using Discord;
using Discord.WebSocket;
using NadekoBot.Common;
using NadekoBot.Common.Replacements;
using NadekoBot.Services.Database.Models;
using NadekoBot.Extensions;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using NadekoBot.Db;
using NadekoBot.Modules.Administration;
using Serilog;

namespace NadekoBot.Services
{
    public class GreetSettingsService : INService
    {
        private readonly DbService _db;

        public ConcurrentDictionary<ulong, GreetSettings> GuildConfigsCache { get; }
        private readonly DiscordSocketClient _client;
        
        private GreetGrouper<IGuildUser> greets = new GreetGrouper<IGuildUser>();
        private GreetGrouper<IGuildUser> byes = new GreetGrouper<IGuildUser>();
        private readonly BotConfigService _bss;
        private readonly IEmbedBuilderService _eb;
        public bool GroupGreets => _bss.Data.GroupGreets;

        public GreetSettingsService(DiscordSocketClient client,
            Bot bot,
            DbService db,
            BotConfigService bss,
            IEmbedBuilderService eb)
        {
            _db = db;
            _client = client;
            _bss = bss;
            _eb = eb;

            GuildConfigsCache = new ConcurrentDictionary<ulong, GreetSettings>(
                bot.AllGuildConfigs
                    .ToDictionary(g => g.GuildId, GreetSettings.Create));

            _client.UserJoined += UserJoined;
            _client.UserLeft += UserLeft;

            bot.JoinedGuild += Bot_JoinedGuild;
            _client.LeftGuild += _client_LeftGuild;
            
            _client.GuildMemberUpdated += ClientOnGuildMemberUpdated;
        }

        private Task ClientOnGuildMemberUpdated(SocketGuildUser oldUser, SocketGuildUser newUser)
        {
            // if user is a new booster
            // or boosted again the same server
            if ((oldUser is { PremiumSince: null } && newUser is { PremiumSince: not null })
                || (oldUser?.PremiumSince is DateTimeOffset oldDate 
                    && newUser?.PremiumSince is DateTimeOffset newDate
                    && newDate > oldDate))
            {
                var conf = GetOrAddSettingsForGuild(newUser.Guild.Id);
                if (!conf.SendBoostMessage) return Task.CompletedTask;

                _ = Task.Run(TriggerBoostMessage(conf, newUser));
            }

            return Task.CompletedTask;
        }

        private Func<Task> TriggerBoostMessage(GreetSettings conf, SocketGuildUser user) => async () =>
        {
            var channel = user.Guild.GetTextChannel(conf.BoostMessageChannelId);
            if (channel is null)
                return;

            if (string.IsNullOrWhiteSpace(conf.BoostMessage))
                return;

            var toSend = SmartText.CreateFrom(conf.BoostMessage);
            var rep = new ReplacementBuilder()
                .WithDefault(user, channel, user.Guild, _client)
                .Build();

            try
            {
                var toDelete = await channel.SendAsync(rep.Replace(toSend));
                if (conf.BoostMessageDeleteAfter > 0)
                {
                    toDelete.DeleteAfter(conf.BoostMessageDeleteAfter);
                }
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Error sending boost message.");
            }
        };

        private Task _client_LeftGuild(SocketGuild arg)
        {
            GuildConfigsCache.TryRemove(arg.Id, out _);
            return Task.CompletedTask;
        }

        private Task Bot_JoinedGuild(GuildConfig gc)
        {
            GuildConfigsCache.AddOrUpdate(gc.GuildId,
                GreetSettings.Create(gc),
                delegate { return GreetSettings.Create(gc); });
            return Task.CompletedTask;
        }

        private Task UserLeft(IGuildUser user)
        {
            var _ = Task.Run(async () =>
            {
                try
                {
                    var conf = GetOrAddSettingsForGuild(user.GuildId);

                    if (!conf.SendChannelByeMessage) return;
                    var channel = (await user.Guild.GetTextChannelsAsync().ConfigureAwait(false)).SingleOrDefault(c => c.Id == conf.ByeMessageChannelId);

                    if (channel is null) //maybe warn the server owner that the channel is missing
                        return;
                    
                    if (GroupGreets)
                    {
                        // if group is newly created, greet that user right away,
                        // but any user which joins in the next 5 seconds will
                        // be greeted in a group greet
                        if (byes.CreateOrAdd(user.GuildId, user))
                        {
                            // greet single user
                            await ByeUsers(conf, channel, new[] {user});
                            var groupClear = false;
                            while(!groupClear)
                            {
                                await Task.Delay(5000).ConfigureAwait(false);
                                groupClear = byes.ClearGroup(user.GuildId, 5, out var toBye);
                                await ByeUsers(conf, channel, toBye);
                            }
                        }
                    }
                    else
                    {
                        await ByeUsers(conf, channel, new[] {user});
                    }
                }
                catch
                {
                    // ignored
                }
            });
            return Task.CompletedTask;
        }

