Replace the date format option with a locale option (#1130)

DiscordChatExporter.Cli.Tests/Infra/ExportWrapper.cs

@@ -59,7 +59,9 @@ public static class ExportWrapper
                 Token = Secrets.DiscordToken,
                 ChannelIds = new[] { channelId },
                 ExportFormat = format,
-                OutputPath = filePath
+                OutputPath = filePath,
+                Locale = "en-US",
+                IsUtcNormalizationEnabled = true
             }.ExecuteAsync(console);
         }
 

DiscordChatExporter.Cli.Tests/Specs/HtmlMarkdownSpecs.cs

@@ -1,8 +1,6 @@
-using System;
+using System.Threading.Tasks;
-using System.Threading.Tasks;
 using AngleSharp.Dom;
 using DiscordChatExporter.Cli.Tests.Infra;
-using DiscordChatExporter.Cli.Tests.Utils;
 using DiscordChatExporter.Core.Discord;
 using FluentAssertions;
 using Xunit;
@@ -14,218 +12,128 @@ public class HtmlMarkdownSpecs
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323136411078787")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Default timestamp: 2/12/2023 1:36 PM");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323136411078787")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Default timestamp: 02/12/2023 3:36 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_short_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323205268967596")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Short time timestamp: 1:36 PM");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323205268967596")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Short time timestamp: 3:36 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_long_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323235342139483")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Long time timestamp: 1:36:12 PM");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323235342139483")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Long time timestamp: 3:36:12 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_short_date_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323326727634984")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Short date timestamp: 2/12/2023");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323326727634984")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Short date timestamp: 02/12/2023");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_long_date_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323350731640863")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Long date timestamp: Sunday, February 12, 2023");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323350731640863")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Long date timestamp: February 12, 2023");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_full_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323374379118593")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Full timestamp: Sunday, February 12, 2023 1:36 PM");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323374379118593")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Full timestamp: February 12, 2023 3:36 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_full_long_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323409095376947")
+        );
 
-        try
+        // Assert
-        {
+        message
-            // Act
+            .Text()
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            .Should()
-                ChannelIds.MarkdownTestCases,
+            .Contain("Full long timestamp: Sunday, February 12, 2023 1:36:12 PM");
-                Snowflake.Parse("1074323409095376947")
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            );
-
-            // Assert
-            message
-                .Text()
-                .Should()
-                .Contain("Full long timestamp: Sunday, February 12, 2023 3:36 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_a_timestamp_marker_in_the_relative_format()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074323436853285004")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Relative timestamp: 2/12/2023 1:36 PM");
-            // Act
+        message.InnerHtml.Should().Contain("Sunday, February 12, 2023 1:36 PM");
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074323436853285004")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Relative timestamp: 02/12/2023 3:36 PM");
-            message.InnerHtml.Should().Contain("Sunday, February 12, 2023 3:36 PM");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 
     [Fact]
     public async Task I_can_export_a_channel_that_contains_a_message_with_an_invalid_timestamp_marker()
     {
-        // Date formatting code relies on the local time zone, so we need to set it to a fixed value
+        // Act
-        TimeZoneInfoEx.SetLocal(TimeSpan.FromHours(+2));
+        var message = await ExportWrapper.GetMessageAsHtmlAsync(
+            ChannelIds.MarkdownTestCases,
+            Snowflake.Parse("1074328534409019563")
+        );
 
-        try
+        // Assert
-        {
+        message.Text().Should().Contain("Invalid timestamp: Invalid date");
-            // Act
-            var message = await ExportWrapper.GetMessageAsHtmlAsync(
-                ChannelIds.MarkdownTestCases,
-                Snowflake.Parse("1074328534409019563")
-            );
-
-            // Assert
-            message.Text().Should().Contain("Invalid timestamp: Invalid date");
-        }
-        finally
-        {
-            TimeZoneInfo.ClearCachedData();
-        }
     }
 }

