Refactor: Modularize AccessToken class

build.gradle

@@ -71,8 +71,8 @@ test.finalizedBy jacocoTestReport
 test {
     useJUnitPlatform()
     reports {
-        junitXml.enabled = false
-        html.enabled = true
+        junitXml.required.set(false)
+        html.required.set(true)
     }
 }
 

src/main/java/com/amadeus/client/AccessToken.java

@@ -1,85 +1,23 @@
 package com.amadeus.client;
 
-import com.amadeus.Configuration;
-import com.amadeus.Constants;
 import com.amadeus.HTTPClient;
-import com.amadeus.HttpVerbs;
-import com.amadeus.Params;
-import com.amadeus.Response;
 import com.amadeus.exceptions.ResponseException;
-import com.google.gson.JsonObject;
 
 /**
  * A memoized Access Token, with the ability to auto-refresh when needed.
  * @hide as only used internally
  */
 public class AccessToken {
-  // Renew the token 10 seconds earlier than required,
-  // just to account for system lag
-  private static final long TOKEN_BUFFER = 10000L;
-  // An instance of the API client
   private final HTTPClient client;
-  // The access token value
-  private String accessToken = null;
-  // The (UNIX) expiry time of this token
-  private long expiresAt;
+  private final TokenManager tokenManager;
 
-  /**
-   * Constructor.
-   * @hides as only used internally
-   */
   public AccessToken(HTTPClient client) {
     this.client = client;
+    this.tokenManager = new TokenManager(client);
   }
 
-  /**
-   * Creates a Bearer header using the cached Access Token.
-   * @hides as only used internally
-   */
   public String getBearerToken() throws ResponseException {
-    lazyUpdateAccessToken();
-    return String.format("Bearer %s", accessToken);
-  }
-
-  // Loads the access token if it's still null
-  // or has expired.
-  private void lazyUpdateAccessToken() throws ResponseException {
-    if (needsRefresh()) {
-      updateAccessToken();
-    }
-  }
-
-  // Fetches the access token and then parses the resuling values.
-  private void updateAccessToken() throws ResponseException {
-    Response response = fetchAccessToken();
-    storeAccessToken(response.getResult());
-  }
-
-  // Checks if this access token needs a refresh.
-  private boolean needsRefresh() {
-    boolean isNull = accessToken == null;
-    boolean expired = (System.currentTimeMillis() + TOKEN_BUFFER) > expiresAt;
-    return isNull || expired;
-  }
-
-  // Fetches a new Access Token using the credentials from the client
-  private Response fetchAccessToken() throws ResponseException {
-    Configuration config = client.getConfiguration();
-    return client.unauthenticatedRequest(
-           HttpVerbs.POST,
-           Constants.AUTH_URL,
-            Params.with(Constants.GRANT_TYPE, Constants.CLIENT_CREDENTIALS)
-                  .and(Constants.CLIENT_ID, config.getClientId())
-                  .and(Constants.CLIENT_SECRET, config.getClientSecret()),
-        null,
-        null
-    );
-  }
-
-  // Store the fetched access token and expiry date
-  private void storeAccessToken(JsonObject result) {
-    this.accessToken = result.get(Constants.ACCESS_TOKEN).getAsString();
-    int expiresIn = result.get(Constants.EXPIRES_IN).getAsInt();
-    this.expiresAt = System.currentTimeMillis() + expiresIn * 1000L;
+    tokenManager.lazyUpdateAccessToken();
+    return String.format("Bearer %s", tokenManager.getTokenValue());
   }
 }

src/main/java/com/amadeus/client/AuthUtils.java

@@ -0,0 +1,36 @@
+package com.amadeus.client;
+
+import com.amadeus.Configuration;
+import com.amadeus.Constants;
+import com.amadeus.HTTPClient;
+import com.amadeus.HttpVerbs;
+import com.amadeus.Params;
+import com.amadeus.Response;
+import com.amadeus.exceptions.ResponseException;
+
+/**
+ * Utility class for authentication-related operations.
+ */
+public class AuthUtils {
+
+  private AuthUtils() {
+    // Prevent instantiation
+  }
+
+  public static Params createAuthRequestParams(Configuration config) {
+    return Params.with(Constants.GRANT_TYPE, Constants.CLIENT_CREDENTIALS)
+      .and(Constants.CLIENT_ID, config.getClientId())
+      .and(Constants.CLIENT_SECRET, config.getClientSecret());
+  }
+
+  public static Response executeUnauthenticatedRequest(HTTPClient client, Params params)
+    throws ResponseException {
+    return client.unauthenticatedRequest(
+      HttpVerbs.POST,
+      Constants.AUTH_URL,
+      params,
+      null,
+      null
+    );
+  }
+}

src/main/java/com/amadeus/client/TokenManager.java

@@ -0,0 +1,62 @@
+package com.amadeus.client;
+
+import com.amadeus.Configuration;
+import com.amadeus.Constants;
+import com.amadeus.HTTPClient;
+import com.amadeus.Params;
+import com.amadeus.Response;
+import com.amadeus.exceptions.ResponseException;
+import com.google.gson.JsonObject;
+import lombok.Getter;
+
+/**
+ * Handles token-related functionality, including fetching and refreshing tokens.
+ */
+public class TokenManager {
+  private static final long TOKEN_BUFFER = 10000L;
+  private static final long MILLISECONDS_IN_SECOND = 1000L;
+
+  private final HTTPClient client;
+  @Getter
+  private String tokenValue = null;
+  private long expiresAt;
+
+  public TokenManager(HTTPClient client) {
+    this.client = client;
+  }
+
+  public void lazyUpdateAccessToken() throws ResponseException {
+    if (isTokenExpiredOrNull()) {
+      updateAccessToken();
+    }
+  }
+
+  private boolean isTokenExpiredOrNull() {
+    return isTokenNull() || isTokenExpired();
+  }
+
+  private boolean isTokenNull() {
+    return tokenValue == null;
+  }
+
+  private boolean isTokenExpired() {
+    return (System.currentTimeMillis() + TOKEN_BUFFER) > expiresAt;
+  }
+
+  private void updateAccessToken() throws ResponseException {
+    Configuration config = client.getConfiguration();
+    Params requestParams = AuthUtils.createAuthRequestParams(config);
+    Response response = AuthUtils.executeUnauthenticatedRequest(client, requestParams);
+    storeAccessTokenDetails(response.getResult());
+  }
+
+  private void storeAccessTokenDetails(JsonObject result) {
+    this.tokenValue = result.get(Constants.ACCESS_TOKEN).getAsString();
+    int expiresIn = result.get(Constants.EXPIRES_IN).getAsInt();
+    this.expiresAt = calculateExpiryTime(expiresIn);
+  }
+
+  private long calculateExpiryTime(int expiresIn) {
+    return System.currentTimeMillis() + expiresIn * MILLISECONDS_IN_SECOND;
+  }
+}