﻿/* Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied.
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 *
 * Author							Change						Date
 *******************************************************************************
 * Mats Alm   		                Added		                2015-04-06
 *******************************************************************************/

using System.Collections.Generic;
using System.Globalization;
using System.Linq;

namespace AppsheetEpplus;

public class DcountA : DatabaseFunction {
  public DcountA()
      : this(new()) {}

  public DcountA(RowMatcher rowMatcher)
      : base(rowMatcher) {}

  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    ValidateArguments(arguments, 2);
    var dbAddress = arguments.ElementAt(0).ValueAsRangeInfo.Address.Address;
    string field = null;
    string criteriaRange;
    if (arguments.Count() == 2) {
      criteriaRange = arguments.ElementAt(1).ValueAsRangeInfo.Address.Address;
    } else {
      field = ArgToString(arguments, 1).ToLower(CultureInfo.InvariantCulture);
      criteriaRange = arguments.ElementAt(2).ValueAsRangeInfo.Address.Address;
    }
    var db = new ExcelDatabase(context.ExcelDataProvider, dbAddress);
    var criteria = new ExcelDatabaseCriteria(context.ExcelDataProvider, criteriaRange);

    var nHits = 0;
    while (db.HasMoreRows) {
      var dataRow = db.Read();
      if (RowMatcher.IsMatch(dataRow, criteria)) {
        // if a fieldname is supplied, count only this row if the value
        // of the supplied field is not blank.
        if (!string.IsNullOrEmpty(field)) {
          var candidate = dataRow[field];
          if (ShouldCount(candidate)) {
            nHits++;
          }
        } else {
          // no fieldname was supplied, always count matching row.
          nHits++;
        }
      }
    }
    return CreateResult(nHits, DataType.Integer);
  }

  private bool ShouldCount(object value) {
    if (value == null) {
      return false;
    }
    return (!string.IsNullOrEmpty(value.ToString()));
  }
}