More restructuring

src/Nadeko.Bot.Common/TypeReaders/GuildDateTimeTypeReader.cs

@@ -0,0 +1,49 @@
+#nullable disable
+namespace NadekoBot.Common.TypeReaders;
+
+public sealed class GuildDateTimeTypeReader : NadekoTypeReader<GuildDateTime>
+{
+    private readonly ITimezoneService _gts;
+
+    public GuildDateTimeTypeReader(ITimezoneService gts)
+        => _gts = gts;
+
+    public override ValueTask<TypeReaderResult<GuildDateTime>> ReadAsync(ICommandContext context, string input)
+    {
+        var gdt = Parse(context.Guild.Id, input);
+        if (gdt is null)
+        {
+            return new(TypeReaderResult.FromError<GuildDateTime>(CommandError.ParseFailed,
+                "Input string is in an incorrect format."));
+        }
+
+        return new(TypeReaderResult.FromSuccess(gdt));
+    }
+
+    private GuildDateTime Parse(ulong guildId, string input)
+    {
+        if (!DateTime.TryParse(input, out var dt))
+            return null;
+
+        var tz = _gts.GetTimeZoneOrUtc(guildId);
+
+        return new(tz, dt);
+    }
+}
+
+public class GuildDateTime
+{
+    public TimeZoneInfo Timezone { get; }
+    public DateTime CurrentGuildTime { get; }
+    public DateTime InputTime { get; }
+    public DateTime InputTimeUtc { get; }
+
+    public GuildDateTime(TimeZoneInfo guildTimezone, DateTime inputTime)
+    {
+        var now = DateTime.UtcNow;
+        Timezone = guildTimezone;
+        CurrentGuildTime = TimeZoneInfo.ConvertTime(now, TimeZoneInfo.Utc, Timezone);
+        InputTime = inputTime;
+        InputTimeUtc = TimeZoneInfo.ConvertTime(inputTime, Timezone, TimeZoneInfo.Utc);
+    }
+}