AppsheetEpplus/FormulaParsing/Excel/Functions/RefAndLookup/LookupFunction.cs

/* 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		                2013-12-03
 *******************************************************************************/


namespace AppsheetEpplus;

public abstract class LookupFunction : ExcelFunction {
  private readonly ValueMatcher _valueMatcher;
  private readonly CompileResultFactory _compileResultFactory;

  public LookupFunction()
      : this(new LookupValueMatcher(), new()) {}

  public LookupFunction(ValueMatcher valueMatcher, CompileResultFactory compileResultFactory) {
    _valueMatcher = valueMatcher;
    _compileResultFactory = compileResultFactory;
  }

  public override bool IsLookupFuction => true;

  protected int IsMatch(object o1, object o2) {
    return _valueMatcher.IsMatch(o1, o2);
  }

  protected LookupDirection GetLookupDirection(RangeAddress rangeAddress) {
    var nRows = rangeAddress.ToRow - rangeAddress.FromRow;
    var nCols = rangeAddress.ToCol - rangeAddress.FromCol;
    return nCols > nRows ? LookupDirection.Horizontal : LookupDirection.Vertical;
  }

  protected CompileResult Lookup(LookupNavigator navigator, LookupArguments lookupArgs) {
    object lastValue = null;
    object lastLookupValue = null;
    int? lastMatchResult = null;
    if (lookupArgs.SearchedValue == null) {
      return new(ExcelErrorValue.Create(eErrorType.Na), DataType.ExcelError);
    }
    do {
      var matchResult = IsMatch(navigator.CurrentValue, lookupArgs.SearchedValue);
      if (matchResult != 0) {
        if (lastValue != null && navigator.CurrentValue == null) {
          break;
        }

        if (lookupArgs.RangeLookup) {
          if (lastValue == null && matchResult > 0) {
            ThrowExcelErrorValueException(eErrorType.Na);
          }
          if (lastValue != null && matchResult > 0 && lastMatchResult < 0) {
            return _compileResultFactory.Create(lastLookupValue);
          }
          lastMatchResult = matchResult;
          lastValue = navigator.CurrentValue;
          lastLookupValue = navigator.GetLookupValue();
        }
      } else {
        return _compileResultFactory.Create(navigator.GetLookupValue());
      }
    } while (navigator.MoveNext());

    if (lookupArgs.RangeLookup) {
      return _compileResultFactory.Create(lastLookupValue);
    }
    return new(ExcelErrorValue.Create(eErrorType.Na), DataType.ExcelError);
  }
}