using System.Collections.Generic;
using System.Globalization;
using System.Text.RegularExpressions;

namespace AppsheetEpplus;

public class Value : ExcelFunction {
  private readonly string _groupSeparator = CultureInfo
      .CurrentCulture
      .NumberFormat
      .NumberGroupSeparator;
  private readonly string _decimalSeparator = CultureInfo
      .CurrentCulture
      .NumberFormat
      .NumberDecimalSeparator;
  private readonly string _timeSeparator = CultureInfo.CurrentCulture.DateTimeFormat.TimeSeparator;
  private readonly DateValue _dateValueFunc = new();
  private readonly TimeValue _timeValueFunc = new();

  public override CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    ValidateArguments(arguments, 1);
    var val = ArgToString(arguments, 0).TrimEnd(' ');
    double result;
    if (Regex.IsMatch(
        val,
        $"^[\\d]*({Regex.Escape(_groupSeparator)}?[\\d]*)?({Regex.Escape(_decimalSeparator)
        }[\\d]*)?[ ?% ?]?$")) {
      if (val.EndsWith("%")) {
        val = val.TrimEnd('%');
        result = double.Parse(val) / 100;
      } else {
        result = double.Parse(val);
      }
      return CreateResult(result, DataType.Decimal);
    }
    if (double.TryParse(val, NumberStyles.Float, CultureInfo.CurrentCulture, out result)) {
      return CreateResult(result, DataType.Decimal);
    }
    var timeSeparator = Regex.Escape(_timeSeparator);
    if (Regex.IsMatch(
        val,
        @"^[\d]{1,2}" + timeSeparator + @"[\d]{2}(" + timeSeparator + @"[\d]{2})?$")) {
      var timeResult = _timeValueFunc.Execute(val);
      if (timeResult.DataType == DataType.Date) {
        return timeResult;
      }
    }
    var dateResult = _dateValueFunc.Execute(val);
    if (dateResult.DataType == DataType.Date) {
      return dateResult;
    }
    return CreateResult(ExcelErrorValue.Create(eErrorType.Value), DataType.ExcelError);
  }
}