using System.Text.RegularExpressions;

namespace GoogleSheetsScheduleImport;

public static class SpreadsheetId
{
    private static readonly Regex IdRegex = new(
        @"/spreadsheets/d/([a-zA-Z0-9-_]+)",
        RegexOptions.Compiled | RegexOptions.CultureInvariant);

    /// <summary>
    /// Extracts spreadsheet id from a full Google Sheets URL or returns the string if it already looks like an id.
    /// </summary>
    public static string FromUrlOrId(string input)
    {
        var trimmed = input.Trim();
        var m = IdRegex.Match(trimmed);
        if (m.Success)
            return m.Groups[1].Value;
        if (trimmed.Length > 20 && !trimmed.Contains('/') && !trimmed.Contains(':'))
            return trimmed;
        throw new ArgumentException(
            "Expected a Google Sheets URL (…/spreadsheets/d/{id}/…) or a raw spreadsheet id.", nameof(input));
    }
}