add a bunch of frontend stuff

web/app/template.go

@@ -0,0 +1,52 @@
+package app
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/flosch/pongo2/v6"
+)
+
+func (app *App) Template(w http.ResponseWriter, r *http.Request, tmplName string, ctx pongo2.Context) error {
+	tmpl, err := app.tmpl.FromCache(tmplName)
+	if err != nil {
+		return err
+	}
+
+	tctx := pongo2.Context{
+		"flash_message": app.getFlash(w, r),
+	}
+	tctx.Update(ctx)
+
+	w.Header().Set("Content-Type", "text/html")
+	return tmpl.ExecuteWriter(tctx, w)
+}
+
+const flashCookieName = "mercury-flash-message"
+
+func (app *App) Flash(w http.ResponseWriter, msg string) {
+	http.SetCookie(w, &http.Cookie{
+		Name:     flashCookieName,
+		Value:    msg,
+		Path:     "/",
+		HttpOnly: true,
+		Expires:  time.Now().Add(time.Minute),
+	})
+}
+
+func (app *App) getFlash(w http.ResponseWriter, r *http.Request) string {
+	cookie, err := r.Cookie(flashCookieName)
+	if err != nil {
+		return ""
+	}
+
+	defer http.SetCookie(w, &http.Cookie{
+		Name:     flashCookieName,
+		Value:    "",
+		Path:     "/",
+		HttpOnly: true,
+		Expires:  time.Now(),
+	})
+
+	return cookie.Value
+}