DiscordChatExporter.Cli.Tests/Utils/TimeZoneInfoEx.cs

@@ -1,14 +0,0 @@
-using System;
-using ReflectionMagic;
-
-namespace DiscordChatExporter.Cli.Tests.Utils;
-
-internal static class TimeZoneInfoEx
-{
-    // https://stackoverflow.com/a/63700512/2205454
-    public static void SetLocal(TimeZoneInfo timeZone) =>
-        typeof(TimeZoneInfo).AsDynamicType().s_cachedData._localTimeZone = timeZone;
-
-    public static void SetLocal(TimeSpan offset) =>
-        SetLocal(TimeZoneInfo.CreateCustomTimeZone("test-tz", offset, "test-tz", "test-tz"));
-}

DiscordChatExporter.Cli/Commands/Base/ExportCommandBase.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
@@ -88,7 +89,7 @@ public abstract class ExportCommandBase : DiscordCommandBase
         "media",
         Description = "Download assets referenced by the export (user avatars, attached files, embedded images, etc.)."
     )]
-    public bool ShouldDownloadAssets { get; init; } = false;
+    public bool ShouldDownloadAssets { get; init; }
 
     [CommandOption(
         "reuse-media",
@@ -111,9 +112,19 @@ public abstract class ExportCommandBase : DiscordCommandBase
         init => _assetsDirPath = value is not null ? Path.GetFullPath(value) : null;
     }
 
-    [CommandOption("dateformat", Description = "Format used when writing dates.")]
+    [Obsolete("This option doesn't do anything. Kept for backwards compatibility.")]
+    [CommandOption(
+        "dateformat",
+        Description = "This option doesn't do anything. Kept for backwards compatibility."
+    )]
     public string DateFormat { get; init; } = "MM/dd/yyyy h:mm tt";
 
+    [CommandOption("locale", Description = "Locale to use when formatting dates and numbers.")]
+    public string Locale { get; init; } = CultureInfo.CurrentCulture.Name;
+
+    [CommandOption("utc", Description = "Normalize all timestamps to UTC+0.")]
+    public bool IsUtcNormalizationEnabled { get; init; } = false;
+
     [CommandOption(
         "fuck-russia",
         EnvironmentVariable = "FUCK_RUSSIA",
@@ -210,7 +221,8 @@ public abstract class ExportCommandBase : DiscordCommandBase
                                         ShouldFormatMarkdown,
                                         ShouldDownloadAssets,
                                         ShouldReuseAssets,
-                                        DateFormat
+                                        Locale,
+                                        IsUtcNormalizationEnabled
                                     );
 
                                     await Exporter.ExportChannelAsync(

DiscordChatExporter.Core/Discord/Data/Common/ImageCdn.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using System.Linq;
 using DiscordChatExporter.Core.Utils.Extensions;
 
@@ -19,7 +20,10 @@ public static class ImageCdn
             ? runes
             : runes.Where(r => r.Value != 0xfe0f);
 
-        var twemojiId = string.Join("-", filteredRunes.Select(r => r.Value.ToString("x")));
+        var twemojiId = string.Join(
+            "-",
+            filteredRunes.Select(r => r.Value.ToString("x", CultureInfo.InvariantCulture))
+        );
 
         return $"https://cdn.jsdelivr.net/gh/twitter/twemoji@latest/assets/svg/{twemojiId}.svg";
     }

DiscordChatExporter.Core/Exporting/ExportContext.cs

@@ -34,6 +34,12 @@ internal class ExportContext
         );
     }
 
+    public DateTimeOffset NormalizeDate(DateTimeOffset instant) =>
+        Request.IsUtcNormalizationEnabled ? instant.ToUniversalTime() : instant.ToLocalTime();
+
+    public string FormatDate(DateTimeOffset instant, string format = "g") =>
+        NormalizeDate(instant).ToString(format, Request.CultureInfo);
+
     public async ValueTask PopulateChannelsAndRolesAsync(
         CancellationToken cancellationToken = default
     )
@@ -41,10 +47,14 @@ internal class ExportContext
         await foreach (
             var channel in Discord.GetGuildChannelsAsync(Request.Guild.Id, cancellationToken)
         )
+        {
             _channelsById[channel.Id] = channel;
+        }
 
         await foreach (var role in Discord.GetGuildRolesAsync(Request.Guild.Id, cancellationToken))
+        {
             _rolesById[role.Id] = role;
+        }
     }
 
     // Because members cannot be pulled in bulk, we need to populate them on demand
@@ -84,14 +94,6 @@ internal class ExportContext
         CancellationToken cancellationToken = default
     ) => await PopulateMemberAsync(user.Id, user, cancellationToken);
 
