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

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

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

        public SendMessageHandler(CachedValue<int> maxMsgLength) {
            MaxMessageLength = maxMsgLength;
        }

        public void AddCommand(IUserCommand command) {
            Commands.Add(command);
        }

        public void AddCommands(IEnumerable<IUserCommand> commands) {
            Commands.AddRange(commands);
        }

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

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

            UserInfo? 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.Permissions.HasFlag(UserPermissions.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 {
                ChannelInfo? channelInfo = ctx.Chat.Channels.Get(
                    ctx.Chat.ChannelsUsers.GetUserLastChannel(user)
                );
                if(channelInfo == null)
                    return;

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

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

                    IUserCommand? command = null;

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

                    if(command != null) {
                        command.Dispatch(context);
                        return;
                    }
                }

                ctx.Chat.DispatchEvent(new MessageCreateEvent(
                    SharpId.Next(),
                    channelInfo,
                    user,
                    DateTimeOffset.Now,
                    messageText,
                    false, false, false
                ));
            } finally {
                ctx.Chat.ContextAccess.Release();
            }
        }
    }
}