using System.Text;

namespace GoogleSheetsScheduleImport;

/// <summary>
/// Google Sheets cells can contain line breaks as LF/CR or Unicode line/paragraph separators.
/// Import text must be one logical line per occurrence.
/// </summary>
public static class TextNormalization
{
    public static string ForSheetCell(string? raw)
    {
        if (string.IsNullOrWhiteSpace(raw))
            return string.Empty;
        return CollapseWhitespace(Core.Utility.TextUtil.SanitizeInput(raw.Trim()));
    }

    public static string ForEmitLine(string? raw)
    {
        if (string.IsNullOrWhiteSpace(raw))
            return string.Empty;
        return CollapseWhitespace(Core.Utility.TextUtil.SanitizeInput(raw.Trim()));
    }

    private static string CollapseWhitespace(string s)
    {
        var sb = new StringBuilder(s.Length);
        var pendingSpace = false;
        foreach (var ch in s)
        {
            if (char.IsWhiteSpace(ch))
                pendingSpace = true;
            else
            {
                if (pendingSpace && sb.Length > 0)
                    sb.Append(' ');
                pendingSpace = false;
                sb.Append(ch);
            }
        }

        return sb.ToString().Trim();
    }
}