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http.go
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// +build !wasm
package app
import (
"bytes"
"crypto/sha1"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"net/url"
"runtime"
"strconv"
"strings"
"sync"
"text/template"
"time"
"github.com/maxence-charriere/go-app/v7/pkg/errors"
)
const (
defaultThemeColor = "#2d2c2c"
)
// Handler is an HTTP handler that serves an HTML page that loads a Go wasm app
// and its resources.
type Handler struct {
// The page authors.
Author string
// A placeholder background color for the application page to display before
// its stylesheets are loaded.
//
// DEFAULT: #2d2c2c.
BackgroundColor string
// The path of the static resources that the browser is caching in order to
// provide offline mode.
//
// Note that Icon, Styles and Scripts are already cached by default.
//
// Paths are relative to the root directory.
CacheableResources []string
// The page description.
Description string
// The environment variables that are passed to the progressive web app.
//
// Reserved keys:
// - GOAPP_VERSION
// - GOAPP_GOAPP_STATIC_RESOURCES_URL
Env Environment
// The icon that is used for the PWA, favicon, loading and default not
// found component.
Icon Icon
// The page keywords.
Keywords []string
// The text displayed while loading a page.
LoadingLabel string
// The name of the web application as it is usually displayed to the user.
Name string
// The static resources that are accessible from custom paths. Files that
// are proxied by default are /robots.txt, /sitemap.xml and /ads.txt.
ProxyResources []ProxyResource
// Additional headers to be added in head element.
RawHeaders []string
// The paths or urls of the JavaScript files to use with the page.
//
// eg:
// app.Handler{
// Scripts: []string{
// "/web/test.js", // Static resource
// "https://foo.com/test.js", // External resource
// },
// },
Scripts []string
// The name of the web application displayed to the user when there is not
// enough space to display Name.
ShortName string
// The resource provider that provides static resources. Static resources
// are always accessed from a path that starts with "/web/".
//
// eg:
// "/web/main.css"
//
// Default: LocalDir("web")
Resources ResourceProvider
// The paths or urls of the CSS files to use with the page.
//
// eg:
// app.Handler{
// Styles: []string{
// "/web/test.css", // Static resource
// "https://foo.com/test.css", // External resource
// },
// },
Styles []string
// The theme color for the application. This affects how the OS displays the
// app (e.g., PWA title bar or Android's task switcher).
//
// DEFAULT: #2d2c2c.
ThemeColor string
// The page title.
Title string
// The version number. This is used in order to update the PWA application
// in the browser. It must be set when deployed on a live system in order to
// prevent recurring updates.
//
// Default: Auto-generated in order to trigger pwa update on a local
// development system.
Version string
once sync.Once
etag string
appWasmPath string
robotPath string
hasRemoteRootDir bool
page bytes.Buffer
manifestJSON bytes.Buffer
appJS bytes.Buffer
appWorkerJS bytes.Buffer
wasmExecJS []byte
appCSS []byte
proxyResourceMutex sync.RWMutex
proxyResources map[string]ProxyResource
proxyResourcesCache map[string]proxyResourceCache
}
func (h *Handler) init() {
h.initVersion()
h.initStaticResources()
h.initStyles()
h.initScripts()
h.initCacheableResources()
h.initIcon()
h.initPWA()
h.initPage()
h.initWasmJS()
h.initAppJS()
h.initWorkerJS()
h.initManifestJSON()
h.initScripts()
h.initAppCSS()
h.initProxyResources()
}
func (h *Handler) initVersion() {
if h.Version == "" {
t := time.Now().UTC().String()
h.Version = fmt.Sprintf(`%x`, sha1.Sum([]byte(t)))
}
h.etag = `"` + h.Version + `"`
}
func (h *Handler) initStaticResources() {
if h.Resources == nil {
h.Resources = LocalDir("web")
}
}
func (h *Handler) initStyles() {
for i, path := range h.Styles {
h.Styles[i] = h.staticResource(path)
}
}
func (h *Handler) initScripts() {
for i, path := range h.Scripts {
h.Scripts[i] = h.staticResource(path)
}
}
func (h *Handler) initCacheableResources() {
for i, path := range h.CacheableResources {
h.CacheableResources[i] = h.staticResource(path)
}
}
func (h *Handler) initIcon() {
if h.Icon.Default == "" {
h.Icon.Default = "https://storage.googleapis.com/murlok-github/icon-192.png"
h.Icon.Large = "https://storage.googleapis.com/murlok-github/icon-512.png"
}
if h.Icon.AppleTouch == "" {
h.Icon.AppleTouch = h.Icon.Default
}
h.Icon.Default = h.staticResource(h.Icon.Default)
h.Icon.Large = h.staticResource(h.Icon.Large)
h.Icon.AppleTouch = h.staticResource(h.Icon.AppleTouch)
}
func (h *Handler) initPWA() {
if h.Name == "" && h.ShortName == "" && h.Title == "" {
h.Name = "App PWA"
}
if h.ShortName == "" {
h.ShortName = h.Name
}
if h.Name == "" {
h.Name = h.ShortName
}
if h.BackgroundColor == "" {
h.BackgroundColor = defaultThemeColor
}
if h.ThemeColor == "" {
h.ThemeColor = defaultThemeColor
}
if h.LoadingLabel == "" {
h.LoadingLabel = "Loading"
}
}
func (h *Handler) initPage() {
h.page.WriteString("<!DOCTYPE html>\n")
html := Html().Body(
Head().Body(
Meta().Charset("UTF-8"),
Meta().
