Simplify auth method

src/client.rs

@@ -5,12 +5,11 @@ use crate::services::{
     OnboardModifyBuilder, ReconciliationBuilder, SingleInvoiceBuilder, TransactionReversalBuilder,
     TransactionStatusBuilder,
 };
-use crate::{ApiError, MpesaError};
+use crate::MpesaError;
 use openssl::base64;
 use openssl::rsa::Padding;
 use openssl::x509::X509;
 use reqwest::Client as HttpClient;
-use serde_json::Value;
 use std::cell::RefCell;
 
 /// Source: [test credentials](https://developer.safaricom.co.ke/test_credentials)
@@ -113,22 +112,11 @@ impl<'mpesa, Env: ApiEnvironment> Mpesa<Env> {
             .get(&url)
             .basic_auth(&self.client_key, Some(&self.client_secret))
             .send()
+            .await?
+            .error_for_status()?
+            .json::<AuthResponse>()
             .await?;
-        if response.status().is_success() {
-            let value = response.json::<Value>().await?;
-            let access_token = value
-                .get("access_token")
-                .ok_or_else(|| String::from("Failed to extract token from the response"))
-                .unwrap();
-            let access_token = access_token
-                .as_str()
-                .ok_or_else(|| String::from("Error converting access token to string"))
-                .unwrap();
-
-            return Ok(access_token.to_string());
-        }
-        let error = response.json::<ApiError>().await?;
-        Err(MpesaError::AuthenticationError(error))
+        Ok(response.access_token)
     }
 
     /// **B2C Builder**
@@ -524,6 +512,11 @@ impl<'mpesa, Env: ApiEnvironment> Mpesa<Env> {
     }
 }
 
+#[derive(Debug, serde::Deserialize)]
+struct AuthResponse {
+    pub access_token: String,
+}
+
 #[cfg(test)]
 mod tests {
     use crate::Sandbox;