﻿/* 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
 *******************************************************************************/

using System.Collections.Generic;
using System.Globalization;
using OfficeOpenXml.FormulaParsing.ExpressionGraph;
using OfficeOpenXml.Utils;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Math;

public class Average : HiddenValuesHandlingFunction {
  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    ValidateArguments(arguments, 1, eErrorType.Div0);
    double nValues = 0d,
        result = 0d;
    foreach (var arg in arguments) {
      Calculate(arg, context, ref result, ref nValues);
    }
    return CreateResult(Divide(result, nValues), DataType.Decimal);
  }

  private void Calculate(
      FunctionArgument arg,
      ParsingContext context,
      ref double retVal,
      ref double nValues,
      bool isInArray = false) {
    if (ShouldIgnore(arg)) {
      return;
    }
    if (arg.Value is IEnumerable<FunctionArgument> value) {
      foreach (var item in value) {
        Calculate(item, context, ref retVal, ref nValues, true);
      }
    } else if (arg.IsExcelRange) {
      foreach (var c in arg.ValueAsRangeInfo) {
        if (ShouldIgnore(c, context)) {
          continue;
        }
        CheckForAndHandleExcelError(c);
        if (!IsNumeric(c.Value)) {
          continue;
        }
        nValues++;
        retVal += c.ValueDouble;
      }
    } else {
      var numericValue = GetNumericValue(arg.Value, isInArray);
      if (numericValue.HasValue) {
        nValues++;
        retVal += numericValue.Value;
      } else if ((arg.Value is string) && !ConvertUtil.IsNumericString(arg.Value)) {
        if (!isInArray) {
          ThrowExcelErrorValueException(eErrorType.Value);
        }
      }
    }
    CheckForAndHandleExcelError(arg);
  }

  private double? GetNumericValue(object obj, bool isInArray) {
    if (IsNumeric(obj)) {
      return ConvertUtil.GetValueDouble(obj);
    }
    if ((obj is bool) && !isInArray) {
      return ConvertUtil.GetValueDouble(obj);
    }
    if (ConvertUtil.IsNumericString(obj)) {
      return double.Parse(obj.ToString(), CultureInfo.InvariantCulture);
    }
    return default(double?);
  }
}