Converted most metrics to non-wmi

Signed-off-by: Ben Ridley <benridley29@gmail.com>

headers/custom/custom.go

@@ -0,0 +1,54 @@
+package custom
+
+import (
+	"log"
+	"os"
+	"strings"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+// GetSizeStoredInPagingFiles returns the total size of paging files across all discs.
+func GetSizeStoredInPagingFiles() (int64, error) {
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management`, registry.QUERY_VALUE)
+	if err != nil {
+		return 0, err
+	}
+	pagingFiles, _, err := k.GetStringsValue("ExistingPageFiles")
+	if err != nil {
+		return 0, err
+	}
+
+	var size int64 = 0
+	for _, pagingFile := range pagingFiles {
+		fileString := strings.ReplaceAll(pagingFile, `\??\`, "")
+		file, err := os.Stat(fileString)
+		if err != nil {
+			return 0, err
+		}
+		size += file.Size()
+	}
+	return size, nil
+}
+
+// GetProductDetails returns the ProductName and CurrentBuildNumber values from the registry.
+func GetProductDetails() (string, string) {
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion`, registry.QUERY_VALUE)
+	if err != nil {
+		log.Fatal(err)
+	}
+	pn, _, err := k.GetStringValue("ProductName")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	bn, _, err := k.GetStringValue("CurrentBuildNumber")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if err := k.Close(); err != nil {
+		log.Fatal(err)
+	}
+	return pn, bn
+}