Upgrade to Wordpress Plugin (API Based)

(API Project - only submit proposal if you can work/finish it now)

Hello, i need an upgrade to a wordpress plugin (attached)..

Currently, i have a plugin that only create a new invoice at the accounting software for any new order using a predefined customer and product (static)

While the upgrade need to work as below once receiving new order:

1- To create a new customer (if not exist) at the accounting software.
2- To create a new product (if not exist) at the accounting software.
3- To create a new invoice using the order details (date, amount, custom fields, variation, attribute, coupon, discount, order note, shipping and payment method)
4- To get QR code from software, convirt it from string to png and use it in thank you page and pdf invoice.
5- For refunded/cancelled orders, To create credit note at the accounting software.

Expample of creating invoice (API):

curl --location --request POST 'https://com/api/2.0/invoices' \
--header 'API-KEY: insert-your-api-key-here' \
--header 'Content-Type: application/json' \
--data-raw '{
"invoice": {
"contact_id": 2,
"reference": "api-inv-2",
"description": "an example invoice",
"issue_date": "2019-10-30",
"due_date": "2019-10-30",
"status": "Approved",
"inventory_id": 1,
"line_items": [
{
"product_id": 1,
"description": "",
"quantity": 1.0,
"unit_price": 589.2,
"discount": 20,
"discount_type": "percentage",
"tax_percent": 15
},
{
"product_id": 2,
"description": "",
"quantity": 2,
"unit_price": 200,
"discount": 50,
"discount_type": "amount",
"tax_percent": 15
}
]
}
}
'