// simpleadmin-web is a web panel for CS2-SimpleAdmin: a public ban list, staff list and live
// scoreboard, and a staff panel for bans, gags and mutes, ranks and server settings.
package main

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"
	"time"
	_ "time/tzdata" // SimpleAdmin's Timezone must load even in a minimal container

	"github.com/go-sql-driver/mysql"

	"git.zio.sh/cs2/simpleadmin-web/internal/live"
	"git.zio.sh/cs2/simpleadmin-web/internal/rcon"
	"git.zio.sh/cs2/simpleadmin-web/internal/saconfig"
	"git.zio.sh/cs2/simpleadmin-web/internal/store"
	"git.zio.sh/cs2/simpleadmin-web/internal/web"
)

func env(key, def string) string {
	if v := strings.TrimSpace(os.Getenv(key)); v != "" {
		return v
	}
	return def
}

func envInt(key string, def int) (int, error) {
	v := env(key, "")
	if v == "" {
		return def, nil
	}
	n, err := strconv.Atoi(v)
	if err != nil {
		return 0, fmt.Errorf("%s must be a number", key)
	}
	return n, nil
}

func main() {
	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, nil)))
	if err := run(); err != nil {
		slog.Error("simpleadmin-web", "err", err)
		os.Exit(1)
	}
}

func run() error {
	baseURL := strings.TrimRight(env("SAW_BASE_URL", ""), "/")
	if baseURL == "" {
		return errors.New("set SAW_BASE_URL to the panel's public address, like https://bans.example.com")
	}
	secret := env("SAW_SESSION_SECRET", "")
	if len(secret) < 32 {
		return errors.New("set SAW_SESSION_SECRET to at least 32 random characters (e.g. openssl rand -hex 32)")
	}

	var sacfg *saconfig.File
	general := saconfig.General{Timezone: "UTC", MultiServerMode: true}
	if path := env("SAW_SA_CONFIG", ""); path != "" {
		sacfg = saconfig.Open(path)
		g, err := sacfg.General()
		if err != nil {
			return fmt.Errorf("SAW_SA_CONFIG: %w", err)
		}
		general = g
	}

	tzName := env("SAW_TIMEZONE", general.Timezone)
	loc, err := time.LoadLocation(tzName)
	if err != nil {
		return fmt.Errorf("timezone %q: %w", tzName, err)
	}

	db, err := openDB(sacfg)
	if err != nil {
		return err
	}
	defer db.Close()

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

	serverID, err := envInt("SAW_SERVER_ID", 0)
	if err != nil {
		return err
	}
	timeMode := 1
	maxBan, maxMute := 60*24*7, 60*24*7
	if sacfg != nil {
		if v, err := sacfg.Values(); err == nil {
			timeMode, maxBan, maxMute = v["TimeMode"].(int), v["MaxBanDuration"].(int), v["MaxMuteDuration"].(int)
		}
	}

	// Find this server in sa_servers. SimpleAdmin records its address and RCON password there.
	st := store.New(db, loc, 0, timeMode)
	servers, err := st.Servers(ctx)
	if err != nil {
		return fmt.Errorf("read sa_servers (is this SimpleAdmin's database?): %w", err)
	}
	var srv store.Server
	switch {
	case serverID > 0:
		for _, s := range servers {
			if s.ID == int64(serverID) {
				srv = s
			}
		}
		if srv.ID == 0 {
			return fmt.Errorf("SAW_SERVER_ID %d isn't in sa_servers", serverID)
		}
	case len(servers) == 1:
		srv = servers[0]
	case len(servers) == 0:
		slog.Warn("sa_servers is empty; SimpleAdmin hasn't registered the server yet")
	default:
		return errors.New("sa_servers lists several servers; set SAW_SERVER_ID to this server's id")
	}
	st = store.New(db, loc, srv.ID, timeMode)

	rconAddr := env("SAW_RCON_ADDR", srv.Address)
	rconPass := env("SAW_RCON_PASSWORD", srv.RconPassword)
	if rconAddr == "" || rconPass == "" {
		slog.Warn("no RCON address or password; live status and in-game actions are off. Set SAW_RCON_ADDR and SAW_RCON_PASSWORD.")
	}
	rc := rcon.New(rconAddr, rconPass)
	defer rc.Close()

	pollSecs, err := envInt("SAW_POLL_SECONDS", 5)
	if err != nil {
		return err
	}
	poller := live.NewPoller(rc, time.Duration(max(pollSecs, 2))*time.Second)
	go poller.Run(ctx)

	joinAddr := env("SAW_JOIN_ADDRESS", srv.Address)
	app, err := web.New(web.Config{
		BaseURL:         baseURL,
		SessionSecret:   []byte(secret),
		SiteFile:        env("SAW_SITE_CONFIG", ""),
		ServerAddress:   joinAddr,
		MaxBanDuration:  maxBan,
		MaxMuteDuration: maxMute,
	}, st, rc, poller, sacfg)
	if err != nil {
		return err
	}

	listen := env("SAW_LISTEN", ":8080")
	hs := &http.Server{
		Addr:              listen,
		Handler:           app.Handler(),
		ReadHeaderTimeout: 10 * time.Second,
		BaseContext:       func(net.Listener) context.Context { return ctx },
	}
	go func() {
		<-ctx.Done()
		shut, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		_ = hs.Shutdown(shut)
	}()
	slog.Info("listening", "addr", listen, "base", baseURL, "server", srv.ID, "rcon", rconAddr, "timezone", loc.String())
	if err := hs.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		return err
	}
	return nil
}

// openDB connects with SAW_DB_DSN, or with the DatabaseConfig in CS2-SimpleAdmin.json.
func openDB(sacfg *saconfig.File) (*sql.DB, error) {
	var cfg *mysql.Config
	if dsn := env("SAW_DB_DSN", ""); dsn != "" {
		c, err := mysql.ParseDSN(dsn)
		if err != nil {
			return nil, fmt.Errorf("SAW_DB_DSN: %w", err)
		}
		cfg = c
	} else if sacfg != nil {
		d, err := sacfg.Database()
		if err != nil {
			return nil, err
		}
		if !strings.EqualFold(d.Type, "mysql") {
			return nil, fmt.Errorf("SimpleAdmin uses %s; the panel only supports MySQL", d.Type)
		}
		cfg = mysql.NewConfig()
		cfg.User, cfg.Passwd, cfg.DBName = d.User, d.Password, d.Name
		cfg.Net, cfg.Addr = "tcp", net.JoinHostPort(d.Host, strconv.Itoa(d.Port))
		if h := env("SAW_DB_HOST", ""); h != "" {
			cfg.Addr = h
		}
	} else {
		return nil, errors.New("set SAW_DB_DSN, or SAW_SA_CONFIG to CS2-SimpleAdmin.json to use its database settings")
	}
	// Timestamps are SimpleAdmin's wall-clock values; the store interprets them in SimpleAdmin's
	// Timezone, so the driver must pass them through unconverted.
	cfg.ParseTime = true
	cfg.Loc = time.UTC
	db, err := sql.Open("mysql", cfg.FormatDSN())
	if err != nil {
		return nil, err
	}
	db.SetMaxOpenConns(10)
	db.SetConnMaxLifetime(5 * time.Minute)
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := db.PingContext(ctx); err != nil {
		return nil, fmt.Errorf("connect to the database at %s: %w", cfg.Addr, err)
	}
	return db, nil
}