Implement SPA handling in Backend

http/http.go

@@ -1,8 +1,11 @@
 package http
 
 import (
+	"errors"
+	"io"
 	"io/fs"
 	"net/http"
+	"path"
 	"strings"
 
 	"git.javil.eu/jacob1123/budgeteer"
@@ -18,6 +21,7 @@ type Handler struct {
 	Service             *postgres.Database
 	TokenVerifier       budgeteer.TokenVerifier
 	CredentialsVerifier *bcrypt.Verifier
+	StaticFS            http.FileSystem
 }
 
 const (
@@ -37,14 +41,10 @@ func (h *Handler) LoadRoutes(router *gin.Engine) {
 	if err != nil {
 		panic("couldn't open static files")
 	}
-	staticFS := http.FS(static)
+	h.StaticFS = http.FS(static)
 
 	router.Use(enableCachingForStaticFiles())
-	router.NoRoute(
-		func(c *gin.Context) {
-			c.FileFromFS(c.Request.URL.Path, staticFS)
-		},
-	)
+	router.NoRoute(h.ServeStatic)
 
 	withLogin := router.Group("")
 	withLogin.Use(h.verifyLoginWithRedirect)
@@ -81,6 +81,35 @@ func (h *Handler) LoadRoutes(router *gin.Engine) {
 	transaction.POST("/new", h.newTransaction)
 	transaction.POST("/:transactionid", h.newTransaction)
 }
+func (h *Handler) ServeStatic(c *gin.Context) {
+	h.ServeStaticFile(c, c.Request.URL.Path)
+}
+
+func (h *Handler) ServeStaticFile(c *gin.Context, fullPath string) {
+	file, err := h.StaticFS.Open(fullPath)
+	if errors.Is(err, fs.ErrNotExist) {
+		h.ServeStaticFile(c, path.Join("/", "/index.html"))
+		return
+	}
+
+	if err != nil {
+		c.AbortWithError(http.StatusInternalServerError, err)
+		return
+	}
+
+	stat, err := file.Stat()
+	if err != nil {
+		c.AbortWithError(http.StatusInternalServerError, err)
+		return
+	}
+
+	if stat.IsDir() {
+		h.ServeStaticFile(c, path.Join(fullPath, "index.html"))
+		return
+	}
+
+	http.ServeContent(c.Writer, c.Request, stat.Name(), stat.ModTime(), file.(io.ReadSeeker))
+}
 
 func enableCachingForStaticFiles() gin.HandlerFunc {
 	return func(c *gin.Context) {