77 lines
3.0 KiB
C#
77 lines
3.0 KiB
C#
#nullable enable
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using System;
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using System.Linq;
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using System.Text.RegularExpressions;
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using System.Threading.Tasks;
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using Myriad.Extensions;
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using Myriad.Types;
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namespace PluralKit.Bot
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{
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public static class ContextAvatarExt
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{
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// Rewrite cdn.discordapp.com URLs to media.discordapp.net for jpg/png files
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// This lets us add resizing parameters to "borrow" their media proxy server to downsize the image
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// which in turn makes it more likely to be underneath the size limit!
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private static readonly Regex DiscordCdnUrl = new Regex(@"^https?://(?:cdn\.discordapp\.com|media\.discordapp\.net)/attachments/(\d{17,19})/(\d{17,19})/([^/\\&\?]+)\.(png|jpg|jpeg|webp)(\?.*)?$");
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private static readonly string DiscordMediaUrlReplacement = "https://media.discordapp.net/attachments/$1/$2/$3.$4?width=256&height=256";
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public static async Task<ParsedImage?> MatchImage(this Context ctx)
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{
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// If we have a user @mention/ID, use their avatar
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if (await ctx.MatchUser() is { } user)
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{
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var url = user.AvatarUrl("png", 256);
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return new ParsedImage {Url = url, Source = AvatarSource.User, SourceUser = user};
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}
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// If we have a positional argument, try to parse it as a URL
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var arg = ctx.RemainderOrNull();
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if (arg != null)
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{
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// Allow surrounding the URL with <angle brackets> to "de-embed"
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if (arg.StartsWith("<") && arg.EndsWith(">"))
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arg = arg.Substring(1, arg.Length - 2);
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if (!Uri.TryCreate(arg, UriKind.Absolute, out var uri))
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throw Errors.InvalidUrl(arg);
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if (uri.Scheme != "http" && uri.Scheme != "https")
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throw Errors.InvalidUrl(arg);
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// ToString URL-decodes, which breaks URLs to spaces; AbsoluteUri doesn't
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return new ParsedImage {Url = TryRewriteCdnUrl(uri.AbsoluteUri), Source = AvatarSource.Url};
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}
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// If we have an attachment, use that
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if (ctx.Message.Attachments.FirstOrDefault() is {} attachment)
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{
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var url = TryRewriteCdnUrl(attachment.ProxyUrl);
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return new ParsedImage {Url = url, Source = AvatarSource.Attachment};
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}
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// We should only get here if there are no arguments (which would get parsed as URL + throw if error)
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// and if there are no attachments (which would have been caught just before)
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return null;
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}
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private static string TryRewriteCdnUrl(string url) =>
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DiscordCdnUrl.Replace(url, DiscordMediaUrlReplacement);
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}
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public struct ParsedImage
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{
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public string Url;
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public AvatarSource Source;
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public User? SourceUser;
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}
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public enum AvatarSource
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{
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Url,
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User,
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Attachment
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}
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}
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