Expand system time selection logic

PluralKit.Bot/Commands/SystemCommands.cs

@@ -157,8 +157,7 @@ namespace PluralKit.Bot.Commands
                 return;
             }
 
-            var zones = DateTimeZoneProviders.Tzdb;
-            var zone = zones.GetZoneOrNull(zoneStr);
+            var zone = await FindTimeZone(zoneStr);
             if (zone == null) throw Errors.InvalidTimeZone(zoneStr);
 
             var currentTime = SystemClock.Instance.GetCurrentInstant().InZone(zone);
@@ -171,6 +170,64 @@ namespace PluralKit.Bot.Commands
             await Context.Channel.SendMessageAsync($"System time zone changed to {zone.Id}.");
         }
 
+        public async Task<DateTimeZone> FindTimeZone(string zoneStr) {
+            // First, if we're given a flag emoji, we extract the flag emoji code from it.
+            zoneStr = PluralKit.Utils.ExtractCountryFlag(zoneStr) ?? zoneStr;
+            
+            // Then, we find all *locations* matching either the given country code or the country name.
+            var locations = TzdbDateTimeZoneSource.Default.Zone1970Locations;
+            var matchingLocations = locations.Where(l => l.Countries.Any(c =>
+                string.Equals(c.Code, zoneStr, StringComparison.InvariantCultureIgnoreCase) ||
+                string.Equals(c.Name, zoneStr, StringComparison.InvariantCultureIgnoreCase)));
+            
+            // Then, we find all (unique) time zone IDs that match.
+            var matchingZones = matchingLocations.Select(l => DateTimeZoneProviders.Tzdb.GetZoneOrNull(l.ZoneId))
+                .Distinct().ToList();
+            
+            // If the set of matching zones is empty (ie. we didn't find anything), we try a few other things.
+            if (matchingZones.Count == 0)
+            {
+                // First, we try to just find the time zone given directly and return that.
+                var givenZone = DateTimeZoneProviders.Tzdb.GetZoneOrNull(zoneStr);
+                if (givenZone != null) return givenZone;
+
+                // If we didn't find anything there either, we try parsing the string as an offset, then
+                // find all possible zones that match that offset. For an offset like UTC+2, this doesn't *quite*
+                // work, since there are 57(!) matching zones (as of 2019-06-13) - but for less populated time zones
+                // this could work nicely.
+                var inputWithoutUtc = zoneStr.Replace("UTC", "").Replace("GMT", "");
+
+                var res = OffsetPattern.CreateWithInvariantCulture("+H").Parse(inputWithoutUtc);
+                if (!res.Success) res = OffsetPattern.CreateWithInvariantCulture("+H:mm").Parse(inputWithoutUtc);
+
+                // If *this* didn't parse correctly, fuck it, bail.
+                if (!res.Success) return null;
+                var offset = res.Value;
+
+                // To try to reduce the count, we go by locations from the 1970+ database instead of just the full database
+                // This elides regions that have been identical since 1970, omitting small distinctions due to Ancient History(tm).
+                var allZones = TzdbDateTimeZoneSource.Default.Zone1970Locations.Select(l => l.ZoneId).Distinct();
+                matchingZones = allZones.Select(z => DateTimeZoneProviders.Tzdb.GetZoneOrNull(z))
+                    .Where(z => z.GetUtcOffset(SystemClock.Instance.GetCurrentInstant()) == offset).ToList();
+            }
+            
+            // If we have a list of viable time zones, we ask the user which is correct.
+            
+            // If we only have one, return that one.
+            if (matchingZones.Count == 1)
+                return matchingZones.First();
+            
+            // Otherwise, prompt and return!
+            return await Context.Choose("There were multiple matches for your time zone query. Please select the region that matches you the closest:", matchingZones,
+                z =>
+                {
+                    if (TzdbDateTimeZoneSource.Default.Aliases.Contains(z.Id))
+                        return $"**{z.Id}**, {string.Join(", ", TzdbDateTimeZoneSource.Default.Aliases[z.Id])}";
+
+                    return $"**{z.Id}**";
+                });
+        } 
+
         public override async Task<PKSystem> ReadContextParameterAsync(string value)
         {
             var res = await new PKSystemTypeReader().ReadAsync(Context, value, _services);

