using MySqlConnector;
using SharpChat.Events;
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using System.Text.Json;

namespace SharpChat.EventStorage {
    public partial class MariaDBEventStorage : IEventStorage {
        private string ConnectionString { get; }

        private readonly JsonSerializerOptions jsonOpts = new() {
            DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingDefault,
        };

        private static readonly Dictionary<string, Type> EventDataTypes = new();

        static MariaDBEventStorage() {
            foreach(Type type in Assembly.GetExecutingAssembly().GetTypes()) {
                ChatEventDataForAttribute? forAttr = type.GetCustomAttribute<ChatEventDataForAttribute>();
                if(forAttr == null)
                    continue;
                if(EventDataTypes.ContainsKey(forAttr.EventName))
                    throw new InvalidOperationException($"Attempted to register more than one data type for {forAttr.EventName}!");

                EventDataTypes.Add(forAttr.EventName, type);
            }
        }

        public MariaDBEventStorage(string connString) {
            ConnectionString = connString;
        }

        public void HandleEvent(ChatEventInfo info) {
            MySqlParameter dataParam = new("data", MySqlDbType.Blob) {
                Value = JsonSerializer.SerializeToUtf8Bytes(info.Data, info.Data.GetType(), jsonOpts)
            };

            RunCommand(
                "INSERT INTO `sqc_events` (`event_id`, `event_created`, `event_type`, `event_target`, `event_data`"
                + ", `event_sender`, `event_sender_name`, `event_sender_colour`, `event_sender_rank`, `event_sender_nick`, `event_sender_perms`)"
                + " VALUES (@id, NOW(), @type, @target, @data"
                + ", @sender, @sender_name, @sender_colour, @sender_rank, @sender_nick, @sender_perms)",
                new MySqlParameter("id", info.Id),
                new MySqlParameter("type", info.Type),
                new MySqlParameter("target", string.IsNullOrWhiteSpace(info.ChannelName) ? null : info.ChannelName),
                dataParam,
                new MySqlParameter("sender", info.SenderId < 1 ? null : info.SenderId),
                new MySqlParameter("sender_name", info.SenderName),
                new MySqlParameter("sender_colour", info.SenderColour.ToMisuzu()),
                new MySqlParameter("sender_rank", info.SenderRank),
                new MySqlParameter("sender_nick", info.SenderNickName),
                new MySqlParameter("sender_perms", info.SenderPerms)
            );

            if(info.Type.Equals("msg:delete") && info.Data is MessageDeleteEventData msgDelete)
                RunCommand(
                    "UPDATE IGNORE `sqc_events` SET `event_deleted` = NOW() WHERE `event_id` = @id AND `event_deleted` IS NULL",
                    new MySqlParameter("id", msgDelete.MessageId)
                );
        }

        public ChatEventInfo? GetEvent(long eventId) {
            try {
                using MySqlDataReader? reader = RunQuery(
                    "SELECT `event_id`, `event_type`, `event_data`, `event_target`"
                    + ", `event_sender`, `event_sender_name`, `event_sender_colour`, `event_sender_rank`, `event_sender_nick`, `event_sender_perms`"
                    + ", UNIX_TIMESTAMP(`event_created`) AS `event_created`"
                    + ", UNIX_TIMESTAMP(`event_deleted`) AS `event_deleted`"
                    + " FROM `sqc_events`"
                    + " WHERE `event_id` = @id",
                    new MySqlParameter("id", eventId)
                );

                if(reader != null)
                    while(reader.Read()) {
                        ChatEventInfo evt = ReadEvent(reader);
                        if(evt != null)
                            return evt;
                    }
            } catch(MySqlException ex) {
                Logger.Write(ex);
            }

            return null;
        }

        private static ChatEventInfo ReadEvent(MySqlDataReader reader) {
            string eventType = Encoding.ASCII.GetString((byte[])reader["event_type"]);
            ChatEventData eventData = EventDataTypes.ContainsKey(eventType)
                ? (ChatEventData)(JsonSerializer.Deserialize((byte[])reader["event_data"], EventDataTypes[eventType]) ?? ChatEventData.EmptyInstance)
                : ChatEventData.EmptyInstance;

            return new ChatEventInfo(
                reader.GetInt64("event_id"),
                eventType,
                DateTimeOffset.FromUnixTimeSeconds(reader.GetInt32("event_created")),
                reader.IsDBNull(reader.GetOrdinal("event_target")) ? string.Empty : Encoding.ASCII.GetString((byte[])reader["event_target"]),
                reader.IsDBNull(reader.GetOrdinal("event_sender")) ? -1 : reader.GetInt64("event_sender"),
                reader.IsDBNull(reader.GetOrdinal("event_sender_name")) ? string.Empty : reader.GetString("event_sender_name"),
                reader.IsDBNull(reader.GetOrdinal("event_sender_colour")) ? Colour.None : Colour.FromMisuzu(reader.GetInt32("event_sender_colour")),
                reader.GetInt32("event_sender_rank"),
                reader.IsDBNull(reader.GetOrdinal("event_sender_nick")) ? null : reader.GetString("event_sender_nick"),
                (UserPermissions)reader.GetInt32("event_sender_perms"),
                eventData
            );
        }

        public IEnumerable<ChatEventInfo> GetChannelEventLog(string channelName, int amount = 20, int startAt = 0) {
            List<ChatEventInfo> events = new();

            try {
                using MySqlDataReader? reader = RunQuery(
                    "SELECT `event_id`, `event_type`, `event_data`, `event_target`"
                    + ", `event_sender`, `event_sender_name`, `event_sender_colour`, `event_sender_rank`, `event_sender_nick`, `event_sender_perms`"
                    + ", UNIX_TIMESTAMP(`event_created`) AS `event_created`"
                    + ", UNIX_TIMESTAMP(`event_deleted`) AS `event_deleted`"
                    + " FROM `sqc_events`"
                    + " WHERE `event_deleted` IS NULL AND (`event_target` = @target OR `event_target` IS NULL)"
                    + " AND `event_id` > @offset"
                    + " ORDER BY `event_id` DESC"
                    + " LIMIT @amount",
                    new MySqlParameter("target", channelName),
                    new MySqlParameter("amount", amount),
                    new MySqlParameter("offset", startAt)
                );

                if(reader != null)
                    while(reader.Read()) {
                        ChatEventInfo evt = ReadEvent(reader);
                        if(evt != null)
                            events.Add(evt);
                    }
            } catch(MySqlException ex) {
                Logger.Write(ex);
            }

            events.Reverse();

            return events;
        }
    }
}