HTTPEquiv("Content-Type").
Content("text/html; charset=utf-8"),
Meta().
Name("author").
Content(h.Author),
Meta().
Name("description").
Content(h.Description),
Meta().
Name("keywords").
Content(strings.Join(h.Keywords, ", ")),
Meta().
Name("theme-color").
Content(h.ThemeColor),
Meta().
Name("viewport").
Content("width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0, viewport-fit=cover"),
Title().Text(h.Title),
Link().
Rel("icon").
Type("image/png").
Href(h.Icon.Default),
Link().
Rel("apple-touch-icon").
Href(h.Icon.AppleTouch),
Link().
Rel("manifest").
Href(h.appResource("/manifest.webmanifest")),
Link().
Type("text/css").
Rel("stylesheet").
Href(h.appResource("/app.css")),
Script().
Defer(true).
Src(h.appResource("/wasm_exec.js")),
Script().
Defer(true).
Src(h.appResource("/app.js")),
Range(h.Styles).Slice(func(i int) UI {
return Link().
Type("text/css").
Rel("stylesheet").
Href(h.Styles[i])
}),
Range(h.Scripts).Slice(func(i int) UI {
return Script().
Defer(true).
Src(h.Scripts[i])
}),
Range(h.RawHeaders).Slice(func(i int) UI {
return Raw(h.RawHeaders[i])
}),
),
Body().Body(
Div().
ID("app-wasm-layout").
Class("goapp-app-info").
Body(
Img().
ID("app-wasm-loader-icon").
Class("goapp-logo goapp-spin").
Src(h.Icon.Default),
P().
ID("app-wasm-loader-label").
Class("goapp-label").
Body(Text(h.LoadingLabel)),
),
Div().ID("app-context-menu"),
Div().ID("app-end"),
),
)
html.(writableNode).html(&h.page)
}
func (h *Handler) initWasmJS() {
h.wasmExecJS = []byte(wasmExecJS)
}
func (h *Handler) initAppJS() {
if h.Env == nil {
h.Env = make(map[string]string, 2)
}
h.Env["GOAPP_VERSION"] = h.Version
h.Env["GOAPP_STATIC_RESOURCES_URL"] = h.Resources.StaticResources()
h.Env["GOAPP_ROOT_PREFIX"] = h.Resources.AppResources()
env, err := json.Marshal(h.Env)
if err != nil {
panic(errors.New("encoding pwa env failed").
Tag("env", h.Env).
Wrap(err),
)
}
if err := template.
Must(template.New("app.js").Parse(appJS)).
Execute(&h.appJS, struct {
Env string
Wasm string
WorkerJS string
}{
Env: btos(env),
Wasm: h.Resources.AppWASM(),
WorkerJS: h.appResource("/app-worker.js"),
}); err != nil {
panic(errors.New("initializing app.js failed").Wrap(err))
}
}
func (h *Handler) initWorkerJS() {
cacheableResources := map[string]struct{}{
h.appResource("/app.css"): {},
h.appResource("/app.js"): {},
h.appResource("/manifest.webmanifest"): {},
h.appResource("/wasm_exec.js"): {},
h.appResource("/"): {},
h.Resources.AppWASM(): {},
h.Icon.Default: {},
h.Icon.Large: {},
h.Icon.AppleTouch: {},
}
cacheResources := func(res []string) {
for _, r := range res {
cacheableResources[r] = struct{}{}
}
}
cacheResources(h.Styles)
cacheResources(h.Scripts)
cacheResources(h.CacheableResources)
if err := template.
