PluralKit/PluralKit.Core/Utils/MiscUtils.cs

using System.Text.RegularExpressions;

namespace PluralKit.Core;

public static class MiscUtils
{
    // discord mediaproxy URLs used to be stored directly in the database, so now we cleanup image urls before using them outside of proxying
    private static readonly Regex MediaProxyUrl =
        new(
            @"^https?://media.discordapp.net/attachments/(\d{17,19})/(\d{17,19})/([^/\\&\?]+)\.(png|jpg|jpeg|webp)(\?.*)?$");

    private static readonly string DiscordCdnReplacement = "https://cdn.discordapp.com/attachments/$1/$2/$3.$4";

    public static bool TryMatchUri(string input, out Uri uri)
    {
        try
        {
            uri = new Uri(input);
            if (!uri.IsAbsoluteUri || uri.Scheme != "http" && uri.Scheme != "https")
                return false;
        }
        catch (UriFormatException)
        {
            uri = null;
            return false;
        }

        return true;
    }

    public static string? TryGetCleanCdnUrl(this string? url) =>
        url == null ? null : MediaProxyUrl.Replace(url, DiscordCdnReplacement);
}