chore(lib/policy): move Checker to its own package to avoid import cycles

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/policy/config/geoip.go

@@ -0,0 +1,36 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var (
+	countryCodeRegexp = regexp.MustCompile(`^\w{2}$`)
+
+	ErrNotCountryCode = errors.New("config.Bot: invalid country code")
+)
+
+type GeoIP struct {
+	Countries []string `json:"countries"`
+}
+
+func (g *GeoIP) Valid() error {
+	var errs []error
+
+	for i, cc := range g.Countries {
+		if !countryCodeRegexp.MatchString(cc) {
+			errs = append(errs, fmt.Errorf("%w: %s", ErrNotCountryCode, cc))
+		}
+
+		g.Countries[i] = strings.ToLower(cc)
+	}
+
+	if len(errs) != 0 {
+		return fmt.Errorf("bot.GeoIP: invalid GeoIP settings: %w", errors.Join(errs...))
+	}
+
+	return nil
+}