Must(template.New("app-worker.js").Parse(appWorkerJS)).
Execute(&h.appWorkerJS, struct {
Version string
ResourcesToCache map[string]struct{}
}{
Version: h.Version,
ResourcesToCache: cacheableResources,
}); err != nil {
panic(errors.New("initializing app-worker.js failed").Wrap(err))
}
}
func (h *Handler) initManifestJSON() {
normalize := func(s string) string {
if !strings.HasPrefix(s, "/") {
s = "/" + s
}
if !strings.HasSuffix(s, "/") {
s += "/"
}
return s
}
if err := template.
Must(template.New("manifest.webmanifest").Parse(manifestJSON)).
Execute(&h.manifestJSON, struct {
ShortName string
Name string
DefaultIcon string
LargeIcon string
BackgroundColor string
ThemeColor string
Scope string
StartURL string
}{
ShortName: h.ShortName,
Name: h.Name,
DefaultIcon: h.Icon.Default,
LargeIcon: h.Icon.Large,
BackgroundColor: h.BackgroundColor,
ThemeColor: h.ThemeColor,
Scope: normalize(h.Resources.AppResources()),
StartURL: normalize(h.Resources.AppResources()),
}); err != nil {
panic(errors.New("initializing manifest.webmanifest failed").Wrap(err))
}
}
func (h *Handler) initAppCSS() {
h.appCSS = stob(appCSS)
}
func (h *Handler) initProxyResources() {
resources := make(map[string]ProxyResource)
for _, r := range h.ProxyResources {
switch r.Path {
case "/wasm_exec.js",
"/goapp.js",
"/app.js",
"/app-worker.js",
"/manifest.json",
"/manifest.webmanifest",
"/app.css",
"/app.wasm",
"/goapp.wasm",
"/":
continue
default:
if strings.HasPrefix(r.Path, "/") && strings.HasPrefix(r.ResourcePath, "/web/") {
resources[r.Path] = r
}
}
}
if _, ok := resources["/robots.txt"]; !ok {
resources["/robots.txt"] = ProxyResource{
Path: "/robots.txt",
ResourcePath: "/web/robots.txt",
}
}
if _, ok := resources["/sitemap.xml"]; !ok {
resources["/sitemap.xml"] = ProxyResource{
Path: "/sitemap.xml",
ResourcePath: "/web/sitemap.xml",
}
}
if _, ok := resources["/ads.txt"]; !ok {
resources["/ads.txt"] = ProxyResource{
Path: "/ads.txt",
ResourcePath: "/web/ads.txt",
}
}
h.proxyResources = resources
h.proxyResourcesCache = make(map[string]proxyResourceCache, len(resources))
}
func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
h.once.Do(h.init)
w.Header().Set("Cache-Control", "no-cache")
w.Header().Set("ETag", h.etag)
etag := r.Header.Get("If-None-Match")
if etag == h.etag {
w.WriteHeader(http.StatusNotModified)
return
}
path := r.URL.Path
staticResourcesHandler, servesStaticResources := h.Resources.(http.Handler)
if servesStaticResources && strings.HasPrefix(path, "/web/") {
staticResourcesHandler.ServeHTTP(w, r)
return
}
switch path {
case "/wasm_exec.js":
h.serveWasmExecJS(w, r)
return
case "/app.js", "/goapp.js":
h.serveAppJS(w, r)
return
case "/app-worker.js":
h.serveAppWorkerJS(w, r)
return
case "/manifest.json", "/manifest.webmanifest":
h.serveManifestJSON(w, r)
return
case "/app.css":
h.serveAppCSS(w, r)
return
case "/app.wasm", "/goapp.wasm":
if servesStaticResources {
r2 := *r
r2.URL.Path = h.Resources.AppWASM()
staticResourcesHandler.ServeHTTP(w, &r2)
return
}
w.WriteHeader(http.StatusNotFound)
return
}
if proxyResource, ok := h.proxyResources[path]; ok {
h.serveProxyResource(proxyResource, w, r)
return
}
h.servePage(w, r)
}
func (h *Handler) servePage(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(h.page.Len()))
w.Header().Set("Content-Type", "text/html")
w.WriteHeader(http.StatusOK)
w.Write(h.page.Bytes())
}
func (h *Handler) serveWasmExecJS(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(len(h.wasmExecJS)))
w.Header().Set("Content-Type", "application/javascript")
w.WriteHeader(http.StatusOK)
w.Write(h.wasmExecJS)
}
func (h *Handler) serveAppJS(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(h.appJS.Len()))
