SSO Refactoring (#2818)

# Description of Changes

* Refactoring of SSO code around OAuth & SAML 2
* Enabling auto-login with SAML 2 via the new `SSOAutoLogin` property
* Correcting typos & general cleanup

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [x] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [x] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [x] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

src/main/java/stirling/software/SPDF/model/provider/KeycloakProvider.java

@@ -1,106 +1,72 @@
 package stirling.software.SPDF.model.provider;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
-import java.util.stream.Collectors;
 
-import stirling.software.SPDF.model.Provider;
+import lombok.NoArgsConstructor;
+import stirling.software.SPDF.model.UsernameAttribute;
 
+@NoArgsConstructor
 public class KeycloakProvider extends Provider {
 
-    private String issuer;
-    private String clientId;
-    private String clientSecret;
-    private Collection<String> scopes = new ArrayList<>();
-    private String useAsUsername = "email";
+    private static final String NAME = "keycloak";
+    private static final String CLIENT_NAME = "Keycloak";
 
-    @Override
-    public String getIssuer() {
-        return this.issuer;
+    public KeycloakProvider(
+            String issuer,
+            String clientId,
+            String clientSecret,
+            Collection<String> scopes,
+            UsernameAttribute useAsUsername) {
+        super(
+                issuer,
+                NAME,
+                CLIENT_NAME,
+                clientId,
+                clientSecret,
+                scopes,
+                useAsUsername,
+                null,
+                null,
+                null,
+                null);
     }
 
     @Override
-    public void setIssuer(String issuer) {
-        this.issuer = issuer;
+    public String getName() {
+        return NAME;
     }
 
     @Override
-    public String getClientId() {
-        return this.clientId;
-    }
-
-    @Override
-    public void setClientId(String clientId) {
-        this.clientId = clientId;
-    }
-
-    @Override
-    public String getClientSecret() {
-        return this.clientSecret;
-    }
-
-    @Override
-    public void setClientSecret(String clientSecret) {
-        this.clientSecret = clientSecret;
+    public String getClientName() {
+        return CLIENT_NAME;
     }
 
     @Override
     public Collection<String> getScopes() {
+        Collection<String> scopes = super.getScopes();
+
         if (scopes == null || scopes.isEmpty()) {
             scopes = new ArrayList<>();
             scopes.add("profile");
             scopes.add("email");
         }
+
         return scopes;
     }
 
-    @Override
-    public void setScopes(String scopes) {
-        this.scopes =
-                Arrays.stream(scopes.split(",")).map(String::trim).collect(Collectors.toList());
-    }
-
-    @Override
-    public String getUseAsUsername() {
-        return this.useAsUsername;
-    }
-
-    @Override
-    public void setUseAsUsername(String useAsUsername) {
-        this.useAsUsername = useAsUsername;
-    }
-
     @Override
     public String toString() {
         return "Keycloak [issuer="
-                + issuer
+                + getIssuer()
                 + ", clientId="
-                + clientId
+                + getClientId()
                 + ", clientSecret="
-                + (clientSecret != null && !clientSecret.isEmpty() ? "MASKED" : "NULL")
+                + (getClientSecret() != null && !getClientSecret().isBlank() ? "*****" : "NULL")
                 + ", scopes="
-                + scopes
+                + getScopes()
                 + ", useAsUsername="
-                + useAsUsername
+                + getUseAsUsername()
                 + "]";
     }
-
-    @Override
-    public String getName() {
-        return "keycloak";
-    }
-
-    @Override
-    public String getClientName() {
-        return "Keycloak";
-    }
-
-    public boolean isSettingsValid() {
-        return isValid(this.getIssuer(), "issuer")
-                && isValid(this.getClientId(), "clientId")
-                && isValid(this.getClientSecret(), "clientSecret")
-                && isValid(this.getScopes(), "scopes")
-                && isValid(this.getUseAsUsername(), "useAsUsername");
-    }
 }