Fix filepath separator and external files on windows

For some reason, '/' is used instead of '\' on windows when loading
lang. FSJoin will now use whatever already exists in the path.
app.GetPath now creates a DirFS from the containing directory instead of
app.systemFS, which fixes loading on windows.

config.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"io/fs"
+	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -17,7 +18,8 @@ func (app *appContext) GetPath(sect, key string) (fs.FS, string) {
 	if strings.HasPrefix(val, "jfa-go:") {
 		return localFS, strings.TrimPrefix(val, "jfa-go:")
 	}
-	return app.systemFS, strings.TrimPrefix(val, "/")
+	dir, file := filepath.Split(val)
+	return os.DirFS(dir), file
 }
 
 func (app *appContext) loadConfig() error {

embed/external.go

@@ -5,12 +5,25 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"strings"
 )
 
 var localFS fs.FS
 var langFS fs.FS
 
-func FSJoin(elem ...string) string { return filepath.Join(elem...) }
+// When using os.DirFS, even on Windows the separator seems to be '/'.
+// func FSJoin(elem ...string) string { return filepath.Join(elem...) }
+func FSJoin(elem ...string) string {
+	sep := "/"
+	if strings.Contains(elem[0], "\\") {
+		sep = "\\"
+	}
+	path := ""
+	for _, el := range elem {
+		path += el + sep
+	}
+	return strings.TrimSuffix(path, sep)
+}
 
 func loadFilesystems() {
 	log.Println("Using external storage")

main.go

@@ -65,7 +65,6 @@ type appContext struct {
 	configBasePath string
 	configBase     settings
 	dataPath       string
-	systemFS       fs.FS
 	webFS          httpFS
 	cssClass       string
 	jellyfinLogin  bool
@@ -141,7 +140,6 @@ func start(asDaemon, firstCall bool) {
 	userConfigDir, _ := os.UserConfigDir()
 	app.dataPath = filepath.Join(userConfigDir, "jfa-go")
 	app.configPath = filepath.Join(app.dataPath, "config.ini")
-	app.systemFS = os.DirFS("/")
 	// gin-static doesn't just take a plain http.FileSystem, so we implement it's ServeFileSystem. See static.go.
 	app.webFS = httpFS{
 		hfs: http.FS(localFS),

package-lock.json

@@ -228,9 +228,9 @@
       "integrity": "sha1-vfpzUplmTfr9NFKe1PhSKidf6lY="
     },
     "esbuild": {
-      "version": "0.8.46",
+      "version": "0.8.47",
-      "resolved": "https://registry.npm.taobao.org/esbuild/download/esbuild-0.8.46.tgz",
+      "resolved": "https://registry.npm.taobao.org/esbuild/download/esbuild-0.8.47.tgz",
-      "integrity": "sha1-j8cjDOMBmxLiVTOZ8MA4dacpwms="
+      "integrity": "sha1-XVxZt9y4og3632WpheXlynsk7/I="
     },
     "escalade": {
       "version": "3.1.1",

package.json

@@ -18,7 +18,7 @@
   "homepage": "https://github.com/hrfee/jfa-go#readme",
   "dependencies": {
     "a17t": "^0.4.0",
-    "esbuild": "^0.8.46",
+    "esbuild": "^0.8.47",
     "lodash": "^4.17.19",
     "mjml": "^4.8.0",
     "remixicon": "^2.5.0",