75 lines
3.1 KiB
C#
75 lines
3.1 KiB
C#
using System;
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using System.Collections.Concurrent;
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using System.Linq;
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using System.Threading.Tasks;
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using Discord;
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using Serilog;
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namespace PluralKit.Bot
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{
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public class WebhookCacheService
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{
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public static readonly string WebhookName = "PluralKit Proxy Webhook";
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private IDiscordClient _client;
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private ConcurrentDictionary<ulong, Lazy<Task<IWebhook>>> _webhooks;
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private ILogger _logger;
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public WebhookCacheService(IDiscordClient client, ILogger logger)
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{
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_client = client;
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_logger = logger.ForContext<WebhookCacheService>();
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_webhooks = new ConcurrentDictionary<ulong, Lazy<Task<IWebhook>>>();
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}
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public async Task<IWebhook> GetWebhook(ulong channelId)
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{
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var channel = await _client.GetChannelAsync(channelId) as ITextChannel;
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if (channel == null) return null;
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return await GetWebhook(channel);
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}
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public async Task<IWebhook> GetWebhook(ITextChannel channel)
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{
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// We cache the webhook through a Lazy<Task<T>>, this way we make sure to only create one webhook per channel
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// If the webhook is requested twice before it's actually been found, the Lazy<T> wrapper will stop the
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// webhook from being created twice.
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var lazyWebhookValue =
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_webhooks.GetOrAdd(channel.Id, new Lazy<Task<IWebhook>>(() => GetOrCreateWebhook(channel)));
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// It's possible to "move" a webhook to a different channel after creation
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// Here, we ensure it's actually still pointing towards the proper channel, and if not, wipe and refetch one.
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var webhook = await lazyWebhookValue.Value;
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if (webhook.Channel.Id != channel.Id) return await InvalidateAndRefreshWebhook(webhook);
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return webhook;
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}
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public async Task<IWebhook> InvalidateAndRefreshWebhook(IWebhook webhook)
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{
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_logger.Information("Refreshing webhook for channel {Channel}", webhook.ChannelId);
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_webhooks.TryRemove(webhook.ChannelId, out _);
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return await GetWebhook(webhook.ChannelId);
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}
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private async Task<IWebhook> GetOrCreateWebhook(ITextChannel channel) =>
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await FindExistingWebhook(channel) ?? await DoCreateWebhook(channel);
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private async Task<IWebhook> FindExistingWebhook(ITextChannel channel)
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{
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_logger.Debug("Finding webhook for channel {Channel}", channel.Id);
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return (await channel.GetWebhooksAsync()).FirstOrDefault(IsWebhookMine);
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}
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private async Task<IWebhook> DoCreateWebhook(ITextChannel channel)
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{
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_logger.Information("Creating new webhook for channel {Channel}", channel.Id);
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return await channel.CreateWebhookAsync(WebhookName);
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}
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private bool IsWebhookMine(IWebhook arg) => arg.Creator.Id == _client.CurrentUser.Id && arg.Name == WebhookName;
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public int CacheSize => _webhooks.Count;
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}
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} |