add new functionality and improve backend server structure

- Enhance server functionality and optimize backend code
- Add multi-database support (PostgreSQL, MySQL, SQLite)

server/core_backend-server/tools/osutils/cmd.go

@@ -0,0 +1,65 @@
+package osutils
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+
+	"github.com/go-ozzo/ozzo-validation/v4/is"
+)
+
+// LaunchURL attempts to open the provided url in the user's default browser.
+//
+// It is platform dependent and it uses:
+//   - "open" on macOS
+//   - "rundll32" on Windows
+//   - "xdg-open" on everything else (Linux, FreeBSD, etc.)
+func LaunchURL(url string) error {
+	if err := is.URL.Validate(url); err != nil {
+		return err
+	}
+
+	switch runtime.GOOS {
+	case "darwin":
+		return exec.Command("open", url).Start()
+	case "windows":
+		// not sure if this is the best command but seems to be the most reliable based on the comments in
+		// https://stackoverflow.com/questions/3739327/launching-a-website-via-the-windows-commandline#answer-49115945
+		return exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
+	default:
+		return exec.Command("xdg-open", url).Start()
+	}
+}
+
+// YesNoPrompt performs a console prompt that asks the user for Yes/No answer.
+//
+// If the user just press Enter (aka. doesn't type anything) it returns the fallback value.
+func YesNoPrompt(message string, fallback bool) bool {
+	options := "Y/n"
+	if !fallback {
+		options = "y/N"
+	}
+
+	r := bufio.NewReader(os.Stdin)
+
+	var s string
+	for {
+		fmt.Fprintf(os.Stderr, "%s (%s) ", message, options)
+
+		s, _ = r.ReadString('\n')
+
+		s = strings.ToLower(strings.TrimSpace(s))
+
+		switch s {
+		case "":
+			return fallback
+		case "y", "yes":
+			return true
+		case "n", "no":
+			return false
+		}
+	}
+}