using Discord;
using Discord.WebSocket;
using NadekoBot.Common.ModuleBehaviors;
using NadekoBot.Extensions;
using Serilog;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

namespace NadekoBot.Services
{
    public class StatsService : IStatsService, IReadyExecutor, INService, IDisposable
    {
        private readonly Process _currentProcess = Process.GetCurrentProcess();
        private readonly DiscordSocketClient _client;
        private readonly IBotCredentials _creds;
        private readonly DateTime _started;

        public const string BotVersion = "3.0.13";
        public string Author => "Kwoth#2452";
        public string Library => "Discord.Net";
        public double MessagesPerSecond => MessageCounter / GetUptime().TotalSeconds;

        private long _textChannels;
        public long TextChannels => Interlocked.Read(ref _textChannels);
        private long _voiceChannels;
        public long VoiceChannels => Interlocked.Read(ref _voiceChannels);
        private long _messageCounter;
        public long MessageCounter => Interlocked.Read(ref _messageCounter);
        private long _commandsRan;
        public long CommandsRan => Interlocked.Read(ref _commandsRan);

        private readonly Timer _botlistTimer;
        private readonly IHttpClientFactory _httpFactory;

        public StatsService(DiscordSocketClient client, CommandHandler cmdHandler,
            IBotCredentials creds, IHttpClientFactory factory)
        {
            _client = client;
            _creds = creds;
            _httpFactory = factory;

            _started = DateTime.UtcNow;
            _client.MessageReceived += _ => Task.FromResult(Interlocked.Increment(ref _messageCounter));
            cmdHandler.CommandExecuted += (_, e) => Task.FromResult(Interlocked.Increment(ref _commandsRan));

            _client.ChannelCreated += (c) =>
            {
                var _ = Task.Run(() =>
                {
                    if (c is ITextChannel)
                        Interlocked.Increment(ref _textChannels);
                    else if (c is IVoiceChannel)
                        Interlocked.Increment(ref _voiceChannels);
                });

                return Task.CompletedTask;
            };

            _client.ChannelDestroyed += (c) =>
            {
                var _ = Task.Run(() =>
                {
                    if (c is ITextChannel)
                        Interlocked.Decrement(ref _textChannels);
                    else if (c is IVoiceChannel)
                        Interlocked.Decrement(ref _voiceChannels);
                });

                return Task.CompletedTask;
            };

            _client.GuildAvailable += (g) =>
            {
                var _ = Task.Run(() =>
                {
                    var tc = g.Channels.Count(cx => cx is ITextChannel);
                    var vc = g.Channels.Count - tc;
                    Interlocked.Add(ref _textChannels, tc);
                    Interlocked.Add(ref _voiceChannels, vc);
                });
                return Task.CompletedTask;
            };

            _client.JoinedGuild += (g) =>
            {
                var _ = Task.Run(() =>
                {
                    var tc = g.Channels.Count(cx => cx is ITextChannel);
                    var vc = g.Channels.Count - tc;
                    Interlocked.Add(ref _textChannels, tc);
                    Interlocked.Add(ref _voiceChannels, vc);
                });
                return Task.CompletedTask;
            };

            _client.GuildUnavailable += (g) =>
            {
                var _ = Task.Run(() =>
                {
                    var tc = g.Channels.Count(cx => cx is ITextChannel);
                    var vc = g.Channels.Count - tc;
                    Interlocked.Add(ref _textChannels, -tc);
                    Interlocked.Add(ref _voiceChannels, -vc);
                });

                return Task.CompletedTask;
            };

            _client.LeftGuild += (g) =>
            {
                var _ = Task.Run(() =>
                {
                    var tc = g.Channels.Count(cx => cx is ITextChannel);
                    var vc = g.Channels.Count - tc;
                    Interlocked.Add(ref _textChannels, -tc);
                    Interlocked.Add(ref _voiceChannels, -vc);
                });

                return Task.CompletedTask;
            };

            _botlistTimer = new Timer(async (state) =>
            {
                if (string.IsNullOrWhiteSpace(_creds.BotListToken))
                    return;
                try
                {
                    using (var http = _httpFactory.CreateClient())
                    {
                        using (var content = new FormUrlEncodedContent(
                            new Dictionary<string, string> {
                                    { "shard_count",  _creds.TotalShards.ToString()},
                                    { "shard_id", client.ShardId.ToString() },
                                    { "server_count", client.Guilds.Count().ToString() }
                            }))
                        {
                            content.Headers.Clear();
                            content.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
                            http.DefaultRequestHeaders.Add("Authorization", _creds.BotListToken);

                            using (await http.PostAsync(new Uri($"https://discordbots.org/api/bots/{client.CurrentUser.Id}/stats"), content).ConfigureAwait(false)) { }
                        }
                    }
                }
                catch (Exception ex)
                {
                    Log.Error(ex, "Error ");
                    // ignored
                }
            }, null, TimeSpan.FromMinutes(5), TimeSpan.FromHours(1));
        }

        public TimeSpan GetUptime() =>
            DateTime.UtcNow - _started;

        public string GetUptimeString(string separator = ", ")
        {
            var time = GetUptime();
            return $"{time.Days} days{separator}{time.Hours} hours{separator}{time.Minutes} minutes";
        }

        public Task OnReadyAsync()
        {
            var guilds = _client.Guilds;
            _textChannels = guilds.Sum(g => g.Channels.Count(cx => cx is ITextChannel));
            _voiceChannels = guilds.Sum(g => g.Channels.Count(cx => cx is IVoiceChannel));
            return Task.CompletedTask;
        }

        public double GetPrivateMemory()
        {
            _currentProcess.Refresh();
            return _currentProcess.PrivateMemorySize64 / (double)1.MiB();
        }

        public void Dispose()
        {
            _currentProcess.Dispose();
            GC.SuppressFinalize(this);
        }
    }
}