feat(proxy): add support for x-www-form-urlencoded request payloads

This change inspects headers and uses RequestContent::FormUrlEncoded when required.

Author: dmatviichuk

crates/router/src/core/proxy.rs

@@ -9,6 +9,7 @@ use common_utils::{
 use error_stack::ResultExt;
 use hyperswitch_interfaces::types::Response;
 use serde_json::Value;
+use std::collections::HashMap;
 
 pub async fn proxy_core(
     state: SessionState,
@@ -83,17 +84,60 @@ fn extract_field_from_vault_data(vault_data: &Value, field_name: &str) -> Router
     }
 }
 
+fn convert_value_to_form_data(value: Value) -> RouterResult<HashMap<String, String>> {
+    match value {
+        Value::Object(obj) => {
+            obj.into_iter()
+                .map(|(k, v)| {
+                    let val_str = match v {
+                        Value::String(s) => Ok(s),
+                        Value::Number(n) => Ok(n.to_string()),
+                        Value::Bool(b) => Ok(b.to_string()),
+                        Value::Null => Ok(String::new()),
+                        Value::Array(_) | Value::Object(_) => {
+                            serde_json::to_string(&v)
+                                .change_context(errors::ApiErrorResponse::InternalServerError)
+                                .attach_printable("Failed to serialize nested value")
+                        }
+                    }
+                    .map(|s| (k, s))
+                })
+                .collect::<Result<HashMap<_, _>, _>>()
+        }
+        _ => Err(errors::ApiErrorResponse::InternalServerError)
+            .attach_printable("Request body must be a JSON object for form-urlencoded conversion"),
+    }
+}
+
 async fn execute_proxy_request(
     state: &SessionState,
     req_wrapper: &utils::ProxyRequestWrapper,
     processed_body: Value,
 ) -> RouterResult<Response> {
+
+    let headers = req_wrapper.get_headers();
+    let is_form_urlencoded = headers
+        .iter()
+        .find(|(key, _)| key.eq_ignore_ascii_case("content-type"))
+        .map(|(_, value)| {
+            value.clone().into_inner()
+                .eq_ignore_ascii_case("application/x-www-form-urlencoded")
+        })
+        .unwrap_or(false);
+
+    let request_body = if is_form_urlencoded {
+        convert_value_to_form_data(processed_body)
+            .map(|form_data| request::RequestContent::FormUrlEncoded(Box::new(form_data)))?
+    } else {
+        request::RequestContent::Json(Box::new(processed_body))
+    };
+
     let request = RequestBuilder::new()
         .method(req_wrapper.get_method())
         .attach_default_headers()
         .headers(req_wrapper.get_headers())
         .url(req_wrapper.get_destination_url())
-        .set_body(request::RequestContent::Json(Box::new(processed_body)))
+        .set_body(request_body)
         .build();
 
     let response = services::call_connector_api(state, request, "proxy")