-    public string FormatDate(DateTimeOffset instant) =>
-        Request.DateFormat switch
-        {
-            "unix" => instant.ToUnixTimeSeconds().ToString(),
-            "unixms" => instant.ToUnixTimeMilliseconds().ToString(),
-            var format => instant.ToLocalString(format)
-        };
-
     public Member? TryGetMember(Snowflake id) => _membersById.GetValueOrDefault(id);
 
     public Channel? TryGetChannel(Snowflake id) => _channelsById.GetValueOrDefault(id);

DiscordChatExporter.Core/Exporting/ExportRequest.cs

@@ -39,7 +39,11 @@ public partial class ExportRequest
 
     public bool ShouldReuseAssets { get; }
 
-    public string DateFormat { get; }
+    public string Locale { get; }
+
+    public CultureInfo CultureInfo { get; }
+
+    public bool IsUtcNormalizationEnabled { get; }
 
     public ExportRequest(
         Guild guild,
@@ -54,7 +58,8 @@ public partial class ExportRequest
         bool shouldFormatMarkdown,
         bool shouldDownloadAssets,
         bool shouldReuseAssets,
-        string dateFormat
+        string locale,
+        bool isUtcNormalizationEnabled
     )
     {
         Guild = guild;
@@ -67,7 +72,8 @@ public partial class ExportRequest
         ShouldFormatMarkdown = shouldFormatMarkdown;
         ShouldDownloadAssets = shouldDownloadAssets;
         ShouldReuseAssets = shouldReuseAssets;
-        DateFormat = dateFormat;
+        Locale = locale;
+        IsUtcNormalizationEnabled = isUtcNormalizationEnabled;
 
         OutputFilePath = GetOutputBaseFilePath(Guild, Channel, outputPath, Format, After, Before);
 
@@ -76,6 +82,8 @@ public partial class ExportRequest
         AssetsDirPath = !string.IsNullOrWhiteSpace(assetsDirPath)
             ? FormatPath(assetsDirPath, Guild, Channel, After, Before)
             : $"{OutputFilePath}_Files{Path.DirectorySeparatorChar}";
+
+        CultureInfo = CultureInfo.GetCultureInfo(Locale);
     }
 }
 

DiscordChatExporter.Core/Exporting/HtmlMarkdownVisitor.cs

@@ -317,12 +317,12 @@ internal partial class HtmlMarkdownVisitor : MarkdownVisitor
     )
     {
         var formatted = timestamp.Instant is not null
-            ? !string.IsNullOrWhiteSpace(timestamp.Format)
+            ? _context.FormatDate(timestamp.Instant.Value, timestamp.Format ?? "g")
-                ? timestamp.Instant.Value.ToLocalString(timestamp.Format)
-                : _context.FormatDate(timestamp.Instant.Value)
             : "Invalid date";
 
-        var formattedLong = timestamp.Instant?.ToLocalString("dddd, MMMM d, yyyy h:mm tt") ?? "";
+        var formattedLong = timestamp.Instant is not null
+            ? _context.FormatDate(timestamp.Instant.Value, "f")
+            : "";
 
         _buffer.Append(
             // lang=html

DiscordChatExporter.Core/Exporting/HtmlMessageWriter.cs

@@ -139,7 +139,7 @@ internal class HtmlMessageWriter : MessageWriter
             Minify(
                 await new PostambleTemplate
                 {
-                    ExportContext = Context,
+                    Context = Context,
                     MessagesWritten = MessagesWritten
                 }.RenderAsync(cancellationToken)
             )

DiscordChatExporter.Core/Exporting/JsonMessageWriter.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Text.Encodings.Web;
 using System.Text.Json;
@@ -196,7 +197,7 @@ internal class JsonMessageWriter : MessageWriter
             await FormatMarkdownAsync(embed.Title ?? "", cancellationToken)
         );
         _writer.WriteString("url", embed.Url);
-        _writer.WriteString("timestamp", embed.Timestamp);
+        _writer.WriteString("timestamp", embed.Timestamp?.Pipe(Context.NormalizeDate));
         _writer.WriteString(
             "description",
             await FormatMarkdownAsync(embed.Description ?? "", cancellationToken)
@@ -292,12 +293,12 @@ internal class JsonMessageWriter : MessageWriter
 
