VolcanicAgenticCore/extensions/Volcanic.AgenticCore.Extensions.Mcp/ShellWords.cs

using System.Text;

namespace Volcanic.AgenticCore.Extensions.Mcp;

/// <summary>Splits a command-line fragment into argv the way a POSIX shell would, without expansion.</summary>
internal static class ShellWords
{
    /// <summary>Whitespace separates words; '…' is literal; "…" allows \" and \\. Backslashes elsewhere are kept (Windows paths).</summary>
    public static IReadOnlyList<string> Split(string text)
    {
        var words = new List<string>();
        var current = new StringBuilder();
        var inWord = false;
        char? quote = null;
        for (var i = 0; i < text.Length; i++)
        {
            var c = text[i];
            if (quote == '\'')
            {
                if (c == '\'') quote = null; else current.Append(c);
                continue;
            }
            if (quote == '"')
            {
                if (c == '"') quote = null;
                else if (c == '\\' && i + 1 < text.Length && text[i + 1] is '"' or '\\') current.Append(text[++i]);
                else current.Append(c);
                continue;
            }
            if (char.IsWhiteSpace(c))
            {
                if (inWord) { words.Add(current.ToString()); current.Clear(); inWord = false; }
                continue;
            }
            inWord = true;
            if (c is '"' or '\'') quote = c;
            else current.Append(c);
        }
        if (quote is { } open) throw new FormatException($"unterminated {open} quote");
        if (inWord) words.Add(current.ToString());
        return words;
    }
}