using System.Linq;
using System.Text;

namespace Yavsc.Abstract.FileSystem
{
    public static class FileSystemHelpers
    {
        public static bool IsValidYavscPath(this string path)
        {
            if (string.IsNullOrEmpty(path)) return true;
            foreach (var name in path.Split('/'))
            {
                if (!IsValidDirectoryName(name) || name.Equals("..") || name.Equals("."))
                        return false;
            }
            if (path[path.Length-1]==FileSystemConstants.RemoteDirectorySeparator) return false;
            return true;
        }
        public static bool IsValidDirectoryName(this string name)
        {
            return !name.Any(c => !FileSystemConstants.ValidFileNameChars.Contains(c));
        }
        // Ensure this path is canonical,
        // No "dirto/./this", neither "dirt/to/that/"
        // no .. and each char must be listed as valid in constants

        public static string FilterFileName(string fileName)
        {
            if (fileName==null) return null;
            StringBuilder sb = new StringBuilder();
            foreach (var c in fileName)
            {
                if (FileSystemConstants.ValidFileNameChars.Contains(c))
                    sb.Append(c);
                else sb.Append('_');
            }
           return sb.ToString();
        }
    }

    public static  class FileSystemConstants
    {
        public const char RemoteDirectorySeparator = '/';
        public static char[] ValidFileNameChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-=_~. ".ToCharArray();
    }
}