feature: add UpdateAsync to SocketModal (#2289)

src/Discord.Net.WebSocket/Entities/Interaction/Modals/SocketModal.cs

@@ -174,6 +174,91 @@ namespace Discord.WebSocket
             HasResponded = true;
         }
 
+        public async Task UpdateAsync(Action<MessageProperties> func, RequestOptions options = null)
+        {
+            var args = new MessageProperties();
+            func(args);
+
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            if (args.AllowedMentions.IsSpecified)
+            {
+                var allowedMentions = args.AllowedMentions.Value;
+                Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions), "A max of 100 role Ids are allowed.");
+                Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions), "A max of 100 user Ids are allowed.");
+            }
+
+            var embed = args.Embed;
+            var embeds = args.Embeds;
+
+            bool hasText = args.Content.IsSpecified ? !string.IsNullOrEmpty(args.Content.Value) : false;
+            bool hasEmbeds = embed.IsSpecified && embed.Value != null || embeds.IsSpecified && embeds.Value?.Length > 0;
+
+            if (!hasText && !hasEmbeds)
+                Preconditions.NotNullOrEmpty(args.Content.IsSpecified ? args.Content.Value : string.Empty, nameof(args.Content));
+
+            var apiEmbeds = embed.IsSpecified || embeds.IsSpecified ? new List<API.Embed>() : null;
+
+            if (embed.IsSpecified && embed.Value != null)
+            {
+                apiEmbeds.Add(embed.Value.ToModel());
+            }
+
+            if (embeds.IsSpecified && embeds.Value != null)
+            {
+                apiEmbeds.AddRange(embeds.Value.Select(x => x.ToModel()));
+            }
+
+            Preconditions.AtMost(apiEmbeds?.Count ?? 0, 10, nameof(args.Embeds), "A max of 10 embeds are allowed.");
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (args.AllowedMentions.IsSpecified && args.AllowedMentions.Value != null && args.AllowedMentions.Value.AllowedTypes.HasValue)
+            {
+                var allowedMentions = args.AllowedMentions.Value;
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users)
+                && allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(args.AllowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles)
+                && allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(args.AllowedMentions));
+                }
+            }
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.UpdateMessage,
+                Data = new API.InteractionCallbackData
+                {
+                    Content = args.Content,
+                    AllowedMentions = args.AllowedMentions.IsSpecified ? args.AllowedMentions.Value?.ToModel() : Optional<API.AllowedMentions>.Unspecified,
+                    Embeds = apiEmbeds?.ToArray() ?? Optional<API.Embed[]>.Unspecified,
+                    Components = args.Components.IsSpecified
+                        ? args.Components.Value?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Array.Empty<API.ActionRowComponent>()
+                        : Optional<API.ActionRowComponent[]>.Unspecified,
+                    Flags = args.Flags.IsSpecified ? args.Flags.Value ?? Optional<MessageFlags>.Unspecified : Optional<MessageFlags>.Unspecified
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond, update, or defer twice to the same interaction");
+                }
+            }
+
+            await InteractionHelper.SendInteractionResponseAsync(Discord, response, this, Channel, options).ConfigureAwait(false);
+            HasResponded = true;
+        }
+
         /// <inheritdoc/>
         public override async Task<RestFollowupMessage> FollowupAsync(
             string text = null,