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backend/internal/modules/chat/presenter.go

@@ -0,0 +1,55 @@
+package chat
+
+import (
+	"encoding/json"
+	"gorm.io/datatypes"
+	"strings"
+)
+
+func normalizePagination(page, pageSize int) (int, int) {
+	if page < 1 {
+		page = 1
+	}
+	if pageSize < 1 {
+		pageSize = 20
+	}
+	if pageSize > 100 {
+		pageSize = 100
+	}
+	return page, pageSize
+}
+func truncatePreview(content string) string {
+	runes := []rune(content)
+	if len(runes) <= 80 {
+		return content
+	}
+	return string(runes[:80])
+}
+func messagePreview(content string, attachments []string) string {
+	content = strings.TrimSpace(content)
+	if content != "" {
+		return truncatePreview(content)
+	}
+	if len(attachments) > 0 {
+		return "[图片]"
+	}
+	return ""
+}
+func emptyJSONList() datatypes.JSON {
+	raw, _ := json.Marshal([]string{})
+	return datatypes.JSON(raw)
+}
+func encodeStringList(items []string) datatypes.JSON {
+	raw, _ := json.Marshal(items)
+	return datatypes.JSON(raw)
+}
+func decodeStringList(raw datatypes.JSON) []string {
+	if len(raw) == 0 {
+		return []string{}
+	}
+	var items []string
+	if err := json.Unmarshal(raw, &items); err != nil {
+		return []string{}
+	}
+	return items
+}