         // Date range
         _writer.WriteStartObject("dateRange");
-        _writer.WriteString("after", Context.Request.After?.ToDate());
+        _writer.WriteString("after", Context.Request.After?.ToDate().Pipe(Context.NormalizeDate));
-        _writer.WriteString("before", Context.Request.Before?.ToDate());
+        _writer.WriteString("before", Context.Request.Before?.ToDate().Pipe(Context.NormalizeDate));
         _writer.WriteEndObject();
 
         // Timestamp
-        _writer.WriteString("exportedAt", System.DateTimeOffset.UtcNow);
+        _writer.WriteString("exportedAt", Context.NormalizeDate(DateTimeOffset.UtcNow));
 
         // Message array (start)
         _writer.WriteStartArray("messages");
@@ -316,9 +317,15 @@ internal class JsonMessageWriter : MessageWriter
         // Metadata
         _writer.WriteString("id", message.Id.ToString());
         _writer.WriteString("type", message.Kind.ToString());
-        _writer.WriteString("timestamp", message.Timestamp);
+        _writer.WriteString("timestamp", Context.NormalizeDate(message.Timestamp));
-        _writer.WriteString("timestampEdited", message.EditedTimestamp);
+        _writer.WriteString(
-        _writer.WriteString("callEndedTimestamp", message.CallEndedTimestamp);
+            "timestampEdited",
+            message.EditedTimestamp?.Pipe(Context.NormalizeDate)
+        );
+        _writer.WriteString(
+            "callEndedTimestamp",
+            message.CallEndedTimestamp?.Pipe(Context.NormalizeDate)
+        );
         _writer.WriteBoolean("isPinned", message.IsPinned);
 
         // Content

DiscordChatExporter.Core/Exporting/MessageGroupTemplate.cshtml

@@ -1,6 +1,5 @@
 @using System
 @using System.Collections.Generic
-@using System.Globalization
 @using System.Linq
 @using System.Threading.Tasks
 @using DiscordChatExporter.Core.Discord.Data
@@ -20,8 +19,8 @@
     ValueTask<string> ResolveAssetUrlAsync(string url) =>
         Context.ResolveAssetUrlAsync(url, CancellationToken);
 
-    string FormatDate(DateTimeOffset instant) =>
+    string FormatDate(DateTimeOffset instant, string format = "g") =>
-        Context.FormatDate(instant);
+        Context.FormatDate(instant, format);
 
     async ValueTask<string> FormatMarkdownAsync(string markdown) =>
         Context.Request.ShouldFormatMarkdown
@@ -100,7 +99,7 @@
                         }
                         else if (message.Kind == MessageKind.Call)
                         {
-                            <span>started a call that lasted @(((message.CallEndedTimestamp ?? message.Timestamp) - message.Timestamp).TotalMinutes.ToString("n0", CultureInfo.InvariantCulture)) minutes</span>
+                            <span>started a call that lasted @(((message.CallEndedTimestamp ?? message.Timestamp) - message.Timestamp).TotalMinutes.ToString("n0", Context.Request.CultureInfo)) minutes</span>
                         }
                         else if (message.Kind == MessageKind.ChannelNameChange)
                         {
@@ -132,7 +131,7 @@
                     </span>
 
                     @* Timestamp *@
-                    <span class="chatlog__system-notification-timestamp">
+                    <span class="chatlog__system-notification-timestamp" title="@FormatDate(message.Timestamp, "f")">
                         <a href="#chatlog__message-container-@message.Id">@FormatDate(message.Timestamp)</a>
                     </span>
                 </div>
@@ -154,7 +153,7 @@
                     }
                     else
                     {
-                        <div class="chatlog__short-timestamp" title="@FormatDate(message.Timestamp)">@message.Timestamp.ToLocalString("t")</div>
+                        <div class="chatlog__short-timestamp" title="@FormatDate(message.Timestamp, "f")">@FormatDate(message.Timestamp, "t")</div>
                     }
                 </div>
 
