Update app.py

app.py

@@ -3,7 +3,7 @@ import tempfile
 from typing import List
 import gradio as gr
 from PyPDF2 import PdfReader, PdfWriter
-import pikepdf 
+import pikepdf  # for advanced compression
 
 # Load custom CSS
 with open(os.path.join(os.path.dirname(__file__), "fancy.css")) as f:
@@ -98,19 +98,34 @@ with gr.Blocks(css=custom_css) as demo:
     with gr.Tabs():
         # Split
         with gr.TabItem("Split PDF"):
-            inp, ranges = gr.File(label="PDF"), gr.Textbox(label="Ranges")
+            inp = gr.File(label="PDF")
+            ranges = gr.Textbox(label="Page ranges", placeholder="e.g. 1-3,6-8")
             btn = gr.Button("Split")
             out, err = gr.File(), gr.Textbox(visible=False)
             btn.click(lambda f,r: (*split_pdf(f,r),), [inp,ranges],[out,err,err])
 
-        # Merge
+                # Merge
         with gr.TabItem("Merge PDF"):
-            files = gr.Files(label="PDFs")
-            order_df = gr.Dataframe(headers=["Filename","Order"], interactive=True)
-            files.change(lambda fs: [[os.path.basename(f.name), i+1] for i,f in enumerate(fs)], inputs=files, outputs=order_df)
-            btn_m = gr.Button("Merge")
-            out_m, err_m = gr.File(), gr.Textbox(visible=False)
-            btn_m.click(lambda fs,df: merge_pdfs(fs,[int(r[1]) for r in df] if df else None), [files,order_df], [out_m,err_m,err_m])
+            files = gr.Files(label="Upload PDFs to merge (max 1 GB each)")
+            reorder = gr.Sortable([], label="Drag to reorder files by filename")
+
+            def update_reorder(file_list):
+                return [os.path.basename(f.name) for f in file_list] if file_list else []
+            files.change(update_reorder, inputs=files, outputs=reorder)
+
+            btn_m = gr.Button("Merge PDFs", variant="primary")
+            out_m = gr.File(label="Download Merged PDF")
+            err_m = gr.Textbox(label="Error", interactive=False, visible=False)
+
+            def run_merge(file_list, order_list):
+                if not file_list or len(file_list) < 2:
+                    return None, "Please upload at least two PDFs.", True
+                name_to_file = {os.path.basename(f.name): f for f in file_list}
+                ordered_files = [name_to_file[name] for name in order_list if name in name_to_file]
+                out, err = merge_pdfs(ordered_files)
+                return out, err, err is not None
+
+            btn_m.click(run_merge, [files, reorder], [out_m, err_m, err_m])
 
         # Compress
         with gr.TabItem("Compress PDF"):