VORTEX-REC-LEAK/Discord/Commands/LinkCode.cs

using DeluxeBackend.Models;
using DeluxeBackend.Services;
using Discord;
using Discord.Interactions;
using Discord.WebSocket;
using System.Security.Cryptography;
using static DeluxeBackend.Enums;

namespace DeluxeBackend.Discord.Commands
{
    public class LinkCode : InteractionModuleBase<SocketInteractionContext>
    {
        private readonly ILiteDbService _db;
        private readonly INotificationService _ws;

        private static readonly HashSet<ulong> GameRoles = new()
        {
            1502718783700078767, 1495587327593021490, 1495580320525844581,
            1495580213529280563, 1495909230643908729, 1500323661251477635,
            1495580027453046804, 1501711512996282369, 1495580006712213674,
            1495580717134905457
        };

        public LinkCode(ILiteDbService db, INotificationService ws)
        {
            _db = db;
            _ws = ws;
        }

        [SlashCommand("ping", "Check bot latency")]
        public async Task Ping() => await RespondAsync($"{Context.Client.Latency}ms");

        [SlashCommand("link", "Generate a unique code to link your Deluxe account")]
        public async Task LinkAccount()
        {
            await DeferAsync(ephemeral: true);

            if (Context.User is not SocketGuildUser guildUser)
            {
                await FollowupAsync("This command must be used within a server.");
                return;
            }

            if (!guildUser.Roles.Any(r => GameRoles.Contains(r.Id)))
            {
                await FollowupAsync("You do not have the required permissions.", ephemeral: true);
                return;
            }
            Account? account = _db.Accounts.FindOne(x => x.DiscordId == guildUser.Id);
            if (account != null)
            {
                var linkedEmbed = new EmbedBuilder()
                    .WithDescription("Your Discord profile is **already linked** to a Deluxe account.")
                    .WithColor(Color.LighterGrey)
                    .Build();

                await FollowupAsync(embed: linkedEmbed, ephemeral: true);
                return;
            }

            var pendingLink = _db.ActionLinks.FindOne(x =>
                x.ExtraData!.DiscordUserId == guildUser.Id &&
                x.ExpiresAt > DateTime.UtcNow &&
                x.Uses < x.MaxUses);

            if (pendingLink != null)
            {
                long unixTime = ((DateTimeOffset)pendingLink.ExpiresAt).ToUnixTimeSeconds();
                var existingEmbed = new EmbedBuilder()
                    .WithDescription($"You already have an active code:\n\n**`{pendingLink.Code}`**\n\nIt expires **<t:{unixTime}:R>** (<t:{unixTime}:f>).")
                    .WithColor(Color.LighterGrey)
                    .Build();

                await FollowupAsync(embed: existingEmbed, ephemeral: true);
                return;
            }

            string code;
            while (true)
            {
                code = GenerateSecureCode(8);
                var existing = _db.ActionLinks.FindOne(x => x.Code == code);

                if (existing == null) break;

                if (!existing.IsValid)
                {
                    _db.ActionLinks.Delete(existing.Id);
                    break;
                }
            }

            DateTime expiry = DateTime.UtcNow.AddMinutes(10);
            long expiryUnix = ((DateTimeOffset)expiry).ToUnixTimeSeconds();

            var actionLink = new ActionLink
            {
                Code = code,
                CreatorPlayerId = 1,
                Description = $"Discord Link: {guildUser.Username}",
                ExpiresAt = expiry,
                Type = ActionLinkType.DiscordLink,
                ExtraData = new ActionLinkExtraData { DiscordUserId = guildUser.Id },
                MaxUses = 1
            };

            _db.ActionLinks.Insert(actionLink);

            var embed = new EmbedBuilder()
                .WithDescription($"Use the code below to link your account:\n\n**`{code}`**\n\nExpires **<t:{expiryUnix}:R>**.")
                .WithColor(Color.LighterGrey)
                .Build();

            await FollowupAsync(embed: embed, ephemeral: true);
        }

        private static string GenerateSecureCode(int length)
        {
            const string chars = "abcdefghijklmnopqrstuvwxyz0123456789";
            return string.Create(length, chars, (buffer, symbols) =>
            {
                for (int i = 0; i < buffer.Length; i++)
                {
                    buffer[i] = symbols[RandomNumberGenerator.GetInt32(symbols.Length)];
                }
            });
        }
    }
}