platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/routes_cache_helpers_nft.go

@@ -0,0 +1,73 @@
+package app
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+)
+
+func snapshotNftSetToFile(setName, dst string) (int, error) {
+	elems, err := readNftSetElements(setName)
+	if err != nil {
+		return 0, err
+	}
+	if err := writeLinesFile(dst, elems); err != nil {
+		return 0, err
+	}
+	return len(elems), nil
+}
+
+func readNftSetElements(setName string) ([]string, error) {
+	out, stderr, code, err := runCommandTimeout(
+		8*time.Second, "nft", "list", "set", "inet", "agvpn", setName,
+	)
+	if err != nil || code != 0 {
+		msg := strings.ToLower(strings.TrimSpace(out + " " + stderr))
+		if strings.Contains(msg, "no such file") ||
+			strings.Contains(msg, "not found") ||
+			strings.Contains(msg, "does not exist") {
+			return nil, nil
+		}
+		if err != nil {
+			return nil, fmt.Errorf("nft list set %s failed: %w", setName, err)
+		}
+		return nil, fmt.Errorf("nft list set %s failed: %s", setName, strings.TrimSpace(stderr))
+	}
+	return parseNftSetElementsText(out), nil
+}
+
+func parseNftSetElementsText(raw string) []string {
+	idx := strings.Index(raw, "elements =")
+	if idx < 0 {
+		return nil
+	}
+	chunk := raw[idx:]
+	open := strings.Index(chunk, "{")
+	if open < 0 {
+		return nil
+	}
+	body := chunk[open+1:]
+	closeIdx := strings.Index(body, "}")
+	if closeIdx >= 0 {
+		body = body[:closeIdx]
+	}
+	body = strings.ReplaceAll(body, "\r", " ")
+	body = strings.ReplaceAll(body, "\n", " ")
+
+	seen := map[string]struct{}{}
+	out := make([]string, 0, 1024)
+	for _, tok := range strings.Split(body, ",") {
+		val := strings.TrimSpace(tok)
+		if val == "" {
+			continue
+		}
+		if _, ok := seen[val]; ok {
+			continue
+		}
+		seen[val] = struct{}{}
+		out = append(out, val)
+	}
+	sort.Strings(out)
+	return out
+}