feat: enforce tenant content moderation

server/moderation/local.go

@@ -0,0 +1,74 @@
+package moderation
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/mozillazg/go-pinyin"
+	"github.com/tinode/chat/server/store/types"
+)
+
+func matchLocalWords(text, scene string, words *types.SensitiveWordSet) *ProviderResult {
+	normalized := strings.ToLower(strings.TrimSpace(text))
+	if normalized == "" || words == nil {
+		return nil
+	}
+	for _, rule := range words.Items {
+		if rule == nil || strings.TrimSpace(rule.Word) == "" || !sceneEnabled(rule.Scenes, scene) {
+			continue
+		}
+		matched := false
+		switch strings.ToLower(strings.TrimSpace(rule.MatchType)) {
+		case "exact":
+			matched = normalized == strings.ToLower(strings.TrimSpace(rule.Word))
+		case "regex":
+			pattern, err := regexp.Compile(rule.Word)
+			matched = err == nil && pattern.MatchString(text)
+		case "pinyin":
+			args := pinyin.NewArgs()
+			args.Style = pinyin.Normal
+			textPinyin := strings.Join(pinyin.LazyConvert(text, &args), "")
+			wordPinyin := strings.Join(pinyin.LazyConvert(rule.Word, &args), "")
+			if wordPinyin == "" {
+				wordPinyin = strings.ToLower(strings.TrimSpace(rule.Word))
+			}
+			matched = wordPinyin != "" && strings.Contains(strings.ToLower(textPinyin), strings.ToLower(wordPinyin))
+		default:
+			matched = strings.Contains(normalized, strings.ToLower(strings.TrimSpace(rule.Word)))
+		}
+		if matched {
+			return &ProviderResult{RiskLevel: normalizedRisk(rule.RiskLevel), RiskLabels: []string{"local_sensitive_word"}, Summary: normalizedAction(rule.Action)}
+		}
+	}
+	return nil
+}
+
+func sceneEnabled(scenes []string, scene string) bool {
+	if len(scenes) == 0 {
+		return true
+	}
+	for _, value := range scenes {
+		if value == "*" || value == scene {
+			return true
+		}
+	}
+	return false
+}
+
+func normalizedRisk(value string) string {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case "high", "medium", "low":
+		return strings.ToLower(strings.TrimSpace(value))
+	default:
+		return "none"
+	}
+}
+
+func normalizedAction(value string) string {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case ActionBlock, ActionAuditOnly:
+		return strings.ToLower(strings.TrimSpace(value))
+	default:
+		return ActionAllow
+	}
+}