[Integration] Discord integration

backend/src/Notifo.Domain.Integrations.Abstractions/MessagingMessage.cs

@@ -9,7 +9,17 @@ namespace Notifo.Domain.Integrations;
 
 public sealed class MessagingMessage : BaseMessage
 {
+    public IReadOnlyDictionary<string, string> Targets { get; set; }
+
     public string Text { get; set; }
 
-    public IReadOnlyDictionary<string, string> Targets { get; set; }
+    public string? Body { get; init; }
+
+    public string? ImageLarge { get; init; }
+
+    public string? ImageSmall { get; init; }
+
+    public string? LinkText { get; init; }
+
+    public string? LinkUrl { get; init; }
 }

backend/src/Notifo.Domain.Integrations/CachePool.cs

@@ -33,39 +33,61 @@ protected TItem GetOrCreate(object key, TimeSpan expiration, Func<TItem> factory
             entry.AbsoluteExpirationRelativeToNow = expiration;
 
             var item = factory();
+            HandleDispose(item, entry);
 
-            switch (item)
-            {
-                case IDisposable disposable:
+            return item;
+        })!;
+    }
+
+    protected Task<TItem> GetOrCreateAsync(object key, Func<Task<TItem>> factory)
+    {
+        return GetOrCreateAsync(key, DefaultExpiration, factory);
+    }
+
+    protected Task<TItem> GetOrCreateAsync(object key, TimeSpan expiration, Func<Task<TItem>> factory)
+    {
+        return memoryCache.GetOrCreateAsync(key, async entry =>
+        {
+            entry.AbsoluteExpirationRelativeToNow = expiration;
+
+            var item = await factory();
+            HandleDispose(item, entry);
+
+            return item;
+        })!;
+    }
+
+    private void HandleDispose(TItem item, ICacheEntry entry)
+    {
+        switch (item)
+        {
+            case IDisposable disposable:
+                {
+                    entry.PostEvictionCallbacks.Add(new PostEvictionCallbackRegistration
                     {
-                        entry.PostEvictionCallbacks.Add(new PostEvictionCallbackRegistration
+                        EvictionCallback = (key, value, reason, state) =>
                         {
-                            EvictionCallback = (key, value, reason, state) =>
-                            {
-                                disposable.Dispose();
-                            }
-                        });
-                        break;
-                    }
+                            disposable.Dispose();
+                        }
+                    });
+                    break;
+                }
 
-                case IAsyncDisposable asyncDisposable:
+            case IAsyncDisposable asyncDisposable:
+                {
+                    entry.PostEvictionCallbacks.Add(new PostEvictionCallbackRegistration
                     {
-                        entry.PostEvictionCallbacks.Add(new PostEvictionCallbackRegistration
+                        EvictionCallback = (key, value, reason, state) =>
                         {
-                            EvictionCallback = (key, value, reason, state) =>
-                            {
 #pragma warning disable CA2012 // Use ValueTasks correctly
 #pragma warning disable MA0134 // Observe result of async calls
-                                asyncDisposable.DisposeAsync();
+                            asyncDisposable.DisposeAsync();
 #pragma warning restore MA0134 // Observe result of async calls
 #pragma warning restore CA2012 // Use ValueTasks correctly
-                            }
-                        });
-                        break;
-                    }
-            }
-
-            return item;
-        })!;
+                        }
+                    });
+                    break;
+                }
+        }
     }
 }

backend/src/Notifo.Domain.Integrations/Discord/DiscordBotClientPool.cs

@@ -0,0 +1,36 @@
+// ==========================================================================
+//  Notifo.io
+// ==========================================================================
+//  Copyright (c) Sebastian Stehle
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Discord;
+using Microsoft.Extensions.Caching.Memory;
+
+namespace Notifo.Domain.Integrations.Discord;
+
+public class DiscordBotClientPool : CachePool<IDiscordClient>
+{
+    public DiscordBotClientPool(IMemoryCache memoryCache)
+        : base(memoryCache)
+    {
+    }
+
+    public async Task<IDiscordClient> GetDiscordClient(string botToken, CancellationToken ct)
+    {
+        var cacheKey = $"{nameof(IDiscordClient)}_{botToken}";
+
+        var found = await GetOrCreateAsync(cacheKey, TimeSpan.FromMinutes(5), async () =>
+        {
+            var client = new DiscordClient();
+
+            // Method provides no option to pass CancellationToken
+            await client.LoginAsync(TokenType.Bot, botToken);
+
+            return client;
+        });
+
+        return found;
+    }
+}