        public string GetDmGreetMsg(ulong id)
        {
            using (var uow = _db.GetDbContext())
            {
                return uow.GuildConfigsForId(id, set => set)?.DmGreetMessageText;
            }
        }

        public string GetGreetMsg(ulong gid)
        {
            using (var uow = _db.GetDbContext())
            {
                return uow.GuildConfigsForId(gid, set => set).ChannelGreetMessageText;
            }
        }

        private Task ByeUsers(GreetSettings conf, ITextChannel channel, IUser user)
            => ByeUsers(conf, channel, new[] {user});
        private async Task ByeUsers(GreetSettings conf, ITextChannel channel, IEnumerable<IUser> users)
        {
            if (!users.Any())
                return;
            
            var rep = new ReplacementBuilder()
                .WithChannel(channel)
                .WithClient(_client)
                .WithServer(_client, (SocketGuild) channel.Guild)
                .WithManyUsers(users)
                .Build();

            var text = SmartText.CreateFrom(conf.ChannelByeMessageText);
            text = rep.Replace(text);
            try
            {
                var toDelete = await channel.SendAsync(text);
                if (conf.AutoDeleteByeMessagesTimer > 0)
                {
                    toDelete.DeleteAfter(conf.AutoDeleteByeMessagesTimer);
                }
            }
            catch (Exception ex)
            {
                Log.Warning(ex, "Error embeding bye message");
            }
        }
        
        private Task GreetUsers(GreetSettings conf, ITextChannel channel, IGuildUser user)
            => GreetUsers(conf, channel, new[] {user});
        
        private async Task GreetUsers(GreetSettings conf, ITextChannel channel, IEnumerable<IGuildUser> users)
        {
            if (!users.Any())
                return;
            
            var rep = new ReplacementBuilder()
                .WithChannel(channel)
                .WithClient(_client)
                .WithServer(_client, (SocketGuild) channel.Guild)
                .WithManyUsers(users)
                .Build();

            var text = SmartText.CreateFrom(conf.ChannelGreetMessageText);
            text = rep.Replace(text);
            try
            {
                var toDelete = await channel.SendAsync(text).ConfigureAwait(false);
                if (conf.AutoDeleteGreetMessagesTimer > 0)
                {
                    toDelete.DeleteAfter(conf.AutoDeleteGreetMessagesTimer);
                }
            }
            catch (Exception ex)
            {
                Log.Warning(ex, "Error embeding greet message");
            }
        }

        private async Task<bool> GreetDmUser(GreetSettings conf, IDMChannel channel, IGuildUser user)
        {
            var rep = new ReplacementBuilder()
                .WithDefault(user, channel, (SocketGuild)user.Guild, _client)
                .Build();

            var text = SmartText.CreateFrom(conf.DmGreetMessageText);
            rep.Replace(text);
            try
            {
                await channel.SendAsync(text).ConfigureAwait(false);
            }
            catch
            {
                return false;
            }

            return true;
        }

        private Task UserJoined(IGuildUser user)
        {
            var _ = Task.Run(async () =>
            {
                try
                {
                    var conf = GetOrAddSettingsForGuild(user.GuildId);

                    if (conf.SendChannelGreetMessage)
                    {
                        var channel = await user.Guild.GetTextChannelAsync(conf.GreetMessageChannelId);
                        if (channel != null)
                        {
                            if (GroupGreets)
                            {
                                // if group is newly created, greet that user right away,
                                // but any user which joins in the next 5 seconds will
                                // be greeted in a group greet
                                if (greets.CreateOrAdd(user.GuildId, user))
                                {
                                    // greet single user
                                    await GreetUsers(conf, channel, new[] {user});
                                    var groupClear = false;
                                    while(!groupClear)
                                    {
                                        await Task.Delay(5000).ConfigureAwait(false);
                                        groupClear = greets.ClearGroup(user.GuildId, 5, out var toGreet);
                                        await GreetUsers(conf, channel, toGreet);
                                    }
                                }
                            }
                            else
                            {
                                await GreetUsers(conf, channel, new[] {user});
                            }
                        }

                    }

                    if (conf.SendDmGreetMessage)
                    {
                        var channel = await user.GetOrCreateDMChannelAsync().ConfigureAwait(false);

                        if (channel != null)
                        {
                            await GreetDmUser(conf, channel, user);
                        }
                    }
                }
                catch
                {
                    // ignored
                }
            });
            return Task.CompletedTask;
        }

        public string GetByeMessage(ulong gid)
        {
            using (var uow = _db.GetDbContext())
            {
                return uow.GuildConfigsForId(gid, set => set).ChannelByeMessageText;
            }
        }

        public GreetSettings GetOrAddSettingsForGuild(ulong guildId)
        {
            if (GuildConfigsCache.TryGetValue(guildId, out var settings) &&
                settings != null)
                return settings;

            using (var uow = _db.GetDbContext())
            {
                var gc = uow.GuildConfigsForId(guildId, set => set);
                settings = GreetSettings.Create(gc);
            }

