feat: add toast for no content

src/lib/seoHelper.ts

@@ -0,0 +1,80 @@
+import { Language } from './translations';
+
+interface SEOContent {
+  title: string;
+  description: string;
+  keywords: string;
+}
+
+const seoContent: Record<Language, SEOContent> = {
+  zh: {
+    title: '⚡️ TexPixel - 公式识别工具',
+    description: '在线公式识别工具，支持印刷体和手写体数学公式识别，快速准确地将图片中的数学公式转换为可编辑文本。',
+    keywords: '公式识别,数学公式,OCR,手写公式识别,印刷体识别,AI识别,数学工具,免费,混合文字识别,texpixel,TexPixel',
+  },
+  en: {
+    title: '⚡️ TexPixel - Formula Recognition Tool',
+    description: 'Online formula recognition tool supporting printed and handwritten math formulas. Convert images to LaTeX, MathML, and Markdown quickly and accurately.',
+    keywords: 'formula recognition,math formula,OCR,handwriting recognition,latex,mathml,markdown,AI recognition,math tool,free,texpixel,TexPixel,document recognition',
+  },
+};
+
+/**
+ * Update document metadata based on current language
+ */
+export function updatePageMeta(language: Language): void {
+  const content = seoContent[language];
+  
+  // Update title
+  document.title = content.title;
+  
+  // Update HTML lang attribute
+  document.documentElement.lang = language === 'zh' ? 'zh-CN' : 'en';
+  
+  // Update meta description
+  const metaDescription = document.querySelector('meta[name="description"]');
+  if (metaDescription) {
+    metaDescription.setAttribute('content', content.description);
+  }
+  
+  // Update meta keywords
+  const metaKeywords = document.querySelector('meta[name="keywords"]');
+  if (metaKeywords) {
+    metaKeywords.setAttribute('content', content.keywords);
+  }
+  
+  // Update Open Graph meta tags
+  const ogTitle = document.querySelector('meta[property="og:title"]');
+  if (ogTitle) {
+    ogTitle.setAttribute('content', content.title);
+  }
+  
+  const ogDescription = document.querySelector('meta[property="og:description"]');
+  if (ogDescription) {
+    ogDescription.setAttribute('content', content.description);
+  }
+  
+  // Update Twitter Card meta tags
+  const twitterTitle = document.querySelector('meta[name="twitter:title"]');
+  if (twitterTitle) {
+    twitterTitle.setAttribute('content', content.title);
+  }
+  
+  const twitterDescription = document.querySelector('meta[name="twitter:description"]');
+  if (twitterDescription) {
+    twitterDescription.setAttribute('content', content.description);
+  }
+  
+  // Update og:locale
+  const ogLocale = document.querySelector('meta[property="og:locale"]');
+  if (ogLocale) {
+    ogLocale.setAttribute('content', language === 'zh' ? 'zh_CN' : 'en_US');
+  }
+}
+
+/**
+ * Get SEO content for a specific language
+ */
+export function getSEOContent(language: Language): SEOContent {
+  return seoContent[language];
+}