feat: add version subcommand to help with issues (#400)

cmd/cameradar/main.go

@@ -121,11 +121,25 @@ func realMain() (code int) {
 		}
 	}()
 
+	scanCommand := &cli.Command{
+		Name:   "scan",
+		Usage:  "Scan targets for RTSP streams",
+		Flags:  flags,
+		Action: runCameradar,
+	}
+
 	app := &cli.Command{
-		Name:    "Cameradar",
-		Version: version,
-		Flags:   flags,
-		Action:  runCameradar,
+		Name:           "Cameradar",
+		Version:        version,
+		DefaultCommand: scanCommand.Name,
+		Commands: []*cli.Command{
+			scanCommand,
+			{
+				Name:   "version",
+				Usage:  "Print version information",
+				Action: printVersion,
+			},
+		},
 	}
 
 	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)

cmd/cameradar/version.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/Ullaakut/cameradar/v6/internal/ui"
+	"github.com/urfave/cli/v3"
+)
+
+func printVersion(ctx context.Context, _ *cli.Command) error {
+	buildInfo := ui.BuildInfo{Version: version, Commit: commit, Date: date}
+	nmapVersion := getNmapVersion(ctx)
+	_, err := fmt.Fprintf(
+		os.Stdout,
+		"Version:\t%s\nCommit:\t\t%s\nBuild date:\t%s\nNmap:\t\t%s\n",
+		buildInfo.DisplayVersion(),
+		buildInfo.ShortCommit(),
+		buildInfo.Date,
+		nmapVersion,
+	)
+	return err
+}
+
+const unknownVersion = "unknown"
+
+func getNmapVersion(ctx context.Context) string {
+	output, err := exec.CommandContext(ctx, "nmap", "--version").Output()
+	if err != nil {
+		return unknownVersion
+	}
+
+	lines := strings.SplitN(string(output), "\n", 2)
+	firstLine := strings.TrimSpace(lines[0])
+	const prefix = "Nmap version "
+	if !strings.HasPrefix(firstLine, prefix) {
+		return unknownVersion
+	}
+
+	versionPart := strings.TrimSpace(strings.TrimPrefix(firstLine, prefix))
+	fields := strings.Fields(versionPart)
+	if len(fields) == 0 {
+		return unknownVersion
+	}
+	return fields[0]
+}