feat: 从黄果 NET hgdjnet-server 9bfbafe 导入 HKDJ 官网后端

来源：hgdjnet-server 9bfbafe10d417deea959bd53117bc88a10e60a83
项目身份 HKDJ / JHA-216，独立官网仓库，Jenkins 守卫键 hkdjnet
测试目录 /server/hkdj_net，App/Web API 30331/30332

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

pub/common/utils/strings.go

@@ -0,0 +1,129 @@
+package utils
+
+import (
+	"encoding/json"
+	"hkdj-web-server/pub/common/netutil"
+	"math/rand/v2"
+	"strings"
+
+	"github.com/gosimple/slug"
+)
+
+// BinarySearch BinarySearch
+func BinarySearch(s []string, t string, n int) (idx int) {
+	idx = -1
+	if n == 0 {
+		return
+	}
+	start, end := 0, n-1
+	for start <= end {
+		mid := (start + end) >> 1
+		if s[mid] < t {
+			start = mid + 1
+		} else if s[mid] > t {
+			end = mid - 1
+		} else {
+			idx = mid
+			break
+		}
+	}
+	return
+}
+
+var YesOrNo = map[bool]string{
+	true:  "是",
+	false: "否",
+}
+
+// ApplyImgCdn 尝试解析节点 Content JSON，若含 "img" 字段则对其拼接 CDN 后重新序列化。
+// 不符合 {"img": "..."} 结构的 Content 原样返回。
+func ApplyImgCdn(cdn, content string) string {
+	if content == "" || cdn == "" {
+		return content
+	}
+	var m map[string]interface{}
+	if err := json.Unmarshal([]byte(content), &m); err != nil {
+		return content // 非 JSON 对象，原样返回
+	}
+	imgVal, ok := m["img"]
+	if !ok {
+		return content // 无 img 字段，原样返回
+	}
+	imgStr, ok := imgVal.(string)
+	if !ok || imgStr == "" {
+		return content
+	}
+	m["img"] = netutil.MergeURL(cdn, imgStr)
+	b, err := json.Marshal(m)
+	if err != nil {
+		return content
+	}
+	return string(b)
+}
+
+// 截取指定长度的字符串
+func GetPrefix(s string, n int) string {
+	runes := []rune(s)
+	if len(runes) <= n {
+		return s
+	}
+	return string(runes[:n])
+}
+
+func GetRandomLetters(n int) string {
+	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	b := make([]byte, n)
+	for i := range b {
+		b[i] = letters[rand.IntN(len(letters))]
+	}
+	return string(b)
+}
+
+func GetSlugInfo(text string) string {
+	return SanitizeSlug(slug.Make(text))
+}
+
+// SanitizeSlug 去掉 slug 中的横杠等特殊符号，只保留字母和数字
+func SanitizeSlug(s string) string {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return ""
+	}
+	var b strings.Builder
+	b.Grow(len(s))
+	for _, r := range s {
+		if r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' {
+			b.WriteRune(r)
+		}
+	}
+	return b.String()
+}
+
+// IsSlugAllDigits 判断 slug 是否全为数字
+func IsSlugAllDigits(s string) bool {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return false
+	}
+	for _, r := range s {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+// MakeUniqueSlug 生成唯一 slug；exists 返回 true 表示已被占用。生成结果不能全是数字。
+func MakeUniqueSlug(source string, exists func(string) bool) string {
+	pinyin := GetSlugInfo(source)
+	if pinyin == "" {
+		pinyin = GetRandomLetters(5)
+	} else if IsSlugAllDigits(pinyin) {
+		pinyin = pinyin + GetRandomLetters(3)
+	}
+	finalSlug := pinyin
+	for exists(finalSlug) {
+		finalSlug = pinyin + GetRandomLetters(3)
+	}
+	return finalSlug
+}