1// SPDX-License-Identifier: AGPL-3.0-or-later
2
3package web
4
5import (
6 "crypto/sha256"
7 "embed"
8 "encoding/hex"
9 "encoding/json"
10 "errors"
11 "io/fs"
12 "net/http"
13 "path"
14 "sort"
15 "strings"
16)
17
18//go:embed static
19var staticFS embed.FS
20
21// StaticPrefix is where the embedded assets are served.
22const StaticPrefix = "/-/static/"
23
24// Assets are the URLs of the assets a page loads. Their names carry a hash of
25// the content, so they can be cached for ever.
26type Assets struct {
27 CSS, HTMX, Live, SSE, Store, App, Files, Passkey, Log, MR, Icon string
28 // Manifest is the web app manifest (install on a phone's home screen),
29 // AppleIcon the home screen icon iOS reads from a link instead.
30 Manifest, AppleIcon string
31 // Font is the UI font, preloaded by every page.
32 Font string
33 // Rules is the speculation rules file named by the Speculation-Rules header.
34 Rules string
35}
36
37// asset is one embedded file under its content-hashed name.
38type asset struct {
39 body []byte
40 typ string
41 // gz is the gzip form of body, compressed once at load; nil when the type
42 // is already compressed or gzip does not make the body smaller.
43 gz []byte
44}
45
46// assetSet is the embedded files by hashed URL path (under StaticPrefix).
47type assetSet struct {
48 byName map[string]asset
49 urls Assets
50 sw serviceWorker
51}
52
53// scripts are the JavaScript files of the page, in embedded static/js: the
54// file to serve, as it is named in Assets.
55var scripts = []struct {
56 file string
57 set func(*Assets, string)
58}{
59 {"htmx.min.js", func(a *Assets, u string) { a.HTMX = u }},
60 {"hx-live.min.js", func(a *Assets, u string) { a.Live = u }},
61 {"hx-sse.min.js", func(a *Assets, u string) { a.SSE = u }},
62 {"store.js", func(a *Assets, u string) { a.Store = u }},
63 {"ermite.js", func(a *Assets, u string) { a.App = u }},
64 {"files.js", func(a *Assets, u string) { a.Files = u }},
65 {"passkey.js", func(a *Assets, u string) { a.Passkey = u }},
66 {"log.js", func(a *Assets, u string) { a.Log = u }},
67 {"mr.js", func(a *Assets, u string) { a.MR = u }},
68}
69
70// sheetAssets are the files the stylesheet references as url(<dir>/<file>):
71// fonts and icons (pages hold no inline SVG; icons are CSS masks).
72var sheetAssets = []struct{ glob, typ string }{
73 {"static/fonts/*.woff2", "font/woff2"},
74 {"static/icons/*.svg", "image/svg+xml"},
75}
76
77// loadAssets hashes the embedded files. The stylesheet is the concatenation
78// of static/css/*.css in name order; its url(<dir>/<file>) references become
79// the hashed URLs of the files of sheetAssets.
80func loadAssets() (*assetSet, error) {
81 s := &assetSet{byName: map[string]asset{}}
82 put := func(dir, file string, body []byte, typ string) string {
83 sum := sha256.Sum256(body)
84 ext := path.Ext(file)
85 name := dir + "/" + strings.TrimSuffix(file, ext) + "." + hex.EncodeToString(sum[:6]) + ext
86 a := asset{body: body, typ: typ}
87 if compressible(typ) {
88 if z, err := gzipBest(body); err == nil && len(z) < len(body) {
89 a.gz = z
90 }
91 }
92 s.byName[name] = a
93 return StaticPrefix + name
94 }
95
96 var refs []string
97 for _, sa := range sheetAssets {
98 files, err := fs.Glob(staticFS, sa.glob)
99 if err != nil {
100 return nil, err
101 }
102 for _, f := range files {
103 b, err := staticFS.ReadFile(f)
104 if err != nil {
105 return nil, err
106 }
107 dir := path.Base(path.Dir(f))
108 u := put(dir, path.Base(f), b, sa.typ)
109 refs = append(refs, "url("+dir+"/"+path.Base(f)+")", "url("+u+")")
110 if f == "static/fonts/atkinson-next.woff2" {
111 s.urls.Font = u
112 }
113 }
114 }
115
116 files, err := fs.Glob(staticFS, "static/css/*.css")
117 if err != nil {
118 return nil, err
119 }
120 sort.Strings(files)
121 var css strings.Builder
122 for _, f := range files {
123 b, err := staticFS.ReadFile(f)
124 if err != nil {
125 return nil, err
126 }
127 css.WriteString("/* " + path.Base(f) + " */\n")
128 css.Write(b)
129 }
130 if s.urls.Font == "" {
131 return nil, errors.New("web: the UI font static/fonts/atkinson-next.woff2 is missing")
132 }
133 sheet := strings.NewReplacer(refs...).Replace(css.String())
134 s.urls.CSS = put("css", "ermite.css", []byte(sheet), "text/css; charset=utf-8")
135
136 rules, err := staticFS.ReadFile("static/rules.json")
137 if err != nil {
138 return nil, err
139 }
140 s.urls.Rules = put("rules", "rules.json", rules, "application/speculationrules+json")
141
142 for _, sc := range scripts {
143 b, err := staticFS.ReadFile("static/js/" + sc.file)
144 if err != nil {
145 return nil, err
146 }
147 sc.set(&s.urls, put("js", sc.file, b, "text/javascript; charset=utf-8"))
148 }
149
150 // The favicon is the brand picture of the header.
