V2 alpha - initial version (#172)

Initial alpha codebase for version 2 of WireGuard Portal.
This version is considered unstable and incomplete (for example, no public REST API)! 
Use with care!


Fixes/Implements the following issues:
 - OAuth support #154, #1 
 - New Web UI with internationalisation support #98, #107, #89, #62
 - Postgres Support #49 
 - Improved Email handling #47, #119 
 - DNS Search Domain support #46 
 - Bugfixes #94, #48 

---------

Co-authored-by: Fabian Wechselberger <wechselbergerf@hotmail.com>

internal/app/api/v0/handlers/session.go

@@ -0,0 +1,92 @@
+package handlers
+
+import (
+	"encoding/gob"
+	"fmt"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+)
+
+func init() {
+	gob.Register(SessionData{})
+}
+
+type SessionData struct {
+	LoggedIn bool
+	IsAdmin  bool
+
+	UserIdentifier string
+
+	Firstname string
+	Lastname  string
+	Email     string
+
+	OauthState    string
+	OauthNonce    string
+	OauthProvider string
+	OauthReturnTo string
+}
+
+type SessionStore interface {
+	DefaultSessionData() SessionData
+
+	GetData(c *gin.Context) SessionData
+	SetData(c *gin.Context, data SessionData)
+
+	DestroyData(c *gin.Context)
+}
+
+type GinSessionStore struct {
+	sessionIdentifier string
+}
+
+func (g GinSessionStore) GetData(c *gin.Context) SessionData {
+	session := sessions.Default(c)
+	rawSessionData := session.Get(g.sessionIdentifier)
+
+	var sessionData SessionData
+	if rawSessionData != nil {
+		sessionData = rawSessionData.(SessionData)
+	} else {
+		// init a new default session
+		sessionData = g.DefaultSessionData()
+		session.Set(g.sessionIdentifier, sessionData)
+		if err := session.Save(); err != nil {
+			panic(fmt.Sprintf("failed to store session: %v", err))
+		}
+	}
+
+	return sessionData
+}
+
+func (g GinSessionStore) DefaultSessionData() SessionData {
+	return SessionData{
+		LoggedIn:       false,
+		IsAdmin:        false,
+		UserIdentifier: "",
+		Firstname:      "",
+		Lastname:       "",
+		Email:          "",
+		OauthState:     "",
+		OauthNonce:     "",
+		OauthProvider:  "",
+		OauthReturnTo:  "",
+	}
+}
+
+func (g GinSessionStore) SetData(c *gin.Context, data SessionData) {
+	session := sessions.Default(c)
+	session.Set(g.sessionIdentifier, data)
+	if err := session.Save(); err != nil {
+		panic(fmt.Sprintf("failed to store session: %v", err))
+	}
+}
+
+func (g GinSessionStore) DestroyData(c *gin.Context) {
+	session := sessions.Default(c)
+	session.Delete(g.sessionIdentifier)
+	if err := session.Save(); err != nil {
+		panic(fmt.Sprintf("failed to store session: %v", err))
+	}
+}