package db

import (
	"context"
	"fmt"
	"log/slog"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

func Connect(ctx context.Context, dsn string) (*pgxpool.Pool, error) {
	cfg, err := pgxpool.ParseConfig(dsn)
	if err != nil {
		return nil, fmt.Errorf("parse dsn: %w", err)
	}
	cfg.MaxConns = 10
	cfg.MinConns = 1
	cfg.MaxConnLifetime = time.Hour
	cfg.HealthCheckPeriod = time.Minute

	var pool *pgxpool.Pool
	var lastErr error
	backoff := time.Second
	for attempt := 1; attempt <= 10; attempt++ {
		pool, err = pgxpool.NewWithConfig(ctx, cfg)
		if err == nil {
			pingCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
			err = pool.Ping(pingCtx)
			cancel()
			if err == nil {
				return pool, nil
			}
			pool.Close()
		}
		lastErr = err
		slog.Warn("db connect attempt failed", "attempt", attempt, "error", err)
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		case <-time.After(backoff):
		}
		if backoff < 15*time.Second {
			backoff *= 2
		}
	}
	return nil, fmt.Errorf("connect to database after retries: %w", lastErr)
}