using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Xml;

namespace AIPractice.Shared.Labels
{
    public class LabelContainer
    {
        private const string _encryptKey = "VINNO123";

        private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

        /// <summary>
        /// All labels included in this container.
        /// </summary>
        public IList<RootLabel> Labels { get; } = new List<RootLabel>();

        public static LabelContainer FromXml(string xmlContent)
        {
            var container = new LabelContainer();
            using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(xmlContent)))
            {
                using (var r = XmlReader.Create(ms))
                {
                    r.Read();
                    while (r.NodeType == XmlNodeType.Element && r.Name == nameof(RootLabel) ||
                           r.ReadToDescendant(nameof(RootLabel)))
                    {
                        container.Labels.Add(RootLabel.FromXml(r.ReadOuterXml()));
                    }

                    return container;
                }
            }
        }

        public string ToXml()
        {
            var sb = new StringBuilder();
            sb.Append($"<{nameof(LabelContainer)}>");
            foreach (var label in Labels)
            {
                sb.Append(label.ToXml());
            }
            sb.Append($"</{nameof(LabelContainer)}>");
            return sb.ToString();
        }


        private static byte[] Encode(string data)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(_encryptKey.Substring(0, 8));
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Encoding.UTF8.GetBytes(data);
                DESCryptoServiceProvider dcsp = new DESCryptoServiceProvider();
                using (MemoryStream ms = new MemoryStream())
                {
                    using (var cs = new CryptoStream(ms, dcsp.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write))
                    {
                        cs.Write(inputByteArray, 0, inputByteArray.Length);
                        cs.FlushFinalBlock();
                        return ms.ToArray();
                    }
                }
            }
            catch
            {
                return new byte[0];
            }
        }


        private static string Decode(byte[] data)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(_encryptKey);
                byte[] rgbIV = Keys;
                byte[] inputByteArray = data;
                DESCryptoServiceProvider dcsp = new DESCryptoServiceProvider();
                using (MemoryStream ms = new MemoryStream())
                {
                    using (var cs = new CryptoStream(ms, dcsp.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write))
                    {
                        cs.Write(inputByteArray, 0, inputByteArray.Length);
                        cs.FlushFinalBlock();
                        return Encoding.UTF8.GetString(ms.ToArray());
                    }
                }
            }
            catch
            {
                return string.Empty;
            }
        }


        public void Save(string fileName)
        {
            var ext = Path.GetExtension(fileName);
            if (ext.ToLower() == ".xml")
            {
                File.WriteAllText(fileName, ToXml());
            }
            else
            {
                var data = Encode(ToXml());
                File.WriteAllBytes(fileName, data);
            }
        }


        public static LabelContainer Open(string fileName)
        {
            var ext = Path.GetExtension(fileName);
            if (ext.ToLower() == ".xml")
            {
                return FromXml(File.ReadAllText(fileName));
            }
            else
            {
                var data = File.ReadAllBytes(fileName);
                var content = Decode(data);
                return FromXml(content);
            }
        }

    }
}