Improve emote resolving for .emote and .react commands (#33)

src/commands/utilities/emote.ts

@@ -1,5 +1,5 @@
 import Command from "../../core/command";
-import {queryClosestEmoteByName} from "./subcommands/emote-utils";
+import {processEmoteQueryFormatted} from "./subcommands/emote-utils";
 import {botHasPermission} from "../../core/lib";
 import {Permissions} from "discord.js";
 
@@ -10,9 +10,8 @@ export default new Command({
         description: "The emote(s) to send.",
         usage: "<emotes...>",
         async run({guild, channel, message, args}) {
-            let output = "";
-            for (const query of args) output += queryClosestEmoteByName(query).toString();
-            channel.send(output);
+            const output = processEmoteQueryFormatted(args);
+            if (output.length > 0) channel.send(output);
         }
     })
 });

src/commands/utilities/react.ts

@@ -1,7 +1,7 @@
 import Command from "../../core/command";
 import {CommonLibrary} from "../../core/lib";
 import {Message, Channel, TextChannel} from "discord.js";
-import {queryClosestEmoteByName} from "./subcommands/emote-utils";
+import {processEmoteQueryArray} from "./subcommands/emote-utils";
 
 export default new Command({
     description:
@@ -11,16 +11,10 @@ export default new Command({
         let target: Message | undefined;
         let distance = 1;
 
-        // allows reactions by using an in-line reply
-        if($.message.reference){
-            const messageID = $.message.reference.messageID;
-            try{
-                target = await $.channel.messages.fetch(messageID!)
-            }catch{
-                return $.channel.send("Unknown error occurred!")
-            }
+        if ($.message.reference) {
+            // If the command message is a reply to another message, use that as the react target.
+            target = await $.channel.messages.fetch($.message.reference.messageID!);
         }
-        
         // handles reacts by message id/distance
         else if ($.args.length >= 2) {
             const last = $.args[$.args.length - 1]; // Because this is optional, do not .pop() unless you're sure it's a message link indicator.
@@ -106,9 +100,8 @@ export default new Command({
             ).last();
         }
 
-        for (const search of $.args) {
+        for (const emote of processEmoteQueryArray($.args)) {
             // Even though the bot will always grab *some* emote, the user can choose not to keep that emote there if it isn't what they want
-            const emote = queryClosestEmoteByName(search);
             const reaction = await target!.react(emote);
 
             // This part is called with a promise because you don't want to wait 5 seconds between each reaction.

src/commands/utilities/subcommands/emote-utils.ts

@@ -1,33 +1,114 @@
+import {GuildEmoji} from "discord.js";
 import {client} from "../../../index";
 
-// Calculate and match the list of emotes against the queried emote, then sort the IDs based on calculated priority.
-export function queryClosestEmoteByName(query: string) {
-    const priorityTable: {[id: string]: number} = {};
+// Levenshtein distance coefficients for all transformation types.
+// TODO: Investigate what values result in the most optimal matching strategy.
+const directMatchWeight = 0.0;
+const uppercaseWeight = 0.2;
+const lowercaseWeight = 0.5;
+const substitutionWeight = 1.0;
+const deletionWeight = 1.5;
+const insertionWeight = 1.5;
 
-    for (const emote of client.emojis.cache.values()) priorityTable[emote.id] = compareEmoteNames(emote.name, query);
+// Maximum Levenshtein distance for an emote to be considered a suitable match candidate.
+const maxAcceptedDistance = 3.0;
 
-    const resultingIDs = Object.keys(priorityTable).sort((a, b) => priorityTable[b] - priorityTable[a]);
-    return client.emojis.cache.get(resultingIDs[0])!;
-}
+// Algorithm taken from https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows
+// Modified for separate handling of uppercasing and lowercasing transformations.
+function levenshtein(s: string, t: string): number {
+    const m = s.length;
+    const n = t.length;
 
-// Compare an emote's name against a query to see how alike the two are. The higher the number, the closer they are. Takes into account length and capitalization.
-function compareEmoteNames(emote: string, query: string) {
-    let likeness = -Math.abs(emote.length - query.length);
-    const isQueryLonger = query.length > emote.length;
+    let v0 = new Array(n + 1);
+    let v1 = new Array(n + 1);
 
-    // Loop through all indexes that the two strings share then compare each letter.
-    for (let i = 0; i < (isQueryLonger ? emote.length : query.length); i++) {
-        const c = emote[i];
-        const q = query[i];
+    let i, j;
 
