Issue:
Bug: feat(connector): [Shift4] Refund webhooks 



Refund webhook support for connector shift4

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [x] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
Refund webhook support for shift4 ([status mapping ref](https://dev.shift4.com/docs/api#event-types)) . We always update the status by psync as we don't have source verification for shift4 .

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!-- 
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Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
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Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

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can focus on the implementation (unless its an obvious bug or documentation fix
that will have little conversation).
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## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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**payment webhook**
<img width="1181" alt="Screenshot 2023-05-29 at 6 51 42 PM" src="https://github.com/juspay/hyperswitch/assets/121822803/f077b49d-eb93-4612-a187-dfc7ea8e06e0">
**Refund webhook**
<img width="1184" alt="Screenshot 2023-05-29 at 6 51 05 PM" src="https://github.com/juspay/hyperswitch/assets/121822803/b5b1e489-a3bb-4e77-b073-11d5ff8e5edc">


## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:

**payment webhook**
<img width="1181" alt="Screenshot 2023-05-29 at 6 51 42 PM" src="https://github.com/juspay/hyperswitch/assets/121822803/f077b49d-eb93-4612-a187-dfc7ea8e06e0">
**Refund webhook**
<img width="1184" alt="Screenshot 2023-05-29 at 6 51 05 PM" src="https://github.com/juspay/hyperswitch/assets/121822803/b5b1e489-a3bb-4e77-b073-11d5ff8e5edc">

Patch:
diff --git a/crates/router/src/connector/shift4.rs b/crates/router/src/connector/shift4.rs
index 8f8d6cee56b..d75a0896583 100644
--- a/crates/router/src/connector/shift4.rs
+++ b/crates/router/src/connector/shift4.rs
@@ -3,7 +3,7 @@ mod transformers;
 use std::fmt::Debug;
 
 use common_utils::ext_traits::ByteSliceExt;
-use error_stack::ResultExt;
+use error_stack::{IntoReport, ResultExt};
 use transformers as shift4;
 
 use super::utils::RefundsRequestData;
@@ -737,9 +737,25 @@ impl api::IncomingWebhook for Shift4 {
             .parse_struct("Shift4WebhookObjectId")
             .change_context(errors::ConnectorError::WebhookReferenceIdNotFound)?;
 
-        Ok(api_models::webhooks::ObjectReferenceId::PaymentId(
-            api_models::payments::PaymentIdType::ConnectorTransactionId(details.data.id),
-        ))
+        if shift4::is_transaction_event(&details.event_type) {
+            Ok(api_models::webhooks::ObjectReferenceId::PaymentId(
+                api_models::payments::PaymentIdType::ConnectorTransactionId(details.data.id),
+            ))
+        } else if shift4::is_refund_event(&details.event_type) {
+            Ok(api_models::webhooks::ObjectReferenceId::RefundId(
+                api_models::webhooks::RefundIdType::ConnectorRefundId(
+                    details
+                        .data
+                        .refunds
+                        .and_then(|refund| {
+                            refund.first().map(|refund_object| refund_object.id.clone())
+                        })
+                        .ok_or(errors::ConnectorError::WebhookReferenceIdNotFound)?,
+                ),
+            ))
+        } else {
+            Err(errors::ConnectorError::WebhookReferenceIdNotFound).into_report()
+        }
     }
 
     fn get_webhook_event_type(
@@ -750,12 +766,7 @@ impl api::IncomingWebhook for Shift4 {
             .body
             .parse_struct("Shift4WebhookObjectEventType")
             .change_context(errors::ConnectorError::WebhookEventTypeNotFound)?;
-        Ok(match details.event_type {
-            shift4::Shift4WebhookEvent::ChargeSucceeded => {
-                api::IncomingWebhookEvent::PaymentIntentSuccess
-            }
-            shift4::Shift4WebhookEvent::Unknown => api::IncomingWebhookEvent::EventNotSupported,
-        })
+        Ok(api::IncomingWebhookEvent::from(details.event_type))
     }
 
     fn get_webhook_resource_object(
diff --git a/crates/router/src/connector/shift4/transformers.rs b/crates/router/src/connector/shift4/transformers.rs
index dc5f4efbeb5..22a3ae58a77 100644
--- a/crates/router/src/connector/shift4/transformers.rs
+++ b/crates/router/src/connector/shift4/transformers.rs
@@ -323,8 +323,13 @@ pub struct Shift4WebhookObjectEventType {
 }
 
 #[derive(Debug, Deserialize)]
+#[allow(clippy::enum_variant_names)]
 pub enum Shift4WebhookEvent {
     ChargeSucceeded,
+    ChargeFailed,
+    ChargeUpdated,
+    ChargeCaptured,
+    ChargeRefunded,
     #[serde(other)]
     Unknown,
 }
@@ -332,10 +337,18 @@ pub enum Shift4WebhookEvent {
 #[derive(Debug, Deserialize)]
 pub struct Shift4WebhookObjectData {
     pub id: String,
+    pub refunds: Option<Vec<RefundIdObject>>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RefundIdObject {
+    pub id: String,
 }
 
 #[derive(Debug, Deserialize)]
 pub struct Shift4WebhookObjectId {
+    #[serde(rename = "type")]
+    pub event_type: Shift4WebhookEvent,
     pub data: Shift4WebhookObjectData,
 }
 
@@ -604,3 +617,32 @@ pub struct ApiErrorResponse {
     pub code: Option<String>,
     pub message: String,
 }
+
+pub fn is_transaction_event(event: &Shift4WebhookEvent) -> bool {
+    matches!(
+        event,
+        Shift4WebhookEvent::ChargeCaptured
+            | Shift4WebhookEvent::ChargeFailed
+            | Shift4WebhookEvent::ChargeSucceeded
+            | Shift4WebhookEvent::ChargeUpdated
+    )
+}
+
+pub fn is_refund_event(event: &Shift4WebhookEvent) -> bool {
+    matches!(event, Shift4WebhookEvent::ChargeRefunded)
+}
+
+impl From<Shift4WebhookEvent> for api::IncomingWebhookEvent {
+    fn from(event: Shift4WebhookEvent) -> Self {
+        match event {
+            Shift4WebhookEvent::ChargeSucceeded | Shift4WebhookEvent::ChargeUpdated => {
+                //reference : https://dev.shift4.com/docs/api#event-types
+                Self::PaymentIntentProcessing
+            }
+            Shift4WebhookEvent::ChargeCaptured => Self::PaymentIntentSuccess,
+            Shift4WebhookEvent::ChargeFailed => Self::PaymentIntentFailure,
+            Shift4WebhookEvent::ChargeRefunded => Self::RefundSuccess,
+            Shift4WebhookEvent::Unknown => Self::EventNotSupported,
+        }
+    }
+}