[BACKEND] Initialize Go backend structure and dependencies (#23)

server/database/database.go

@@ -0,0 +1,55 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+
+	_ "github.com/lib/pq"
+
+	"git.gobha.me/xcaliber/chat-switchboard/config"
+)
+
+// DB is the application-wide database connection pool.
+var DB *sql.DB
+
+// Connect opens a connection pool to PostgreSQL using the
+// DATABASE_URL from config. It pings to verify connectivity.
+func Connect(cfg *config.Config) error {
+	if cfg.DatabaseURL == "" {
+		log.Println("⚠ DATABASE_URL not set — running without database")
+		return nil
+	}
+
+	var err error
+	DB, err = sql.Open("postgres", cfg.DatabaseURL)
+	if err != nil {
+		return fmt.Errorf("database open: %w", err)
+	}
+
+	// Connection pool tuning
+	DB.SetMaxOpenConns(25)
+	DB.SetMaxIdleConns(5)
+
+	if err := DB.Ping(); err != nil {
+		return fmt.Errorf("database ping: %w", err)
+	}
+
+	log.Println("✅ Database connected")
+	return nil
+}
+
+// Close gracefully shuts down the connection pool.
+func Close() {
+	if DB != nil {
+		DB.Close()
+	}
+}
+
+// IsConnected returns true if a database connection is available.
+func IsConnected() bool {
+	if DB == nil {
+		return false
+	}
+	return DB.Ping() == nil
+}