using System;
using System.Collections.Generic;
using System.Data;
using global::System.IO;
using System.Linq;
using global::System.Net;
using global::Newtonsoft.Json.Linq;

namespace Pilz.Networking
{
    public abstract class ConnectionManagerBase
    {
        private const int HEADER_LENGTH = 12;
        private bool listening = false;
        private readonly Dictionary<int, Dictionary<int, byte[]>> dicData = new Dictionary<int, Dictionary<int, byte[]>>();

        public int Port { get; private set; }
        public bool UseAssemblyQualifiedName { get; set; } = false;

        public event RetriveDataEventHandler RetriveData;

        public delegate void RetriveDataEventHandler(ConnectionManagerBase manager, string senderIP, string cmd, object content);

        public bool IsListening
        {
            get
            {
                return listening;
            }

            protected set
            {
                listening = value;
            }
        }

        public ConnectionManagerBase(int port)
        {
            Port = port;
        }

        ~ConnectionManagerBase()
        {
            Stop();
        }

        public abstract void Start();
        public abstract void Stop();
        protected abstract void SendData(IPEndPoint endPoint, byte[] data);
        protected abstract int GetBufferSize();

        public virtual void Send(string empfängerIP, string cmd)
        {
            Send(empfängerIP, cmd, string.Empty);
        }

        public virtual void Send(string empfängerIP, string cmd, string info)
        {
            Send(empfängerIP, cmd, info);
        }

        private void RaiseRetriveData(string senderIP, string cmd, object content)
        {
            RetriveData?.Invoke(this, senderIP, cmd, content);
        }

        protected void ProcessRetrivedData(string senderIP, byte[] buf)
        {
            int readInteger(int index) => buf[index] << 24 | buf[index + 1] << 16 | buf[index + 2] << 8 | buf[index + 3];
            int dataID = readInteger(0);
            int packageID = readInteger(4);
            int packageCount = readInteger(8);
            bool resolveData = true;

            // Remember data
            var data = buf.Skip(HEADER_LENGTH).ToArray();
            Dictionary<int, byte[]> dicMyData;
            if (dicData.ContainsKey(dataID))
            {
                dicMyData = dicData[dataID];
                if (dicMyData.ContainsKey(packageID))
                {
                    dicMyData[packageID] = data;
                }
                else
                {
                    dicMyData.Add(packageID, data);
                }
            }
            else
            {
                dicMyData = new Dictionary<int, byte[]>() { { packageID, data } };
                dicData.Add(dataID, dicMyData);
            }

            if (dicMyData.Count < packageCount)
            {
                resolveData = false;
            }

            // Resolve Data
            if (resolveData)
            {
                if (dicMyData is null)
                {
                    dicMyData = dicData[dataID];
                }

                var myData = new List<byte>();
                foreach (var kvp in dicMyData.OrderBy(n => n.Key))
                    myData.AddRange(kvp.Value);
                dicMyData.Remove(dataID);
                object content = null;
                string cmd = string.Empty;
                try
                {
                    var res = DecodeFromBytes(myData.ToArray());
                    cmd = res.cmd;
                    content = res.content;
                }
                catch (Exception ex)
                {
                }

                RaiseRetriveData(senderIP, cmd, content);
            }
        }

        private Random send_Rnd = new Random();
        public void Send(string empfängerIP, string cmd, object content)
        {
            var ep = new IPEndPoint(NetworkFeatures.GetIPFromHost(empfängerIP).MapToIPv4(), Port);
            var finalBuffer = new List<byte>();
            int maxBufferSize = GetBufferSize();
            int maxDataSize = maxBufferSize - HEADER_LENGTH;
            var data = EncodeToBytes(cmd, content, UseAssemblyQualifiedName);
            int dataID = send_Rnd.Next();

            // Some methods for later user
            void send() => SendData(ep, finalBuffer.ToArray());
            void addInteger(int value) => finalBuffer.AddRange(new byte[] { (byte)((value >> 24) & 0xFF), (byte)((value >> 16) & 0xFF), (byte)((value >> 8) & 0xFF), (byte)(value & 0xFF) });
            void addHeader(int packageID, int packagesCount)
            {
                addInteger(dataID); // Data ID
                addInteger(packageID); // Package ID
                addInteger(packagesCount); // Packages Count
            };

            // Send data (this if statement and else content might be useless)
            if (data.Length > maxDataSize)
            {
                int curIndex = 0;
                int curID = 0;
                int packagesCount = (int)Math.Ceiling(data.Length / (double)maxDataSize);
                while (curIndex < data.Length)
                {
                    finalBuffer.Clear();
                    addHeader(curID, packagesCount);
                    for (int i = 1, loopTo = maxDataSize; i <= loopTo; i++)
                    {
                        if (curIndex < data.Length)
                        {
                            finalBuffer.Add(data[curIndex]);
                            curIndex += 1;
                        }
                    }

                    send();
                    curID += 1;
                }
            }
            else
            {
                addHeader(0, 1);
                finalBuffer.AddRange(data);
                send();
            }
        }

        private static byte[] EncodeToBytes(string cmd, object content, bool useAssemblyQualifiedName)
        {
            var ms = new MemoryStream();
            var bw = new BinaryWriter(ms);
            var obj = new JObject();

            // Write header
            obj["Cmd"] = cmd;
            obj["ContentType"] = useAssemblyQualifiedName ? content?.GetType()?.AssemblyQualifiedName : content?.GetType()?.ToString();

            // Content
            obj["Content"] = JToken.FromObject(content);

            // Write Json to MemoryStream
            bw.Write(System.Text.Encoding.Default.GetBytes(obj.ToString()));

            // Get Buffer Bytes
            var buf = ms.ToArray();
            ms.Close();
            return buf;
        }

        private static (string cmd, object content) DecodeFromBytes(byte[] buf)
        {
            string contentstring = System.Text.Encoding.Default.GetString(buf);
            object content = null;
            var contentobj = JObject.Parse(contentstring);
            string cmd = (string)contentobj["Cmd"];
            string contenttypestring = (string)contentobj["ContentType"];
            var contentlinq = contentobj["Content"];
            if (!string.IsNullOrEmpty(contenttypestring))
            {
                var contenttype = Type.GetType(contenttypestring);
                content = contentlinq.ToObject(contenttype);
            }

            return (cmd, content);
        }
    }
}