package main

import (
	"context"
	"embed"
	"flag"
	"html/template"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
)

//go:embed templates
var templatesFS embed.FS

func main() {
	listen  := flag.String("listen", ":8080", "HTTP listen address")
	target  := flag.String("target", "localhost:9091", "default gRPC endpoint (aggregator or collector)")
	n       := flag.Int("n", 25, "default number of table rows")
	refresh := flag.Int("refresh", 30, "meta-refresh interval in seconds (0 = disabled)")
	flag.Parse()

	funcMap := template.FuncMap{"fmtCount": fmtCount}
	tmpl := template.Must(
		template.New("").Funcs(funcMap).ParseFS(templatesFS, "templates/*.html"),
	)

	h := &Handler{
		defaultTarget: *target,
		defaultN:      *n,
		refreshSecs:   *refresh,
		tmpl:          tmpl,
	}

	srv := &http.Server{Addr: *listen, Handler: h}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	go func() {
		log.Printf("frontend: listening on %s (default target %s)", *listen, *target)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Printf("frontend: %v", err)
			os.Exit(1)
		}
	}()

	<-ctx.Done()
	log.Printf("frontend: shutting down")
	srv.Shutdown(context.Background())
}