fix: serve UI as a SPA

close #75

pkg/api/index.go

@@ -2,12 +2,44 @@ package api
 
 import (
 	"net/http"
+	"os"
 	"path"
+	"path/filepath"
 
 	"github.com/ncarlier/readflow/pkg/config"
 	"github.com/rs/zerolog/log"
 )
 
+type SPAHandler struct {
+	baseDir string
+	handler http.Handler
+}
+
+func newSPAHandler(baseDir string) http.Handler {
+	return &SPAHandler{
+		baseDir: baseDir,
+		handler: http.FileServer(http.Dir(baseDir)),
+	}
+}
+
+func (s SPAHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	path := filepath.Join(s.baseDir, r.URL.Path)
+	fi, err := os.Stat(path)
+	if os.IsNotExist(err) || fi.IsDir() {
+		// serve index.html if path does not exist
+		http.ServeFile(w, r, filepath.Join(s.baseDir, "index.html"))
+		return
+	}
+
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// otherwise,serve static files
+	s.handler.ServeHTTP(w, r)
+}
+
 // index is the handler to show API details.
 func index(conf *config.Config) http.Handler {
 	if conf.UI.Directory != "" {
@@ -17,7 +49,7 @@ func index(conf *config.Config) http.Handler {
 		if err := conf.WriteUIConfigFile(configFilename); err != nil {
 			log.Warn().Err(err).Str("filename", configFilename).Msg("unable to generate UI config file")
 		}
-		return http.FileServer(http.Dir(conf.UI.Directory))
+		return newSPAHandler(conf.UI.Directory)
 	}
 	return http.RedirectHandler("/info", http.StatusSeeOther)
 }