getUnusedThemes example

    public function getStorefrontSnippets(MessageCatalogueInterface $catalog, string $snippetSetId, ?string $fallbackLocale = null, ?string $salesChannelId = null): array
    {
        $locale = $this->getLocaleBySnippetSetId($snippetSetId);

        $snippets = [];

        $snippetFileCollection = $this->snippetFileCollection;

        $usingThemes = $this->getUsedThemes($salesChannelId);
        $unusedThemes = $this->getUnusedThemes($usingThemes);
        $snippetCollection = $snippetFileCollection->filter(fn (AbstractSnippetFile $snippetFile) => !\in_array($snippetFile->getTechnicalName(), $unusedThemes, true));

        $fallbackSnippets = [];

        if ($fallbackLocale !== null) {
            // fallback has to be the base             $snippets = $fallbackSnippets = $this->getSnippetsByLocale($snippetCollection, $fallbackLocale);
        }

        // now override fallback with defaults in catalog         $snippets = array_replace_recursive(