refactor: improve block modularity on server (#758)

blocks/text/server.ts

@@ -0,0 +1,70 @@
+import { smoothStream, streamText } from 'ai';
+import { myProvider } from '@/lib/ai/models';
+import { createDocumentHandler } from '@/lib/blocks/server';
+import { updateDocumentPrompt } from '@/lib/ai/prompts';
+
+export const textDocumentHandler = createDocumentHandler<'text'>({
+  kind: 'text',
+  onCreateDocument: async ({ title, dataStream }) => {
+    let draftContent = '';
+
+    const { fullStream } = streamText({
+      model: myProvider.languageModel('block-model'),
+      system:
+        'Write about the given topic. Markdown is supported. Use headings wherever appropriate.',
+      experimental_transform: smoothStream({ chunking: 'word' }),
+      prompt: title,
+    });
+
+    for await (const delta of fullStream) {
+      const { type } = delta;
+
+      if (type === 'text-delta') {
+        const { textDelta } = delta;
+
+        draftContent += textDelta;
+
+        dataStream.writeData({
+          type: 'text-delta',
+          content: textDelta,
+        });
+      }
+    }
+
+    return draftContent;
+  },
+  onUpdateDocument: async ({ document, description, dataStream }) => {
+    let draftContent = '';
+
+    const { fullStream } = streamText({
+      model: myProvider.languageModel('block-model'),
+      system: updateDocumentPrompt(document.content, 'text'),
+      experimental_transform: smoothStream({ chunking: 'word' }),
+      prompt: description,
+      experimental_providerMetadata: {
+        openai: {
+          prediction: {
+            type: 'content',
+            content: document.content,
+          },
+        },
+      },
+    });
+
+    for await (const delta of fullStream) {
+      const { type } = delta;
+
+      if (type === 'text-delta') {
+        const { textDelta } = delta;
+
+        draftContent += textDelta;
+        dataStream.writeData({
+          type: 'text-delta',
+          content: textDelta,
+        });
+      }
+    }
+
+    return draftContent;
+  },
+});