Add new providers.

internal/providers/gitlab.go

@@ -0,0 +1,73 @@
+package providers
+
+import (
+	"net/url"
+)
+
+// GitLabProvider encapsulates GitLab-specific OIDC logic.
+type GitLabProvider struct {
+	*BaseProvider
+}
+
+// NewGitLabProvider creates a new instance of the GitLabProvider.
+func NewGitLabProvider() *GitLabProvider {
+	return &GitLabProvider{
+		BaseProvider: NewBaseProvider(),
+	}
+}
+
+// GetType returns the provider's type.
+func (p *GitLabProvider) GetType() ProviderType {
+	return ProviderTypeGitLab
+}
+
+// GetCapabilities returns the specific capabilities of the GitLab provider.
+func (p *GitLabProvider) GetCapabilities() ProviderCapabilities {
+	return ProviderCapabilities{
+		SupportsRefreshTokens:      true,
+		RequiresOfflineAccessScope: false, // GitLab doesn't use offline_access scope
+		RequiresPromptConsent:      false,
+		PreferredTokenValidation:   "id", // GitLab typically uses ID tokens
+	}
+}
+
+// BuildAuthParams configures GitLab-specific authentication parameters.
+func (p *GitLabProvider) BuildAuthParams(baseParams url.Values, scopes []string) (*AuthParams, error) {
+	// GitLab supports standard OAuth 2.0 parameters
+	baseParams.Set("response_type", "code")
+
+	// Remove offline_access scope as GitLab doesn't use it
+	var filteredScopes []string
+	for _, scope := range scopes {
+		if scope != "offline_access" {
+			filteredScopes = append(filteredScopes, scope)
+		}
+	}
+
+	// Ensure openid scope is present for OIDC
+	hasOpenID := false
+	for _, scope := range filteredScopes {
+		if scope == "openid" {
+			hasOpenID = true
+			break
+		}
+	}
+	if !hasOpenID {
+		filteredScopes = append(filteredScopes, "openid")
+	}
+
+	// Default GitLab scopes if none specified
+	if len(filteredScopes) == 1 && filteredScopes[0] == "openid" {
+		filteredScopes = append(filteredScopes, "profile", "email")
+	}
+
+	return &AuthParams{
+		URLValues: baseParams,
+		Scopes:    filteredScopes,
+	}, nil
+}
+
+// GitLab requires application configuration and proper redirect URIs.
+func (p *GitLabProvider) ValidateConfig() error {
+	return p.BaseProvider.ValidateConfig()
+}