write complete invoice

src/invoice_generator/html_generator.py

@@ -2,6 +2,9 @@ from pathlib import Path
 from jinja2 import FileSystemLoader, TemplateNotFound, Environment
 
 from xhtml2pdf import pisa
+from datetime import date, timedelta
+
+import markdown
 
 
 class HtmlTemplate:
@@ -15,12 +18,42 @@ class HtmlTemplate:
         try:
             loader = FileSystemLoader(self.templates)
             env = Environment(loader=loader)
+            env.globals['format_float'] = self.format_float
+            env.globals['calculate_total'] = self.calculate_total
+
+            env.filters['markdown_to_html'] = self.markdown_to_html
+            env.filters['named_replace'] = self.named_replace
+            env.filters['add_days'] = self.add_days
 
             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 calculate_total(invoice_data):
+        return sum(
+            (pos['Quantity'] * (pos['PricePerUnit'] or invoice_data.PricePerUnit)) for pos in invoice_data.Positions)
+
+    @staticmethod
+    def named_replace(value, **replacements):
+        for key, replacement in replacements.items():
+            value = value.replace(f"%%{key}%%", str(replacement))
+        return value
+
+    @staticmethod
+    def format_float(value):
+        return f'{value:,.2f}'
+
+    @staticmethod
+    def add_days(date, number_of_days):
+        return date + timedelta(days=number_of_days)
+
+    @staticmethod
+    def markdown_to_html(md_content):
+        html_content = markdown.markdown(md_content)
+        return html_content
+
     @staticmethod
     def convert_html_to_pdf(source_html, output_filename):
         # open output file for writing (truncated binary)