-        // If they're the exact same character
-        if (c === q) likeness += 1.5;
-        // If the emote is uppercase but the query is lowercase
-        else if (c === q.toUpperCase()) likeness += 1;
-        // If the emote is lowercase but the query is uppercase
-        else if (c === q.toLowerCase()) likeness += 0.5;
-        // Otherwise, if they're different characters, don't add anything (this isn't a spellchecker)
+    for (i = 0; i <= n; i++) v0[i] = i;
+
+    for (i = 0; i < m; i++) {
+        v1[0] = i + 1;
+
+        for (j = 0; j < n; j++) {
+            let r;
+
+            if (s[i] === t[j]) r = directMatchWeight;
+            else if (s[i] === t[j].toUpperCase()) r = uppercaseWeight;
+            else if (s[i] === t[j].toLowerCase()) r = lowercaseWeight;
+            else r = substitutionWeight;
+
+            v1[j + 1] = Math.min(
+                v0[j + 1] + deletionWeight,
+                v1[j] + insertionWeight,
+                v0[j] + r);
+        }
+
+        const tmp = v1;
+        v1 = v0, v0 = tmp;
     }
 
-    return likeness;
+    return v0[n];
 }
+
+function searchSimilarEmotes(query: string): GuildEmoji[] {
+    const emoteCandidates: {emote: GuildEmoji, dist: number}[] = [];
+
+    for (const emote of client.emojis.cache.values()) {
+        const dist = levenshtein(emote.name, query);
+        if (dist <= maxAcceptedDistance) {
+            emoteCandidates.push({ emote, dist });
+        }
+    }
+
+    emoteCandidates.sort((b, a) => b.dist - a.dist);
+    return emoteCandidates.map(em => em.emote);
+}
+
+const unicodeEmojiRegex = /^(?:[\u2700-\u27bf]|(?:\ud83c[\udde6-\uddff]){2}|[\ud800-\udbff][\udc00-\udfff]|[\u0023-\u0039]\ufe0f?\u20e3|\u3299|\u3297|\u303d|\u3030|\u24c2|\ud83c[\udd70-\udd71]|\ud83c[\udd7e-\udd7f]|\ud83c\udd8e|\ud83c[\udd91-\udd9a]|\ud83c[\udde6-\uddff]|\ud83c[\ude01-\ude02]|\ud83c\ude1a|\ud83c\ude2f|\ud83c[\ude32-\ude3a]|\ud83c[\ude50-\ude51]|\u203c|\u2049|[\u25aa-\u25ab]|\u25b6|\u25c0|[\u25fb-\u25fe]|\u00a9|\u00ae|\u2122|\u2139|\ud83c\udc04|[\u2600-\u26FF]|\u2b05|\u2b06|\u2b07|\u2b1b|\u2b1c|\u2b50|\u2b55|\u231a|\u231b|\u2328|\u23cf|[\u23e9-\u23f3]|[\u23f8-\u23fa]|\ud83c\udccf|\u2934|\u2935|[\u2190-\u21ff])[\ufe00-\ufe0f]?$/;
+const discordEmoteMentionRegex = /^<a?:\w+:\d+>$/;
+const emoteNameWithSelectorRegex = /^(.+)~(\d+)$/;
+
+function processEmoteQuery(query: string[], isFormatted: boolean): string[] {
+    return query.map(emote => {
+        emote = emote.trim();
+
+        // If the query directly matches a Unicode emoji or a Discord custom emote mention, pass it as-is.
+        if (discordEmoteMentionRegex.test(emote)
+            || unicodeEmojiRegex.test(emote)) return emote;
+
+        // If formatted mode is enabled, parse whitespace and newline elements.
+        if (isFormatted) {
+            if (emote == "-") return " ";
+            if (emote == "+") return "\n";
+        }
+
+        // Selector number used for disambiguating multiple emotes with same name.
+        let selector = 0;
+
+        // If the query has emoteName~123 format, extract the actual name and the selector number.
+        const queryWithSelector = emote.match(emoteNameWithSelectorRegex);
+        if (queryWithSelector) {
+            emote = queryWithSelector[1];
+            selector = +queryWithSelector[2];
+        }
+
+        // Try to match an emote name directly if the selector is for the closest match.
+        if (selector == 0) {
+            const directMatchEmote = client.emojis.cache.find(em => em.name === emote);
+            if (directMatchEmote) return directMatchEmote.toString();
+        }
+
+        // Find all similar emote candidates within certian threshold and select Nth top one according to the selector.
+        const similarEmotes = searchSimilarEmotes(emote);
+        if (similarEmotes.length > 0) {
+            selector = Math.min(selector, similarEmotes.length);
+            return similarEmotes[selector].toString();
+        }
+
+        // Return some "missing/invalid emote" indicator.
+        return "❓";
+    });
+}
+
+export const processEmoteQueryArray = (query: string[]): string[] => processEmoteQuery(query, false);
+export const processEmoteQueryFormatted = (query: string[]): string => processEmoteQuery(query, true).join("");