Installable as an app (PWA): manifests, offline-only service worker, icons

internal/web/pwa.go

@@ -0,0 +1,71 @@
+package web
+
+import (
+	"encoding/json"
+	"io/fs"
+	"net/http"
+)
+
+// The site installs as an app (a PWA): a web app manifest, plus the service worker in
+// assets/sw.js. The public site and the staff panel are separate apps, so each opens on its own
+// page; both cover the whole site, since signing in goes through /auth.
+
+type manifest struct {
+	ID              string         `json:"id"`
+	Name            string         `json:"name"`
+	ShortName       string         `json:"short_name"`
+	Description     string         `json:"description"`
+	StartURL        string         `json:"start_url"`
+	Scope           string         `json:"scope"`
+	Display         string         `json:"display"`
+	BackgroundColor string         `json:"background_color"`
+	ThemeColor      string         `json:"theme_color"`
+	Icons           []manifestIcon `json:"icons"`
+}
+
+type manifestIcon struct {
+	Src     string `json:"src"`
+	Sizes   string `json:"sizes"`
+	Type    string `json:"type"`
+	Purpose string `json:"purpose,omitempty"`
+}
+
+func (s *Server) manifest(staff bool) http.HandlerFunc {
+	m := manifest{
+		ID:              "/",
+		Name:            s.site.Title,
+		ShortName:       s.site.Title,
+		Description:     "Live server, bans and staff.",
+		StartURL:        "/",
+		Scope:           "/",
+		Display:         "standalone",
+		BackgroundColor: "#14161b",
+		ThemeColor:      "#1b1e25",
+		Icons: []manifestIcon{
+			{Src: "/static/icon-192.png", Sizes: "192x192", Type: "image/png"},
+			{Src: "/static/icon-512.png", Sizes: "512x512", Type: "image/png"},
+			{Src: "/static/icon-maskable-512.png", Sizes: "512x512", Type: "image/png", Purpose: "maskable"},
+		},
+	}
+	if staff {
+		m.ID = "/admin"
+		m.Name = s.site.Title + " staff panel"
+		m.ShortName = s.site.Title + " staff"
+		m.Description = "Bans, mutes, ranks and the live server, for staff."
+		m.StartURL = "/admin"
+	}
+	body, _ := json.Marshal(m)
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/manifest+json")
+		w.Header().Set("Cache-Control", "no-cache")
+		w.Write(body)
+	}
+}
+
+// serviceWorker serves sw.js from the root, since a worker only controls pages under its own path.
+func serviceWorker(static fs.FS) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-cache")
+		http.ServeFileFS(w, r, static, "sw.js")
+	}
+}