package server

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/hachem-wtf/benson/internal/config"
)

const (
	stopTimeout = 60 * time.Second
	pingTimeout = 2 * time.Second
)

type Status struct {
	Running    bool
	PID        int
	Reachable  bool
	Version    string
	MOTD       string
	Players    int
	MaxPlayers int
	Address    string
}

func pidPath(cfg *config.Config) string {
	return filepath.Join(cfg.ServerLocation, "benson-server.pid")
}

func LogPath(cfg *config.Config) string {
	return filepath.Join(cfg.ServerLocation, "benson-server.log")
}

func javaCmd(cfg *config.Config) string {
	if cfg.JavaPath != "" {
		return cfg.JavaPath
	}
	return "java"
}

func readPID(cfg *config.Config) (int, bool) {
	data, err := os.ReadFile(pidPath(cfg))
	if err != nil {
		return 0, false
	}
	pid, err := strconv.Atoi(strings.TrimSpace(string(data)))
	if err != nil {
		return 0, false
	}
	return pid, true
}

func Running(cfg *config.Config) (int, bool) {
	pid, ok := readPID(cfg)
	if !ok {
		return 0, false
	}
	if !isAlive(pid) {
		os.Remove(pidPath(cfg))
		return 0, false
	}
	return pid, true
}

func Start(cfg *config.Config) (int, error) {
	if cfg.ServerLocation == "" {
		return 0, errors.New("server_location must be set in config")
	}
	if pid, ok := Running(cfg); ok {
		return 0, fmt.Errorf("server already running (pid %d)", pid)
	}

	jar := filepath.Join(cfg.ServerLocation, "server.jar")
	if _, err := os.Stat(jar); err != nil {
		return 0, errors.New("no server.jar in server_location — run generate and merge first")
	}

	eula := filepath.Join(cfg.ServerLocation, "eula.txt")
	if _, err := os.Stat(eula); os.IsNotExist(err) {
		if err := os.WriteFile(eula, []byte("eula=true\n"), 0o644); err != nil {
			return 0, err
		}
	}

	logFile, err := os.Create(LogPath(cfg))
	if err != nil {
		return 0, err
	}
	defer logFile.Close()

	cmd := exec.Command(javaCmd(cfg), "-jar", "server.jar", "nogui")
	cmd.Dir = cfg.ServerLocation
	cmd.Stdout = logFile
	cmd.Stderr = logFile
	cmd.SysProcAttr = detachAttr()

	if err := cmd.Start(); err != nil {
		return 0, err
	}

	pid := cmd.Process.Pid
	if err := os.WriteFile(pidPath(cfg), []byte(strconv.Itoa(pid)+"\n"), 0o644); err != nil {
		return pid, err
	}
	go cmd.Wait()
	return pid, nil
}

func Stop(cfg *config.Config, progress func(string)) error {
	pid, ok := Running(cfg)
	if !ok {
		return errors.New("server is not running")
	}

	progress(fmt.Sprintf("Sending stop signal to pid %d…", pid))
	if err := signalStop(pid); err != nil {
		return err
	}

	progress("Waiting for the server to save and shut down…")
	deadline := time.Now().Add(stopTimeout)
	for time.Now().Before(deadline) {
		if !isAlive(pid) {
			os.Remove(pidPath(cfg))
			return nil
		}
		time.Sleep(500 * time.Millisecond)
	}

	progress("Timed out — forcing shutdown…")
	forceKill(pid)
	os.Remove(pidPath(cfg))
	return nil
}

func Restart(cfg *config.Config, progress func(string)) error {
	if _, ok := Running(cfg); ok {
		if err := Stop(cfg, progress); err != nil {
			return err
		}
		time.Sleep(1 * time.Second)
	}

	pid, err := Start(cfg)
	if err != nil {
		return err
	}
	progress(fmt.Sprintf("Server started (pid %d).", pid))
	return nil
}

func GetStatus(cfg *config.Config) Status {
	pid, running := Running(cfg)
	port := serverPort(cfg)

	s := Status{
		Running: running,
		PID:     pid,
		Address: fmt.Sprintf("localhost:%d", port),
	}

	if ping, err := pingServer("localhost", port, pingTimeout); err == nil {
		s.Reachable = true
		s.Version = ping.Version.Name
		s.Players = ping.Players.Online
		s.MaxPlayers = ping.Players.Max
		s.MOTD = ping.motdText()
	}
	return s
}

func serverPort(cfg *config.Config) int {
	f, err := os.Open(filepath.Join(cfg.ServerLocation, "server.properties"))
	if err != nil {
		return 25565
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if value, ok := strings.CutPrefix(line, "server-port="); ok {
			if port, err := strconv.Atoi(strings.TrimSpace(value)); err == nil {
				return port
			}
		}
	}
	return 25565
}