feature/tu/first_implementation (#2)

Co-authored-by: Torsten Ueberschar <torsten@ueberschar.de>
Reviewed-on: torsten/freelance_invoice#2

README.md

@@ -1,2 +1,97 @@
-# freelance_invoice
+# Freelance Invoice
+
+is a simple command line tool to generate invoices for freelance work. It uses a simple template system based
+on `jinja2` to generate the
+invoice in HTML and then converts it to a PDF using `xhtml2pdf`.
+
+## Install
+
+Use python venv:
+
+```bash
+python -m venv .venv
+source .venv/bin/activate
+``` 
+
+Build executable:
+
+```bash
+pip install --upgrade build
+python -m build
+```
+
+Install the executable:
+
+```bash
+pip install .
+```
+
+See where it is installed:
+```bash
+which invoice
+```
+
+## usage
+
+```bash
+invoice -h
+
+
+
+```
+
+There are two yaml files describing your invoice:
+
+- [RG004211.yaml](test_data/RG004211.yaml) Contains the invoice data. The filename is takes as the invoice id-number.
+- [envelope.yaml](test_data/envelope.yaml) contains the address data of the sender and the recipient
+
+The invoice data is read from the `invoice.yaml` file and the address data is read from the `envelope.yaml` file. The
+invoice data is then used to fill in the invoice template and the address data is used to fill in the address fields of
+the invoice.
+
+Some data are globaly available from the envelope template. Some of them can be overriden by the invoice template.
+
+invoice.yaml - The Name of the invoice file is used as the invoice number but you are free to override it in the
+invoice.yaml file.
+
+
+
+
+```yaml
+
+
+```bash
+python src/main.py --help
+Simple invoice generator for freelancers and small businesses by Torsten Ueberschar
+
+usage: main.py [-h] -b BASE -i INVOICE [-e ENVELOPE] [-t TEMPLATE]
+
+Read invoice and envelope data from yaml file
+
+options:
+  -h, --help            show this help message and exit
+  -b BASE, --base BASE  base directory for invoice and envelope files
+  -i INVOICE, --invoice INVOICE
+                        Invoice file name
+  -e ENVELOPE, --envelope ENVELOPE
+                        Envelope file name
+  -t TEMPLATE, --template TEMPLATE
+                        directory for template files
+```
+
+## example
+
+```bash
+invoice -b test_data -i invoice.yaml -e envelope.yaml -t test_data/templates
+```
+
+## to do
+
+- give more structure to code 
+- make code testable
+
+## see also
+
+- https://xhtml2pdf.readthedocs.io/en/latest/index.html
+- https://jinja.palletsprojects.com/