feat(router): add /retrieve api for relay

[ShankarSinghC]

Type of Change

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

Description

/relay is a api that will be used to just forward the request sent by merchant without performing any application logic on it. This is particular to support the refunds for the payments that was directly performed with the connector (example stripe) with out hyperswitch involved during the payment flow.

This PR introduces changes to add a retrieve API for relay refunds.

The retrieve API will:

1. Return the relay status from our database when a retrieve call is made.
2. If force_sync = true is passed and the relay status is not in a terminal state in our system, the API will call the connector to fetch the latest status.

Flow

1. Merchant performs payment directly with processor and stores the payment reference id associated with it.
2. Merchant tiggers the refund through hyperswitch using the processor reference id for the payment.
3. Merchant makes retrieve call for the relay status

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 merchant connector account
-> Make a refund request with invalid connector_resource_id

curl --location 'http://localhost:8080/relay' \
--header 'Content-Type: application/json' \
--header 'X-Profile-Id: pro_rIikb0gPrzd0vEY8hIiP' \
--header 'api-key: dev_qqMQAuMWCclJSk4uMBeNNSpqAPlsKlBA3blQOwOoq5ogTSFVON3taShABqtqYNA4' \
--data '{
  "connector_id": "mca_8W0CQfwE89J1BJBbpcnt",
  "connector_resource_id": "7349526182906968904951",
  "data": {
      "refund": {
    "amount": 50,
    "currency": "USD"
  }},
  "type": "refund"
}'

{
    "id": "relay_4lgXCQW0EnqKddZ9CC3b",
    "status": "pending",
    "connector_resource_id": "7349526182906968904951",
    "error": null,
    "connector_reference_id": "7349526431306986204951",
    "connector_id": "mca_8W0CQfwE89J1BJBbpcnt",
    "profile_id": "pro_rIikb0gPrzd0vEY8hIiP",
    "type": "refund",
    "data": {
        "refund": {
            "amount": 50,
            "currency": "USD",
            "reason": null
        }
    }
}

-> Relay retrieve

curl --location 'http://localhost:8080/relay/relay_4lgXCQW0EnqKddZ9CC3b' \
--header 'Content-Type: application/json' \
--header 'X-Idempotency-Key: <x-idempotency-key>' \
--header 'X-Profile-Id: pro_rIikb0gPrzd0vEY8hIiP' \
--header 'api-key: dev_qqMQAuMWCclJSk4uMBeNNSpqAPlsKlBA3blQOwOoq5ogTSFVON3taShABqtqYNA4' \
--data ''

{
    "id": "relay_4lgXCQW0EnqKddZ9CC3b",
    "status": "pending",
    "connector_resource_id": "7349526182906968904951",
    "error": null,
    "connector_reference_id": "7349526431306986204951",
    "connector_id": "mca_8W0CQfwE89J1BJBbpcnt",
    "profile_id": "pro_rIikb0gPrzd0vEY8hIiP",
    "type": "refund",
    "data": {
        "refund": {
            "amount": 50,
            "currency": "USD",
            "reason": null
        }
    }
}

-> Relay retrieve force_sync = true

curl --location 'http://localhost:8080/relay/relay_4lgXCQW0EnqKddZ9CC3b?force_sync=true' \
--header 'Content-Type: application/json' \
--header 'X-Idempotency-Key: <x-idempotency-key>' \
--header 'X-Profile-Id: pro_rIikb0gPrzd0vEY8hIiP' \
--header 'api-key: dev_qqMQAuMWCclJSk4uMBeNNSpqAPlsKlBA3blQOwOoq5ogTSFVON3taShABqtqYNA4' \
--data ''

{
    "id": "relay_4lgXCQW0EnqKddZ9CC3b",
    "status": "success",
    "connector_resource_id": "7349526182906968904951",
    "error": null,
    "connector_reference_id": "7349526431306986204951",
    "connector_id": "mca_8W0CQfwE89J1BJBbpcnt",
    "profile_id": "pro_rIikb0gPrzd0vEY8hIiP",
    "type": "refund",
    "data": {
        "refund": {
            "amount": 50,
            "currency": "USD",
            "reason": 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

[semanticdiff-com]

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Changed Files

File	Status
crates/api_models/src/relay.rs	10% smaller
crates/router/src/routes/lock_utils.rs	5% smaller
crates/router/src/core/relay.rs	4% smaller
crates/diesel_models/src/query/relay.rs	0% smaller
crates/diesel_models/src/relay.rs	0% smaller
crates/router/src/db/relay.rs	0% smaller
crates/router/src/routes/app.rs	0% smaller
crates/router/src/routes/relay.rs	0% smaller
crates/router_env/src/logger/types.rs	0% smaller