using SharpChat.Commands;
using SharpChat.Config;
using SharpChat.Events;
using SharpChat.Packet;
using System;
using System.Collections.Generic;
using System.Linq;

namespace SharpChat.PacketHandlers {
    public class SendMessageHandler : IChatPacketHandler {
        private readonly CachedValue<int> MaxMessageLength;

        private List<IChatCommand> Commands { get; } = new();

        public SendMessageHandler(CachedValue<int> maxMsgLength) {
            MaxMessageLength = maxMsgLength ?? throw new ArgumentNullException(nameof(maxMsgLength));
        }

        public void AddCommand(IChatCommand command) {
            Commands.Add(command ?? throw new ArgumentNullException(nameof(command)));
        }

        public void AddCommands(IEnumerable<IChatCommand> commands) {
            Commands.AddRange(commands ?? throw new ArgumentNullException(nameof(commands)));
        }

        public bool IsMatch(ChatPacketHandlerContext ctx) {
            return ctx.CheckPacketId("2");
        }

        public void Handle(ChatPacketHandlerContext ctx) {
            string[] args = ctx.SplitText(3);

            ChatUser user = ctx.Connection.User;

            // No longer concats everything after index 1 with \t, no previous implementation did that either
            string messageText = args.ElementAtOrDefault(2);

            if(user == null || !user.Can(ChatUserPermissions.SendMessage) || string.IsNullOrWhiteSpace(messageText))
                return;

            // Extra validation step, not necessary at all but enforces proper formatting in SCv1.
            if(!long.TryParse(args[1], out long mUserId) || user.UserId != mUserId)
                return;

            ctx.Chat.ContextAccess.Wait();
            try {
                if(!ctx.Chat.UserLastChannel.TryGetValue(user.UserId, out ChatChannel channel)
                    && !ctx.Chat.IsInChannel(user, channel)
                    /*|| (user.IsSilenced && !user.Can(ChatUserPermissions.SilenceUser))*/)
                    return;

                if(user.Status != ChatUserStatus.Online)
                    ctx.Chat.UpdateUser(user, status: ChatUserStatus.Online);

                int maxMsgLength = MaxMessageLength;
                if(messageText.Length > maxMsgLength)
                    messageText = messageText[..maxMsgLength];

                messageText = messageText.Trim();

#if DEBUG
                Logger.Write($"<{ctx.Connection.Id} {user.UserName}> {messageText}");
#endif

                IChatMessage message = null;

                if(messageText.StartsWith("/")) {
                    ChatCommandContext context = new(messageText, ctx.Chat, user, ctx.Connection, channel);

                    IChatCommand command = null;

                    foreach(IChatCommand cmd in Commands)
                        if(cmd.IsMatch(context)) {
                            command = cmd;
                            break;
                        }

                    if(command != null) {
                        if(command is ActionCommand actionCommand)
                            message = actionCommand.ActionDispatch(context);
                        else {
                            command.Dispatch(context);
                            return;
                        }
                    }
                }

                message ??= new ChatMessage {
                    ChannelName = channel.Name,
                    DateTime = DateTimeOffset.UtcNow,
                    Sender = user,
                    Text = messageText,
                };

                ctx.Chat.Events.AddEvent(message);
                ctx.Chat.SendTo(channel, new ChatMessageAddPacket(message));
            } finally {
                ctx.Chat.ContextAccess.Release();
            }
        }
    }
}