Issue:
Bug: feat(dynamic_routing): add get api for dynamic routing volume split





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 -->
This pull request introduces a new feature for retrieving dynamic routing volume split configurations and includes related updates across multiple files. The changes primarily focus on adding a new API endpoint, defining associated data structures, and integrating the functionality into the existing routing system.

### New Feature: Retrieve Dynamic Routing Volume Split

#### API Enhancements:
* Added a new endpoint `/get_volume_split` to retrieve dynamic routing volume split configurations. This endpoint is defined in `crates/router/src/routes/app.rs` and implemented in `crates/router/src/routes/routing.rs`. [[1]](diffhunk://#diff-a6e49b399ffdee83dd322b3cb8bee170c65fb9c6e2e52c14222ec310f6927c54R2055-R2058) [[2]](diffhunk://#diff-bdc480582fe22076ee5ec5bc2452ff57bf86b1b746607bdad4b4ed248c44c45fR1505-R1545)

#### Data Structures:
* Introduced a new struct `RoutingVolumeSplitResponse` in `crates/api_models/src/routing.rs` to encapsulate the volume split value (`split: u8`).
* Updated the `ApiEventMetric` trait implementation to include `RoutingVolumeSplitResponse` and `ToggleDynamicRoutingPath`.

#### Backend Logic:
* Added a new function `retrieve_dynamic_routing_volume_split` in `crates/router/src/core/routing.rs` to handle the business logic for fetching the volume split value from the database and returning it as a response.

#### Dependency Updates:
* Updated imports in `crates/api_models/src/events/routing.rs` and `crates/openapi/src/openapi.rs` to include the new `RoutingVolumeSplitResponse` type. [[1]](diffhunk://#diff-040f264f6e1e25cf7598bf4fafabb91f2d54d7d848ed356a9cf5ec356d5be087L9-R11) [[2]](diffhunk://#diff-449ddbba20051c3e750e25f17452d490a28f78cfe4bcda279865a0365c6b29d8R668)

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

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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## How did you test it?
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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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1. Create merchant account and api_key
2. Using the default profile created during merchant account creation, hit below api to set volume split

```
curl --location --request POST 'http://localhost:8080/account/merchant_1747932999/business_profile/pro_kXrizzzc7yklUW8sfxXz/dynamic_routing/set_volume_split?split=50' \
--header 'api-key: xyz'
```

3. Hit get api which is added in this PR to get the volume split set in above api

```
curl --location 'http://localhost:8080/account/merchant_1747932999/business_profile/pro_kXrizzzc7yklUW8sfxXz/dynamic_routing/get_volume_split' \
--header 'api-key: xyz'
```


## 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 the submitted code
- [ ] I added unit tests for my changes where possible


Testing:

1. Create merchant account and api_key
2. Using the default profile created during merchant account creation, hit below api to set volume split

```
curl --location --request POST 'http://localhost:8080/account/merchant_1747932999/business_profile/pro_kXrizzzc7yklUW8sfxXz/dynamic_routing/set_volume_split?split=50' \
--header 'api-key: xyz'
```

3. Hit get api which is added in this PR to get the volume split set in above api

```
curl --location 'http://localhost:8080/account/merchant_1747932999/business_profile/pro_kXrizzzc7yklUW8sfxXz/dynamic_routing/get_volume_split' \
--header 'api-key: xyz'
```

Patch:
diff --git a/crates/api_models/src/events/routing.rs b/crates/api_models/src/events/routing.rs
index 750bfde2710..f1ba35bd9f3 100644
--- a/crates/api_models/src/events/routing.rs
+++ b/crates/api_models/src/events/routing.rs
@@ -7,8 +7,9 @@ use crate::routing::{
     RoutingAlgorithmId, RoutingConfigRequest, RoutingDictionaryRecord, RoutingKind,
     RoutingLinkWrapper, RoutingPayloadWrapper, RoutingRetrieveLinkQuery,
     RoutingRetrieveLinkQueryWrapper, RoutingRetrieveQuery, RoutingVolumeSplit,
-    RoutingVolumeSplitWrapper, SuccessBasedRoutingConfig, SuccessBasedRoutingPayloadWrapper,
-    ToggleDynamicRoutingQuery, ToggleDynamicRoutingWrapper,
+    RoutingVolumeSplitResponse, RoutingVolumeSplitWrapper, SuccessBasedRoutingConfig,
+    SuccessBasedRoutingPayloadWrapper, ToggleDynamicRoutingPath, ToggleDynamicRoutingQuery,
+    ToggleDynamicRoutingWrapper,
 };
 
 impl ApiEventMetric for RoutingKind {
@@ -135,6 +136,18 @@ impl ApiEventMetric for RoutingVolumeSplitWrapper {
     }
 }
 
+impl ApiEventMetric for ToggleDynamicRoutingPath {
+    fn get_api_event_type(&self) -> Option<ApiEventsType> {
+        Some(ApiEventsType::Routing)
+    }
+}
+
+impl ApiEventMetric for RoutingVolumeSplitResponse {
+    fn get_api_event_type(&self) -> Option<ApiEventsType> {
+        Some(ApiEventsType::Routing)
+    }
+}
+
 impl ApiEventMetric for RoutingVolumeSplit {
     fn get_api_event_type(&self) -> Option<ApiEventsType> {
         Some(ApiEventsType::Routing)
diff --git a/crates/api_models/src/routing.rs b/crates/api_models/src/routing.rs
index a15b135ac1f..527e8353b8c 100644
--- a/crates/api_models/src/routing.rs
+++ b/crates/api_models/src/routing.rs
@@ -857,6 +857,11 @@ pub struct ToggleDynamicRoutingPath {
     pub profile_id: common_utils::id_type::ProfileId,
 }
 
