// Command rogue is the Go port of Rogue 5.4.4: Exploring the Dungeons of
// Doom. It is a faithful function-by-function port of the classic C game;
// see ARCHITECTURE.md at the repository root.
package main

import (
	"flag"
	"fmt"
	"os"
	"os/signal"
	"os/user"
	"strconv"
	"syscall"
	"time"

	"git.eeqj.de/sneak/rgoue/game"
	"git.eeqj.de/sneak/rgoue/term"
)

func main() {
	os.Exit(run())
}

// run carries the real main so that deferred terminal restoration runs
// before the process exits (os.Exit skips defers).
func run() int {
	scores := flag.Bool("s", false, "print the scoreboard and exit")
	deathDemo := flag.Bool("d", false, "die a random death (demo)")

	flag.Parse()

	cfg := loadConfig()

	if *scores {
		game.NewGame(cfg).ShowScores()

		return 0
	}

	t, err := term.New()
	if err != nil {
		fmt.Fprintln(os.Stderr, err)

		return 1
	}
	defer t.Fini()

	cfg.Term = t

	var g *game.RogueGame

	if args := flag.Args(); len(args) == 1 && !*deathDemo {
		// restore a saved game
		g, err = game.Restore(args[0], cfg)
		if err != nil {
			t.Fini()
			fmt.Fprintln(os.Stderr, err)

			return 1
		}
	} else {
		g = game.NewGame(cfg)
	}

	if *deathDemo {
		g.DeathDemo()

		return 0
	}

	installAutosave(g, t)

	runErr := g.Run()
	if runErr != nil {
		t.Fini()
		fmt.Fprintln(os.Stderr, runErr)

		return 1
	}

	return 0
}

// loadConfig gathers the game configuration from the environment: home
// directory, ROGUEOPTS, user name, wizard mode, and the dungeon seed
// (main.c's startup).
func loadConfig() game.Config {
	home, _ := os.UserHomeDir()

	name := ""

	u, userErr := user.Current()
	if userErr == nil {
		name = u.Username
	}

	wizard := os.Getenv("ROGUE_WIZARD") != ""

	return game.Config{
		Seed:      chooseSeed(wizard),
		Name:      name,
		RogueOpts: os.Getenv("ROGUEOPTS"),
		Home:      home,
		ScorePath: home + "/.rogue.scores",
		Wizard:    wizard,
	}
}

// installAutosave saves the game and exits on SIGHUP/SIGTERM (save.c
// auto_save).
func installAutosave(g *game.RogueGame, t *term.Tcell) {
	sig := make(chan os.Signal, 1)

	signal.Notify(sig, syscall.SIGHUP, syscall.SIGTERM)

	go func() {
		<-sig
		g.AutoSave()
		t.Fini()
		os.Exit(0)
	}()
}

// chooseSeed picks the dungeon number: SEED for reproducible dungeons
// (wizard mode, as in the C game), else time+pid (main.c).
func chooseSeed(wizard bool) int32 {
	if env := os.Getenv("SEED"); env != "" && wizard {
		n, err := strconv.ParseInt(env, 10, 32)
		if err == nil {
			return int32(n)
		}
	}

	// The C game computed `lowtime + getpid()` in int; the truncation to
	// 32 bits is the same wraparound the C int arithmetic performed.
	return int32(time.Now().Unix()&0x7fffffff) + //nolint:gosec // G115: deliberate wrap
		int32(os.Getpid()&0x7fffffff) //nolint:gosec // G115: deliberate wrap
}