WHMCS Module for Export Invoics in CSV Format -- 2

We are looking for an experienced developer for WHMCS modules. The aim is to have an additional entry in the backend which allows the export of invoice data in DATEV-CSV format.
Basically, the module only needs to execute an existing SQL command and save the result in a CSV file. The period to be exported for the evaluation must be configurable via a date field for current year and month.
The CSV files exported so far are displayed in a clearly organised list. The name for the created export can be entered in a text field.
To configure the module, following configure able fields must been available, which gets inserted into the SQL Statement so the export gest modified:
- Month of evaluation (it is a string with the format ‘YYYY-MM’)
- Customer number format (it’s a number which gets added with the userid in the database, usually it is 10000)
- Contra Account number for DE Invoices (its usually a string with length of 4)
- Contra Account number for EU Invoices (its usually a string with length of 4)
- Contra Account number for everywhere else Invoices (its usually a string with length of 4)
- Invoice path prefix for locally saved invoices in pdf format (its usually a string)