feat: Implement authentication provider management components

- Added new templates for managing authentication providers, including forms for creating and editing providers.
- Implemented backend logic to handle retrieval, creation, and deletion of authentication providers.
- Introduced new database migrations to support the storage of authentication provider data.
- Enhanced the user interface to display available authentication providers and their statuses.
- Added routes and handlers for managing authentication provider actions in the web application.

internal/db/auth_provider.go

@@ -0,0 +1,154 @@
+package db
+
+import (
+	"database/sql"
+	"encoding/json"
+	"time"
+)
+
+// ProviderType represents the type of authentication provider
+type ProviderType string
+
+const (
+	// ProviderTypeAuthentik represents an Authentik authentication provider
+	ProviderTypeAuthentik ProviderType = "authentik"
+
+	// ProviderTypeOIDC represents an OpenID Connect authentication provider
+	ProviderTypeOIDC ProviderType = "oidc"
+
+	// ProviderTypeSAML represents a SAML authentication provider
+	ProviderTypeSAML ProviderType = "saml"
+
+	// ProviderTypeOAuth2 represents an OAuth2 authentication provider
+	ProviderTypeOAuth2 ProviderType = "oauth2"
+)
+
+// AuthProvider represents an external authentication provider configuration
+type AuthProvider struct {
+	ID               uint         `gorm:"primarykey" json:"id"`
+	Name             string       `gorm:"not null" json:"name"`
+	Type             ProviderType `gorm:"not null" json:"type"`
+	Enabled          bool         `gorm:"default:true" json:"enabled"`
+	Description      string       `json:"description"`
+	ProviderURL      string       `json:"provider_url"`
+	ClientID         string       `json:"client_id"`
+	ClientSecret     string       `json:"-"` // Not returned in JSON responses
+	RedirectURL      string       `json:"redirect_url"`
+	Scopes           string       `json:"scopes"`
+	AttributeMapping string       `json:"attribute_mapping"`
+	Config           string       `json:"-"`        // Stores provider-specific configuration
+	IconURL          string       `json:"icon_url"` // URL to provider icon
+	SuccessfulLogins int          `json:"successful_logins"`
+	LastUsed         sql.NullTime `json:"last_used"`
+	CreatedAt        time.Time    `json:"created_at"`
+	UpdatedAt        time.Time    `json:"updated_at"`
+
+	// Unmarshalled config
+	configData map[string]interface{} `gorm:"-" json:"-"`
+}
+
+// GetConfig returns the unmarshalled configuration data
+func (p *AuthProvider) GetConfig() (map[string]interface{}, error) {
+	if p.configData == nil && p.Config != "" {
+		err := json.Unmarshal([]byte(p.Config), &p.configData)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if p.configData == nil {
+		p.configData = make(map[string]interface{})
+	}
+
+	return p.configData, nil
+}
+
+// SetConfig sets the configuration data and marshals it to JSON
+func (p *AuthProvider) SetConfig(data map[string]interface{}) error {
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	p.Config = string(jsonData)
+	p.configData = data
+	return nil
+}
+
+// ExternalUserIdentity represents a user identity from an external authentication provider
+type ExternalUserIdentity struct {
+	ID           uint         `gorm:"primarykey" json:"id"`
+	UserID       uint         `gorm:"not null" json:"user_id"`
+	ProviderID   uint         `gorm:"not null" json:"provider_id"`
+	ProviderType ProviderType `gorm:"not null" json:"provider_type"`
+	ExternalID   string       `gorm:"not null" json:"external_id"`
+	Email        string       `gorm:"not null" json:"email"`
+	Username     string       `json:"username"`
+	DisplayName  string       `json:"display_name"`
+	Groups       string       `json:"groups"` // JSON array of groups
+	LastLogin    sql.NullTime `json:"last_login"`
+	ProviderData string       `json:"-"` // Raw data from provider
+	CreatedAt    time.Time    `json:"created_at"`
+	UpdatedAt    time.Time    `json:"updated_at"`
+
+	// Foreign key relationships
+	User     User         `gorm:"foreignKey:UserID" json:"-"`
+	Provider AuthProvider `gorm:"foreignKey:ProviderID" json:"-"`
+
+	// Unmarshalled provider data
+	providerDataObj map[string]interface{} `gorm:"-" json:"-"`
+}
+
+// GetProviderData returns the unmarshalled provider data
+func (e *ExternalUserIdentity) GetProviderData() (map[string]interface{}, error) {
+	if e.providerDataObj == nil && e.ProviderData != "" {
+		err := json.Unmarshal([]byte(e.ProviderData), &e.providerDataObj)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if e.providerDataObj == nil {
+		e.providerDataObj = make(map[string]interface{})
+	}
+
+	return e.providerDataObj, nil
+}
+
+// SetProviderData sets the provider data and marshals it to JSON
+func (e *ExternalUserIdentity) SetProviderData(data map[string]interface{}) error {
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	e.ProviderData = string(jsonData)
+	e.providerDataObj = data
+	return nil
+}
+
+// GetGroups returns the unmarshalled groups
+func (e *ExternalUserIdentity) GetGroups() ([]string, error) {
+	var groups []string
+	if e.Groups == "" {
+		return groups, nil
+	}
+
+	err := json.Unmarshal([]byte(e.Groups), &groups)
+	if err != nil {
+		return nil, err
+	}
+
+	return groups, nil
+}
+
+// SetGroups sets the groups and marshals them to JSON
+func (e *ExternalUserIdentity) SetGroups(groups []string) error {
+	jsonData, err := json.Marshal(groups)
+	if err != nil {
+		return err
+	}
+
+	e.Groups = string(jsonData)
+	return nil
+}