93 lines
3.8 KiB
C#
93 lines
3.8 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.Net.Http;
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using System.Threading.Tasks;
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using DSharpPlus;
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using DSharpPlus.Entities;
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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 DiscordShardedClient _client;
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private ConcurrentDictionary<ulong, Lazy<Task<DiscordWebhook>>> _webhooks;
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private ILogger _logger;
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public WebhookCacheService(DiscordShardedClient 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<DiscordWebhook>>>();
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}
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public async Task<DiscordWebhook> GetWebhook(DiscordClient client, ulong channelId)
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{
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var channel = await client.GetChannelAsync(channelId);
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if (channel == null) return null;
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if (channel.Type == ChannelType.Text) return null;
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return await GetWebhook(channel);
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}
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public async Task<DiscordWebhook> GetWebhook(DiscordChannel 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<DiscordWebhook>>(() => 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.ChannelId != channel.Id) return await InvalidateAndRefreshWebhook(channel, webhook);
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return webhook;
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}
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public async Task<DiscordWebhook> InvalidateAndRefreshWebhook(DiscordChannel channel, DiscordWebhook 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(channel);
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}
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private async Task<DiscordWebhook> GetOrCreateWebhook(DiscordChannel channel)
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{
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_logger.Debug("Webhook for channel {Channel} not found in cache, trying to fetch", channel.Id);
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return await FindExistingWebhook(channel) ?? await DoCreateWebhook(channel);
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}
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private async Task<DiscordWebhook> FindExistingWebhook(DiscordChannel channel)
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{
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_logger.Debug("Finding webhook for channel {Channel}", channel.Id);
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try
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{
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return (await channel.GetWebhooksAsync()).FirstOrDefault(IsWebhookMine);
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}
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catch (HttpRequestException e)
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{
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_logger.Warning(e, "Error occurred while fetching webhook list");
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// This happens sometimes when Discord returns a malformed request for the webhook list
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// Nothing we can do than just assume that none exist and return null.
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return null;
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}
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}
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private Task<DiscordWebhook> DoCreateWebhook(DiscordChannel channel)
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{
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_logger.Information("Creating new webhook for channel {Channel}", channel.Id);
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return channel.CreateWebhookAsync(WebhookName);
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}
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private bool IsWebhookMine(DiscordWebhook arg) => arg.User.Id == _client.CurrentUser.Id && arg.Name == WebhookName;
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public int CacheSize => _webhooks.Count;
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}
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} |