@@ -194,7 +193,7 @@
 
                                         @if (message.ReferencedMessage.EditedTimestamp is not null)
                                         {
-                                            <span class="chatlog__reply-edited-timestamp" title="@FormatDate(message.ReferencedMessage.EditedTimestamp.Value)">(edited)</span>
+                                            <span class="chatlog__reply-edited-timestamp" title="@FormatDate(message.ReferencedMessage.EditedTimestamp.Value, "f")">(edited)</span>
                                         }
                                     </div>
                                 }
@@ -241,7 +240,7 @@
                             }
 
                             @* Timestamp *@
-                            <span class="chatlog__timestamp"><a href="#chatlog__message-container-@message.Id">@FormatDate(message.Timestamp)</a></span>
+                            <span class="chatlog__timestamp" title="@FormatDate(message.Timestamp, "f")"><a href="#chatlog__message-container-@message.Id">@FormatDate(message.Timestamp)</a></span>
                         </div>
                     }
 
@@ -258,7 +257,7 @@
                             @* Edited timestamp *@
                             @if (message.EditedTimestamp is not null)
                             {
-                                <span class="chatlog__edited-timestamp" title="@FormatDate(message.EditedTimestamp.Value)">(edited)</span>
+                                <span class="chatlog__edited-timestamp" title="@FormatDate(message.EditedTimestamp.Value, "f")">(edited)</span>
                             }
                         </div>
                     }

DiscordChatExporter.Core/Exporting/PlainTextMarkdownVisitor.cs

@@ -91,9 +91,7 @@ internal partial class PlainTextMarkdownVisitor : MarkdownVisitor
     {
         _buffer.Append(
             timestamp.Instant is not null
-                ? !string.IsNullOrWhiteSpace(timestamp.Format)
+                ? _context.FormatDate(timestamp.Instant.Value, timestamp.Format ?? "g")
-                    ? timestamp.Instant.Value.ToLocalString(timestamp.Format)
-                    : _context.FormatDate(timestamp.Instant.Value)
                 : "Invalid date"
         );
 

DiscordChatExporter.Core/Exporting/PostambleTemplate.cshtml

@@ -1,7 +1,9 @@
-@inherits RazorBlade.HtmlTemplate
+@using System
+
+@inherits RazorBlade.HtmlTemplate
 
 @functions {
-    public required ExportContext ExportContext { get; init; }
+    public required ExportContext Context { get; init; }
 
     public required long MessagesWritten { get; init; }
 }
@@ -14,7 +16,8 @@
 <!--/wmm:ignore-->
 
 <div class="postamble">
-    <div class="postamble__entry">Exported @MessagesWritten.ToString("n0") message(s)</div>
+    <div class="postamble__entry">Exported @MessagesWritten.ToString("n0", Context.Request.CultureInfo) message(s)</div>
+    <div class="postamble__entry">Timezone: UTC@((Context.Request.IsUtcNormalizationEnabled ? 0 : TimeZoneInfo.Local.BaseUtcOffset.TotalHours).ToString("+#.#;-#.#;+0", Context.Request.CultureInfo))</div>
 </div>
 
 </body>

DiscordChatExporter.Core/Exporting/PreambleTemplate.cshtml

@@ -21,8 +21,8 @@
     ValueTask<string> ResolveAssetUrlAsync(string url) =>
         Context.ResolveAssetUrlAsync(url, CancellationToken);
 
-    string FormatDate(DateTimeOffset instant) =>
+    string FormatDate(DateTimeOffset instant, string format = "g") =>
-        Context.FormatDate(instant);
+        Context.FormatDate(instant, format);
 
     async ValueTask<string> FormatMarkdownAsync(string markdown) =>
         Context.Request.ShouldFormatMarkdown

DiscordChatExporter.Core/Markdown/Parsing/MarkdownParser.cs

@@ -340,16 +340,13 @@ internal static partial class MarkdownParser
                             )
                         );
 
-                    var format = m.Groups[2].Value switch
+                    var format = m.Groups[2].Value.NullIfWhiteSpace() switch
                     {
-                        "t" => "h:mm tt",
+                        // Ignore the 'relative' format because it doesn't make sense in a static export
-                        "T" => "h:mm:ss tt",
+                        "r" => null,
-                        "d" => "MM/dd/yyyy",
+                        "R" => null,
-                        "D" => "MMMM dd, yyyy",
+                        // Discord's date formats are (mostly) compatible with .NET's date formats
-                        "f" => "MMMM dd, yyyy h:mm tt",
+                        var f => f
-                        "F" => "dddd, MMMM dd, yyyy h:mm tt",
-                        // Relative format is ignored because it doesn't make much sense in a static export
-                        _ => null
                     };
 
                     return new TimestampNode(instant, format);

