enhance: uniform theme color (#8702)

* enhance: make theme color format uniform

All newly fetched instance theme colors will be uniformely formatted
as hashtag followed by 6 hexadecimal digits.

Colors are checked for validity and invalid colors are not handled.

* better input validation for own theme color

* migration to unify theme color formats

Fixes theme colors of other instances as well as the local instance.

* add changelog entry

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/backend/migration/1652859567549-uniform-themecolor.js

@@ -0,0 +1,38 @@
+import tinycolor from 'tinycolor2';
+
+export class uniformThemecolor1652859567549 {
+	name = 'uniformThemecolor1652859567549'
+
+	async up(queryRunner) {
+		const formatColor = (color) => {
+			let tc = new tinycolor(color);
+			if (color.isValid()) {
+				return color.toHexString();
+			} else {
+				return null;
+			}
+		};
+
+		await Promise.all(queryRunner.query('SELECT "id", "themeColor" FROM "instance" WHERE "themeColor" IS NOT NULL')
+		.then(instances => instances.map(instance => {
+			// update theme color to uniform format, e.g. #00ff00
+			// invalid theme colors get set to null
+			instance.color = formatColor(instance.color);
+
+			return queryRunner.query('UPDATE "instance" SET "themeColor" = :themeColor WHERE "id" = :id', instance);
+		})));
+
+		// also fix own theme color
+		await queryRunner.query('SELECT "themeColor" FROM "meta" WHERE "themeColor" IS NOT NULL LIMIT 1')
+		.then(metas => {
+			if (metas.length > 0) {
+				return queryRunner.query('UPDATE "meta" SET "themeColor" = :color', { color: formatColor(metas[0].color) });
+			}
+		});
+	}
+
+	async down(queryRunner) {
+		// The original representation is not stored, so migrating back is not possible.
+		// The new format also works in older versions so this is not a problem.
+	}
+}