Can someone translate this code from C# to PHP?

[Remoh]

private string Reflect(string mirrorId)
{
mirrorId = mirrorId.Remove(0, 1);
StringBuilder fileId = new StringBuilder();
foreach (char c in mirrorId)
{
if (c >= '0' && c <= '9')
{
fileId.Append(c);
}
else if (c == '-')
{
fileId.Append("52");
}
else if (c == '_')
{
fileId.Append("53");
}
else
{
if (char.ToLower(c) < 'f')
{
fileId.Append('0');
}
fileId.Append(((char.ToLower(c) - 'a') * 2) + Convert.ToInt32(char.IsUpper(c)));
}
}
return fileId.ToString();
}

I think it's possible. Thanks in advance