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http.go
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package app
import (
"bytes"
"context"
"crypto/sha1"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"os"
"reflect"
"runtime"
"strconv"
"strings"
"sync"
"text/template"
"time"
"github.com/maxence-charriere/go-app/v9/pkg/errors"
)
const (
defaultThemeColor = "#2d2c2c"
defaultPreRenderCacheSize = 8000000
defaultPreRenderCacheTTL = time.Hour * 24
)
// Handler is an HTTP handler that serves an HTML page that loads a Go wasm app
// and its resources.
type Handler struct {
// The name of the web application as it is usually displayed to the user.
Name string
// The name of the web application displayed to the user when there is not
// enough space to display Name.
ShortName string
// The icon that is used for the PWA, favicon, loading and default not
// found component.
Icon Icon
// A placeholder background color for the application page to display before
// its stylesheets are loaded.
//
// DEFAULT: #2d2c2c.
BackgroundColor 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 text displayed while loading a page.
LoadingLabel string
// The page language.
//
// DEFAULT: en.
Lang string
// The page title.
Title string
// The page description.
Description string
// The page authors.
Author string
// The page keywords.
Keywords []string
// The path of the default image that is used by social networks when
// linking the app.
Image string
// 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 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 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
// Additional headers to be added in head element.
RawHeaders []string
// The page HTML element.
//
// Default: Html().
HTML func() HTMLHtml
// The page body element.
//
// Note that the lang attribute is always overridden by the Handler.Lang
// value.
//
// Default: Body().
Body func() HTMLBody
// The interval between each app auto-update while running in a web browser.
// Zero or negative values deactivates the auto-update mechanism.
//
// Default is 0.
AutoUpdateInterval time.Duration
// The environment variables that are passed to the progressive web app.
//
// Reserved keys:
// - GOAPP_VERSION
// - GOAPP_GOAPP_STATIC_RESOURCES_URL
Env Environment
// The URLs that are launched in the app tab or window.
//
// By default, URLs with a different domain are launched in another tab.
// Specifying internal URLs is to override that behavior. A good use case
// would be the URL for an OAuth authentication.
InternalURLs []string
// The cache that stores pre-rendered pages.
//
// Default: A LRU cache that keeps pages up to 24h and have a maximum size
// of 8MB.
PreRenderCache PreRenderCache
// 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
// 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("")
Resources ResourceProvider
// 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
pwaResources PreRenderCache
proxyResources map[string]ProxyResource
}
func (h *Handler) init() {
h.initVersion()
h.initStaticResources()
h.initImage()
h.initStyles()
h.initScripts()
h.initCacheableResources()
h.initIcon()
h.initPWA()
h.initPageContent()
h.initPreRenderedResources()
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("")
}
}
func (h *Handler) initImage() {
if h.Image != "" {
h.Image = h.resolveStaticPath(h.Image)
}
}
func (h *Handler) initStyles() {
for i, path := range h.Styles {
h.Styles[i] = h.resolveStaticPath(path)
}
}
func (h *Handler) initScripts() {
for i, path := range h.Scripts {
h.Scripts[i] = h.resolveStaticPath(path)
}
}
func (h *Handler) initCacheableResources() {
for i, path := range h.CacheableResources {
h.CacheableResources[i] = h.resolveStaticPath(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.resolveStaticPath(h.Icon.Default)
h.Icon.Large = h.resolveStaticPath(h.Icon.Large)
h.Icon.AppleTouch = h.resolveStaticPath(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.Lang == "" {
h.Lang = "en"
}
if h.LoadingLabel == "" {
h.LoadingLabel = "Loading"
}
}
func (h *Handler) initPageContent() {
if h.HTML == nil {
h.HTML = Html
}
if h.Body == nil {
h.Body = Body
}
}
func (h *Handler) initPreRenderedResources() {
h.pwaResources = newPreRenderCache(5)
ctx := context.TODO()
h.pwaResources.Set(ctx, PreRenderedItem{
Path: "/wasm_exec.js",
ContentType: "application/javascript",
Body: []byte(wasmExecJS),
})
h.pwaResources.Set(ctx, PreRenderedItem{
Path: "/app.js",
ContentType: "application/javascript",
Body: h.makeAppJS(),
})
h.pwaResources.Set(ctx, PreRenderedItem{
Path: "/app-worker.js",
ContentType: "application/javascript",
Body: h.makeAppWorkerJS(),
})
h.pwaResources.Set(ctx, PreRenderedItem{
Path: "/manifest.webmanifest",
ContentType: "application/manifest+json",
Body: h.makeManifestJSON(),
})
h.pwaResources.Set(ctx, PreRenderedItem{
Path: "/app.css",
ContentType: "text/css",
Body: []byte(appCSS),
})
if h.PreRenderCache == nil {
h.PreRenderCache = NewPreRenderLRUCache(
defaultPreRenderCacheSize,
defaultPreRenderCacheTTL,
)
}
}
func (h *Handler) makeAppJS() []byte {
if h.Env == nil {
h.Env = make(map[string]string)
}
internalURLs, _ := json.Marshal(h.InternalURLs)
h.Env["GOAPP_INTERNAL_URLS"] = string(internalURLs)
h.Env["GOAPP_VERSION"] = h.Version
h.Env["GOAPP_STATIC_RESOURCES_URL"] = h.Resources.Static()
h.Env["GOAPP_ROOT_PREFIX"] = h.Resources.Package()
for k, v := range h.Env {
if err := os.Setenv(k, v); err != nil {
Log(errors.New("setting app env variable failed").
