using MySqlConnector;
using SharpChat.Events;
using System;
using System.Collections.Generic;
using System.Reflection;
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) {
            RunCommand(
                "INSERT INTO sqc_events (event_id, event_type, event_created, event_channel, event_data"
                + ", event_sender, event_sender_name, event_sender_colour, event_sender_rank, event_sender_nick, event_sender_perms"
                + ") VALUES (@id, @type, FROM_UNIXTIME(@created), @channel, @data"
                + ", @senderId, @senderName, @senderColour, @senderRank, @senderNickName, @senderPerms)",
                new MySqlParameter("id", info.Id),
                new MySqlParameter("type", info.Type),
                new MySqlParameter("created", info.Created.ToUnixTimeSeconds()),
                new MySqlParameter("channel", string.IsNullOrWhiteSpace(info.ChannelName) ? null : info.ChannelName),
                new MySqlParameter("data", JsonSerializer.Serialize(info.Data, info.Data.GetType(), jsonOpts)),
                new MySqlParameter("senderId", info.SenderId < 1 ? null : info.SenderId),
                new MySqlParameter("senderName", info.SenderName),
                new MySqlParameter("senderColour", info.SenderColour.ToMisuzu()),
                new MySqlParameter("senderRank", info.SenderRank),
                new MySqlParameter("senderNickName", string.IsNullOrWhiteSpace(info.SenderNickName) ? null : info.SenderNickName),
                new MySqlParameter("senderPerms", 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_channel, event_data"
                    + ", 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 = reader.GetString("event_type");
            ChatEventData eventData = EventDataTypes.ContainsKey(eventType)
                ? (ChatEventData)(JsonSerializer.Deserialize(reader.GetString("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_channel")) ? string.Empty : reader.GetString("event_channel"),
                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.IsDBNull(reader.GetOrdinal("event_sender_rank")) ? 0 : reader.GetInt32("event_sender_rank"),
                reader.IsDBNull(reader.GetOrdinal("event_sender_nick")) ? null : reader.GetString("event_sender_nick"),
                (UserPermissions)(reader.IsDBNull(reader.GetOrdinal("event_sender_perms")) ? 0 : reader.GetInt32("event_sender_perms")),
                eventData
            );
        }

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

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

                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;
        }
    }
}