using System.Linq.Expressions;

namespace ApplicationHub.Domain.Contracts.Linq;

public class EntityExpressionConverter<TModel, TEntity> : ExpressionVisitor
{
    private readonly ParameterExpression _entityParameter;
    private readonly ParameterExpression _modelParameter;
    
    public EntityExpressionConverter(ParameterExpression modelParameter)
    {
        _modelParameter = modelParameter;
        _entityParameter = Expression.Parameter(typeof(TEntity), "entity");
    }
    
    public Expression<Func<TEntity, bool>> Convert(Expression<Func<TModel, bool>> expression)
    {
        var body = Visit(expression.Body);
        return Expression.Lambda<Func<TEntity, bool>>(body, _entityParameter);
    }

    protected override Expression VisitParameter(ParameterExpression node)
    {
        return node == _modelParameter ? _entityParameter : base.VisitParameter(node);
    }
    
    protected override Expression VisitMember(MemberExpression node)
    {
        if (node.Expression == _modelParameter)
        {
            return Expression.Property(_entityParameter, node.Member.Name);
        }

        return base.VisitMember(node);
    }
}