DiscordChatExporter.Core/Utils/Extensions/DateExtensions.cs

@@ -1,10 +0,0 @@
-using System;
-using System.Globalization;
-
-namespace DiscordChatExporter.Core.Utils.Extensions;
-
-public static class DateExtensions
-{
-    public static string ToLocalString(this DateTimeOffset instant, string format) =>
-        instant.ToLocalTime().ToString(format, CultureInfo.InvariantCulture);
-}

DiscordChatExporter.Gui/Converters/LocaleToDisplayNameConverter.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Globalization;
+using System.Windows.Data;
+
+namespace DiscordChatExporter.Gui.Converters;
+
+[ValueConversion(typeof(string), typeof(string))]
+public class LocaleToDisplayNameConverter : IValueConverter
+{
+    public static LocaleToDisplayNameConverter Instance { get; } = new();
+
+    public object? Convert(object value, Type targetType, object parameter, CultureInfo culture) =>
+        value is string locale ? CultureInfo.GetCultureInfo(locale).DisplayName : null;
+
+    public object ConvertBack(
+        object value,
+        Type targetType,
+        object parameter,
+        CultureInfo culture
+    ) => throw new NotSupportedException();
+}

DiscordChatExporter.Gui/Services/SettingsService.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Globalization;
 using System.IO;
 using Cogwheel;
 using DiscordChatExporter.Core.Exporting;
@@ -19,7 +20,9 @@ public partial class SettingsService : SettingsBase
 
     public ThreadInclusionMode ThreadInclusionMode { get; set; } = ThreadInclusionMode.None;
 
-    public string DateFormat { get; set; } = "MM/dd/yyyy h:mm tt";
+    public string Locale { get; set; } = CultureInfo.CurrentCulture.Name;
+
+    public bool IsUtcNormalizationEnabled { get; set; }
 
     public int ParallelLimit { get; set; } = 1;
 

DiscordChatExporter.Gui/ViewModels/Components/DashboardViewModel.cs

@@ -78,6 +78,11 @@ public class DashboardViewModel : PropertyChangedBase
                 // due to the channels being asynchronously loaded.
                 AvailableChannels = null;
                 SelectedChannels = null;
+
+                // Pull channels for the selected guild
+                // (ideally this should be called inside `PullGuilds()`,
+                // but Stylet doesn't support async commands)
+                PullChannels();
             }
         );
     }
@@ -88,14 +93,14 @@ public class DashboardViewModel : PropertyChangedBase
             Token = _settingsService.LastToken;
     }
 
-    public async ValueTask ShowSettingsAsync() =>
+    public async void ShowSettings() =>
         await _dialogManager.ShowDialogAsync(_viewModelFactory.CreateSettingsViewModel());
 
     public void ShowHelp() => ProcessEx.StartShellExecute(App.DocumentationUrl);
 
-    public bool CanPullGuildsAsync => !IsBusy && !string.IsNullOrWhiteSpace(Token);
+    public bool CanPullGuilds => !IsBusy && !string.IsNullOrWhiteSpace(Token);
 
-    public async ValueTask PullGuildsAsync()
+    public async void PullGuilds()
     {
         IsBusy = true;
         var progress = _progressMuxer.CreateInput();
@@ -118,9 +123,6 @@ public class DashboardViewModel : PropertyChangedBase
 
             AvailableGuilds = guilds;
             SelectedGuild = guilds.FirstOrDefault();
-
-            // Pull channels for the selected guild
-            await PullChannelsAsync();
         }
         catch (DiscordChatExporterException ex) when (!ex.IsFatal)
         {
@@ -142,10 +144,9 @@ public class DashboardViewModel : PropertyChangedBase
         }
     }
 
-    public bool CanPullChannelsAsync =>
+    public bool CanPullChannels => !IsBusy && _discord is not null && SelectedGuild is not null;
-        !IsBusy && _discord is not null && SelectedGuild is not null;
 