PluralKit.Bot/ContextUtils.cs

@@ -56,6 +56,8 @@ namespace PluralKit.Bot {
         }
 
         public static async Task Paginate<T>(this ICommandContext ctx, ICollection<T> items, int itemsPerPage, string title, Action<EmbedBuilder, IEnumerable<T>> renderer) {
+            // TODO: make this generic enough we can use it in Choose<T> below
+            
             var pageCount = (items.Count / itemsPerPage) + 1;
             Embed MakeEmbedForPage(int page) {
                 var eb = new EmbedBuilder();
@@ -93,6 +95,88 @@ namespace PluralKit.Bot {
             if (await ctx.HasPermission(ChannelPermission.ManageMessages)) await msg.RemoveAllReactionsAsync();
             else await msg.RemoveReactionsAsync(ctx.Client.CurrentUser, botEmojis);
         }
+        
+        public static async Task<T> Choose<T>(this ICommandContext ctx, string description, IList<T> items, Func<T, string> display = null)
+        {
+            // Generate a list of :regional_indicator_?: emoji surrogate pairs (starting at codepoint 0x1F1E6)
+            // We just do 7 (ABCDEFG), this amount is arbitrary (although sending a lot of emojis takes a while)
+            var pageSize = 7;
+            var indicators = new string[pageSize];
+            for (var i = 0; i < pageSize; i++) indicators[i] = char.ConvertFromUtf32(0x1F1E6 + i);
+
+            // Default to x.ToString()
+            if (display == null) display = x => x.ToString();
+
+            string MakeOptionList(int page)
+            {
+                var makeOptionList = string.Join("\n", items
+                    .Skip(page * pageSize)
+                    .Take(pageSize)
+                    .Select((x, i) => $"{indicators[i]} {display(x)}"));
+                return makeOptionList;
+            }
+
+            // If we have more items than the page size, we paginate as appropriate
+            if (items.Count > pageSize)
+            {
+                var currPage = 0;
+                var pageCount = (items.Count-1) / pageSize + 1;
+                
+                // Send the original message
+                var msg = await ctx.Channel.SendMessageAsync($"**[Page {currPage + 1}/{pageCount}]**\n{description}\n{MakeOptionList(currPage)}");
+                
+                // Add back/forward reactions and the actual indicator emojis
+                async Task AddEmojis()
+                {
+                    await msg.AddReactionAsync(new Emoji("\u2B05"));
+                    await msg.AddReactionAsync(new Emoji("\u27A1"));
+                    for (int i = 0; i < items.Count; i++) await msg.AddReactionAsync(new Emoji(indicators[i]));
+                }
+
+                AddEmojis(); // Not concerned about awaiting
+
+
+                while (true)
+                {
+                    // Wait for a reaction
+                    var reaction = await ctx.AwaitReaction(msg, ctx.User);
+                    
+                    // If it's a movement reaction, inc/dec the page index
+                    if (reaction.Emote.Name == "\u2B05") currPage -= 1; // <
+                    if (reaction.Emote.Name == "\u27A1") currPage += 1; // >
+                    if (currPage < 0) currPage += pageCount;
+                    if (currPage >= pageCount) currPage -= pageCount;
+
+                    // If it's an indicator emoji, return the relevant item
+                    if (indicators.Contains(reaction.Emote.Name))
+                    {
+                        var idx = Array.IndexOf(indicators, reaction.Emote.Name) + pageSize * currPage;
+                        // only if it's in bounds, though
+                        // eg. 8 items, we're on page 2, and I hit D (3 + 1*7 = index 10 on an 8-long list) = boom 
+                        if (idx < items.Count) return items[idx];
+                    }
+
+                    msg.RemoveReactionAsync(reaction.Emote, ctx.User); // don't care about awaiting
+                    await msg.ModifyAsync(mp => mp.Content = $"**[Page {currPage + 1}/{pageCount}]**\n{description}\n{MakeOptionList(currPage)}");
+                }
+            }
+            else
+            {
+                var msg = await ctx.Channel.SendMessageAsync($"{description}\n{MakeOptionList(0)}");
+
+                // Add the relevant reactions (we don't care too much about awaiting)
+                async Task AddEmojis()
+                {
+                    for (int i = 0; i < items.Count; i++) await msg.AddReactionAsync(new Emoji(indicators[i]));
+                }
+
+                AddEmojis();
+
+                // Then wait for a reaction and return whichever one we found
+                var reaction = await ctx.AwaitReaction(msg, ctx.User,rx => indicators.Contains(rx.Emote.Name));
+                return items[Array.IndexOf(indicators, reaction.Emote.Name)];
+            }
+        }
 
         public static async Task<ChannelPermissions> Permissions(this ICommandContext ctx) {
             if (ctx.Channel is IGuildChannel) {

PluralKit.Bot/Errors.cs

@@ -60,5 +60,7 @@ namespace PluralKit.Bot {
 
         public static PKError InvalidTimeZone(string zoneStr) => new PKError($"Invalid time zone ID '{zoneStr}'. To find your time zone ID, use the following website: <https://xske.github.io/tz>");
         public static PKError TimezoneChangeCancelled => new PKError("Time zone change cancelled.");
+
+        public static PKError AmbiguousTimeZone(string zoneStr, int count) => new PKError($"The time zone query '{zoneStr}' resulted in **{count}** different time zone regions. Try being more specific - e.g. pass an exact time zone specifier from the following website: <https://xske.github.io/tz>");
     }
 }

PluralKit.Bot/Utils.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 using System.Net.Http;
@@ -9,6 +10,7 @@ using Discord.Commands;
 using Discord.Commands.Builders;
 using Discord.WebSocket;
 using Microsoft.Extensions.DependencyInjection;
+using NodaTime;
 using Image = SixLabors.ImageSharp.Image;
 
 namespace PluralKit.Bot

PluralKit.Core/Utils.cs

@@ -194,6 +194,23 @@ namespace PluralKit
             // Still haven't parsed something, we just give up lmao
             return null;
         }
+        
+        public static string ExtractCountryFlag(string flag)
+        {
+            if (flag.Length != 4) return null;
+            try
+            {
+                var cp1 = char.ConvertToUtf32(flag, 0);
+                var cp2 = char.ConvertToUtf32(flag, 2);
+                if (cp1 < 0x1F1E6 || cp1 > 0x1F1FF) return null;
+                if (cp2 < 0x1F1E6 || cp2 > 0x1F1FF) return null;
+                return $"{(char) (cp1 - 0x1F1E6 + 'A')}{(char) (cp2 - 0x1F1E6 + 'A')}";
+            }
+            catch (ArgumentException)
+            {
+                return null;
+            }
+        }
     }
 
     public static class Emojis {