backend/src/Notifo.Domain.Integrations/Discord/DiscordClient.cs

@@ -0,0 +1,19 @@
+// ==========================================================================
+//  Notifo.io
+// ==========================================================================
+//  Copyright (c) Sebastian Stehle
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Discord.Rest;
+
+namespace Notifo.Domain.Integrations.Discord;
+
+public class DiscordClient : DiscordRestClient, IAsyncDisposable
+{
+    public async new ValueTask DisposeAsync()
+    {
+        await LogoutAsync();
+        await base.DisposeAsync();
+    }
+}

backend/src/Notifo.Domain.Integrations/Discord/DiscordIntegration.Messaging.cs

@@ -0,0 +1,108 @@
+// ==========================================================================
+//  Notifo.io
+// ==========================================================================
+//  Copyright (c) Sebastian Stehle
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Discord;
+using Discord.Net;
+
+namespace Notifo.Domain.Integrations.Discord;
+
+public sealed partial class DiscordIntegration : IMessagingSender
+{
+    private const int Attempts = 5;
+    public const string DiscordChatId = nameof(DiscordChatId);
+
+    public void AddTargets(IDictionary<string, string> targets, UserInfo user)
+    {
+        var userId = GetUserId(user);
+
+        if (!string.IsNullOrWhiteSpace(userId))
+        {
+            targets[DiscordChatId] = userId;
+        }
+    }
+
+    public async Task<DeliveryResult> SendAsync(IntegrationContext context, MessagingMessage message,
+       CancellationToken ct)
+    {
+        if (!message.Targets.TryGetValue(DiscordChatId, out var chatId))
+        {
+            return DeliveryResult.Skipped();
+        }
+
+        return await SendMessageAsync(context, message, chatId, ct);
+    }
+
+    private async Task<DeliveryResult> SendMessageAsync(IntegrationContext context, MessagingMessage message, string chatId,
+       CancellationToken ct)
+    {
+        var botToken = BotToken.GetString(context.Properties);
+
+        for (var i = 1; i <= Attempts; i++)
+        {
+            try
+            {
+                var client = await discordBotClientPool.GetDiscordClient(botToken, ct);
+                var requestOptions = new RequestOptions { CancelToken = ct };
+
+                if (!ulong.TryParse(chatId, out var chatIdParsed))
+                {
+                    throw new InvalidOperationException("Invalid Discord DM chat ID.");
+                }
+
+                var user = await client.GetUserAsync(chatIdParsed, CacheMode.AllowDownload, requestOptions);
+                if (user is null)
+                {
+                    throw new InvalidOperationException("User not found.");
+                }
+
+                EmbedBuilder builder = new EmbedBuilder();
+
+                builder.WithTitle(message.Text);
+                builder.WithDescription(message.Body);
+
+                if (!string.IsNullOrWhiteSpace(message.ImageSmall))
+                {
+                    builder.WithThumbnailUrl(message.ImageSmall);
+                }
+
+                if (!string.IsNullOrWhiteSpace(message.ImageLarge))
+                {
+                    builder.WithImageUrl(message.ImageLarge);
+                }
+
+                if (!string.IsNullOrWhiteSpace(message.LinkUrl))
+                {
+                    builder.WithFields(new EmbedFieldBuilder().WithName(message.LinkText ?? message.LinkUrl).WithValue(message.LinkUrl));
+                }
+
+                builder.WithFooter("Sent with Notifo");
+
+                // Throws HttpException if the user has some privacy settings that make it impossible to text them.
+                await user.SendMessageAsync(string.Empty, false, builder.Build(), requestOptions);
+                break;
+            }
+            catch (HttpException ex) when (ex.DiscordCode == DiscordErrorCode.CannotSendMessageToUser)
+            {
+                return DeliveryResult.Failed("User has privacy settings that prevent sending them DMs on Discord.");
+            }
+            catch
+            {
+                if (i == Attempts)
+                {
+                    return DeliveryResult.Failed("Unknown error when sending Discord DM to user.");
+                }
+            }
+        }
+
+        return DeliveryResult.Handled;
+    }
+
+    private static string? GetUserId(UserInfo user)
+    {
+        return UserId.GetString(user.Properties);
+    }
+}

