xingrin/go-backend/internal/database/database.go

package database

import (
	"fmt"
	"time"

	"github.com/xingrin/go-backend/internal/config"
	"gorm.io/driver/postgres"
	"gorm.io/gorm"
	"gorm.io/gorm/schema"
)

// DB is the global database instance
var DB *gorm.DB

// NewDatabase creates a new database connection
func NewDatabase(cfg *config.DatabaseConfig) (*gorm.DB, error) {
	dsn := cfg.DSN()

	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
		NamingStrategy: schema.NamingStrategy{
			SingularTable: true, // Use singular table names (e.g., "target" not "targets")
		},
		// Disable auto-migration to prevent creating new tables
		DisableForeignKeyConstraintWhenMigrating: true,
	})
	if err != nil {
		return nil, fmt.Errorf("failed to connect to database: %w", err)
	}

	// Get underlying sql.DB to configure connection pool
	sqlDB, err := db.DB()
	if err != nil {
		return nil, fmt.Errorf("failed to get underlying sql.DB: %w", err)
	}

	// Configure connection pool
	sqlDB.SetMaxOpenConns(cfg.MaxOpenConns)
	sqlDB.SetMaxIdleConns(cfg.MaxIdleConns)
	sqlDB.SetConnMaxLifetime(time.Duration(cfg.ConnMaxLifetime) * time.Second)

	// Verify connection
	if err := sqlDB.Ping(); err != nil {
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	return db, nil
}

// InitDatabase initializes the global database instance
func InitDatabase(cfg *config.DatabaseConfig) error {
	var err error
	DB, err = NewDatabase(cfg)
	return err
}

// Close closes the database connection
func Close() error {
	if DB != nil {
		sqlDB, err := DB.DB()
		if err != nil {
			return err
		}
		return sqlDB.Close()
	}
	return nil
}

// Ping checks if the database connection is alive
func Ping() error {
	if DB == nil {
		return fmt.Errorf("database not initialized")
	}
	sqlDB, err := DB.DB()
	if err != nil {
		return err
	}
	return sqlDB.Ping()
}

// GetDB returns the global database instance
func GetDB() *gorm.DB {
	return DB
}