fixes file handling.

static/download_results.js

@@ -2,9 +2,9 @@ function deleteFiles(filePaths) {
     fetch('/delete_files', {
         method: 'POST',
         headers: {
-            'Content-Type': 'application/x-www-form-urlencoded',
+            'Content-Type': 'application/json',
         },
-        body: new URLSearchParams({
+        body: JSON.stringify({
             'file_paths': filePaths
         })
     })
@@ -29,18 +29,37 @@ function deleteSelectedFiles() {
     }
 }
 
+
 function downloadSelectedFiles() {
     const selectedFiles = Array.from(document.querySelectorAll('input[name="fileCheckbox"]:checked'))
         .map(checkbox => checkbox.value);
     if (selectedFiles.length > 0) {
-        selectedFiles.forEach(file => {
-            const link = document.createElement('a');
-            link.href = file;
-            link.download = file.split('/').pop();
-            document.body.appendChild(link);
-            link.click();
-            document.body.removeChild(link);
-        });
+        fetch('/download_files', {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json',
+            },
+            body: JSON.stringify({ 'file_paths': selectedFiles })
+        })
+        .then(response => {
+            if (!response.ok) {
+                return response.json().then(err => { throw new Error(err.error); });
+            }
+            return response.blob();
+        })
+        .then(blob => {
+            if (blob.type !== 'application/zip') {
+                throw new Error("Received invalid ZIP file.");
+            }
+            const url = window.URL.createObjectURL(blob);
+            const a = document.createElement('a');
+            a.href = url;
+            a.download = 'files.zip';
+            document.body.appendChild(a);
+            a.click();
+            a.remove();
+        })
+        .catch(error => alert('Error: ' + error.message));
     } else {
         alert('No files selected');
     }