Add getTokenRequestWithAuthCodeFlow API for completing OAuth server-side

lib/access_token_request.dart

@@ -0,0 +1,23 @@
+class AccessTokenRequest {
+  final String code;
+  final String clientId;
+  final String redirectUri;
+  final String tokenUrl;
+  final String? clientSecret;
+  final String? codeVerifier;
+  List<String>? scopes;
+  Map<String, dynamic>? customParams;
+  dynamic httpClient;
+
+  AccessTokenRequest({
+    required this.code,
+    required this.clientId,
+    required this.redirectUri,
+    required this.tokenUrl,
+    this.clientSecret,
+    this.codeVerifier,
+    this.scopes,
+    this.customParams,
+    this.httpClient,
+  });
+}

lib/oauth2_client.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'package:flutter/services.dart';
 import 'package:http/http.dart' as http;
 import 'package:oauth2_client/access_token_response.dart';
+import 'package:oauth2_client/access_token_request.dart';
 import 'package:oauth2_client/authorization_response.dart';
 import 'package:oauth2_client/oauth2_response.dart';
 import 'package:oauth2_client/src/oauth2_utils.dart';
@@ -128,6 +129,61 @@ class OAuth2Client {
     }
   }
 
+  Future<AccessTokenRequest?> getTokenRequestWithAuthCodeFlow({
+    required String clientId,
+    List<String>? scopes,
+    String? clientSecret,
+    bool enablePKCE = true,
+    bool enableState = true,
+    String? state,
+    String? codeVerifier,
+    Function? afterAuthorizationCodeCb,
+    Map<String, dynamic>? authCodeParams,
+    Map<String, dynamic>? accessTokenParams,
+    httpClient,
+    BaseWebAuth? webAuthClient,
+    Map<String, dynamic>? webAuthOpts,
+  }) async {
+    String? codeChallenge;
+
+    if (enablePKCE) {
+      codeVerifier ??= randomAlphaNumeric(80);
+
+      codeChallenge = OAuth2Utils.generateCodeChallenge(codeVerifier);
+    }
+
+    try {
+      final authResp = await requestAuthorization(
+        webAuthClient: webAuthClient,
+        clientId: clientId,
+        scopes: scopes,
+        codeChallenge: codeChallenge,
+        enableState: enableState,
+        state: state,
+        webAuthOpts: webAuthOpts,
+      );
+
+      if (authResp.isAccessGranted()) {
+        if (afterAuthorizationCodeCb != null) {
+          afterAuthorizationCodeCb(authResp);
+        }
+
+        return AccessTokenRequest(
+          code: authResp.code!,
+          clientId: clientId,
+          scopes: scopes,
+          tokenUrl: tokenUrl,
+          redirectUri: redirectUri,
+          codeVerifier: codeVerifier,
+          customParams: accessTokenParams,
+        );
+      }
+    } catch (e) {
+      return null;
+    }
+    return null;
+  }
+
   /// Requests an Access Token to the OAuth2 endpoint using the Authorization Code Flow.
   Future<AccessTokenResponse> getTokenWithAuthCodeFlow(
       {required String clientId,
@@ -145,40 +201,25 @@ class OAuth2Client {
       Map<String, dynamic>? webAuthOpts}) async {
     AccessTokenResponse? tknResp;
 
-    String? codeChallenge;
-
-    if (enablePKCE) {
-      codeVerifier ??= randomAlphaNumeric(80);
-
-      codeChallenge = OAuth2Utils.generateCodeChallenge(codeVerifier);
-    }
-
     try {
-      var authResp = await requestAuthorization(
-          webAuthClient: webAuthClient,
-          clientId: clientId,
-          scopes: scopes,
-          codeChallenge: codeChallenge,
-          enableState: enableState,
-          state: state,
-          customParams: authCodeParams,
-          webAuthOpts: webAuthOpts);
-
-      if (authResp.isAccessGranted()) {
-        if (afterAuthorizationCodeCb != null) {
-          afterAuthorizationCodeCb(authResp);
-        }
-
-        tknResp = await requestAccessToken(
-            httpClient: httpClient,
-            //If the authorization request was successfull, the code must be set
-            //otherwise an exception is raised in the OAuth2Response constructor
-            code: authResp.code!,
-            clientId: clientId,
-            scopes: scopes,
-            clientSecret: clientSecret,
-            codeVerifier: codeVerifier,
-            customParams: accessTokenParams);
+      final tknReq = await getTokenRequestWithAuthCodeFlow(
+        clientId: clientId,
+        scopes: scopes,
+        clientSecret: clientSecret,
+        enablePKCE: enablePKCE,
+        enableState: enableState,
+        state: state,
+        codeVerifier: codeVerifier,
+        afterAuthorizationCodeCb: afterAuthorizationCodeCb,
+        authCodeParams: authCodeParams,
+        accessTokenParams: accessTokenParams,
+        httpClient: httpClient,
+        webAuthClient: webAuthClient,
+        webAuthOpts: webAuthOpts,
+      );
+
+      if (tknReq != null) {
+        tknResp = await requestAccessToken(tknReq);
       } else {
         tknResp = AccessTokenResponse.errorResponse();
       }
@@ -247,29 +288,24 @@ class OAuth2Client {
   }
 
