package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"runtime"

	"github.com/kr/pretty"
	"go.uber.org/atomic"
)

var (
	hits *atomic.Int64
)

func init() {
	hits = atomic.NewInt64(0)
}

func demoServerHandler(msg string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Route is go!")
		fmt.Fprintf(w, "%s\n", pretty.Sprintf("%s", r.Header))
		hn, _ := os.Hostname()
		fmt.Fprintf(w, "message: %s\n", msg)
		fmt.Fprintf(w, "Served by %s running %s\n", hn, runtime.GOOS)
		fmt.Fprintf(w, "Hit count: %d", hits.Inc())

		ip := r.Header.Get("X-Remote-Ip")
		if ip != "" {
			log.Printf("Hit from %s: %s", ip, r.RequestURI)
		}
	})
}

func demoServer(ctx context.Context, args []string) error {
	fs := flag.NewFlagSet("server", flag.ContinueOnError)

	addr := fs.String("addr", ":9090", "http address to listen on")
	msg := fs.String("msg", "now here's a little lesson in trickery...", "custom message to add to each page render")

	err := fs.Parse(args)
	if err != nil {
		return err
	}

	hs := &http.Server{
		Addr:    *addr,
		Handler: demoServerHandler(*msg),
	}

	go hs.ListenAndServe()

	log.Printf("listening on %s", *addr)

	for {
		select {
		case <-ctx.Done():
			sctx := context.Background()
			hs.Shutdown(sctx)

			return nil
		}
	}
}