package main

import (
	"crypto/rand"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"time"

	"p83.nl/go/websub-hub/cmd/hubserver/storage"
)

func init() {
	log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
}

const challengeBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

// randStringBytes is the hub's challenge. It comes from crypto/rand: a
// challenge a subscriber has to echo is a secret, and math/rand makes it
// predictable for anyone who observes a few of them.
func randStringBytes(n int) string {
	buf := make([]byte, n)
	if _, err := rand.Read(buf); err != nil {
		log.Fatalf("could not read random bytes: %v", err)
	}
	out := make([]byte, n)
	for i, b := range buf {
		out[i] = challengeBytes[int(b)%len(challengeBytes)]
	}
	return string(out)
}

type Stat struct {
	Updates    int
	LastUpdate time.Time
}

func main() {
	hostPort := flag.String("http", ":80", "host and port to listen on")
	baseURL := flag.String("baseurl", "", "baseurl that the server should response with")
	database := flag.String("database", "localhost:9999", "database host:port")
	dbUser := flag.String("database-user", envOr("HUB_DB_USER", "postgres"), "database user")
	dbPassword := flag.String("database-password", envOr("HUB_DB_PASSWORD", "simple"), "database password")
	flag.Parse()

	log.Printf("Using arguments http=%s baseurl=%s database=%s user=%s", *hostPort, *baseURL, *database, *dbUser)
	if os.Getenv("HUB_DB_PASSWORD") == "" {
		log.Printf("warning: HUB_DB_PASSWORD is unset, using the built-in default; set it in the deployment")
	}

	dsn := fmt.Sprintf("postgres://%s:%s@%s/?sslmode=disable", *dbUser, *dbPassword, *database)
	store, err := storage.New(dsn)
	if err != nil {
		log.Fatal(err)
	}
	defer store.Close()

	handler := &subscriptionHandler{
		store:   store,
		baseURL: *baseURL,
		// One client with a timeout: a topic or callback that hangs must not
		// hold the hub forever.
		client: &http.Client{Timeout: 30 * time.Second},
	}
	http.Handle("/", handler)
	log.Fatal(http.ListenAndServe(*hostPort, handler))
}

func envOr(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}