// Package service manages the galahad2lcd systemd unit.
package service

import (
	"context"
	"fmt"
	"os/exec"
)

// Service represents the installed systemd unit.
type Service struct {
	name string
	// runCmd is the command constructor; overridable for tests.
	runCmd func(ctx context.Context, name string, arg ...string) *exec.Cmd
}

// New returns a Service wrapper for the given unit name.
func New(name string) *Service {
	return &Service{name: name, runCmd: exec.CommandContext}
}

// Restart tells systemd to restart the service. It fails early when the
// caller lacks privileges.
func (s *Service) Restart(ctx context.Context) error {
	cmd := s.runCmd(ctx, "systemctl", "restart", s.name)
	out, err := cmd.CombinedOutput()
	if err != nil {
		if len(out) > 0 {
			return fmt.Errorf("systemctl restart %s: %w (%s)", s.name, err, string(out))
		}
		return fmt.Errorf("systemctl restart %s: %w", s.name, err)
	}
	return nil
}