allow reading attachments even if the model is offline

frontend/src/utils/web-file-operations.ts

@@ -0,0 +1,72 @@
+import { getDocument, GlobalWorkerOptions, PDFDocumentProxy } from 'pdfjs-dist';
+import { TextItem } from 'pdfjs-dist/types/src/display/api';
+
+export function webOpenOpenFileDialog({ filterPattern, fnStartLoading }: { filterPattern: string, fnStartLoading: Function | null }): Promise<{ blob: Blob, content?: string }> {
+  return new Promise((resolve, reject) => {
+    const input = document.createElement('input');
+    input.type = 'file';
+    input.accept = filterPattern
+    .replaceAll('*.txt', 'text/plain')
+    .replaceAll('*.', 'application/')
+    .replaceAll(';', ',');
+
+    input.onchange = async e => {
+      // @ts-ignore
+      const file: Blob = e.target?.files[0];
+      if (fnStartLoading && typeof fnStartLoading === 'function')
+        fnStartLoading();
+      if (!GlobalWorkerOptions.workerSrc)
+        // @ts-ignore
+        GlobalWorkerOptions.workerSrc = await import('pdfjs-dist/build/pdf.worker.min.mjs');
+      if (file.type === 'text/plain') {
+        const reader = new FileReader();
+        reader.readAsText(file, 'UTF-8');
+
+        reader.onload = event => {
+          const content = event.target?.result as string;
+          resolve({
+            blob: file,
+            content: content
+          });
+        };
+        reader.onerror = reject;
+      } else if (file.type === 'application/pdf') {
+        const readPDFPage = async (doc: PDFDocumentProxy, pageNo: number) => {
+          const page = await doc.getPage(pageNo);
+          const tokenizedText = await page.getTextContent();
+          return tokenizedText.items.map(token => (token as TextItem).str).join('');
+        };
+        let reader = new FileReader();
+        reader.readAsArrayBuffer(file);
+
+        reader.onload = async (event) => {
+          try {
+            const doc = await getDocument(event.target?.result!).promise;
+            const pageTextPromises = [];
+            for (let pageNo = 1; pageNo <= doc.numPages; pageNo++) {
+              pageTextPromises.push(readPDFPage(doc, pageNo));
+            }
+            const pageTexts = await Promise.all(pageTextPromises);
+            let content;
+            if (pageTexts.length === 1)
+              content = pageTexts[0];
+            else
+              content = pageTexts.map((p, i) => `Page ${i + 1}:\n${p}`).join('\n\n');
+            resolve({
+              blob: file,
+              content: content
+            });
+          } catch (err) {
+            reject(err);
+          }
+        };
+        reader.onerror = reject;
+      } else {
+        resolve({
+          blob: file
+        });
+      }
+    };
+    input.click();
+  });
+}