package web

import (
	"encoding/json"
	"io/fs"
	"net/http"
	"strings"
)

// 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)
	}
}

// assetLinks tells Chrome the Android app belongs to this site, so it opens the site full screen
// (a Trusted Web Activity) instead of with its URL bar showing.
func (s *Server) assetLinks(w http.ResponseWriter, r *http.Request) {
	var certs []string
	for _, c := range s.cfg.AndroidCerts {
		if c = strings.ToUpper(strings.TrimSpace(c)); c != "" {
			certs = append(certs, c)
		}
	}
	if s.cfg.AndroidPackage == "" || len(certs) == 0 {
		http.NotFound(w, r)
		return
	}
	type target struct {
		Namespace    string   `json:"namespace"`
		PackageName  string   `json:"package_name"`
		Fingerprints []string `json:"sha256_cert_fingerprints"`
	}
	type statement struct {
		Relation []string `json:"relation"`
		Target   target   `json:"target"`
	}
	writeJSON(w, http.StatusOK, []statement{{
		Relation: []string{"delegate_permission/common.handle_all_urls"},
		Target:   target{Namespace: "android_app", PackageName: s.cfg.AndroidPackage, Fingerprints: certs},
	}})
}

// 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")
	}
}