mstar-webserver/main.go

package main

import (
	"context"
	"embed"
	"flag"
	"fmt"
	"html/template"
	"net/http"
	"os"
	"os/signal"
	"time"

	"git.mstar.dev/mstar/goutils/middleware"
	"git.mstar.dev/mstar/goutils/other"
	"github.com/rs/zerolog/hlog"
	"github.com/rs/zerolog/log"
)

const HTML_PREFIX = "<!-- "
const HTML_SUFFIX = " -->"

//go:embed templates
var embed_templates embed.FS

//go:embed static
var embed_static embed.FS

//go:embed well-known
var embed_well_known embed.FS

// go: embed robots.txt
var embed_robots_txt string

// go: embed humans.txt
var embed_humans_txt string

func main() {
	other.SetupFlags()
	portFlag := flag.String("port", "8080", "Set the port. Overwrites env vars")
	flag.Parse()
	other.ConfigureLoggingFromCliArgs()

	mux := http.NewServeMux()
	mux.HandleFunc("/{$}", handleRoot)
	// Catchall that just redirects to Hetzner's 10GB speedtest file
	// TODO: Maybe swap that for a forced zip bomb?
	mux.Handle(
		"/",
		http.RedirectHandler("https://hil-speed.hetzner.com/10GB.bin", http.StatusMovedPermanently),
	)

	mux.HandleFunc("/cat/awawawa", awawaStream)

	// static files in /static
	mux.Handle("/static/", http.FileServer(http.FS(embed_static)))

	// .well-known from /well-known
	mux.Handle(
		"/.well-known/",
		http.StripPrefix("/.well-known/", http.FileServer(http.FS(embed_well_known))),
	)

	// Static files not in /static or /.well-known
	mux.HandleFunc("/robots.txt", buildHTTPFileReader(embed_robots_txt))
	mux.HandleFunc("/humans.txt", buildHTTPFileReader(embed_humans_txt))

	server := http.Server{
		Addr:    ":" + *portFlag,
		Handler: middleware.ChainMiddlewares(mux, middleware.LoggingMiddleware),
	}
	exitChan := make(chan os.Signal, 1)
	signal.Notify(exitChan, os.Interrupt)
	go func() {
		log.Info().Str("addr", server.Addr).Msg("Starting server")
		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatal().Err(err).Msg("Server exited unexpectedly")
		}
	}()
	<-exitChan
	log.Info().Msg("Shutting down server due to Interrupt")
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
	defer cancel()
	err := server.Shutdown(ctx)
	if err != nil {
		log.Fatal().Err(err).Msg("Failed to cleanly shut down")
	}
	log.Info().Msg("Clean shutdown complete")
}

func handleRoot(w http.ResponseWriter, r *http.Request) {
	tmpl, err := template.ParseFS(embed_templates, "templates/index.html")
	if err != nil {
		http.Error(w, "Couldn't parse template file", http.StatusInternalServerError)
		return
	}
	err = tmpl.Execute(w, nil)
	if err != nil {
		http.Error(w, "Failed to execute template", http.StatusInternalServerError)
	}
}

func buildHTTPFileReader(embed_content string) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "%s", embed_content)
	}
}

func awawaStream(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/html")
	w.WriteHeader(206)
	w.Header().Set("Status", "206")
	genStub(
		1024,
		w,
	) // Hardcoded. Firefox & Chrome both have this value and a len of 0 wouldn't work
	hlog.FromRequest(r).Debug().Msg("Starting stream")
	i := true
	// Only run every 0.2 seconds, aka 5 times a second
	timer := time.Tick(time.Millisecond * 200)
	for {
		select {
		case <-r.Context().Done():
			hlog.FromRequest(r).Debug().Msg("Stream done")
			return
		case <-timer:
			if i {
				fmt.Fprint(w, "a")
			} else {
				fmt.Fprint(w, "w")
			}
			i = !i
		}
	}
}

func genStub(length int, w http.ResponseWriter) {
	PreSufLen := len(HTML_PREFIX) + len(HTML_SUFFIX)
	fmt.Fprint(w, HTML_PREFIX)
	for i := 0; i < length-PreSufLen; i++ {
		fmt.Fprint(w, '\u0020')
	}
	fmt.Fprint(w, HTML_SUFFIX)
}