using System.Text.RegularExpressions;

namespace StitcherApi.Services.Utilities;

public static class CoordinateHelper
{
    private static readonly Regex CoordRegex = new(@"([A-Z]+)(\d+)", RegexOptions.Compiled);

    public static (int startRow, int endRow, int startCol, int endCol) ParseCanvasRect(
        string rectStr
    )
    {
        var parts = rectStr.Split(':');
        if (parts.Length != 2)
        {
            throw new ArgumentException("Invalid canvas_rect format. Expected format 'A1:H12'.");
        }

        var (r1, c1) = ParseSingleCoordinate(parts[0]);
        var (r2, c2) = ParseSingleCoordinate(parts[1]);

        return (Math.Min(r1, r2), Math.Max(r1, r2), Math.Min(c1, c2), Math.Max(c1, c2));
    }

    public static string IndexToRow(int index)
    {
        index++;
        var result = "";
        while (index > 0)
        {
            int remainder = (index - 1) % 26;
            result = (char)('A' + remainder) + result;
            index = (index - 1) / 26;
        }
        return result;
    }

    private static (int row, int col) ParseSingleCoordinate(string coord)
    {
        var match = CoordRegex.Match(coord);
        if (!match.Success)
        {
            throw new ArgumentException($"Invalid coordinate format: '{coord}'.");
        }

        string rowStr = match.Groups[1].Value;
        int col = int.Parse(match.Groups[2].Value) - 1;
        return (RowToIndex(rowStr), col);
    }

    private static int RowToIndex(string rowStr)
    {
        int index = 0;
        foreach (char c in rowStr)
        {
            index = index * 26 + (c - 'A' + 1);
        }
        return index - 1;
    }
}