package driver

import (
	"context"
	"database/sql"
)

// sqlPinger runs the liveness query against a database/sql handle. It is shared
// by every engine whose Go driver plugs into database/sql.
type sqlPinger struct {
	db *sql.DB
}

func openSQL(driverName, dsn string) (*sqlPinger, error) {
	db, err := sql.Open(driverName, dsn)
	if err != nil {
		return nil, err
	}
	// A readiness check only ever needs one connection; keep the pool tiny so a
	// failed attempt does not leave idle half-open connections behind.
	db.SetMaxOpenConns(1)
	db.SetMaxIdleConns(0)
	return &sqlPinger{db: db}, nil
}

func (p *sqlPinger) Ping(ctx context.Context) error {
	var one int
	return p.db.QueryRowContext(ctx, "SELECT 1").Scan(&one)
}

func (p *sqlPinger) Close() error { return p.db.Close() }