/// <summary>
/// Formats the extension whitelist appropriate for storage in the Host setting
/// </summary>
/// <param name="additionalExtensions">A list of additionalExtensions to add to the current extensions</param>
/// <remarks><paramref name="additionalExtensions"/>case and '.' prefix will be corrected, and duplicates will be excluded from the string</remarks>
/// <returns>A String of the whitelist extensions formatted for storage as a Host setting</returns>
public string ToStorageString(IEnumerable <string> additionalExtensions)
{
IEnumerable <string> allExtensions = CombineLists(additionalExtensions);
var leadingDotRemoved = allExtensions.Select(ext => ext.Substring(1));
return(EscapedString.Combine(leadingDotRemoved));
}
/// <summary>
/// Initializes a new instance of the FileExtensionWhiteList class.
/// </summary>
/// <param name="extensionList">a comma seperated list of file extensions with no '.'</param>
/// <remarks><paramref name="extensionList"/>should match the format used in the FileExtensions Host setting specifically it
/// should not have an '.' in the extensions (e.g. txt,jpg,png,doc)</remarks>
public FileExtensionWhitelist(string extensionList)
{
_extensions = EscapedString.Seperate(extensionList.ToLowerInvariant()).Select(item => "." + item).ToList();
}