using System;
using System.Threading.Tasks;
using DeukBot4.MessageHandlers.CommandHandler;
using DeukBot4.Utilities;
using StackExchange.Redis;

namespace DeukBot4.Database
{
    public static class BirthdayHandler
    {
        private static ConnectionMultiplexer Redis => ReminderHandler.Redis;

        public static async Task<DateTime?> GetBirthday(ulong server, ulong user)
        {
            var db     = Redis.GetDatabase();
            var exists = db.HashGet("birthdays", (RedisValue) $"{server}-{user}");
            if (exists.HasValue)
            {
                var      bdayEntries = db.HashGetAll(exists.ToString());
                DateTime bday        = DateTime.MinValue;
                foreach (var bdayEntry in bdayEntries)
                {
                    if (bdayEntry.Name == "birthday")
                    {
                        bday = DateTime.FromBinary(long.Parse(bdayEntry.Value));
                        break;
                    }
                }
                return bday;
            }
            return null;
        }

        public static async Task AddBirthday(DateTime birthday, ulong server, ulong user)
        {
            try
            {
                var db           = Redis.GetDatabase();
                var exists = db.HashGet("birthdays", (RedisValue) $"{server}-{user}");
                if (exists.HasValue)
                {
                    var bdayEntries = db.HashGetAll(exists.ToString());
                    DateTime bday = DateTime.MinValue;
                    foreach (var bdayEntry in bdayEntries)
                    {
                        if (bdayEntry.Name == "birthday") bday = DateTime.FromBinary(long.Parse(bdayEntry.Value));
                    }
                    db.SetRemove(bday.ToString("ddMM"), exists);
                    db.KeyDelete(exists.ToString());
                }
                var id = Guid.NewGuid().ToString();
                db.HashSet("birthdays", (RedisValue) $"{server}-{user}", id);
                db.SetAdd(birthday.ToString("ddMM"), id);
                db.HashSetAsync((RedisKey) id, new[]
                {
                    new HashEntry("server", server.ToString("D")),
                    new HashEntry("user", user.ToString("D")),
                    new HashEntry("birthday", birthday.ToBinary().ToString("D")),
                });

            }
            catch (Exception e)
            {
                Logger.Main.LogError(e);
            }
        }

        private static int Years(DateTime start, DateTime end)
        {
            return (end.Year - start.Year - 1) +
                   (((end.Month > start.Month) ||
                     ((end.Month == start.Month) && (end.Day >= start.Day))) ? 1 : 0);
        }

        public static void Initialize()
        {
            var db = Redis.GetDatabase();
            var dbValue = db.StringGet("lastCheckedBirthday");
            if (dbValue.HasValue)
                _lastCheckedDate = DateTime.FromBinary(long.Parse(dbValue));
        }

        private static DateTime _lastCheckedDate;
        // ReSharper disable once FunctionRecursiveOnAllPaths
        public static async Task CheckBirthdays()
        {
            var today = DateTime.UtcNow.Date - new TimeSpan(6, 0 , 0);
            while (!Program.IsConnected)
            {
                await Task.Delay(500);
            }
            try
            {
                if (today != _lastCheckedDate)
                {
                    _lastCheckedDate = today;
                    var db = Redis.GetDatabase();
                    db.StringSet("lastCheckedBirthday", _lastCheckedDate.ToBinary().ToString("D"));
                    await ActualBirthdayCheck(today);
                }
            }
            catch (Exception e)
            {
                Logger.Main.LogError(e);
            }
            await Task.Delay(TimeSpan.FromHours(1));
            await CheckBirthdays();
        }


        private static async Task ActualBirthdayCheck(DateTime today)
        {
            var db        = Redis.GetDatabase();
            var reminders = db.SetMembers(today.ToString("ddMM"));
            foreach (var redisValue in reminders)
            {
                ulong    server   = 0;
                ulong    user     = 0;
                DateTime birthday = today;
                var      val      = redisValue.ToString();
                var      data     = db.HashGetAll(val);
                foreach (var hashEntry in data)
                {
                    if (hashEntry.Name      == "server") server     = ulong.Parse(hashEntry.Value);
                    else if (hashEntry.Name == "user") user         = ulong.Parse(hashEntry.Value);
                    else if (hashEntry.Name == "birthday") birthday = DateTime.FromBinary(long.Parse(hashEntry.Value));
                }

                var guild = Program.Client.GetGuild(server);
                if (guild != null)
                {
                    var guildUser = guild.GetUser(user);
                    if (guildUser == null)
                    {
                        Console.WriteLine("Can't celebrate birthday for user, not in guild anymore :(");
                        db.KeyDelete(val);
                        db.SetRemove(birthday.ToString("ddMM"), val);
                        return;
                    }

                    var eb = EmbedFactory.GetStandardEmbedBuilder();
                    eb.Title = $":confetti_ball::confetti_ball: Happy Birthday! :confetti_ball::confetti_ball: ";
                    var age = Years(birthday, today);
                    string ageString = EnglishNumberParser.GetShortOrdinalNumber(age);
                    eb.Description  = $"It's <@!{guildUser.Id}>'s {ageString} birthday!! Have a good one!";
                    eb.ThumbnailUrl = guildUser.GetAvatarUrl();

                    guild.SystemChannel.SendMessageAsync("", embed: eb.Build());
                }
            }
        }
    }
}