// /**
//  * File: Crawler.cs
//  * Author: haraldwolff
//  *
//  * This file and it's content is copyrighted by the Author and / or copyright holder.
//  * Any use wihtout proper permission is illegal and may lead to legal actions.
//  *
//  *
//  **/
using System;
using ln.skyscanner.threads;
using System.Net;
using System.Collections.Generic;
using System.IO;
using ln.logging;
using ln.types;
using System.Linq;
using ln.types.serialize;
using ln.skyscanner.entities;
using System.Net.NetworkInformation;
using ln.snmp;
using ln.snmp.endpoint;
using ln.snmp.rfc1213;
using ln.perfdb;
using ln.perfdb.storage;
using ln.skyscanner.check;
using System.Threading;

namespace ln.skyscanner.crawl
{
    public class Crawler : IPerfFileProvider
    {
        public String BasePath { get; set; }
        public String PerfPath => Path.Combine(BasePath, "perfdb");

        bool stopping;

        Pool crawlThreadPool = new Pool();

        public PoolThreadState[] ThreadStates => crawlThreadPool.ThreadStates;
        public int QueuedJobs => crawlThreadPool.QueuedJobs;

        public DiskObject<CrawlPool> _CrawlPool;
        public CrawlPool CrawlPool => _CrawlPool.Instance;

        public SNMPEngine SNMPEngine { get; }

        Thread threadChecker;

        public Crawler()
        {
            BasePath = Path.GetFullPath("./crawler");

            if (!Directory.Exists(BasePath))
                Directory.CreateDirectory(BasePath);
            if (!Directory.Exists(PerfPath))
                Directory.CreateDirectory(PerfPath);


            SNMPEngine = new SNMPEngine();

            _CrawlPool = new DiskObject<CrawlPool>(String.Format("{0}/pool",BasePath));

            crawlThreadPool.NumThreads = 12;

            threadChecker = new Thread(Checker);
            threadChecker.Start();
        }

        public void Stop()
        {
            stopping = true;
            crawlThreadPool.Close();
            SNMPEngine.Close();
            _CrawlPool.Save();
        }

        public void Enqueue(JobDelegate job)
        {
            crawlThreadPool.Enqueue(job);
        }

        public void Crawl(IPAddress host)
        {
            crawlThreadPool.Enqueue(() => crawlHost(host));
        }

        private void crawlHost(IPAddress host)
        {
            Ping ping = new Ping();
            PingReply pingReply = ping.Send(host,500);

            if (pingReply.Status != IPStatus.Success)
            {
                Logging.Log(LogLevel.INFO, "Host not reachable: {0} {1}", host, pingReply.Status);
            }
            else
            {
                //SnmpV1Endpoint v1endpoint = new SnmpV1Endpoint(engine, new IPEndPoint(IPAddress.Parse("10.75.1.10"), 161), "ByFR4oW98hap");
                //SnmpV2Endpoint v2endpoint = new SnmpV2Endpoint(engine, new IPEndPoint(IPAddress.Parse("10.113.254.4"), 161), "ghE7wUmFPoPpkRno");

                USMEndpoint v3endpoint = new USMEndpoint(SNMPEngine, new IPEndPoint(host, 161));
                v3endpoint.AuthMethod = SnmpV3AuthMethod.SHA;
                v3endpoint.AuthKeyPhrase = "qVy3hnZJ2fov";
                v3endpoint.Username = "skytron";

                try
                {
                    RFC1213.Interface[] interfaces = RFC1213.GetInterfaces(v3endpoint);

                    foreach (RFC1213.Interface netIf in interfaces)
                    {
                        Logging.Log(LogLevel.INFO, "Interface: {0}", netIf);

                        foreach (CIDR ip in netIf.IPAddresses)
                        {
                            Subnet subnet = CrawlPool.GetSubnet(ip.Network);
                            if ((DateTime.Now - subnet.LastScanned).Hours >= 1)
                            {
                                Enqueue(() => crawlSubnet(ip.Network));
                            }
                        }
                    }
                }
                catch (TimeoutException)
                {
                    Logging.Log(LogLevel.INFO, "Host: {0} SNMP communication timed out.", host);
                }

            }
        }

        public void crawlSubnet(CIDR subnet)
        {
            Ping ping = new Ping();

            Subnet sub = CrawlPool.GetSubnet(subnet);
            sub.LastScanned = DateTime.Now;

            Logging.Log(LogLevel.INFO, "Scanning {0}", subnet);

            foreach (CIDR ip in subnet)
            {
                long roundTripTime = 0;
                int success = 0;

                for (int n = 0; n < 4; n++)
                {
                    PingReply reply = ping.Send(ip,250);
                    if (reply.Status == IPStatus.Success)
                    {
                        success++;
                        roundTripTime += reply.RoundtripTime;
                    }
                }

                if (success > 0)
                {
                    roundTripTime /= success;
                    Logging.Log(LogLevel.INFO, "IP {0} reachable ({1}/10) {2}ms", ip, success, roundTripTime);

                    Node node = CrawlPool.GetNode(ip);
                    if ((DateTime.Now - node.LastSeen ).Hours > 0)
                    {
                        Enqueue(() => crawlHost(ip));
                    }

                    string checkID = Hostalive.CalcCheckName(node);
                    if (!CrawlPool.Checks.ContainsKey(checkID))
                    {
                        Hostalive hostalive = new Hostalive(node);
                        CrawlPool.Checks.Add(hostalive.CheckID, hostalive);
                    }

                }
                else
                {
                    Logging.Log(LogLevel.INFO, "IP {0} unreachable", ip);
                }
            }
        }


        /** Checks **/

        private void Checker()
        {
            while (!stopping)
            {
                DateTime now = DateTime.Now;

                Check[] checks = CrawlPool.Checks.Values.ToArray();
                if (checks.Length == 0)
                    Thread.Sleep(1000);

                foreach (Check check in checks)
                {
                    if (check.NextCheck <= now)
                    {
                        check.Mark();
                        Enqueue(() => check.Run(this));
                    }
                }
            }
        }


        /** PerfDB **/

        Dictionary<string, PerfFile> perfFiles = new Dictionary<string, PerfFile>();

        public PerfFile GetPerfFile(string name)
        {
            if (perfFiles.ContainsKey(name))
                return perfFiles[name];

            PerfFile perfFile = new PerfFile(Path.Combine(PerfPath, String.Format("{0}.perf", name)));
            perfFile.Open();

            perfFiles.Add(name, perfFile);

            if (perfFile.FirstSection == null)
            {
                PerfFile.PerfFileSection section = new PerfFile.PerfFileSection(perfFile, null, 1440, 60, AggregationMethod.AVERAGE);
                section = new PerfFile.PerfFileSection(perfFile, section, 1728, 300, AggregationMethod.AVERAGE);
                section = new PerfFile.PerfFileSection(perfFile, section, 2016, 900, AggregationMethod.AVERAGE);
                section = new PerfFile.PerfFileSection(perfFile, section, 1344, 3600, AggregationMethod.AVERAGE);
                section = new PerfFile.PerfFileSection(perfFile, section, 1344, 10800, AggregationMethod.AVERAGE);
            }
            return perfFile;
        }
    }
}