package main

import (
	"context"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
	"github.com/gocraft/dbr/v2"
	"github.com/thanhpk/randstr"
	"io/ioutil"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"tiktak/db"
	"tiktak/keygen"
	"tiktak/server"
	"tiktak/server/auth"
	"tiktak/video"
	"time"
)

func main() {
	// Rotated DB password. Must stay in sync with MYSQL_ROOT_PASSWORD in
	// docker-compose.yml AND with the actual MySQL user (ALTER USER) when the
	// ./db_data volume already exists.
	conn, err := dbr.Open(
		"mysql",
		"root:cRazy_P4ssw0rd_MeOw_Me0W_676767676767@tcp(db:3306)/tiktak", nil)

	if err != nil {
		panic(err)
	}
	defer conn.Close()

	storage := db.New(conn)

	auth.SetSalt(randstr.Hex(20))

	// Videos that already existed when the HMAC keygen was deployed may still
	// be shared with a legacy token the checker is holding. Freeze that cutoff
	// on first boot and persist it, so a container restart cannot widen the
	// window (a wider window means more videos accepting forgeable tokens).
	keygen.SetLegacyCutoff(legacyCutoff(storage))
	config := server.Config{
		StaticFolder:    "public/static",
		VttFolder:       "public/vtt",
		TemplatesFolder: "templates",
	}
	srv := server.NewServer(storage, &video.Storage{Directory: "public/video"}, config)

	// Start server
	go func() {
		if err := http.ListenAndServe(":4000", srv); err != nil {
			fmt.Println("shutting down the server")
		}
	}()

	// Graceful shutdown
	quit := make(chan os.Signal)
	signal.Notify(quit, os.Interrupt)
	<-quit
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := srv.Shutdown(ctx); err != nil {
		panic(err)
	}
}

// legacyCutoffFile lives on the ./public volume so it survives restarts.
const legacyCutoffFile = "public/.legacy_cutoff"

func legacyCutoff(storage *db.Storage) int {
	if b, err := ioutil.ReadFile(legacyCutoffFile); err == nil {
		if n, err := strconv.Atoi(strings.TrimSpace(string(b))); err == nil {
			fmt.Println("legacy token cutoff (pinned):", n)
			return n
		}
	}

	id, err := storage.MaxVideoID(context.Background())
	if err != nil {
		// Fail closed: no legacy tokens rather than an unbounded window.
		fmt.Println("cannot read max video id, legacy tokens disabled:", err)
		return 0
	}
	if err := ioutil.WriteFile(legacyCutoffFile, []byte(strconv.FormatInt(id, 10)), 0644); err != nil {
		fmt.Println("cannot pin legacy cutoff:", err)
	}
	fmt.Println("legacy token cutoff (fresh):", id)
	return int(id)
}