using System;
using System.Collections.Generic;
using System.IO;

namespace Workplace
{
    public class BlackList
    {
        /// <summary>
        /// List of forbidden black listed items
        /// </summary>
        public IList<string> Codes;

        /// <summary>
        /// Default constructor
        /// </summary>
        public BlackList()
        {
            Codes = new List<string>();
        }

        /// <summary>
        /// Constructor from a list of black listed codes
        /// </summary>
        /// <param name="codes"></param>
        public BlackList(IList<string> codes)
        {
            Codes = codes;
        }

        /// <summary>
        /// Read a black listed codes from a file.
        /// Each line of text contains one item/code.
        /// </summary>
        /// <param name="fileName">File name</param>
        /// <returns>BlackList object with codes when successful or null</returns>
        public static BlackList FromFile(string fileName)
        {
            try
            {
                IList<string> codes = new List<string>();

                TextReader rdr = new StreamReader(fileName);

                string line = rdr.ReadLine();
                while (!string.IsNullOrEmpty(line))
                {
                    codes.Add(line);
                    line = rdr.ReadLine();
                }

                return new BlackList(codes);
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>
        /// Write a black listed codes to a file.
        /// Each line of text contains one item/code.
        /// </summary>
        /// <param name="fileName">File name</param>
        /// <returns>true = successful</returns>
        public bool ToFile(string fileName)
        {
            try
            {
                using (TextWriter wrtr = new StreamWriter(fileName))
                {
                    foreach (var code in Codes)
                    {
                        wrtr.WriteLine(code);
                    }
                }

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }
    }
}