Add MusicBrainz to the list of supported providers

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Revocation.cs

@@ -135,6 +135,12 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 response.Content.Headers.ContentType = context.Registration.ProviderType switch
                 {
+                    // MusicBrainz returns empty revocation responses declared as "text/html" responses.
+                    //
+                    // Since empty HTML payloads are not valid JSON nodes, the Content-Length is manually set
+                    // to 0 to prevent OpenIddict from trying to extract a JSON payload from such responses.
+                    ProviderTypes.MusicBrainz when response.Content.Headers.ContentLength is 0 => null,
+
                     // Reddit returns empty revocation responses declared as "application/json" responses.
                     //
                     // Since empty JSON payloads are not valid JSON nodes, the Content-Length is manually set

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.cs

@@ -1136,6 +1136,9 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 // Mailchimp returns the username as a custom "accountname" node:
                 ProviderTypes.Mailchimp => (string?) context.UserinfoResponse?["accountname"],
 
+                // Mailchimp returns the username as a custom "sub" node:
+                ProviderTypes.MusicBrainz => (string?) context.UserinfoResponse?["sub"],
+
                 // Nextcloud returns the username as a custom "displayname" or "display-name" node:
                 ProviderTypes.Nextcloud => (string?) context.UserinfoResponse?["displayname"] ??
                                            (string?) context.UserinfoResponse?["display-name"],
@@ -1216,6 +1219,9 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 // Mixcloud returns the user identifier as a custom "key" node:
                 ProviderTypes.Mixcloud => (string?) context.UserinfoResponse?["key"],
 
+                // MusicBrainz returns the user identifier as a custom "metabrainz_user_id" node:
+                ProviderTypes.MusicBrainz => (string?) context.UserinfoResponse?["metabrainz_user_id"],
+
                 // Notion returns the user identifier as a custom "bot/owner/user/id" node but
                 // requires a special capability to access this node, that may not be present:
                 ProviderTypes.Notion => (string?) context.UserinfoResponse?["bot"]?["owner"]?["user"]?["id"],
@@ -1531,6 +1537,16 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.Request["access_type"] = settings.AccessType;
             }
 
+            // By default, MusicBrainz doesn't return a refresh token but allows sending an "access_type"
+            // parameter to retrieve one (but it is only returned during the first authorization dance).
+            else if (context.Registration.ProviderType is ProviderTypes.MusicBrainz)
+            {
+                var settings = context.Registration.GetMusicBrainzSettings();
+
+                context.Request["access_type"] = settings.AccessType;
+                context.Request["approval_prompt"] = settings.ApprovalPrompt;
+            }
+
             // Pro Santé Connect's specification requires sending an acr_values parameter containing
             // the desired level of authentication (currently, only "eidas1" is supported). For more
             // information, see https://www.legifrance.gouv.fr/jorf/id/JORFTEXT000045551195.

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationProviders.xml

@@ -857,6 +857,42 @@
     </Environment>
   </Provider>
 
+  <!--
+                              ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
+                              ██ ▄▀▄ ██ ██ ██ ▄▄▄ █▄ ▄██ ▄▄▀██ ▄▄▀██ ▄▄▀█ ▄▄▀█▄ ▄██ ▀██ ██ ▄▄▄ ██
+                              ██ █ █ ██ ██ ██▄▄▄▀▀██ ███ █████ ▄▄▀██ ▀▀▄█ ▀▀ ██ ███ █ █ ██▀▀▀▄▄██
+                              ██ ███ ██▄▀▀▄██ ▀▀▀ █▀ ▀██ ▀▀▄██ ▀▀ ██ ██ █ ██ █▀ ▀██ ██▄ ██ ▀▀▀ ██
+                              ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
+  -->
+
+  <Provider Name="MusicBrainz" Id="7b734583-1b96-4a5b-8d8c-d21d9d28b598"
+            Documentation="https://musicbrainz.org/doc/Development/OAuth2">
+    <Environment Issuer="https://musicbrainz.org/">
+      <Configuration AuthorizationEndpoint="https://musicbrainz.org/oauth2/authorize"
+                     RevocationEndpoint="https://musicbrainz.org/oauth2/revoke"
+                     TokenEndpoint="https://musicbrainz.org/oauth2/token"
+                     UserinfoEndpoint="https://musicbrainz.org/oauth2/userinfo">
+        <CodeChallengeMethod Value="plain" />
+        <CodeChallengeMethod Value="S256" />
+
+        <GrantType Value="authorization_code" />
+        <GrantType Value="refresh_token" />
+      </Configuration>
+
+      <!--
+        Note: MusicBrainz requires sending the "profile" scope to be able to use the userinfo endpoint.
+      -->
+
+      <Scope Name="profile" Default="true" Required="true" />
+    </Environment>
+
+    <Setting PropertyName="AccessType" ParameterName="type" Type="String" Required="false"
+             Description="The value used as the 'access_type' parameter (can be set to 'offline' to retrieve a refresh token)" />
+
+    <Setting PropertyName="ApprovalPrompt" ParameterName="prompt" Type="String" Required="false"
+             Description="The value used as the 'approval_prompt' parameter (can be set to 'force' to display the consent form for each authorization demand)" />
+  </Provider>
+
   <!--
                                   ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
                                   ██ ▀██ ██ ▄▄▄█▄▀█▀▄█▄▄ ▄▄██ ▄▄▀██ █████ ▄▄▄ ██ ██ ██ ▄▄▀██

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationProviders.xsd

@@ -552,7 +552,7 @@
 
             <xs:attribute name="DisplayName" use="optional">
               <xs:annotation>
-                <xs:documentation>The display name used in the documentation, if applicable.</xs:documentation>
+                <xs:documentation>The provider display name (if unspecified, the provider name is used as the display name).</xs:documentation>
               </xs:annotation>
 
               <xs:simpleType>