refactor: 重构项目结构，迁移后端至 mengyastore-backend-go，新增 Java 后端、前端功能更新及部署文档

mengyastore-backend-go/internal/storage/sitestore.go

@@ -0,0 +1,146 @@
+package storage
+
+import (
+	"strconv"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+
+	"mengyastore-backend/internal/database"
+)
+
+type SiteStore struct {
+	db *gorm.DB
+}
+
+func NewSiteStore(db *gorm.DB) (*SiteStore, error) {
+	return &SiteStore{db: db}, nil
+}
+
+func (s *SiteStore) get(key string) (string, error) {
+	var row database.SiteSettingRow
+	// `key` 是 MySQL 保留字，需用反引号转义以避免 SQL 语法错误。
+	if err := s.db.Where("`key` = ?", key).First(&row).Error; err != nil {
+		return "", nil // 键不存在时返回零值
+	}
+	return row.Value, nil
+}
+
+func (s *SiteStore) set(key, value string) error {
+	return s.db.Clauses(clause.OnConflict{
+		Columns:   []clause.Column{{Name: "key"}},
+		DoUpdates: clause.AssignmentColumns([]string{"value"}),
+	}).Create(&database.SiteSettingRow{Key: key, Value: value}).Error
+}
+
+func (s *SiteStore) GetTotalVisits() (int, error) {
+	v, err := s.get("totalVisits")
+	if err != nil || v == "" {
+		return 0, err
+	}
+	n, _ := strconv.Atoi(v)
+	return n, nil
+}
+
+func (s *SiteStore) IncrementVisits() (int, error) {
+	current, err := s.GetTotalVisits()
+	if err != nil {
+		return 0, err
+	}
+	current++
+	if err := s.set("totalVisits", strconv.Itoa(current)); err != nil {
+		return 0, err
+	}
+	return current, nil
+}
+
+func (s *SiteStore) GetMaintenance() (enabled bool, reason string, err error) {
+	v, err := s.get("maintenance")
+	if err != nil {
+		return false, "", err
+	}
+	enabled = v == "true"
+	reason, err = s.get("maintenanceReason")
+	return enabled, reason, err
+}
+
+func (s *SiteStore) SetMaintenance(enabled bool, reason string) error {
+	v := "false"
+	if enabled {
+		v = "true"
+	}
+	if err := s.set("maintenance", v); err != nil {
+		return err
+	}
+	return s.set("maintenanceReason", reason)
+}
+
+// RecordVisit 递增访问计数，返回 (总访问量, 是否计入, 错误)。
+// 去重逻辑由上层 handler 的内存指纹完成，此处无条件累加。
+func (s *SiteStore) RecordVisit(_ string) (int, bool, error) {
+	total, err := s.IncrementVisits()
+	return total, true, err
+}
+
+// SMTPConfig 存储数据库中的发件 SMTP 配置。
+type SMTPConfig struct {
+	Enabled  bool   `json:"enabled"`
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	FromName string `json:"fromName"`
+	Host     string `json:"host"`
+	Port     string `json:"port"`
+}
+
+// IsConfiguredEmail 判断邮件通知是否已启用且 SMTP 配置完整。
+func (c SMTPConfig) IsConfiguredEmail() bool {
+	return c.Enabled && c.Email != "" && c.Password != "" && c.Host != ""
+}
+
+func (s *SiteStore) GetSMTPConfig() (SMTPConfig, error) {
+	cfg := SMTPConfig{
+		Enabled: true, // 默认启用
+		Host:    "smtp.qq.com",
+		Port:    "465",
+	}
+	if v, _ := s.get("smtpEnabled"); v == "false" {
+		cfg.Enabled = false
+	}
+	if v, _ := s.get("smtpEmail"); v != "" {
+		cfg.Email = v
+	}
+	if v, _ := s.get("smtpPassword"); v != "" {
+		cfg.Password = v
+	}
+	if v, _ := s.get("smtpFromName"); v != "" {
+		cfg.FromName = v
+	}
+	if v, _ := s.get("smtpHost"); v != "" {
+		cfg.Host = v
+	}
+	if v, _ := s.get("smtpPort"); v != "" {
+		cfg.Port = v
+	}
+	return cfg, nil
+}
+
+func (s *SiteStore) SetSMTPConfig(cfg SMTPConfig) error {
+	enabledVal := "true"
+	if !cfg.Enabled {
+		enabledVal = "false"
+	}
+	pairs := [][2]string{
+		{"smtpEnabled", enabledVal},
+		{"smtpEmail", cfg.Email},
+		{"smtpPassword", cfg.Password},
+		{"smtpFromName", cfg.FromName},
+		{"smtpHost", cfg.Host},
+		{"smtpPort", cfg.Port},
+	}
+	for _, p := range pairs {
+		if err := s.set(p[0], p[1]); err != nil {
+			return err
+		}
+	}
+	return nil
+}