Refactor collectors

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

pkg/winversion/main.go

@@ -0,0 +1,44 @@
+//go:build windows
+
+package winversion
+
+import (
+	"fmt"
+	"strconv"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+var WindowsVersion string
+var WindowsVersionFloat float64
+
+func init() {
+	var err error
+	WindowsVersion, WindowsVersionFloat, err = GetWindowsVersion()
+	if err != nil {
+		panic(err)
+	}
+}
+
+// GetWindowsVersion reads the version number of the OS from the Registry
+// See https://docs.microsoft.com/en-us/windows/desktop/sysinfo/operating-system-version
+func GetWindowsVersion() (string, float64, error) {
+	reg, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+	if err != nil {
+		return "", 0, fmt.Errorf("couldn't open registry: %w", err)
+	}
+
+	defer reg.Close()
+
+	windowsVersion, _, err := reg.GetStringValue("CurrentVersion")
+	if err != nil {
+		return "", 0, fmt.Errorf("couldn't open registry: %w", err)
+	}
+
+	windowsVersionFloat, err := strconv.ParseFloat(windowsVersion, 64)
+	if err != nil {
+		return "", 0, fmt.Errorf("couldn't open registry: %w", err)
+	}
+
+	return windowsVersion, windowsVersionFloat, nil
+}