[FIX] sale_pdf_quote_builder: correctly fill editable fields

PDF written with scribus (and some other software) have a problem when filling fields: the output
does not work as expected. The replaced value is there, but hidden behind a blue overlay, shown
only when clicking on it.

We now show the field value and ensure filled fields are read only.

Additionally, some readers only allow a single value per field name. Even if the values were
different on the documents, only one would be shown. We now rename the fields to ensure they are
different when they have different values.

task-3626047

closes odoo/odoo#145163

Signed-off-by: Morgane Demesmaeker <edm@odoo.com>

odoo/tools/pdf.py

@@ -35,7 +35,7 @@ try:
 except ImportError:
     from PyPDF2 import PdfFileWriter, PdfFileReader
 
-from PyPDF2.generic import DictionaryObject, NameObject, ArrayObject, DecodedStreamObject, NumberObject, createStringObject, ByteStringObject
+from PyPDF2.generic import ArrayObject, BooleanObject, ByteStringObject, DecodedStreamObject, DictionaryObject, IndirectObject, NameObject, NumberObject, createStringObject
 
 try:
     import fontTools
@@ -93,34 +93,48 @@ def merge_pdf(pdf_data):
         writer.write(_buffer)
         return _buffer.getvalue()
 
-def fill_form_fields_pdf(document, form_fields=None):
+def fill_form_fields_pdf(writer, form_fields):
     ''' Fill in the form fields of a PDF
-    :param datastring document: a PDF datastring
+    :param writer: a PdfFileWriter object
     :param dict form_fields: a dictionary of form fields to update in the PDF
     :return: a filled PDF datastring
     '''
-    form_fields = form_fields or {}
-    writer = PdfFileWriter()
-    reader = PdfFileReader(io.BytesIO(document), strict=False)
-    has_fields = form_fields and bool(reader.getFields())
-    if not has_fields:
-        return document
 
-    for page in range(0, reader.getNumPages()):
-        page = reader.getPage(page)
-        writer.addPage(page)
-        try:
+    # This solves a known problem with PyPDF2, where with some pdf software, forms fields aren't
+    # correctly filled until the user click on it, see: https://github.com/py-pdf/pypdf/issues/355
+    if hasattr(writer, 'set_need_appearances_writer'):
+        writer.set_need_appearances_writer()
+        is_upper_version_pypdf2 = True
+    else:  # This method was renamed in PyPDF2 2.0
+        is_upper_version_pypdf2 = False
+        catalog = writer._root_object
+        # get the AcroForm tree
+        if "/AcroForm" not in catalog:
+            writer._root_object.update({
+                NameObject("/AcroForm"): IndirectObject(len(writer._objects), 0, writer)
+            })
+        writer._root_object["/AcroForm"][NameObject("/NeedAppearances")] = BooleanObject(True)
+
+    nbr_pages = len(writer.pages) if is_upper_version_pypdf2 else writer.getNumPages()
+
+    for page_id in range(0, nbr_pages):
+        page = writer.getPage(page_id)
+
+        if is_upper_version_pypdf2:
             writer.update_page_form_field_values(page, form_fields)
-        except AttributeError:  # This method was renamed in PyPDF2 2.0
+        else:
             # This is a known bug on previous version of PyPDF2, fixed in 2.11
             if not page.get('/Annots'):
                 _logger.info("No fields to update in this page")
             else:
                 writer.updatePageFormFieldValues(page, form_fields)
 
-    with io.BytesIO() as _buffer:
-        writer.write(_buffer)
-        return _buffer.getvalue()
+        for raw_annot in page.get('/Annots', []):
+            annot = raw_annot.getObject()
+            for field in form_fields:
+                # Mark filled fields as readonly to avoid the blue overlay:
+                if annot.get('/T') == field:
+                    annot.update({NameObject("/Ff"): NumberObject(1)})
 
 def rotate_pdf(pdf):
     ''' Rotate clockwise PDF (90°) into a new PDF.