w.Header().Set("Content-Type", "application/javascript")
w.WriteHeader(http.StatusOK)
w.Write(h.appJS.Bytes())
}
func (h *Handler) serveAppWorkerJS(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(h.appWorkerJS.Len()))
w.Header().Set("Content-Type", "application/javascript")
w.WriteHeader(http.StatusOK)
w.Write(h.appWorkerJS.Bytes())
}
func (h *Handler) serveManifestJSON(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(h.manifestJSON.Len()))
w.Header().Set("Content-Type", "application/manifest+json")
w.WriteHeader(http.StatusOK)
w.Write(h.manifestJSON.Bytes())
}
func (h *Handler) serveAppCSS(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Length", strconv.Itoa(len(h.appCSS)))
w.Header().Set("Content-Type", "text/css")
w.WriteHeader(http.StatusOK)
w.Write(h.appCSS)
}
func (h *Handler) serveProxyResource(resource ProxyResource, w http.ResponseWriter, r *http.Request) {
h.proxyResourceMutex.RLock()
pres, ok := h.proxyResourcesCache[resource.Path]
h.proxyResourceMutex.RUnlock()
if !ok {
var u string
if _, ok := h.Resources.(http.Handler); ok {
u = "http://" + r.Host + resource.ResourcePath
} else {
u = h.Resources.StaticResources() + resource.ResourcePath
}
res, err := http.Get(u)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
Log("%s", errors.New("getting proxy static resource failed").
Tag("url", u).
Tag("proxy-path", resource.Path).
Tag("static-resource-path", resource.ResourcePath).
Wrap(err),
)
return
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
w.WriteHeader(http.StatusNotFound)
return
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
Log("%s", errors.New("reading proxy static resource failed").
Tag("url", u).
Tag("proxy-path", resource.Path).
Tag("static-resource-path", resource.ResourcePath).
Wrap(err),
)
return
}
pres.Body = body
pres.ContentType = res.Header.Get("Content-Type")
h.proxyResourceMutex.Lock()
h.proxyResourcesCache[resource.Path] = pres
h.proxyResourceMutex.Unlock()
}
w.Header().Set("Content-Length", strconv.Itoa(len(pres.Body)))
w.Header().Set("Content-Type", pres.ContentType)
w.WriteHeader(http.StatusOK)
w.Write(pres.Body)
}
func (h *Handler) appResource(path string) string {
if !strings.HasPrefix(path, "/") {
path = "/" + path
}
path = h.Resources.AppResources() + path
if !strings.HasPrefix(path, "/") {
path = "/" + path
}
if path != "/" && strings.HasSuffix(path, "/") {
path = strings.TrimSuffix(path, "/")
}
return path
}
func (h *Handler) staticResource(path string) string {
if isRemoteLocation(path) {
return path
}
if !strings.HasPrefix(path, "/") {
path = "/" + path
}
return h.Resources.StaticResources() + path
}
// Icon describes a square image that is used in various places such as
// application icon, favicon or loading icon.
type Icon struct {
// The path or url to a square image/png file. It must have a side of 192px.
//
// Path is relative to the root directory.
Default string
// The path or url to larger square image/png file. It must have a side of
// 512px.
//
// Path is relative to the root directory.
Large string
// The path or url to a square image/png file that is used for IOS/IPadOS
// home screen icon. It must have a side of 192px.
//
// Path is relative to the root directory.
//
// DEFAULT: Icon.Default
AppleTouch string
}
// Environment describes the environment variables to pass to the progressive
// web app.
type Environment map[string]string
func normalizeFilePath(path string) string {
if runtime.GOOS == "windows" {
return strings.ReplaceAll(path, "/", `\`)
}
return path
}
func isRemoteLocation(path string) bool {
u, _ := url.Parse(path)
return u.Scheme != ""
}
type proxyResourceCache struct {
Body []byte
ContentType string
}