-    public async ValueTask PullChannelsAsync()
+    public async void PullChannels()
     {
         IsBusy = true;
         var progress = _progressMuxer.CreateInput();
@@ -206,13 +207,13 @@ public class DashboardViewModel : PropertyChangedBase
         }
     }
 
-    public bool CanExportAsync =>
+    public bool CanExport =>
         !IsBusy
         && _discord is not null
         && SelectedGuild is not null
         && SelectedChannels?.Any() is true;
 
-    public async ValueTask ExportAsync()
+    public async void Export()
     {
         IsBusy = true;
 
@@ -267,7 +268,8 @@ public class DashboardViewModel : PropertyChangedBase
                             dialog.ShouldFormatMarkdown,
                             dialog.ShouldDownloadAssets,
                             dialog.ShouldReuseAssets,
-                            _settingsService.DateFormat
+                            _settingsService.Locale,
+                            _settingsService.IsUtcNormalizationEnabled
                         );
 
                         await exporter.ExportChannelAsync(request, progress, cancellationToken);

DiscordChatExporter.Gui/ViewModels/Dialogs/SettingsViewModel.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
 using DiscordChatExporter.Gui.Models;
 using DiscordChatExporter.Gui.Services;
 using DiscordChatExporter.Gui.ViewModels.Framework;
@@ -37,10 +39,52 @@ public class SettingsViewModel : DialogScreen
         set => _settingsService.ThreadInclusionMode = value;
     }
 
-    public string DateFormat
+    public IReadOnlyList<string> AvailableLocales { get; } = new[]
+        {
+            // Current locale
+            CultureInfo.CurrentCulture.Name,
+            // Locales supported by the Discord app
+            "da-DK",
+            "de-DE",
+            "en-GB",
+            "en-US",
+            "es-ES",
+            "fr-FR",
+            "hr-HR",
+            "it-IT",
+            "lt-LT",
+            "hu-HU",
+            "nl-NL",
+            "no-NO",
+            "pl-PL",
+            "pt-BR",
+            "ro-RO",
+            "fi-FI",
+            "sv-SE",
+            "vi-VN",
+            "tr-TR",
+            "cs-CZ",
+            "el-GR",
+            "bg-BG",
+            "ru-RU",
+            "uk-UA",
+            "th-TH",
+            "zh-CN",
+            "ja-JP",
+            "zh-TW",
+            "ko-KR"
+        }.Distinct(StringComparer.OrdinalIgnoreCase).ToArray();
+
+    public string Locale
     {
-        get => _settingsService.DateFormat;
+        get => _settingsService.Locale;
-        set => _settingsService.DateFormat = value;
+        set => _settingsService.Locale = value;
+    }
+
+    public bool IsUtcNormalizationEnabled
+    {
+        get => _settingsService.IsUtcNormalizationEnabled;
+        set => _settingsService.IsUtcNormalizationEnabled = value;
     }
 
     public int ParallelLimit

DiscordChatExporter.Gui/Views/Components/DashboardView.xaml

@@ -105,7 +105,7 @@
                         Grid.Column="2"
                         Margin="0,6,6,6"
                         Padding="4"
-                        Command="{s:Action PullGuildsAsync}"
+                        Command="{s:Action PullGuilds}"
                         IsDefault="True"
                         Style="{DynamicResource MaterialDesignFlatButton}"
                         ToolTip="Pull available guilds and channels (Enter)">
@@ -122,7 +122,7 @@
                 Grid.Column="1"
                 Margin="6"
                 Padding="4"
-                Command="{s:Action ShowSettingsAsync}"
+                Command="{s:Action ShowSettings}"
                 Foreground="{DynamicResource MaterialDesignDarkForeground}"
                 Style="{DynamicResource MaterialDesignFlatButton}"
                 ToolTip="Settings">
@@ -274,7 +274,7 @@
                                     Margin="-8"
                                     Background="Transparent"
                                     Cursor="Hand"
-                                    MouseLeftButtonUp="{s:Action PullChannelsAsync}"
+                                    MouseLeftButtonUp="{s:Action PullChannels}"
                                     ToolTip="{Binding Name}">
                                     <!--  Guild icon placeholder  -->
                                     <Ellipse
@@ -350,7 +350,7 @@
                             <DataTemplate DataType="{x:Type data:Channel}">
                                 <Grid Margin="-8" Background="Transparent">
                                     <Grid.InputBindings>
-                                        <MouseBinding Command="{s:Action ExportAsync}" MouseAction="LeftDoubleClick" />
+                                        <MouseBinding Command="{s:Action Export}" MouseAction="LeftDoubleClick" />
                                     </Grid.InputBindings>
                                     <Grid.ColumnDefinitions>
                                         <ColumnDefinition Width="Auto" />
@@ -412,9 +412,9 @@
                 Margin="32,24"
                 HorizontalAlignment="Right"
                 VerticalAlignment="Bottom"
-                Command="{s:Action ExportAsync}"
+                Command="{s:Action Export}"
                 Style="{DynamicResource MaterialDesignFloatingActionAccentButton}"
-                Visibility="{Binding CanExportAsync, Converter={x:Static s:BoolToVisibilityConverter.Instance}}">
+                Visibility="{Binding CanExport, Converter={x:Static s:BoolToVisibilityConverter.Instance}}">
                 <materialDesign:PackIcon
                     Width="32"
                     Height="32"

