PowerToys/src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.Calc/Helper/NumberTranslator.cs

// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Globalization;
using System.Text;
using System.Text.RegularExpressions;

namespace Microsoft.CmdPal.Ext.Calc.Helper;

/// <summary>
/// Tries to convert all numbers in a text from one culture format to another.
/// </summary>
public class NumberTranslator
{
    private readonly CultureInfo sourceCulture;
    private readonly CultureInfo targetCulture;
    private readonly Regex splitRegexForSource;
    private readonly Regex splitRegexForTarget;

    private NumberTranslator(CultureInfo sourceCulture, CultureInfo targetCulture)
    {
        this.sourceCulture = sourceCulture;
        this.targetCulture = targetCulture;

        splitRegexForSource = GetSplitRegex(this.sourceCulture);
        splitRegexForTarget = GetSplitRegex(this.targetCulture);
    }

    /// <summary>
    /// Create a new <see cref="NumberTranslator"/>.
    /// </summary>
    /// <param name="sourceCulture">source culture</param>
    /// <param name="targetCulture">target culture</param>
    /// <returns>Number translator for target culture</returns>
    public static NumberTranslator Create(CultureInfo sourceCulture, CultureInfo targetCulture)
    {
        ArgumentNullException.ThrowIfNull(sourceCulture);

        ArgumentNullException.ThrowIfNull(targetCulture);

        return new NumberTranslator(sourceCulture, targetCulture);
    }

    /// <summary>
    /// Translate from source to target culture.
    /// </summary>
    /// <param name="input">input string to translate</param>
    /// <returns>translated string</returns>
    public string Translate(string input)
    {
        return Translate(input, sourceCulture, targetCulture, splitRegexForSource);
    }

    /// <summary>
    /// Translate from target to source culture.
    /// </summary>
    /// <param name="input">input string to translate back to source culture</param>
    /// <returns>source culture string</returns>
    public string TranslateBack(string input)
    {
        return Translate(input, targetCulture, sourceCulture, splitRegexForTarget);
    }

    private static string Translate(string input, CultureInfo cultureFrom, CultureInfo cultureTo, Regex splitRegex)
    {
        var outputBuilder = new StringBuilder();
        var hexRegex = new Regex(@"(?:(0x[\da-fA-F]+))");

        var hexTokens = hexRegex.Split(input);

        foreach (var hexToken in hexTokens)
        {
            if (hexToken.StartsWith("0x", StringComparison.InvariantCultureIgnoreCase))
            {
                // Mages engine has issues processing large hex number (larger than 7 hex digits + 0x prefix = 9 characters). So we convert it to decimal and pass it to the engine.
                if (hexToken.Length > 9)
                {
                    try
                    {
                        var num = Convert.ToInt64(hexToken, 16);
                        var numStr = num.ToString(cultureFrom);
                        outputBuilder.Append(numStr);
                    }
                    catch (Exception)
                    {
                        outputBuilder.Append(hexToken);
                    }
                }
                else
                {
                    outputBuilder.Append(hexToken);
                }

                continue;
            }

            var tokens = splitRegex.Split(hexToken);
            foreach (var token in tokens)
            {
                var leadingZeroCount = 0;

                // Count leading zero characters.
                foreach (var c in token)
                {
                    if (c != '0')
                    {
                        break;
                    }

                    leadingZeroCount++;
                }

                // number is all zero characters. no need to add zero characters at the end.
                if (token.Length == leadingZeroCount)
                {
                    leadingZeroCount = 0;
                }

                decimal number;

                outputBuilder.Append(
                    decimal.TryParse(token, NumberStyles.Number, cultureFrom, out number)
                    ? (new string('0', leadingZeroCount) + number.ToString(cultureTo))
                    : token.Replace(cultureFrom.TextInfo.ListSeparator, cultureTo.TextInfo.ListSeparator));
            }
        }

        return outputBuilder.ToString();
    }

    private static Regex GetSplitRegex(CultureInfo culture)
    {
        var splitPattern = $"((?:\\d|{Regex.Escape(culture.NumberFormat.NumberDecimalSeparator)}";
        if (!string.IsNullOrEmpty(culture.NumberFormat.NumberGroupSeparator))
        {
            splitPattern += $"|{Regex.Escape(culture.NumberFormat.NumberGroupSeparator)}";
        }

        splitPattern += ")+)";
        return new Regex(splitPattern);
    }
}