Create a Shopify invoicing plugin integrating with an Invoicing API

/JOB Description As MagniFinance (that is an online invoicing software approved by the Portuguese Tax and Customs Authority), we want to have an integration of our invoicing API with Shopify to allow online stores that uses Shopify to invoicing automatically when a customer buy something online. To do this, you should create/have a sample sandbox Shopify account to test and present the result for us. We will provide you a sandbox account in MagniFinance and our API Documentation that is all that you need to complete the task. Extra Details: 1. We want 3 months of maintenance before launch the plugging. 2. Today we have Soap and Rest API, you want to implement using one of that. 3. Its important to create a documentation about how to use the plugin. And there add that: To setup the plugging it will be necessary to get the user and a token with MagniFinance. 4. Languages Preference: C# Important Features [login to view URL] should be possible to create the following documents: Receipts, Invoices-receipt, normal invoices, simplified invoices, Proformas, Credit notes, Debit notes, Quotes, purchase order, Delivery notes and waybill 2. We want to allow the online stores to send the emails directly from our platform with a personalized message in the email. 3. Allow the online store to setup the Magnifinance’s categories and cost centers about every product that are sell. 4. List the pdf documents on My Account – Orders in Shopify ; 5. Allow the user to manage documents cancelations in Shopify ( Create the credit note) 6. Shopify order item meta on the MagniFinance item description; 7. Allow to config the VAT field on the checkout process. 8. Issue VAT exempt documents (0% VAT); 9. Invoice re-emotion 10. Send Delivery notes directly to the warehouse or the dropshipping supplier; 11. Allow the online store to configure different invoice series. //Acceptance criteria // [login to view URL] want a live video demonstration that show us the plugging working well, and you should present the following scenario to our team: 1.1. In your Shopify online Store install the integration in a new company created for this test passing all the parameters (new api user and new token) . 1.2. Show us the documentation that you created to guide the users to installation process. 1.3. Setup the integration and show how you do this. 1.4. Buy something in the online store filling in all the client information in the buying process to create a normal invoice with all client data ( name, nif, legal name, address, postal code, email, telephone). 1.5. Send the invoice to the client email using our platform and with a custom message configured by the online store and check if the invoice was sent to the client email and if you can download it. 1.6. Check if pdf have all the information correctly. Client information, products, prices, quantity, Tax, totals, etc. 1.7. Create a simplified invoice (final consumer) and check in the PDF if the client information is right ( Nif 999999990) and the type of the document is really simplified invoice. 1.8. Cancel a paid order and ( the process should create the Credit note and send to the user). 1.9 Create an invoice with a product with 0% of VAT (TAX). ( This need a tax exception reason and should be configured in the checkout process) 1.10. Buy a product with a discount an see the invoice with the same value in PDF. 1.11. Create a new product in the online store, buy this item and see the product in the PDF. 1.12. See that the Delivery note or waybill is sending directly to the warehouse or the dropshipping supplier when this is option is configured; 2. After this you should provide an user to us in the management the sandbox account of the online store so we can test for ourselves for one week the integration. 3. Send an attachment with all the code to us, so we will review it too and we will accept or give you feedbacks on how we want the improvements.