feature: Add mapper for hardcoded tenant to OIDC token claims (#46)

src/main/java/dev/sultanov/keycloak/multitenancy/protocol/oidc/mappers/HardcodedTenantMapper.java

@@ -0,0 +1,107 @@
+package dev.sultanov.keycloak.multitenancy.protocol.oidc.mappers;
+
+import dev.sultanov.keycloak.multitenancy.model.TenantMembershipModel;
+import dev.sultanov.keycloak.multitenancy.model.TenantModel;
+import dev.sultanov.keycloak.multitenancy.model.TenantProvider;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+import org.keycloak.models.ClientSessionContext;
+import org.keycloak.models.KeycloakSession;
+import org.keycloak.models.ProtocolMapperModel;
+import org.keycloak.models.UserModel;
+import org.keycloak.models.UserSessionModel;
+import org.keycloak.protocol.oidc.mappers.AbstractOIDCProtocolMapper;
+import org.keycloak.protocol.oidc.mappers.OIDCAccessTokenMapper;
+import org.keycloak.protocol.oidc.mappers.OIDCAttributeMapperHelper;
+import org.keycloak.protocol.oidc.mappers.OIDCIDTokenMapper;
+import org.keycloak.protocol.oidc.mappers.UserInfoTokenMapper;
+import org.keycloak.provider.ProviderConfigProperty;
+import org.keycloak.representations.IDToken;
+
+public class HardcodedTenantMapper extends AbstractOIDCProtocolMapper
+        implements OIDCAccessTokenMapper, OIDCIDTokenMapper, UserInfoTokenMapper {
+
+    private static final String TENANT_ID_PROPERTY_NAME = "hardcoded_tenant_id";
+
+    private static final List<ProviderConfigProperty> CONFIG_PROPERTIES = new ArrayList<>(
+            List.of(new ProviderConfigProperty(
+                    TENANT_ID_PROPERTY_NAME, "Tenant ID", null, ProviderConfigProperty.STRING_TYPE, null, false,
+                    true)));
+
+    static {
+        OIDCAttributeMapperHelper.addTokenClaimNameConfig(CONFIG_PROPERTIES);
+        OIDCAttributeMapperHelper.addIncludeInTokensConfig(CONFIG_PROPERTIES, HardcodedTenantMapper.class);
+    }
+
+    public static final String PROVIDER_ID = "oidc-hardcoded-tenant-mapper";
+
+    public List<ProviderConfigProperty> getConfigProperties() {
+        return CONFIG_PROPERTIES;
+    }
+
+    @Override
+    public String getId() {
+        return PROVIDER_ID;
+    }
+
+    @Override
+    public String getDisplayType() {
+        return "Hardcoded tenant";
+    }
+
+    @Override
+    public String getDisplayCategory() {
+        return TOKEN_MAPPER_CATEGORY;
+    }
+
+    @Override
+    public String getHelpText() {
+        return "Maps hardcoded tenant to a token claim";
+    }
+
+    @Override
+    protected void setClaim(IDToken token, ProtocolMapperModel mappingModel, UserSessionModel userSession,
+            KeycloakSession keycloakSession,
+            ClientSessionContext clientSessionCtx) {
+        var tenantID = mappingModel.getConfig().get(TENANT_ID_PROPERTY_NAME);
+        var provider = keycloakSession.getProvider(TenantProvider.class);
+        var optionalTenant = provider.getTenantById(userSession.getRealm(), tenantID);
+
+        var claimName = mappingModel.getConfig().get(OIDCAttributeMapperHelper.TOKEN_CLAIM_NAME);
+        if (claimName != null && optionalTenant.isPresent()) {
+            var tenant = optionalTenant.get();
+            var user = userSession.getUser();
+            var membership = new TenantMembershipModel() {
+                @Override
+                public String getId() {
+                    return null;
+                }
+
+                @Override
+                public TenantModel getTenant() {
+                    return tenant;
+                }
+
+                @Override
+                public UserModel getUser() {
+                    return user;
+                }
+
+                @Override
+                public Set<String> getRoles() {
+                    return Collections.emptySet();
+                }
+
+                @Override
+                public void updateRoles(Set<String> roles) {
+                    throw new RuntimeException("UNSUPPORTED METHOD");
+                }
+            };
+            token.getOtherClaims().put(claimName, ClaimsFactory.toClaim(membership));
+        }
+    }
+}

src/main/resources/META-INF/services/org.keycloak.protocol.ProtocolMapper

@@ -1,2 +1,3 @@
 dev.sultanov.keycloak.multitenancy.protocol.oidc.mappers.ActiveTenantMapper
-dev.sultanov.keycloak.multitenancy.protocol.oidc.mappers.AllTenantsMapper
+dev.sultanov.keycloak.multitenancy.protocol.oidc.mappers.AllTenantsMapper
+dev.sultanov.keycloak.multitenancy.protocol.oidc.mappers.HardcodedTenantMapper