificationFetcher(string utmSource)
+    {
+        _utmSource = utmSource;
+    }
+
+    public async Task<Notification> GetNotificationAsync()
+    {
+        try
+        {
+            return await GetNotificationInternal();
+        }
+        catch (Exception)
+        {
+            return null;
+        }
+    }
+
+    private async Task<Notification> GetNotificationInternal()
+    {
+        var httpClient = new HttpClient();
+        var response = await httpClient.GetAsync(NotificationEndpoint);
+        if (!response.IsSuccessStatusCode)
+            return null;
+
+        var content = await response.Content.ReadAsStringAsync();
+        var json = JsonDocument.Parse(content).RootElement;
+
+        var notification = json.EnumerateArray()
+            .Where(IsApplicable)
+            .Select(x => (Json: x, File: _notificationDirectory / x.ToString().GetMD5Hash()))
+            .FirstOrDefault(x => !x.File.Exists());
+        if (notification.File == null)
+            return null;
+
+        notification.File.TouchFile();
+
+        return new Notification(
+            Title: notification.Json.GetProperty("title").GetString(),
+            Text: notification.Json.GetProperty("text").GetString(),
+            Links: notification.Json.GetProperty("links").EnumerateArray().Select(GetLink).ToArray());
+
+        bool IsApplicable(JsonElement element)
+            => !element.TryGetProperty("exclude", out var exclusions) ||
+               !exclusions.EnumerateArray().Select(x => x.GetString()).Contains(_utmSource);
+
+        Link GetLink(JsonElement obj)
+        {
+            var originalUrl = new Uri(obj.GetProperty("url").GetString().NotNullOrEmpty())
+                .WithUtmValues(
+                    medium: UtmMedium,
+                    source: _utmSource,
+                    campaign: obj.GetProperty("campaign").GetString());
+            return new Link(
+                Text: obj.GetProperty("title").GetString(),
+                Url: originalUrl.AbsoluteUri);
+        }
+    }
+}