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;
            ChatChannel channel = user.CurrentChannel;

            if(channel == null
                || !user.InChannel(channel)
                || (user.IsSilenced && !user.Can(ChatUserPermissions.SilenceUser)))
                return;

            if(user.Status != ChatUserStatus.Online) {
                user.Status = ChatUserStatus.Online;
                channel.Send(new UserUpdatePacket(user));
            }

            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 {
                Target = channel,
                TargetName = channel.TargetName,
                DateTime = DateTimeOffset.UtcNow,
                Sender = user,
                Text = messageText,
            };

            lock(ctx.Chat.EventsAccess) {
                ctx.Chat.Events.AddEvent(message);
                channel.Send(new ChatMessageAddPacket(message));
            }
        }
    }
}