From ff27d7ff16da80f6f9191ac9111b9b0075b5673e Mon Sep 17 00:00:00 2001
From: Laura Hausmann <laura@hausmann.dev>
Date: Wed, 14 Feb 2024 17:50:57 +0100
Subject: [PATCH] [backend/services] Basic event bus implementation (ISH-60)

---
 .../Mastodon/Schemas/Entities/Notification.cs         |  3 ---
 .../Core/Extensions/ServiceExtensions.cs              |  1 +
 Iceshrimp.Backend/Core/Services/EventService.cs       | 11 +++++++++++
 Iceshrimp.Backend/Core/Services/NoteService.cs        |  7 +++++--
 Iceshrimp.Backend/Iceshrimp.Backend.csproj            |  4 ++++
 5 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 Iceshrimp.Backend/Core/Services/EventService.cs

diff --git a/Iceshrimp.Backend/Controllers/Mastodon/Schemas/Entities/Notification.cs b/Iceshrimp.Backend/Controllers/Mastodon/Schemas/Entities/Notification.cs
index 17374c8a..24a987da 100644
--- a/Iceshrimp.Backend/Controllers/Mastodon/Schemas/Entities/Notification.cs
+++ b/Iceshrimp.Backend/Controllers/Mastodon/Schemas/Entities/Notification.cs
@@ -1,9 +1,6 @@
-using System.Text.Json.Serialization;
 using Iceshrimp.Backend.Core.Database;
-using Iceshrimp.Backend.Core.Database.Tables;
 using Iceshrimp.Backend.Core.Middleware;
 using J = System.Text.Json.Serialization.JsonPropertyNameAttribute;
-using JI = System.Text.Json.Serialization.JsonIgnoreAttribute;
 using static Iceshrimp.Backend.Core.Database.Tables.Notification;
 
 namespace Iceshrimp.Backend.Controllers.Mastodon.Schemas.Entities;
diff --git a/Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs b/Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs
index d488b53f..5efe38f9 100644
--- a/Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs
+++ b/Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs
@@ -54,6 +54,7 @@ public static class ServiceExtensions {
 			.AddSingleton<HttpRequestService>()
 			.AddSingleton<QueueService>()
 			.AddSingleton<ObjectStorageService>()
+			.AddSingleton<EventService>()
 			.AddSingleton<RequestBufferingMiddleware>()
 			.AddSingleton<AuthorizationMiddleware>()
 			.AddSingleton<RequestVerificationMiddleware>()
diff --git a/Iceshrimp.Backend/Core/Services/EventService.cs b/Iceshrimp.Backend/Core/Services/EventService.cs
new file mode 100644
index 00000000..2efadf75
--- /dev/null
+++ b/Iceshrimp.Backend/Core/Services/EventService.cs
@@ -0,0 +1,11 @@
+using Iceshrimp.Backend.Core.Database.Tables;
+
+namespace Iceshrimp.Backend.Core.Services;
+
+public class EventService {
+	public event EventHandler<Note>   NotePublished;
+	public event EventHandler<string> NoteDeleted;
+
+	public void RaiseNotePublished(object? sender, Note note) => NotePublished.Invoke(sender, note);
+	public void RaiseNoteDeleted(object? sender, Note note)   => NoteDeleted.Invoke(sender, note.Id);
+}
\ No newline at end of file
diff --git a/Iceshrimp.Backend/Core/Services/NoteService.cs b/Iceshrimp.Backend/Core/Services/NoteService.cs
index e20ede5b..a829be7a 100644
--- a/Iceshrimp.Backend/Core/Services/NoteService.cs
+++ b/Iceshrimp.Backend/Core/Services/NoteService.cs
@@ -36,7 +36,8 @@ public class NoteService(
 	MentionsResolver mentionsResolver,
 	MfmConverter mfmConverter,
 	DriveService driveSvc,
-	NotificationService notificationSvc
+	NotificationService notificationSvc,
+	EventService eventSvc
 ) {
 	private readonly List<string> _resolverHistory = [];
 	private          int          _recursionLimit  = 100;
@@ -84,6 +85,7 @@ public class NoteService(
 		if (reply != null) reply.RepliesCount++;
 		await db.AddAsync(note);
 		await db.SaveChangesAsync();
+		eventSvc.RaiseNotePublished(this, note);
 		await notificationSvc.GenerateMentionNotifications(note, mentionedLocalUserIds);
 
 		var obj      = await noteRenderer.RenderAsync(note, mentions);
@@ -127,7 +129,7 @@ public class NoteService(
 
 		user.NotesCount--;
 		db.Remove(dbNote);
-
+		eventSvc.RaiseNoteDeleted(this, dbNote);
 		await db.SaveChangesAsync();
 	}
 
@@ -212,6 +214,7 @@ public class NoteService(
 		if (dbNote.Reply != null) dbNote.Reply.RepliesCount++;
 		await db.Notes.AddAsync(dbNote);
 		await db.SaveChangesAsync();
+		eventSvc.RaiseNotePublished(this, dbNote);
 		await notificationSvc.GenerateMentionNotifications(dbNote, mentionedLocalUserIds);
 		await notificationSvc.GenerateReplyNotifications(dbNote, mentionedLocalUserIds);
 		logger.LogDebug("Note {id} created successfully", dbNote.Id);
diff --git a/Iceshrimp.Backend/Iceshrimp.Backend.csproj b/Iceshrimp.Backend/Iceshrimp.Backend.csproj
index 1dddfe66..ee1fe118 100644
--- a/Iceshrimp.Backend/Iceshrimp.Backend.csproj
+++ b/Iceshrimp.Backend/Iceshrimp.Backend.csproj
@@ -57,4 +57,8 @@
         <None Remove="migrate.sql"/>
     </ItemGroup>
 
+    <ItemGroup>
+      <Folder Include="Core\Events\" />
+    </ItemGroup>
+
 </Project>