first try

src/invoice_generator/html_generator.py

@@ -0,0 +1,38 @@
+from pathlib import Path
+from jinja2 import FileSystemLoader, TemplateNotFound, Environment
+
+from xhtml2pdf import pisa
+
+
+class HtmlTemplate:
+    def __init__(self, templates):
+        self.template_name = 'invoice.html'
+        if not Path(templates).exists():
+            raise FileNotFoundError(f'Inivalid path to template files: {templates}')
+        self.templates = templates
+
+    def prepare_template(self, invoice_data, envelope_data):
+        try:
+            loader = FileSystemLoader(self.templates)
+            env = Environment(loader=loader)
+
+            template = env.get_template(self.template_name)
+            return template.render(invoice=invoice_data, envelope=envelope_data)
+        except TemplateNotFound:
+            raise FileNotFoundError(f'Could not find template file: {self.template_name}')
+
+    @staticmethod
+    def convert_html_to_pdf(source_html, output_filename):
+        # open output file for writing (truncated binary)
+        result_file = open(output_filename, "w+b")
+
+        # convert HTML to PDF
+        pisa_status = pisa.CreatePDF(
+            source_html,  # the HTML to convert
+            dest=result_file)  # file handle to recieve result
+
+        # close output file
+        result_file.close()  # close output file
+
+        # return False on success and True on errors
+        return pisa_status.err