Refactor the database logic for the apps into it's own mixin for reuse

module/apps/mixins/DBConnector.mjs

@@ -0,0 +1,89 @@
+import { getFile, lastModifiedAt } from "../../utils/fs.mjs";
+import { __ID__ } from "../../consts.mjs";
+
+
+export function DBConnectorMixin(HandlebarsApp) {
+	class DBConnectorApp extends HandlebarsApp {
+		// #region Instance Data
+		#lastModified = null;
+
+		#connected = false;
+
+		_docID;
+		_doc;
+
+		static dbType = `Unknown`;
+		static dbPath;
+
+		constructor({ docID, ...opts } = {}) {
+			super(opts);
+			if (this.constructor.dbPath == null) {
+				throw `dbPath must be defined on a DB-connected app`;
+			};
+			this._docID = docID;
+		};
+
+		get dbPath() {
+			return this.constructor.dbPath;
+		};
+
+		get dbType() {
+			return this.constructor.dbType;
+		};
+		// #endregion Instance Data
+
+		// #region Lifecycle
+		/**
+		 * Ensures that the app is in a state where it is allowed to render
+		 * before actually letting it render at all.
+		 */
+		async render(options, ...args) {
+			const allowed = await this.#connectToDB();
+			if (!allowed) { return this };
+			return super.render(options, ...args);
+		};
+
+		/**
+		 * This fetches the DB data that we care about for the purposes of being able
+		 * to create/edit entries in the Artists DB
+		 */
+		async #connectToDB() {
+			if (this.#connected) { return true };
+			this.#lastModified ??= await lastModifiedAt(this.dbPath);
+
+			if (this._docID) {
+				const documents = await getFile(this.dbPath);
+
+				if (documents[this._docID] == null) {
+					ui.notifications.error(_loc(
+						`TB.notifs.error.document-ID-404`,
+						{ id: this._docID, dbType: this.dbType },
+					));
+					return false;
+				};
+
+				Object.assign(this._doc, documents[this._docID]);
+			};
+			this.#connected = true;
+			return true;
+		};
+
+		async isAbleToSave() {
+			if (!this._docID) { return true };
+
+			const newLastModified = await lastModifiedAt(this.dbPath);
+			if (newLastModified !== this.#lastModified) {
+				ui.notifications.error(
+					`TB.notifs.error.db-out-of-date`,
+					{ localize: true },
+				);
+				return false;
+			};
+
+			return true;
+		};
+		// #endregion Lifecycle
+	};
+
+	return DBConnectorApp;
+};