一阶段ok

internal/db/db.go

@@ -0,0 +1,54 @@
+package db
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"mail_go/config"
+
+	"gorm.io/driver/mysql"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+// InitDB initializes the database connection and performs auto-migration.
+// It selects the appropriate driver based on cfg.Driver and resolves
+// the DSN path for SQLite relative to the storage base directory.
+func InitDB(cfg config.DatabaseConfig, storageCfg config.StorageConfig) (*gorm.DB, error) {
+	var dialector gorm.Dialector
+
+	switch cfg.Driver {
+	case "sqlite":
+		dsn := cfg.DSN
+		// If the DSN is the default relative path, prepend the storage base directory
+		if dsn == config.DefaultDSNWin || dsn == config.DefaultDSNLinux {
+			dsn = filepath.Join(storageCfg.BaseDir, "mail.db")
+		}
+		// Ensure the parent directory exists for SQLite
+		dir := filepath.Dir(dsn)
+		if err := os.MkdirAll(dir, 0755); err != nil {
+			return nil, fmt.Errorf("创建数据库目录失败 %s: %w", dir, err)
+		}
+		dialector = sqlite.Open(dsn)
+	case "mysql":
+		dialector = mysql.Open(cfg.DSN)
+	default:
+		return nil, fmt.Errorf("不支持的数据库驱动: %s", cfg.Driver)
+	}
+
+	db, err := gorm.Open(dialector, &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Warn),
+	})
+	if err != nil {
+		return nil, fmt.Errorf("连接数据库失败: %w", err)
+	}
+
+	// Auto-migrate all models
+	if err := db.AutoMigrate(&User{}, &Domain{}, &Message{}, &Attachment{}); err != nil {
+		return nil, fmt.Errorf("数据库迁移失败: %w", err)
+	}
+
+	return db, nil
+}