Initial QSfera import

Server/services/web/pkg/assets/server.go

@@ -0,0 +1,114 @@
+package assets
+
+import (
+	"bytes"
+	"io"
+	"io/fs"
+	"mime"
+	"net/http"
+	"path"
+	"path/filepath"
+
+	"golang.org/x/net/html"
+)
+
+type fileServer struct {
+	fsys http.FileSystem
+}
+
+const (
+	webTitle        = "КуСфера"
+	legacyUpdateURL = "https://update.opencloud.eu/"
+	qsferaUpdateURL = "https://update.qsfera.eu/"
+)
+
+// FileServer defines the http handler for the embedded files
+func FileServer(fsys fs.FS) http.Handler {
+	return &fileServer{http.FS(fsys)}
+}
+
+func (f *fileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	uPath := path.Clean(path.Join("/", r.URL.Path))
+	r.URL.Path = uPath
+
+	tryIndex := func() {
+		r.URL.Path = "/index.html"
+
+		// not every fs contains a file named index.html,
+		// therefore, we need to check if the file exists and stop the recursion if it doesn't
+		file, err := f.fsys.Open(r.URL.Path)
+		if err != nil {
+			http.NotFound(w, r)
+			return
+		}
+		defer file.Close()
+
+		f.ServeHTTP(w, r)
+	}
+
+	asset, err := f.fsys.Open(uPath)
+	if err != nil {
+		tryIndex()
+		return
+	}
+	defer asset.Close()
+
+	s, _ := asset.Stat()
+	if s.IsDir() {
+		tryIndex()
+		return
+	}
+
+	w.Header().Set("Content-Type", mime.TypeByExtension(filepath.Ext(s.Name())))
+
+	buf := new(bytes.Buffer)
+
+	switch s.Name() {
+	case "index.html", "oidc-callback.html", "oidc-silent-redirect.html":
+		w.Header().Del("Expires")
+		w.Header().Set("Cache-Control", "no-cache")
+		_ = withBase(buf, asset, "/")
+	default:
+		_, _ = buf.ReadFrom(asset)
+	}
+
+	body := bytes.ReplaceAll(buf.Bytes(), []byte(legacyUpdateURL), []byte(qsferaUpdateURL))
+	_, _ = w.Write(body)
+}
+
+func withBase(w io.Writer, r io.Reader, base string) error {
+	doc, _ := html.Parse(r)
+	var parse func(*html.Node)
+	parse = func(n *html.Node) {
+		if n.Type == html.ElementNode && n.Data == "head" {
+			n.InsertBefore(&html.Node{
+				Type: html.ElementNode,
+				Data: "base",
+				Attr: []html.Attribute{
+					{
+						Key: "href",
+						Val: base,
+					},
+				},
+			}, n.FirstChild)
+		}
+
+		if n.Type == html.ElementNode && n.Data == "title" {
+			if n.FirstChild == nil {
+				n.AppendChild(&html.Node{
+					Type: html.TextNode,
+					Data: webTitle,
+				})
+			} else {
+				n.FirstChild.Data = webTitle
+			}
+		}
+
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			parse(c)
+		}
+	}
+	parse(doc)
+
+	return html.Render(w, doc)
+}