using System;
using System.Collections.Generic;
using System.Linq;
using OfficeOpenXml.FormulaParsing.ExpressionGraph;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Math;

public class CountBlank : ExcelFunction {
  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    ValidateArguments(arguments, 1);
    var arg = arguments.First();
    if (!arg.IsExcelRange) {
      throw new InvalidOperationException("CountBlank only support ranges as arguments");
    }
    var result = arg.ValueAsRangeInfo.GetNCells();
    foreach (var cell in arg.ValueAsRangeInfo) {
      if (!(cell.Value == null || cell.Value == string.Empty)) {
        result--;
      }
    }
    return CreateResult(result, DataType.Integer);
  }
}