fix(api): store branding images as media references (#3313)

fluxer_api/src/api/instance/BrandingAssetReferences.ts

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+export const BRANDING_ASSET_FIELDS = ['icon_url', 'symbol_url', 'logo_url', 'wordmark_url', 'favicon_url'] as const;
+
+export type BrandingAssetField = (typeof BRANDING_ASSET_FIELDS)[number];
+
+const BRANDING_ASSET_REFERENCE = /^branding\/\d{1,20}\/(?:a_)?[0-9a-f]{8}\.[a-z0-9]{2,5}$/;
+const BRANDING_ASSET_PATH = /\/(branding\/\d{1,20}\/(?:a_)?[0-9a-f]{8}\.[a-z0-9]{2,5})$/;
+
+function trimTrailingSlashes(value: string): string {
+	return value.replace(/\/+$/u, '');
+}
+
+export function isBrandingAssetReference(value: string): boolean {
+	return BRANDING_ASSET_REFERENCE.test(value);
+}
+
+export function brandingAssetReferenceFromOwnUrl(value: string, mediaEndpoint: string): string | null {
+	const prefix = `${trimTrailingSlashes(mediaEndpoint)}/`;
+	if (!value.startsWith(prefix)) return null;
+	const remainder = value.slice(prefix.length);
+	return isBrandingAssetReference(remainder) ? remainder : null;
+}
+
+export function brandingAssetReferenceFromAnyUrl(value: string): string | null {
+	let url: URL;
+	try {
+		url = new URL(value);
+	} catch {
+		return null;
+	}
+	if ((url.protocol !== 'https:' && url.protocol !== 'http:') || url.search !== '' || url.hash !== '') return null;
+	return BRANDING_ASSET_PATH.exec(url.pathname)?.[1] ?? null;
+}
+
+export function brandingAssetStorageKey(reference: string): string {
+	const slash = reference.lastIndexOf('/');
+	const file = reference.slice(slash + 1);
+	const hash = file.slice(0, file.indexOf('.')).replace(/^a_/u, '');
+	return `${reference.slice(0, slash)}/${hash}`;
+}
+
+export function toStoredBrandingAsset(
+	value: string | null | undefined,
+	mediaEndpoint: string,
+): string | null | undefined {
+	if (value === undefined || value === null) return value;
+	return brandingAssetReferenceFromOwnUrl(value, mediaEndpoint) ?? value;
+}
+
+export function resolveBrandingAsset(value: string | null, mediaEndpoint: string): string | null {
+	if (value === null || !isBrandingAssetReference(value)) return value;
+	return `${trimTrailingSlashes(mediaEndpoint)}/${value}`;
+}
+
+export function mapBrandingAssets<T extends Partial<Record<BrandingAssetField, string | null | undefined>>>(
+	branding: T,
+	map: (value: string | null | undefined) => string | null | undefined,
+): T {
+	const next = {...branding};
+	for (const field of BRANDING_ASSET_FIELDS) {
+		if (field in next) {
+			next[field] = map(next[field]) as T[BrandingAssetField];
+		}
+	}
+	return next;
+}