151 icon, err := staticFS.ReadFile("static/icons/brand.svg")
152 if err != nil {
153 return nil, err
154 }
155 s.urls.Icon = put("img", "icon.svg", icon, "image/svg+xml")
156
157 if err := s.loadApp(put); err != nil {
158 return nil, err
159 }
160 sw, err := loadServiceWorker()
161 if err != nil {
162 return nil, err
163 }
164 s.sw = sw
165 return s, nil
166}
167
168// appIcons are the PNG icons of the installed app (static/app), in the
169// manifest; purpose "maskable" has the picture inside the safe zone on a
170// full-bleed background, for launchers that crop to a circle or a squircle.
171var appIcons = []struct{ file, sizes, purpose string }{
172 {"icon-192.png", "192x192", "any"},
173 {"icon-512.png", "512x512", "any"},
174 {"icon-maskable-512.png", "512x512", "maskable"},
175}
176
177// webManifest is the shape of the web app manifest: what a browser asks for to
178// offer "install" / "add to home screen", and the id and description of the
179// richer install dialog.
180type webManifest struct {
181 // ID is the identity of the app, independent of the (hashed) URL of the
182 // manifest and of start_url.
183 ID string `json:"id"`
184 Name string `json:"name"`
185 ShortName string `json:"short_name"`
186 Description string `json:"description"`
187 StartURL string `json:"start_url"`
188 Scope string `json:"scope"`
189 Display string `json:"display"`
190 BackgroundColor string `json:"background_color"`
191 ThemeColor string `json:"theme_color"`
192 Icons []manifestIcon `json:"icons"`
193}
194
195type manifestIcon struct {
196 Src string `json:"src"`
197 Sizes string `json:"sizes"`
198 Type string `json:"type"`
199 Purpose string `json:"purpose"`
200}
201
202// appColor is the dark canvas: the splash screen and the bar of the installed
203// app (the pages follow the system theme; the manifest takes one colour).
204const appColor = "#050505"
205
206// loadApp adds the app icons and the manifest, which names them by their
207// hashed URLs.
208func (s *assetSet) loadApp(put func(dir, name string, b []byte, typ string) string) error {
209 m := webManifest{
210 ID: "/", Name: "ermite", ShortName: "ermite", StartURL: "/", Scope: "/", Display: "standalone",
211 Description: "Self-hosted Git forge: browse code, review merge requests and follow CI.",
212 BackgroundColor: appColor, ThemeColor: appColor,
213 }
214 for _, ic := range appIcons {
215 b, err := staticFS.ReadFile("static/app/" + ic.file)
216 if err != nil {
217 return err
218 }
219 m.Icons = append(m.Icons, manifestIcon{Src: put("app", ic.file, b, "image/png"), Sizes: ic.sizes, Type: "image/png", Purpose: ic.purpose})
220 }
221 apple, err := staticFS.ReadFile("static/app/apple-touch-icon.png")
222 if err != nil {
223 return err
224 }
225 s.urls.AppleIcon = put("app", "apple-touch-icon.png", apple, "image/png")
226 b, err := json.Marshal(m)
227 if err != nil {
228 return err
229 }
230 s.urls.Manifest = put("app", "manifest.webmanifest", b, "application/manifest+json")
231 return nil
232}
233
234// serve answers GET /-/static/<hashed name>. A name that does not match a
235// current asset is a 404, so a stale hash never serves the wrong content.
236func (s *assetSet) serve(w http.ResponseWriter, r *http.Request) {
237 a, ok := s.byName[strings.TrimPrefix(r.URL.Path, StaticPrefix)]
238 if !ok {
239 http.NotFound(w, r)
240 return
241 }
242 h := w.Header()
243 h.Set("Content-Type", a.typ)
244 h.Set("Cache-Control", "public, max-age=31536000, immutable")
245 body := a.body
246 if a.gz != nil {
247 addVary(h, "Accept-Encoding")
248 if acceptsGzip(r.Header) {
249 body = a.gz
250 h.Set("Content-Encoding", "gzip")
251 }
252 }
253 h.Set("Content-Length", itoa(len(body)))
254 if r.Method != http.MethodHead {
255 _, _ = w.Write(body)
256 }
257}
258
259// compressible tells whether a content type is worth gzip: text and
260// structured text. Fonts (woff2) and raster images are compressed already.
261func compressible(typ string) bool {
262 mt, _, _ := strings.Cut(typ, ";")
263 mt = strings.TrimSpace(strings.ToLower(mt))
264 return strings.HasPrefix(mt, "text/") || mt == "image/svg+xml" ||
265 mt == "application/javascript" || strings.HasSuffix(mt, "+json") || strings.HasSuffix(mt, "/json")
266}