refactor(payment_methods): Enable deletion of default Payment Methods

[Aprabhat19]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

Previously we did not support the deletion of the Default Payment Method, if it's the only PM for the particular customer. In this PR we enable deletion of default Payment Methods

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

• Create a MA and a MCA
• Do a payment , with setup_future_usag:off_session; the card would be saved
• Do a List PM for Customers, you'll have only one card , which has been set as default

Response
{
    "customer_payment_methods": [
        {
            "payment_token": "token_FC8TupTKMEmhtM69dmYS",
            "payment_method_id": "pm_Syvbg2Nb8mGdZC9oi4Sv",
            "customer_id": "CustomerX",
            "payment_method": "card",
            "payment_method_type": "credit",
            "payment_method_issuer": null,
            "payment_method_issuer_code": null,
            "recurring_enabled": true,
            "installment_payment_enabled": false,
            "payment_experience": [
                "redirect_to_url"
            ],
            "card": {
                "scheme": null,
                "issuer_country": null,
                "last4_digits": "4242",
                "expiry_month": "11",
                "expiry_year": "2040",
                "card_token": null,
                "card_holder_name": "AKA",
                "card_fingerprint": null,
                "nick_name": "HELO",
                "card_network": null,
                "card_isin": "424242",
                "card_issuer": null,
                "card_type": null,
                "saved_to_locker": true
            },
            "metadata": null,
            "created": "2024-06-11T10:14:09.587Z",
            "bank": null,
            "surcharge_details": null,
            "requires_cvv": true,
            "last_used_at": "2024-06-11T10:14:09.587Z",
            "default_payment_method_set": true,
            "billing": {
                "address": {
                    "city": "San Fransico",
                    "country": "US",
                    "line1": "1467",
                    "line2": "Harrison Street",
                    "line3": "Harrison Street",
                    "zip": "94122",
                    "state": "California",
                    "first_name": "joseph",
                    "last_name": "Doe"
                },
                "phone": {
                    "number": "8056594427",
                    "country_code": "+91"
                },
                "email": null
            }
        }
    ],
    "is_guest_customer": null
}

• Delete the Payment Method, it'll be a success

Request
curl --location --request DELETE 'http://localhost:8080/payment_methods/:payment_method_id' \
--header 'Accept: application/json' \
--header 'api-key: dev_u3eBlxHY8BxUeQxxgvZGxKRXf7HEPaAw0sXmhjXjFFTmQ0pfyslENYRDajyrQnOf'

Response
{
    "payment_method_id": "pm_50cS5VsVOhgbKQ63WReh",
    "deleted": true
}

• List the Pm for Customer would be empty

Response

{
    "customer_payment_methods": [],
    "is_guest_customer": null
}

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible

[vspecky]

If we allow deleting default payment methods, then we also need to update the default_payment_method_id field of the customer object in DB, else it will be pointing to a deleted record.

[Aprabhat19]

If we allow deleting default payment methods, then we also need to update the default_payment_method_id field of the customer object in DB, else it will be pointing to a deleted record.

@vspecky here we are just allowing the deletion of the default payment method id if its 1 , the updation of the default_payment_method_id field of the customer object in DB , is already happening