1 files changed, 100 insertions, 0 deletions
diff --git a/packages/backend/src/models/LatestNote.ts b/packages/backend/src/models/LatestNote.ts
new file mode 100644
index 0000000000..064fcccc0a
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+++ b/packages/backend/src/models/LatestNote.ts
@@ -0,0 +1,100 @@
+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { PrimaryColumn, Entity, JoinColumn, Column, ManyToOne } from 'typeorm';
+import { MiUser } from '@/models/User.js';
+import { MiNote } from '@/models/Note.js';
+import { isQuote, isRenote } from '@/misc/is-renote.js';
+
+/**
+ * Maps a user to the most recent post by that user.
+ * Public, home-only, and followers-only posts are included.
+ * DMs are not counted.
+ */
+@Entity('latest_note')
+export class SkLatestNote {
+	@PrimaryColumn({
+		name: 'user_id',
+		type: 'varchar' as const,
+		length: 32,
+	})
+	public userId: string;
+
+	@PrimaryColumn('boolean', {
+		name: 'is_public',
+		default: false,
+	})
+	public isPublic: boolean;
+
+	@PrimaryColumn('boolean', {
+		name: 'is_reply',
+		default: false,
+	})
+	public isReply: boolean;
+
+	@PrimaryColumn('boolean', {
+		name: 'is_quote',
+		default: false,
+	})
+	public isQuote: boolean;
+
+	@ManyToOne(() => MiUser, {
+		onDelete: 'CASCADE',
+	})
+	@JoinColumn({
+		name: 'user_id',
+	})
+	public user: MiUser | null;
+
+	@Column({
+		name: 'note_id',
+		type: 'varchar' as const,
+		length: 32,
+	})
+	public noteId: string;
+
+	@ManyToOne(() => MiNote, {
+		onDelete: 'CASCADE',
+	})
+	@JoinColumn({
+		name: 'note_id',
+	})
+	public note: MiNote | null;
+
+	constructor(data?: Partial<SkLatestNote>) {
+		if (!data) return;
+
+		for (const [k, v] of Object.entries(data)) {
+			(this as Record<string, unknown>)[k] = v;
+		}
+	}
+
+	/**
+	 * Generates a compound key matching a provided note.
+	 */
+	static keyFor(note: MiNote) {
+		return {
+			userId: note.userId,
+			isPublic: note.visibility === 'public',
+			isReply: note.replyId != null,
+			isQuote: isRenote(note) && isQuote(note),
+		};
+	}
+
+	/**
+	 * Checks if two notes would produce equivalent compound keys.
+	 */
+	static areEquivalent(first: MiNote, second: MiNote): boolean {
+		const firstKey = SkLatestNote.keyFor(first);
+		const secondKey = SkLatestNote.keyFor(second);
+
+		return (
+			firstKey.userId === secondKey.userId &&
+			firstKey.isPublic === secondKey.isPublic &&
+			firstKey.isReply === secondKey.isReply &&
+			firstKey.isQuote === secondKey.isQuote
+		);
+	}
+}