using Connected.Expressions.Expressions;
using Connected.Expressions.Visitors;
using System.Linq.Expressions;

namespace Connected.Expressions.Translation;

public sealed class AggregateChecker : DatabaseVisitor
{
    private AggregateChecker()
    {

    }

    private bool HasAggregate { get; set; }

    public static bool HasAggregates(SelectExpression expression)
    {
        var checker = new AggregateChecker();

        checker.Visit(expression);

        return checker.HasAggregate;
    }

    protected override Expression VisitAggregate(AggregateExpression aggregate)
    {
        HasAggregate = true;

        return aggregate;
    }

    protected override Expression VisitSelect(SelectExpression select)
    {
        Visit(select.Where);
        VisitOrderBy(select.OrderBy);
        VisitColumnDeclarations(select.Columns);

        return select;
    }

    protected override Expression VisitSubquery(SubqueryExpression subquery) => subquery;
}