camper/pkg/app/app.go

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Add the skeleton of the web application It does nothing more than to server a single page that does nothing interesting. This time i do not use a router. Instead, i am trying out a technique i have seen in an article[0] that i have tried in other, smaller, projects and seems to work surprisingly well: it just “cuts off” the URI path by path, passing the request from handler to handler until it finds its way to a handler that actually serves the request. That helps to loosen the coupling between the application and lower handlers, and makes dependencies explicit, because i need to pass the locale, company, etc. down instead of storing them in contexts. Let’s see if i do not regret it on a later date. I also made a lot more packages that in Numerus. In Numerus i actually only have the single pkg package, and it works, kind of, but i notice how i name my methods to avoid clashing instead of using packages for that. That is, instead of pkg.NewApp i now have app.New. Initially i thought that Locale should be inside app, but then there was a circular dependency between app and template. That is why i created a separate package, but now i am wondering if template should be inside app too, but then i would have app.MustRenderTemplate instead of template.MustRender. The CSS is the most bare-bones file i could write because i am focusing in markup right now; Oriol will fill in the file once the application is working. [0]: https://blog.merovius.de/posts/2017-06-18-how-not-to-use-an-http-router/
2023-07-22 22:11:00 +00:00
/*
* SPDX-FileCopyrightText: 2023 jordi fita mas <jfita@peritasoft.com>
* SPDX-License-Identifier: AGPL-3.0-only
*/
package app
import (
"net/http"
"path"
"strings"
"golang.org/x/text/language"
"dev.tandem.ws/tandem/camper/pkg/database"
middleware "dev.tandem.ws/tandem/camper/pkg/http"
"dev.tandem.ws/tandem/camper/pkg/locale"
"dev.tandem.ws/tandem/camper/pkg/template"
)
func shiftPath(p string) (head, tail string) {
p = path.Clean("/" + p)
if i := strings.IndexByte(p[1:], '/') + 1; i <= 0 {
return p[1:], "/"
} else {
return p[1:i], p[i:]
}
}
func methodNotAllowed(w http.ResponseWriter, _ *http.Request, allowed ...string) {
w.Header().Set("Allow", strings.Join(allowed, ", "))
http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
}
type App struct {
db *database.DB
fileHandler http.Handler
locales locale.Locales
defaultLocale *locale.Locale
languageMatcher language.Matcher
}
func New(db *database.DB) http.Handler {
locales := locale.MustGetAll(db)
app := &App{
db: db,
fileHandler: http.FileServer(http.Dir("web/static")),
locales: locales,
defaultLocale: locales[language.Catalan],
languageMatcher: language.NewMatcher(locales.Tags()),
}
var handler http.Handler = app
handler = middleware.RecoverPanic(handler)
handler = middleware.LogRequest(handler)
return handler
}
func (h *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {
var head string
head, r.URL.Path = shiftPath(r.URL.Path)
switch head {
case "static":
h.fileHandler.ServeHTTP(w, r)
case "":
switch r.Method {
case http.MethodGet:
h.handleGet(w, r)
default:
methodNotAllowed(w, r, http.MethodGet)
}
default:
http.NotFound(w, r)
}
}
func (h *App) handleGet(w http.ResponseWriter, r *http.Request) {
l := locale.Match(r, h.locales, h.defaultLocale, h.languageMatcher)
template.MustRender(w, l, "login.gohtml", nil)
}