package repo

import (
	"context"
	"fmt"
	"time"

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

// NewPool creates a pgxpool with sensible defaults for ingest workloads.
// Pool size is small because ingest is mostly cache hits — Postgres is only
// touched on cache miss (write key lookup, schema upsert).
func NewPool(ctx context.Context, dsn string) (*pgxpool.Pool, error) {
	cfg, err := pgxpool.ParseConfig(dsn)
	if err != nil {
		return nil, fmt.Errorf("parse pg dsn: %w", err)
	}
	cfg.MaxConns = 16
	cfg.MinConns = 2
	cfg.MaxConnIdleTime = 5 * time.Minute
	cfg.HealthCheckPeriod = 30 * time.Second

	pool, err := pgxpool.NewWithConfig(ctx, cfg)
	if err != nil {
		return nil, fmt.Errorf("pg connect: %w", err)
	}
	if err := pool.Ping(ctx); err != nil {
		pool.Close()
		return nil, fmt.Errorf("pg ping: %w", err)
	}
	return pool, nil
}