package daemon

import (
	"fmt"
	"os"
	"path/filepath"
	"runtime"

	"github.com/kardianos/service"
)

// program implements the kardianos/service.Interface for greywall daemon
// lifecycle management. It delegates actual work to the Server type.
type program struct {
	server        *Server
	socketPath    string
	tun2socksPath string
	debug         bool
}

// NewProgram creates a new program instance for use with kardianos/service.
func NewProgram(socketPath, tun2socksPath string, debug bool) *program {
	return &program{
		socketPath:    socketPath,
		tun2socksPath: tun2socksPath,
		debug:         debug,
	}
}

// Start is called by kardianos/service when the service starts. It verifies
// the tun2socks binary exists, creates and starts the Server. The accept loop
// already runs in a goroutine, so this returns immediately.
func (p *program) Start(_ service.Service) error {
	if _, err := os.Stat(p.tun2socksPath); err != nil {
		return fmt.Errorf("tun2socks binary not found at %s (run 'sudo greywall daemon install' first)", p.tun2socksPath)
	}

	Logf("Starting daemon (tun2socks=%s, socket=%s)", p.tun2socksPath, p.socketPath)

	p.server = NewServer(p.socketPath, p.tun2socksPath, p.debug)
	if err := p.server.Start(); err != nil {
		return fmt.Errorf("failed to start daemon server: %w", err)
	}

	Logf("Daemon started, listening on %s", p.socketPath)
	return nil
}

// Stop is called by kardianos/service when the service stops.
func (p *program) Stop(_ service.Service) error {
	if p.server == nil {
		return nil
	}

	Logf("Stopping daemon")
	if err := p.server.Stop(); err != nil {
		Logf("Shutdown error: %v", err)
		return err
	}

	Logf("Daemon stopped")
	return nil
}

// NewServiceConfig returns a kardianos/service config matching the existing
// LaunchDaemon setup. The Name matches LaunchDaemonLabel so service.Control()
// can find and manage the already-installed service.
func NewServiceConfig() *service.Config {
	return &service.Config{
		Name:        LaunchDaemonLabel,
		DisplayName: "Greywall Daemon",
		Description: "Greywall transparent network sandboxing daemon",
		Arguments:   []string{"daemon", "run"},
	}
}

// DefaultTun2socksPath returns the expected tun2socks binary path based on
// the install directory and current architecture.
func DefaultTun2socksPath() string {
	return filepath.Join(InstallLibDir, "tun2socks-darwin-"+runtime.GOARCH)
}