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize, ToSchema)]
+pub struct RoutingVolumeSplitResponse {
+    pub split: u8,
+}
+
 #[derive(serde::Serialize, serde::Deserialize, Debug, Clone, ToSchema)]
 #[serde(deny_unknown_fields)]
 pub struct EliminationRoutingConfig {
diff --git a/crates/openapi/src/openapi.rs b/crates/openapi/src/openapi.rs
index 8612dd080bd..4de9b85cd7c 100644
--- a/crates/openapi/src/openapi.rs
+++ b/crates/openapi/src/openapi.rs
@@ -671,6 +671,7 @@ Never share your secret api keys. Keep them guarded and secure.
         api_models::routing::SuccessRateSpecificityLevel,
         api_models::routing::ToggleDynamicRoutingQuery,
         api_models::routing::ToggleDynamicRoutingPath,
+        api_models::routing::RoutingVolumeSplitResponse,
         api_models::routing::ast::RoutableChoiceKind,
         api_models::enums::RoutableConnectors,
         api_models::routing::ast::ProgramConnectorSelection,
diff --git a/crates/router/src/core/routing.rs b/crates/router/src/core/routing.rs
index df6189ea424..1811f43d51e 100644
--- a/crates/router/src/core/routing.rs
+++ b/crates/router/src/core/routing.rs
@@ -1554,6 +1554,48 @@ pub async fn configure_dynamic_routing_volume_split(
     Ok(service_api::ApplicationResponse::Json(routing_info))
 }
 
+#[cfg(feature = "v1")]
+pub async fn retrieve_dynamic_routing_volume_split(
+    state: SessionState,
+    merchant_context: domain::MerchantContext,
+    profile_id: common_utils::id_type::ProfileId,
+) -> RouterResponse<routing_types::RoutingVolumeSplitResponse> {
+    let db = state.store.as_ref();
+    let key_manager_state = &(&state).into();
+
+    let business_profile: domain::Profile = core_utils::validate_and_get_business_profile(
+        db,
+        key_manager_state,
+        merchant_context.get_merchant_key_store(),
+        Some(&profile_id),
+        merchant_context.get_merchant_account().get_id(),
+    )
+    .await?
+    .get_required_value("Profile")
+    .change_context(errors::ApiErrorResponse::ProfileNotFound {
+        id: profile_id.get_string_repr().to_owned(),
+    })?;
+
+    let dynamic_routing_algo_ref: routing_types::DynamicRoutingAlgorithmRef = business_profile
+        .dynamic_routing_algorithm
+        .clone()
+        .map(|val| val.parse_value("DynamicRoutingAlgorithmRef"))
+        .transpose()
+        .change_context(errors::ApiErrorResponse::InternalServerError)
+        .attach_printable(
+            "unable to deserialize dynamic routing algorithm ref from business profile",
+        )?
+        .unwrap_or_default();
+
+    let resp = routing_types::RoutingVolumeSplitResponse {
+        split: dynamic_routing_algo_ref
+            .dynamic_routing_volume_split
+            .unwrap_or_default(),
+    };
+
+    Ok(service_api::ApplicationResponse::Json(resp))
+}
+
 #[cfg(all(feature = "v1", feature = "dynamic_routing"))]
 pub async fn success_based_routing_update_configs(
     state: SessionState,
diff --git a/crates/router/src/routes/app.rs b/crates/router/src/routes/app.rs
index 6071a9ee0b0..7e082296e7f 100644
--- a/crates/router/src/routes/app.rs
+++ b/crates/router/src/routes/app.rs
@@ -2082,6 +2082,10 @@ impl Profile {
                         web::resource("/set_volume_split")
                             .route(web::post().to(routing::set_dynamic_routing_volume_split)),
                     )
+                    .service(
+                        web::resource("/get_volume_split")
+                            .route(web::get().to(routing::get_dynamic_routing_volume_split)),
+                    )
                     .service(
                         web::scope("/elimination")
                             .service(
diff --git a/crates/router/src/routes/routing.rs b/crates/router/src/routes/routing.rs
index ba041cbe5ac..ff8ad06e91c 100644
--- a/crates/router/src/routes/routing.rs
+++ b/crates/router/src/routes/routing.rs
@@ -1502,3 +1502,44 @@ pub async fn set_dynamic_routing_volume_split(
     ))
     .await
 }
+
+#[cfg(all(feature = "olap", feature = "v1"))]
+#[instrument(skip_all)]
+pub async fn get_dynamic_routing_volume_split(
+    state: web::Data<AppState>,
+    req: HttpRequest,
+    path: web::Path<routing_types::ToggleDynamicRoutingPath>,
+) -> impl Responder {
+    let flow = Flow::VolumeSplitOnRoutingType;
+
+    let payload = path.into_inner();
+    Box::pin(oss_api::server_wrap(
+        flow,
+        state,
+        &req,
+        payload.clone(),
+        |state, auth: auth::AuthenticationData, payload, _| {
+            let merchant_context = domain::MerchantContext::NormalMerchant(Box::new(
+                domain::Context(auth.merchant_account, auth.key_store),
+            ));
+            routing::retrieve_dynamic_routing_volume_split(
+                state,
+                merchant_context,
+                payload.profile_id,
+            )
+        },
+        auth::auth_type(
+            &auth::HeaderAuth(auth::ApiKeyAuth {
+                is_connected_allowed: false,
+                is_platform_allowed: false,
+            }),
+            &auth::JWTAuthProfileFromRoute {
+                profile_id: payload.profile_id,
+                required_permission: Permission::ProfileRoutingRead,
+            },
+            req.headers(),
+        ),
+        api_locking::LockAction::NotApplicable,
+    ))
+    .await
+}