feat: add database connection and configuration

- Add PostgreSQL database connection setup with GORM
- Include database initialization and migration functionality
- Add connection pooling and error handling
- Support for environment-based database configuration

db/conn.go

@@ -0,0 +1,120 @@
+package db
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"git.secnex.io/secnex/idp-api/models"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+// Global database instance
+var DB *gorm.DB
+
+type Database struct {
+	Host     string
+	Port     string
+	User     string
+	Password string
+	DBName   string
+	SSLMode  string
+	Conn     *gorm.DB
+}
+
+type DatabaseConnection struct {
+	DB *gorm.DB
+}
+
+func NewDatabase(host, port, user, password, dbName, sslMode string) *Database {
+	return &Database{Host: host, Port: port, User: user, Password: password, DBName: dbName, SSLMode: sslMode}
+}
+
+// InitializeDB initializes the global database connection with connection pooling
+func InitializeDB() error {
+	// Get database configuration from environment variables
+	host := getEnv("DB_HOST", "10.2.1.2")
+	port := getEnv("DB_PORT", "5432")
+	user := getEnv("DB_USER", "postgres")
+	password := getEnv("DB_PASSWORD", "postgres")
+	dbName := getEnv("DB_NAME", "idp")
+	sslMode := getEnv("DB_SSLMODE", "disable")
+
+	dsn := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=%s",
+		host, port, user, password, dbName, sslMode)
+
+	// Configure GORM with connection pooling
+	config := &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Info),
+	}
+
+	db, err := gorm.Open(postgres.Open(dsn), config)
+	if err != nil {
+		return fmt.Errorf("failed to connect to database: %w", err)
+	}
+
+	// Configure connection pool
+	sqlDB, err := db.DB()
+	if err != nil {
+		return fmt.Errorf("failed to get underlying sql.DB: %w", err)
+	}
+
+	// Set connection pool settings
+	sqlDB.SetMaxIdleConns(10)           // Maximum number of idle connections
+	sqlDB.SetMaxOpenConns(100)          // Maximum number of open connections
+	sqlDB.SetConnMaxLifetime(time.Hour) // Maximum lifetime of a connection
+
+	// Auto migrate models
+	if err := db.AutoMigrate(&models.User{}, &models.Session{}, &models.ApiKey{}); err != nil {
+		return fmt.Errorf("failed to auto migrate: %w", err)
+	}
+
+	// Set global database instance
+	DB = db
+
+	return nil
+}
+
+// GetDB returns the global database instance
+func GetDB() *gorm.DB {
+	return DB
+}
+
+// CloseDB closes the database connection
+func CloseDB() error {
+	if DB != nil {
+		sqlDB, err := DB.DB()
+		if err != nil {
+			return err
+		}
+		return sqlDB.Close()
+	}
+	return nil
+}
+
+// Helper function to get environment variables with fallback
+func getEnv(key, fallback string) string {
+	if value := os.Getenv(key); value != "" {
+		return value
+	}
+	return fallback
+}
+
+// Legacy methods for backward compatibility
+func (d *Database) Connect() (*gorm.DB, error) {
+	dsn := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=%s",
+		d.Host, d.Port, d.User, d.Password, d.DBName, d.SSLMode)
+
+	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
+	if err != nil {
+		return nil, err
+	}
+
+	if err := db.AutoMigrate(&models.User{}, &models.Session{}, &models.ApiKey{}); err != nil {
+		return nil, err
+	}
+
+	return db, nil
+}