Tag("name", k).
Tag("value", v).
Wrap(err))
}
}
env, err := json.Marshal(h.Env)
if err != nil {
panic(errors.New("encoding pwa env failed").
Tag("env", h.Env).
Wrap(err),
)
}
var b bytes.Buffer
if err := template.
Must(template.New("app.js").Parse(appJS)).
Execute(&b, struct {
Env string
Wasm string
WorkerJS string
AutoUpdateInterval int64
}{
Env: btos(env),
Wasm: h.Resources.AppWASM(),
WorkerJS: h.resolvePackagePath("/app-worker.js"),
AutoUpdateInterval: h.AutoUpdateInterval.Milliseconds(),
}); err != nil {
panic(errors.New("initializing app.js failed").Wrap(err))
}
return b.Bytes()
}
func (h *Handler) makeAppWorkerJS() []byte {
cacheableResources := map[string]struct{}{
h.resolvePackagePath("/app.css"): {},
h.resolvePackagePath("/app.js"): {},
h.resolvePackagePath("/manifest.webmanifest"): {},
h.resolvePackagePath("/wasm_exec.js"): {},
h.resolvePackagePath("/"): {},
h.Resources.AppWASM(): {},
}
cacheResources := func(res ...string) {
for _, r := range res {
if r == "" {
continue
}
cacheableResources[r] = struct{}{}
}
}
cacheResources(h.Icon.Default, h.Icon.Large, h.Icon.AppleTouch)
cacheResources(h.Styles...)
cacheResources(h.Scripts...)
cacheResources(h.CacheableResources...)
var b bytes.Buffer
if err := template.
Must(template.New("app-worker.js").Parse(appWorkerJS)).
Execute(&b, struct {
Version string
ResourcesToCache map[string]struct{}
}{
Version: h.Version,
ResourcesToCache: cacheableResources,
}); err != nil {
panic(errors.New("initializing app-worker.js failed").Wrap(err))
}
return b.Bytes()
}
func (h *Handler) makeManifestJSON() []byte {
normalize := func(s string) string {
if !strings.HasPrefix(s, "/") {
s = "/" + s
}
if !strings.HasSuffix(s, "/") {
s += "/"
}
return s
}
var b bytes.Buffer
if err := template.
Must(template.New("manifest.webmanifest").Parse(manifestJSON)).
Execute(&b, struct {
ShortName string
Name string
Description string
DefaultIcon string
LargeIcon string
BackgroundColor string
ThemeColor string
Scope string
StartURL string
}{
ShortName: h.ShortName,
Name: h.Name,
Description: h.Description,
DefaultIcon: h.Icon.Default,
LargeIcon: h.Icon.Large,
BackgroundColor: h.BackgroundColor,
ThemeColor: h.ThemeColor,
Scope: normalize(h.Resources.Package()),
StartURL: normalize(h.Resources.Package()),
}); err != nil {
panic(errors.New("initializing manifest.webmanifest failed").Wrap(err))
}
return b.Bytes()
}
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
}
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
fileHandler, isServingStaticResources := h.Resources.(http.Handler)
if isServingStaticResources && strings.HasPrefix(path, "/web/") {
fileHandler.ServeHTTP(w, r)
return
}
switch path {
case "/goapp.js":
path = "/app.js"
case "/manifest.json":
path = "/manifest.webmanifest"
case "/app.wasm", "/goapp.wasm":
if isServingStaticResources {
r2 := *r
r2.URL.Path = h.Resources.AppWASM()
fileHandler.ServeHTTP(w, &r2)
return
}
w.WriteHeader(http.StatusNotFound)
return
}
if res, ok := h.pwaResources.Get(r.Context(), path); ok {
h.servePreRenderedItem(w, res)
return
}
if res, ok := h.PreRenderCache.Get(r.Context(), path); ok {
h.servePreRenderedItem(w, res)
return
}
if proxyResource, ok := h.proxyResources[path]; ok {
h.serveProxyResource(proxyResource, w, r)
return
}
h.servePage(w, r)
}
func (h *Handler) servePreRenderedItem(w http.ResponseWriter, r PreRenderedItem) {
w.Header().Set("Content-Length", strconv.Itoa(r.Size()))
w.Header().Set("Content-Type", r.ContentType)
if r.ContentEncoding != "" {
w.Header().Set("Content-Encoding", r.ContentEncoding)
}
w.WriteHeader(http.StatusOK)
w.Write(r.Body)
}
func (h *Handler) serveProxyResource(resource ProxyResource, w http.ResponseWriter, r *http.Request) {
var u string
if _, ok := h.Resources.(http.Handler); ok {
u = "http://" + r.Host + resource.ResourcePath
} else {
u = h.Resources.Static() + resource.ResourcePath
}
res, err := http.Get(u)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
Log(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(errors.New("reading proxy static resource failed").