            GuildConfigsCache.TryAdd(guildId, settings);
            return settings;
        }

        public async Task<bool> SetSettings(ulong guildId, GreetSettings settings)
        {
            if (settings.AutoDeleteByeMessagesTimer > 600 ||
                settings.AutoDeleteByeMessagesTimer < 0 ||
                settings.AutoDeleteGreetMessagesTimer > 600 ||
                settings.AutoDeleteGreetMessagesTimer < 0)
            {
                return false;
            }

            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                conf.DmGreetMessageText = settings.DmGreetMessageText?.SanitizeMentions();
                conf.ChannelGreetMessageText = settings.ChannelGreetMessageText?.SanitizeMentions();
                conf.ChannelByeMessageText = settings.ChannelByeMessageText?.SanitizeMentions();

                conf.AutoDeleteGreetMessagesTimer = settings.AutoDeleteGreetMessagesTimer;
                conf.AutoDeleteGreetMessages = settings.AutoDeleteGreetMessagesTimer > 0;

                conf.AutoDeleteByeMessagesTimer = settings.AutoDeleteByeMessagesTimer;
                conf.AutoDeleteByeMessages = settings.AutoDeleteByeMessagesTimer > 0;

                conf.GreetMessageChannelId = settings.GreetMessageChannelId;
                conf.ByeMessageChannelId = settings.ByeMessageChannelId;

                conf.SendChannelGreetMessage = settings.SendChannelGreetMessage;
                conf.SendChannelByeMessage = settings.SendChannelByeMessage;

                await uow.SaveChangesAsync();

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);
            }

            return true;
        }

        public async Task<bool> SetGreet(ulong guildId, ulong channelId, bool? value = null)
        {
            bool enabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                enabled = conf.SendChannelGreetMessage = value ?? !conf.SendChannelGreetMessage;
                conf.GreetMessageChannelId = channelId;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                await uow.SaveChangesAsync();
            }
            return enabled;
        }

        public bool SetGreetMessage(ulong guildId, ref string message)
        {
            message = message?.SanitizeMentions();

            if (string.IsNullOrWhiteSpace(message))
                throw new ArgumentNullException(nameof(message));

            bool greetMsgEnabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                conf.ChannelGreetMessageText = message;
                greetMsgEnabled = conf.SendChannelGreetMessage;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                uow.SaveChanges();
            }
            return greetMsgEnabled;
        }

        public async Task<bool> SetGreetDm(ulong guildId, bool? value = null)
        {
            bool enabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                enabled = conf.SendDmGreetMessage = value ?? !conf.SendDmGreetMessage;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                await uow.SaveChangesAsync();
            }
            return enabled;
        }

        #region Get Enabled Status
        public bool GetGreetDmEnabled(ulong guildId)
        {
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                return conf.SendDmGreetMessage;
            }
        }
        
        public bool GetGreetEnabled(ulong guildId)
        {
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                return conf.SendChannelGreetMessage;
            }
        }
        
        public bool GetByeEnabled(ulong guildId)
        {
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                return conf.SendChannelByeMessage;
            }
        }
        #endregion
        
        #region Test Messages

        public Task ByeTest(ITextChannel channel, IGuildUser user)
        {
            var conf = GetOrAddSettingsForGuild(user.GuildId);
            return ByeUsers(conf, channel, user);
        }
        
        public Task GreetTest(ITextChannel channel, IGuildUser user)
        {
            var conf = GetOrAddSettingsForGuild(user.GuildId);
            return GreetUsers(conf, channel, user);
        }
        
        public Task<bool> GreetDmTest(IDMChannel channel, IGuildUser user)
        {
            var conf = GetOrAddSettingsForGuild(user.GuildId);
            return GreetDmUser(conf, channel, user);
        }
        #endregion

        public bool SetGreetDmMessage(ulong guildId, ref string message)
        {
            message = message?.SanitizeMentions();

            if (string.IsNullOrWhiteSpace(message))
                throw new ArgumentNullException(nameof(message));

            bool greetMsgEnabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                conf.DmGreetMessageText = message;
                greetMsgEnabled = conf.SendDmGreetMessage;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                uow.SaveChanges();
            }
            return greetMsgEnabled;
        }

        public async Task<bool> SetBye(ulong guildId, ulong channelId, bool? value = null)
        {
            bool enabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                enabled = conf.SendChannelByeMessage = value ?? !conf.SendChannelByeMessage;
                conf.ByeMessageChannelId = channelId;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                await uow.SaveChangesAsync();
            }
            return enabled;
        }

        public bool SetByeMessage(ulong guildId, ref string message)
        {
            message = message?.SanitizeMentions();

            if (string.IsNullOrWhiteSpace(message))
                throw new ArgumentNullException(nameof(message));

            bool byeMsgEnabled;
            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                conf.ChannelByeMessageText = message;
                byeMsgEnabled = conf.SendChannelByeMessage;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                uow.SaveChanges();
            }
            return byeMsgEnabled;
        }

        public async Task SetByeDel(ulong guildId, int timer)
        {
            if (timer < 0 || timer > 600)
                return;

