snapshot of https://github.com/cortezaproject/corteza.git (2024.9.x, 2026-09-18; blobs > 131072B omitted)

server/pkg/http/file_server.go

@@ -0,0 +1,152 @@
+package http
+
+import (
+	"io/fs"
+	"net/http"
+	"path"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+	"go.uber.org/zap"
+)
+
+type (
+	// special file-server meant to be used for serving single page applications
+	// or anything that needs a bit of extra attention like fallback handling
+	// 404 handler, error handler and URL prefixing
+	fileServer struct {
+		// fileServer files
+		files http.FileSystem
+
+		urlPrefix string
+
+		fallbacks []string
+
+		// Final not-found handler
+		notFound http.HandlerFunc
+
+		// how errors are handled
+		errHandler func(w http.ResponseWriter, error string, code int)
+
+		logger *zap.Logger
+	}
+
+	configurator func(*fileServer) error
+)
+
+// MountSPA helper function, preconfigures FileServer for SPA serving
+// and mounts it to chi Router
+func MountSPA(r chi.Router, path string, root fs.FS, cc ...configurator) error {
+	path = "/" + strings.Trim(strings.TrimRight(path, "*"), "/") + "/"
+
+	cc = append(
+		[]configurator{UrlPrefix(path), Fallbacks("index.html")},
+		// appnd all configurators at the end and allow override of prefix & fallbacks
+		cc...
+	)
+
+	handler, err := FileServer(root, cc...)
+	if err != nil {
+		return err
+	}
+
+	r.Handle(
+		strings.TrimRight(path, "/"),
+		http.RedirectHandler("."+path, http.StatusTemporaryRedirect),
+	)
+
+	r.Handle(path+"*", handler)
+	return nil
+}
+
+func FileServer(files fs.FS, cc ...configurator) (h *fileServer, err error) {
+	h = &fileServer{
+		files:      http.FS(files),
+		notFound:   http.NotFound,
+		errHandler: http.Error,
+		logger:     zap.NewNop(),
+	}
+
+	for _, configure := range cc {
+		if err = configure(h); err != nil {
+			return
+		}
+	}
+
+	return
+}
+
+func UrlPrefix(prefix string) configurator {
+	return func(s *fileServer) error {
+		s.urlPrefix = prefix
+		return nil
+	}
+}
+
+func Fallbacks(ff ...string) configurator {
+	return func(s *fileServer) error {
+		s.fallbacks = ff
+		return nil
+	}
+}
+
+func NotFound(h http.HandlerFunc) configurator {
+	return func(s *fileServer) error {
+		s.notFound = h
+		return nil
+	}
+}
+
+func Logger(l *zap.Logger) configurator {
+	return func(s *fileServer) error {
+		s.logger = l
+		return nil
+	}
+}
+
+// Serves the single-page-application
+//
+// This is file-server with some special logic for handling missing
+// files (404s) and directories.
+// In both cases we serve index file directly
+func (h *fileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// catch requests for non-existing files and redirect to index.html
+	if h.files == nil {
+		h.errHandler(w, "configured without files", http.StatusInternalServerError)
+		return
+	}
+
+	trimmed := path.Clean(strings.TrimPrefix(r.URL.Path, h.urlPrefix))
+	h.logger.Debug(r.URL.Path, zap.String("trimmed", trimmed), zap.String("urlPrefix", h.urlPrefix))
+	r.URL.Path = trimmed
+
+	var (
+		err error
+		fh  http.File
+		st  fs.FileInfo
+	)
+
+	for _, candidate := range append([]string{r.URL.Path}, h.fallbacks...) {
+		if len(candidate) == 0 {
+			continue
+		}
+
+		if fh, err = h.files.Open(candidate); err != nil {
+			continue
+		} else if st, err = fh.Stat(); err != nil {
+			continue
+		} else if st.IsDir() {
+			// index
+			continue
+		}
+
+		break
+	}
+
+	if fh == nil || st == nil {
+		h.notFound(w, r)
+		return
+	}
+
+	http.ServeContent(w, r, st.Name(), st.ModTime(), fh)
+}