backend/src/Notifo.Domain.Integrations/Discord/DiscordIntegration.cs

@@ -0,0 +1,73 @@
+// ==========================================================================
+//  Notifo.io
+// ==========================================================================
+//  Copyright (c) Sebastian Stehle
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Discord;
+using Notifo.Domain.Integrations.Resources;
+using Notifo.Infrastructure.Validation;
+
+namespace Notifo.Domain.Integrations.Discord;
+
+public sealed partial class DiscordIntegration : IIntegration
+{
+    private readonly DiscordBotClientPool discordBotClientPool;
+
+    public static readonly IntegrationProperty UserId = new IntegrationProperty("discordUserId", PropertyType.Text)
+    {
+        EditorLabel = Texts.Discord_UserIdLabel,
+        EditorDescription = Texts.Discord_UserIdDescription
+    };
+
+    public static readonly IntegrationProperty BotToken = new IntegrationProperty("discordBotToken", PropertyType.Text)
+    {
+        EditorLabel = Texts.Discord_BotTokenLabel,
+        EditorDescription = Texts.Discord_BotTokenDescription,
+        IsRequired = true
+    };
+
+    public IntegrationDefinition Definition { get; } =
+    new IntegrationDefinition(
+        "Discord",
+        Texts.Discord_Name,
+        "<svg xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"0 0 127.14 96.36\"><path fill=\"#5865f2\" d=\"M107.7,8.07A105.15,105.15,0,0,0,81.47,0a72.06,72.06,0,0,0-3.36,6.83A97.68,97.68,0,0,0,49,6.83,72.37,72.37,0,0,0,45.64,0,105.89,105.89,0,0,0,19.39,8.09C2.79,32.65-1.71,56.6.54,80.21h0A105.73,105.73,0,0,0,32.71,96.36,77.7,77.7,0,0,0,39.6,85.25a68.42,68.42,0,0,1-10.85-5.18c.91-.66,1.8-1.34,2.66-2a75.57,75.57,0,0,0,64.32,0c.87.71,1.76,1.39,2.66,2a68.68,68.68,0,0,1-10.87,5.19,77,77,0,0,0,6.89,11.1A105.25,105.25,0,0,0,126.6,80.22h0C129.24,52.84,122.09,29.11,107.7,8.07ZM42.45,65.69C36.18,65.69,31,60,31,53s5-12.74,11.43-12.74S54,46,53.89,53,48.84,65.69,42.45,65.69Zm42.24,0C78.41,65.69,73.25,60,73.25,53s5-12.74,11.44-12.74S96.23,46,96.12,53,91.08,65.69,84.69,65.69Z\"/></svg>",
+        new List<IntegrationProperty>
+        {
+            BotToken
+        },
+        new List<IntegrationProperty>
+        {
+            UserId
+        },
+        new HashSet<string>
+        {
+            Providers.Messaging,
+        })
+    {
+        Description = Texts.Discord_Description
+    };
+
+    public DiscordIntegration(DiscordBotClientPool discordBotClientPool)
+    {
+        this.discordBotClientPool = discordBotClientPool;
+    }
+
+    public Task<IntegrationStatus> OnConfiguredAsync(IntegrationContext context, IntegrationConfiguration? previous,
+          CancellationToken ct)
+    {
+        var botToken = BotToken.GetString(context.Properties);
+
+        try
+        {
+            TokenUtils.ValidateToken(TokenType.Bot, botToken);
+        }
+        catch
+        {
+            throw new ValidationException("The Discord bot token is invalid.");
+        }
+
+        return Task.FromResult(IntegrationStatus.Verified);
+    }
+}

backend/src/Notifo.Domain.Integrations/Discord/DiscordServiceExtensions.cs

@@ -0,0 +1,25 @@
+// ==========================================================================
+//  Notifo.io
+// ==========================================================================
+//  Copyright (c) Sebastian Stehle
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Notifo.Domain.Integrations;
+using Notifo.Domain.Integrations.Discord;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+public static class DiscordServiceExtensions
+{
+    public static IServiceCollection AddIntegrationDiscord(this IServiceCollection services)
+    {
+        services.AddSingletonAs<DiscordIntegration>()
+            .As<IIntegration>();
+
+        services.AddSingletonAs<DiscordBotClientPool>()
+            .AsSelf();
+
+        return services;
+    }
+}

backend/src/Notifo.Domain.Integrations/Notifo.Domain.Integrations.csproj

@@ -11,6 +11,7 @@
   <ItemGroup>
     <PackageReference Include="AWSSDK.SimpleEmail" Version="3.7.300.60" />
     <PackageReference Include="Confluent.Kafka" Version="2.3.0" />
+    <PackageReference Include="Discord.Net" Version="3.15.2" />
     <PackageReference Include="FirebaseAdmin" Version="2.4.0" />
     <PackageReference Include="FluentValidation" Version="11.9.0" />
     <PackageReference Include="Fluid.Core" Version="2.7.0" />