Radicade/Server/Chat/ChatPhotoMessages.cs

using System.Text.RegularExpressions;

namespace RadicadeServer.API
{
	public static class ChatPhotoMessages
	{
		public static readonly TimeSpan UploadWindow = TimeSpan.FromMinutes(15);

		private static readonly Regex ImageReference = new(@"<Image:([^>]*)>", RegexOptions.Compiled);

		private static readonly Regex PhotoEnvelope = new("\"Type\"\\s*:\\s*2(?![0-9])", RegexOptions.Compiled);

		public static bool IsPhotoEnvelope(string? contents)
			=> !string.IsNullOrEmpty(contents) && PhotoEnvelope.IsMatch(contents);

		public static bool HasUnresolvedImageReference(string? contents)
		{
			if (string.IsNullOrEmpty(contents))
				return false;

			foreach (Match match in ImageReference.Matches(contents))
			{
				if (!ResolvesToAnImage(match.Groups[1].Value))
					return true;
			}

			return false;
		}

		public static string ResolveImageReference(string contents, long imageId)
		{
			return ImageReference.Replace(contents, match =>
				ResolvesToAnImage(match.Groups[1].Value) ? match.Value : $"<Image:{imageId}>");
		}

		private static bool ResolvesToAnImage(string rawReference)
			=> long.TryParse(rawReference, out var imageId) && imageId > 0;
	}
}