   /// Requests and Access Token using the provided Authorization [code].
-  Future<AccessTokenResponse> requestAccessToken(
-      {required String code,
-      required String clientId,
-      String? clientSecret,
-      String? codeVerifier,
-      List<String>? scopes,
-      Map<String, dynamic>? customParams,
-      httpClient}) async {
+  Future<AccessTokenResponse> requestAccessToken(AccessTokenRequest req) async {
     final params = getTokenUrlParams(
-        code: code,
-        redirectUri: redirectUri,
-        codeVerifier: codeVerifier,
-        customParams: customParams);
+      code: req.code,
+      redirectUri: redirectUri,
+      codeVerifier: req.codeVerifier,
+      customParams: req.customParams,
+    );
 
     var response = await _performAuthorizedRequest(
-        url: tokenUrl,
-        clientId: clientId,
-        clientSecret: clientSecret,
-        params: params,
-        headers: _accessTokenRequestHeaders,
-        httpClient: httpClient);
-
-    return http2TokenResponse(response, requestedScopes: scopes);
+      url: tokenUrl,
+      clientId: req.clientId,
+      clientSecret: req.clientSecret,
+      params: params,
+      headers: _accessTokenRequestHeaders,
+      httpClient: req.httpClient,
+    );
+
+    return http2TokenResponse(response, requestedScopes: req.scopes);
   }
 
   /// Refreshes an Access Token issuing a refresh_token grant to the OAuth2 server.

test/oauth2_client_test.dart

@@ -2,6 +2,7 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:mockito/annotations.dart';
 import 'package:mockito/mockito.dart';
 import 'package:http/http.dart' as http;
+import 'package:oauth2_client/access_token_request.dart';
 import 'package:oauth2_client/access_token_response.dart';
 import 'package:oauth2_client/oauth2_client.dart';
 import 'package:oauth2_client/src/oauth2_utils.dart';
@@ -94,10 +95,15 @@ void main() {
               200));
 
       final tknResponse = await oauth2Client.requestAccessToken(
-          httpClient: httpClient,
+        AccessTokenRequest(
           code: authCode,
+          tokenUrl: tokenUrl,
           clientId: clientId,
-          codeVerifier: codeVerifier);
+          redirectUri: redirectUri,
+          httpClient: httpClient,
+          codeVerifier: codeVerifier,
+        ),
+      );
 
       expect(
           verify(httpClient.post(Uri.parse(tokenUrl),
@@ -135,10 +141,15 @@ void main() {
               200));
 
       final tknResponse = await oauth2Client.requestAccessToken(
-          httpClient: httpClient,
+        AccessTokenRequest(
           code: authCode,
+          tokenUrl: tokenUrl,
           clientId: clientId,
-          codeVerifier: codeVerifier);
+          redirectUri: redirectUri,
+          httpClient: httpClient,
+          codeVerifier: codeVerifier,
+        ),
+      );
 
       expect(
           verify(httpClient.post(Uri.parse(tokenUrl),
@@ -203,11 +214,15 @@ void main() {
           .thenAnswer((_) async => http.Response('', 404));
 
       final tknResponse = await oauth2Client.requestAccessToken(
-          httpClient: httpClient,
+        AccessTokenRequest(
           code: authCode,
+          tokenUrl: tokenUrl,
           clientId: clientId,
-          // clientSecret: clientSecret,
-          codeVerifier: codeVerifier);
+          redirectUri: redirectUri,
+          httpClient: httpClient,
+          codeVerifier: codeVerifier,
+        ),
+      );
 
       expect(tknResponse.isValid(), false);
     });