Use dictionaries for storing context members, channels, and roles

DiscordChatExporter.Core/Exporting/ChannelExporter.cs

@@ -5,7 +5,6 @@ using System.Threading;
 using System.Threading.Tasks;
 using DiscordChatExporter.Core.Discord;
 using DiscordChatExporter.Core.Discord.Data;
-using DiscordChatExporter.Core.Discord.Data.Common;
 using DiscordChatExporter.Core.Exceptions;
 using DiscordChatExporter.Core.Utils.Extensions;
 using Gress;
@@ -24,11 +23,16 @@ public class ChannelExporter
         CancellationToken cancellationToken = default)
     {
         // Build context
-        var contextMembers = new HashSet<Member>(IdBasedEqualityComparer.Instance);
-        var contextChannels = await _discord.GetGuildChannelsAsync(request.Guild.Id, cancellationToken);
-        var contextRoles = await _discord.GetGuildRolesAsync(request.Guild.Id, cancellationToken);
+        var contextMembers = new Dictionary<Snowflake, Member>();
+
+        var contextChannels = (await _discord.GetGuildChannelsAsync(request.Guild.Id, cancellationToken))
+            .ToDictionary(c => c.Id);
+
+        var contextRoles = (await _discord.GetGuildRolesAsync(request.Guild.Id, cancellationToken))
+            .ToDictionary(r => r.Id);
 
         var context = new ExportContext(
+            _discord,
             request,
             contextMembers,
             contextChannels,
@@ -38,9 +42,6 @@ public class ChannelExporter
         // Export messages
         await using var messageExporter = new MessageExporter(context);
 
-        var exportedAnything = false;
-        var encounteredUsers = new HashSet<User>(IdBasedEqualityComparer.Instance);
-
         await foreach (var message in _discord.GetMessagesAsync(
                            request.Channel.Id,
                            request.After,
@@ -48,16 +49,10 @@ public class ChannelExporter
                            progress,
                            cancellationToken))
         {
-            cancellationToken.ThrowIfCancellationRequested();
-
-            // Skip messages that fail to pass the supplied filter
-            if (!request.MessageFilter.IsMatch(message))
-                continue;
-
             // Resolve members for referenced users
             foreach (var referencedUser in message.MentionedUsers.Prepend(message.Author))
             {
-                if (!encounteredUsers.Add(referencedUser))
+                if (contextMembers.ContainsKey(referencedUser.Id))
                     continue;
 
                 var member = await _discord.GetGuildMemberAsync(
@@ -66,16 +61,16 @@ public class ChannelExporter
                     cancellationToken
                 );
 
-                contextMembers.Add(member);
+                contextMembers[member.Id] = member;
             }
 
-            // Export message
-            await messageExporter.ExportMessageAsync(message, cancellationToken);
-            exportedAnything = true;
+            // Export the message
+            if (request.MessageFilter.IsMatch(message))
+                await messageExporter.ExportMessageAsync(message, cancellationToken);
         }
 
         // Throw if no messages were exported
-        if (!exportedAnything)
+        if (messageExporter.MessagesExported <= 0)
             throw DiscordChatExporterException.ChannelIsEmpty();
     }
 }

DiscordChatExporter.Core/Exporting/ExportContext.cs

@@ -12,31 +12,17 @@ using DiscordChatExporter.Core.Utils.Extensions;
 
 namespace DiscordChatExporter.Core.Exporting;
 
-internal class ExportContext
+internal record ExportContext(
+    DiscordClient Discord,
+    ExportRequest Request,
+    IReadOnlyDictionary<Snowflake, Member> Members,
+    IReadOnlyDictionary<Snowflake, Channel> Channels,
+    IReadOnlyDictionary<Snowflake, Role> Roles)
 {
-    private readonly ExportAssetDownloader _assetDownloader;
-
-    public ExportRequest Request { get; }
-
-    public IReadOnlyCollection<Member> Members { get; }
-
-    public IReadOnlyCollection<Channel> Channels { get; }
-
-    public IReadOnlyCollection<Role> Roles { get; }
-
-    public ExportContext(
-        ExportRequest request,
-        IReadOnlyCollection<Member> members,
-        IReadOnlyCollection<Channel> channels,
-        IReadOnlyCollection<Role> roles)
-    {
-        Request = request;
-        Members = members;
-        Channels = channels;
-        Roles = roles;
-
-        _assetDownloader = new ExportAssetDownloader(request.OutputAssetsDirPath, request.ShouldReuseAssets);
-    }
+    private readonly ExportAssetDownloader _assetDownloader = new(
+        Request.OutputAssetsDirPath,
+        Request.ShouldReuseAssets
+    );
 
     public string FormatDate(DateTimeOffset instant) => Request.DateFormat switch
     {
@@ -45,18 +31,23 @@ internal class ExportContext
         var format => instant.ToLocalString(format)
     };
 
-    public Member? TryGetMember(Snowflake id) => Members.FirstOrDefault(m => m.Id == id);
+    public Member? TryGetMember(Snowflake id) => Members.GetValueOrDefault(id);
 
-    public Channel? TryGetChannel(Snowflake id) => Channels.FirstOrDefault(c => c.Id == id);
+    public Channel? TryGetChannel(Snowflake id) => Channels.GetValueOrDefault(id);
 
-    public Role? TryGetRole(Snowflake id) => Roles.FirstOrDefault(r => r.Id == id);
+    public Role? TryGetRole(Snowflake id) => Roles.GetValueOrDefault(id);
 
     public Color? TryGetUserColor(Snowflake id)
     {
         var member = TryGetMember(id);
-        var roles = member?.RoleIds.Join(Roles, i => i, r => r.Id, (_, role) => role);
 
-        return roles?
+        var memberRoles = member?
+            .RoleIds
+            .Select(TryGetRole)
+            .WhereNotNull()
+            .ToArray();
+
+        return memberRoles?
             .Where(r => r.Color is not null)
             .OrderByDescending(r => r.Position)
             .Select(r => r.Color)

DiscordChatExporter.Core/Exporting/MessageExporter.cs

@@ -13,6 +13,8 @@ internal partial class MessageExporter : IAsyncDisposable
     private int _partitionIndex;
     private MessageWriter? _writer;
 
+    public long MessagesExported { get; private set; }
+
     public MessageExporter(ExportContext context)
     {
         _context = context;
@@ -62,6 +64,7 @@ internal partial class MessageExporter : IAsyncDisposable
     {
         var writer = await GetWriterAsync(cancellationToken);
         await writer.WriteMessageAsync(message, cancellationToken);
+        MessagesExported++;
     }
 
     public async ValueTask DisposeAsync() => await ResetWriterAsync();

DiscordChatExporter.Core/Utils/Extensions/CollectionExtensions.cs

@@ -15,4 +15,13 @@ public static class CollectionExtensions
         foreach (var o in source)
             yield return (o, i++);
     }
+
+    public static IEnumerable<T> WhereNotNull<T>(this IEnumerable<T?> source) where T : class
+    {
+        foreach (var o in source)
+        {
+            if (o is not null)
+                yield return o;
+        }
+    }
 }