namespace QWERTYkez.ExcelProcessor;

internal static class CellAddressHelper
{
    const string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static readonly uint[] _powers = [1, 26, 676];

    public static uint ColumnLetterToIndex(string col)
    {
        uint index = 0;
        foreach (char ch in col)
        {
            char c = char.ToUpperInvariant(ch);
            if (c < 'A' || c > 'Z') return 0;
            index = index * 26 + (uint)(c - 'A' + 1);
        }
        return index;
    }

    public static string ColumnIndexToLetter(uint col)
    {
        if (col == 0) return "";
        uint n = col;
        char[] buf = new char[3];
        int idx = 0;
        while (n > 0)
        {
            n--;
            buf[idx++] = (char)('A' + (n % 26));
            n /= 26;
        }
        return new string(buf, 0, idx);
    }

    public static bool TryParseCellReference(string reference, out uint row, out uint col)
    {
        row = 0; col = 0;
        if (string.IsNullOrEmpty(reference)) return false;
        int i = 0;
        while (i < reference.Length && char.IsLetter(reference[i])) i++;
        if (i == 0) return false;
        string colPart = reference.Substring(0, i);
        string rowPart = reference.Substring(i);
        if (!uint.TryParse(rowPart, out row)) return false;
        col = CellAddressHelper.ColumnLetterToIndex(colPart);
        return true;
    }
}