class CsvReader : IEnumerable
{
    IEnumerator _enumerator;

    public CsvReader(string path, string headerToReturn)
    {
        _enumerator = new CsvEnumerator(path, headerToReturn);
    }

    public IEnumerator GetEnumerator()
    {
        return _enumerator;
    }


    static void Main(string[] args)
    {
        CsvReader csvReader = new CsvReader("imdb.csv", "URL");

        foreach (string s in csvReader)
        {
            Console.WriteLine(s);
        }

        Console.WriteLine();
    }
}

class CsvEnumerator : IEnumerator
{
    private FileStream fs;
    private StreamReader sr;
    private string line, headerToReturn;
    private char delimiter = ',';
    private int headerPosition = -1;

    public CsvEnumerator(string path, string headerToReturn)
    {
        this.headerToReturn = headerToReturn;

        fs = File.OpenRead(path);

        if (!fs.CanRead)
            throw new IOException("File cannot be read: " + path);

        sr = new StreamReader(fs);

        if (headerToReturn == null)
        {
            Console.WriteLine("Warning!: Header not specified. Returning all of the text.");
            return;
        }

        if (this.MoveNext())
        {
            string headerStr = (string)this.Current;

            string[] headers = headerStr.Split(delimiter);

            for (int i = 0; i < headers.Length; i++)
            {
                if (headers[i].Equals(headerToReturn))
                    headerPosition = i;
            }
        }
    }

    public object Current
    {
        get {
            if(headerPosition != -1)
                return line.Split(delimiter)[headerPosition];
            else
                return line;
        }
    }

    public bool MoveNext()
    {
        line = sr.ReadLine();
        return line != null;
    }

    public void Reset()
    {
        if (sr != null)
            sr.Close();

        sr = new StreamReader(fs);
    }
}