Tag("url", u).
Tag("proxy-path", resource.Path).
Tag("static-resource-path", resource.ResourcePath).
Wrap(err),
)
return
}
item := PreRenderedItem{
Path: resource.Path,
ContentType: res.Header.Get("Content-Type"),
ContentEncoding: res.Header.Get("Content-Encoding"),
Body: body,
}
h.PreRenderCache.Set(r.Context(), item)
h.servePreRenderedItem(w, item)
}
func (h *Handler) servePage(w http.ResponseWriter, r *http.Request) {
content, ok := routes.createComponent(r.URL.Path)
if !ok {
http.NotFound(w, r)
return
}
url := *r.URL
url.Host = r.Host
url.Scheme = "http"
var page requestPage
page.SetTitle(h.Title)
page.SetLang(h.Lang)
page.SetDescription(h.Description)
page.SetAuthor(h.Author)
page.SetKeywords(h.Keywords...)
page.SetLoadingLabel(h.LoadingLabel)
page.SetImage(h.Image)
page.url = &url
disp := engine{
Page: &page,
RunsInServer: true,
ResolveStaticResources: h.resolveStaticPath,
ActionHandlers: actionHandlers,
}
body := h.Body().privateBody(
Div().Body(
Aside().
ID("app-wasm-loader").
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").
Text(page.loadingLabel),
),
Div().ID("app-pre-render").Body(content),
),
)
if err := mount(&disp, body); err != nil {
panic(errors.New("mounting pre-rendering container failed").
Tag("server-side", disp.runsInServer()).
Tag("body-type", reflect.TypeOf(disp.Body)).
Wrap(err))
}
disp.Body = body
disp.init()
defer disp.Close()
disp.PreRender()
for len(disp.dispatches) != 0 {
disp.Consume()
disp.Wait()
}
var b bytes.Buffer
b.WriteString("<!DOCTYPE html>\n")
PrintHTML(&b, h.HTML().
Lang(page.Lang()).
privateBody(
Head().Body(
Meta().Charset("UTF-8"),
Meta().
HTTPEquiv("Content-Type").
Content("text/html; charset=utf-8"),
Meta().
Name("author").
Content(page.Author()),
Meta().
Name("description").
Content(page.Description()),
Meta().
Name("keywords").
Content(page.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"),
Meta().
Property("og:url").
Content(page.URL().String()),
Meta().
Property("og:title").
Content(page.Title()),
Meta().
Property("og:description").
Content(page.Description()),
Meta().
Property("og:type").
Content("website"),
Meta().
Property("og:image").
Content(page.Image()),
Title().Text(page.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.resolvePackagePath("/manifest.webmanifest")),
Link().
Type("text/css").
Rel("stylesheet").
Href(h.resolvePackagePath("/app.css")),
Script().
Defer(true).
Src(h.resolvePackagePath("/wasm_exec.js")),
Script().
Defer(true).
Src(h.resolvePackagePath("/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,
))
item := PreRenderedItem{
Path: page.URL().Path,
Body: b.Bytes(),
ContentType: "text/html",
}
h.PreRenderCache.Set(r.Context(), item)
h.servePreRenderedItem(w, item)
}
func (h *Handler) resolvePackagePath(path string) string {
var b strings.Builder
b.WriteByte('/')
appResources := strings.Trim(h.Resources.Package(), "/")
b.WriteString(appResources)
path = strings.Trim(path, "/")
if b.Len() != 1 && path != "" {
b.WriteByte('/')
}
b.WriteString(path)
return b.String()
}
func (h *Handler) resolveStaticPath(path string) string {
if isRemoteLocation(path) || !isStaticResourcePath(path) {
return path
}
var b strings.Builder
staticResources := strings.TrimSuffix(h.Resources.Static(), "/")
b.WriteString(staticResources)
path = strings.Trim(path, "/")
b.WriteByte('/')
b.WriteString(path)
return b.String()
}
// 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 {
return strings.HasPrefix(path, "https://") ||
strings.HasPrefix(path, "http://")
}
func isStaticResourcePath(path string) bool {
return strings.HasPrefix(path, "/web/") ||
strings.HasPrefix(path, "web/")
}
type httpResource struct {
Path string
ContentType string
Body []byte
ExpireAt time.Time
}
func (r httpResource) Len() int {
return len(r.Body)
}
func (r httpResource) IsExpired() bool {
return r.ExpireAt != time.Time{} && r.ExpireAt.Before(time.Now())
}