DiscordChatExporter.Gui/Views/Dialogs/SettingsView.xaml

@@ -2,6 +2,7 @@
     x:Class="DiscordChatExporter.Gui.Views.Dialogs.SettingsView"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:converters="clr-namespace:DiscordChatExporter.Gui.Converters"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:dialogs="clr-namespace:DiscordChatExporter.Gui.ViewModels.Dialogs"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
@@ -93,27 +94,51 @@
                             DockPanel.Dock="Left"
                             Text="Show threads" />
                         <ComboBox
+                            Width="150"
                             VerticalAlignment="Center"
                             DockPanel.Dock="Right"
                             ItemsSource="{Binding AvailableThreadInclusions}"
                             SelectedItem="{Binding ThreadInclusionMode}" />
                     </DockPanel>
 
-                    <!--  Date format  -->
+                    <!--  Locale  -->
                     <DockPanel
                         Margin="16,8"
                         Background="Transparent"
                         LastChildFill="False"
-                        ToolTip="Format used when writing dates (uses .NET date formatting rules)">
+                        ToolTip="Locale to use when formatting dates and numbers">
                         <TextBlock
                             VerticalAlignment="Center"
                             DockPanel.Dock="Left"
-                            Text="Date format" />
+                            Text="Locale" />
-                        <TextBox
+                        <ComboBox
                             Width="150"
                             VerticalAlignment="Center"
                             DockPanel.Dock="Right"
-                            Text="{Binding DateFormat}" />
+                            ItemsSource="{Binding AvailableLocales}"
+                            SelectedItem="{Binding Locale}">
+                            <ComboBox.ItemTemplate>
+                                <DataTemplate>
+                                    <TextBlock Text="{Binding Converter={x:Static converters:LocaleToDisplayNameConverter.Instance}}" />
+                                </DataTemplate>
+                            </ComboBox.ItemTemplate>
+                        </ComboBox>
+                    </DockPanel>
+
+                    <!--  UTC normalization  -->
+                    <DockPanel
+                        Margin="16,8"
+                        Background="Transparent"
+                        LastChildFill="False"
+                        ToolTip="Normalize all timestamps to UTC+0">
+                        <TextBlock
+                            VerticalAlignment="Center"
+                            DockPanel.Dock="Left"
+                            Text="Normalize to UTC" />
+                        <ToggleButton
+                            VerticalAlignment="Center"
+                            DockPanel.Dock="Right"
+                            IsChecked="{Binding IsUtcNormalizationEnabled}" />
                     </DockPanel>
 
                     <!--  Parallel limit  -->
@@ -139,9 +164,13 @@
                             <Slider
                                 Width="150"
                                 VerticalAlignment="Center"
+                                IsSnapToTickEnabled="True"
+                                LargeChange="1"
                                 Maximum="10"
                                 Minimum="1"
+                                SmallChange="1"
                                 Style="{DynamicResource MaterialDesignThinSlider}"
+                                TickFrequency="1"
                                 Value="{Binding ParallelLimit}" />
                         </StackPanel>
                     </DockPanel>