general cleanup - removed old comments, enforced naming conventions etc

backend/internal/database/postgres.go

@@ -0,0 +1,68 @@
+package database
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+const (
+
+	maxConnIdleSeconds = 30
+
+	maxConnLifetimeMinutes = 5
+
+	connectTimeoutSeconds = 10
+
+	maxConns = 20
+
+	minConns = 2
+)
+
+var pool *pgxpool.Pool //nolint:gochecknoglobals
+
+// establishPostgreSQL connection pool using the given DSN.
+func Connect(dsn string) (*pgxpool.Pool, error) {
+	cfg, err := pgxpool.ParseConfig(dsn)
+	if err != nil {
+		return nil, fmt.Errorf("parse database config: %w", err)
+	}
+
+	cfg.MaxConns = maxConns
+	cfg.MinConns = minConns
+	cfg.MaxConnIdleTime = maxConnIdleSeconds * time.Second
+	cfg.MaxConnLifetime = maxConnLifetimeMinutes * time.Minute
+
+	ctx, cancel := context.WithTimeout(context.Background(), connectTimeoutSeconds*time.Second)
+	defer cancel()
+
+	p, err := pgxpool.NewWithConfig(ctx, cfg)
+	if err != nil {
+		return nil, fmt.Errorf("create connection pool: %w", err)
+	}
+
+	if err := p.Ping(ctx); err != nil {
+		p.Close()
+
+		return nil, fmt.Errorf("ping database: %w", err)
+	}
+
+	log.Println("Connected to PostgreSQL database")
+	pool = p
+
+	return p, nil
+}
+
+func Pool() *pgxpool.Pool {
+	return pool
+}
+
+func Close() {
+	if pool != nil {
+		pool.Close()
+		log.Println("Database connection pool closed")
+	}
+}