/// <summary>Creates (or finds if pre-existing) a shortening for the specified URL, returning its key</summary>
/// <param name="url">The URL to shorten</param>
/// <returns>The key for the specified URL</returns>
public async Task <string> CreateUrlShortening(string url)
{
if (string.IsNullOrWhiteSpace(url))
{
throw new ArgumentException("Invalid (null or whitespace) URL");
}
else if (url.Length > _settings.MaxUrlLength)
{
throw new ArgumentException("Invalid URL (max supported length is " + _settings.MaxUrlLength + ")");
}
url = url.ToLower();
int urlHashCode = url.GetStableHashCode();
if (_settings.ValidateUrls && !UrlUtility.IsUrlValid(url))
{
throw new ArgumentException("Invalid URL");
}
object returnValue = null;
using (var connection = new NpgsqlConnection(_settings.RepositoryConnectionString))
{
await connection.OpenAsync();
using (var command = connection.CreateCommand())
{
command.CommandType = CommandType.Text;
command.CommandText = $@"SELECT urls.""CreateUrlShortening""(@url, @urlHashCode);";
command.Parameters.Add(new NpgsqlParameter("url", NpgsqlDbType.Text)
{
Value = url
});
command.Parameters.Add(new NpgsqlParameter("urlHashCode", NpgsqlDbType.Integer)
{
Value = urlHashCode
});
returnValue = await command.ExecuteScalarAsync();
}
}
if (returnValue == DBNull.Value)
{
return(null);
}
return(UrlUtility.ConvertIdToKey((long)returnValue));
}