add: control flow

1 files changed, 196 insertions, 0 deletions

diff --git a/internal/server/server.go b/internal/server/server.go
new file mode 100644
index 0000000..8e2019d
--- /dev/null
+++ b/internal/server/server.go
@@ -0,0 +1,196 @@
+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
+}