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/configfile/template.go

@@ -0,0 +1,68 @@
+package configfile
+
+import (
+	"bytes"
+	"embed"
+	"fmt"
+	"io"
+	"text/template"
+
+	"github.com/h44z/wg-portal/internal/domain"
+)
+
+//go:embed tpl_files/*
+var TemplateFiles embed.FS
+
+type TemplateHandler struct {
+	templates *template.Template
+}
+
+func newTemplateHandler() (*TemplateHandler, error) {
+	tplFuncs := template.FuncMap{
+		"CidrsToString": domain.CidrsToString,
+	}
+
+	templateCache, err := template.New("WireGuard").Funcs(tplFuncs).ParseFS(TemplateFiles, "tpl_files/*.tpl")
+	if err != nil {
+		return nil, err
+	}
+
+	handler := &TemplateHandler{
+		templates: templateCache,
+	}
+
+	return handler, nil
+}
+
+func (c TemplateHandler) GetInterfaceConfig(cfg *domain.Interface, peers []domain.Peer) (io.Reader, error) {
+	var tplBuff bytes.Buffer
+
+	err := c.templates.ExecuteTemplate(&tplBuff, "wg_interface.tpl", map[string]interface{}{
+		"Interface": cfg,
+		"Peers":     peers,
+		"Portal": map[string]interface{}{
+			"Version": "unknown",
+		},
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute interface template for %s: %w", cfg.Identifier, err)
+	}
+
+	return &tplBuff, nil
+}
+
+func (c TemplateHandler) GetPeerConfig(peer *domain.Peer) (io.Reader, error) {
+	var tplBuff bytes.Buffer
+
+	err := c.templates.ExecuteTemplate(&tplBuff, "wg_peer.tpl", map[string]interface{}{
+		"Peer": peer,
+		"Portal": map[string]interface{}{
+			"Version": "unknown",
+		},
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to execute peer template for %s: %w", peer.Identifier, err)
+	}
+
+	return &tplBuff, nil
+}