            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(guildId, set => set);
                conf.AutoDeleteByeMessagesTimer = timer;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(guildId, toAdd, (key, old) => toAdd);

                await uow.SaveChangesAsync();
            }
        }

        public async Task SetGreetDel(ulong id, int timer)
        {
            if (timer < 0 || timer > 600)
                return;

            using (var uow = _db.GetDbContext())
            {
                var conf = uow.GuildConfigsForId(id, set => set);
                conf.AutoDeleteGreetMessagesTimer = timer;

                var toAdd = GreetSettings.Create(conf);
                GuildConfigsCache.AddOrUpdate(id, toAdd, (key, old) => toAdd);

                await uow.SaveChangesAsync();
            }
        }

        public bool SetBoostMessage(ulong guildId, ref string message)
        {
            message = message?.SanitizeMentions();
                
            using var uow = _db.GetDbContext();
            var conf = uow.GuildConfigsForId(guildId, set => set);
            conf.BoostMessage = message;
            
            var toAdd = GreetSettings.Create(conf);
            GuildConfigsCache.AddOrUpdate(guildId, toAdd,(_, _) => toAdd);

            uow.SaveChanges();
            return conf.SendBoostMessage;
        }

        public async Task SetBoostDel(ulong guildId, int timer)
        {
            if (timer < 0 || timer > 600)
                throw new ArgumentOutOfRangeException(nameof(timer));
            
            using var uow = _db.GetDbContext();
            var conf = uow.GuildConfigsForId(guildId, set => set);
            conf.BoostMessageDeleteAfter = timer;
            
            var toAdd = GreetSettings.Create(conf);
            GuildConfigsCache.AddOrUpdate(guildId, toAdd,(_, _) => toAdd);
            
            await uow.SaveChangesAsync();
        }

        public async Task<bool> ToggleBoost(ulong guildId, ulong channelId)
        {
            using var uow = _db.GetDbContext();
            var conf = uow.GuildConfigsForId(guildId, set => set);
            conf.SendBoostMessage = !conf.SendBoostMessage;
            conf.BoostMessageChannelId = channelId;
            await uow.SaveChangesAsync();

            var toAdd = GreetSettings.Create(conf);
            GuildConfigsCache.AddOrUpdate(guildId, toAdd,(_, _) => toAdd);
            return conf.SendBoostMessage;
        }
    }

    public class GreetSettings
    {
        public int AutoDeleteGreetMessagesTimer { get; set; }
        public int AutoDeleteByeMessagesTimer { get; set; }

        public ulong GreetMessageChannelId { get; set; }
        public ulong ByeMessageChannelId { get; set; }

        public bool SendDmGreetMessage { get; set; }
        public string DmGreetMessageText { get; set; }

        public bool SendChannelGreetMessage { get; set; }
        public string ChannelGreetMessageText { get; set; }

        public bool SendChannelByeMessage { get; set; }
        public string ChannelByeMessageText { get; set; }
        
        public bool SendBoostMessage { get; set; }
        public string BoostMessage { get; set; }
        public int BoostMessageDeleteAfter { get; set; }
        public ulong BoostMessageChannelId { get; set; }

        public static GreetSettings Create(GuildConfig g) => new GreetSettings()
        {
            AutoDeleteByeMessagesTimer = g.AutoDeleteByeMessagesTimer,
            AutoDeleteGreetMessagesTimer = g.AutoDeleteGreetMessagesTimer,
            GreetMessageChannelId = g.GreetMessageChannelId,
            ByeMessageChannelId = g.ByeMessageChannelId,
            SendDmGreetMessage = g.SendDmGreetMessage,
            DmGreetMessageText = g.DmGreetMessageText,
            SendChannelGreetMessage = g.SendChannelGreetMessage,
            ChannelGreetMessageText = g.ChannelGreetMessageText,
            SendChannelByeMessage = g.SendChannelByeMessage,
            ChannelByeMessageText = g.ChannelByeMessageText,
            
            SendBoostMessage = g.SendBoostMessage,
            BoostMessage = g.BoostMessage,
            BoostMessageDeleteAfter = g.BoostMessageDeleteAfter,
            BoostMessageChannelId = g.BoostMessageChannelId
        };
    }
}