From 824b2375154d6495a66c07d9ade7eaa09798ed8f Mon Sep 17 00:00:00 2001
From: Rstar284 <me@rstar.ml>
Date: Tue, 26 Apr 2022 15:34:22 +0400
Subject: [PATCH] feat: allow the bot to search through the list of tags and
 aliases to get the closest matching tag

---
 .../src/plugins/Tags/commands/TagCreateCmd.ts |  5 +++
 backend/src/plugins/Tags/util/fuzzySearch.ts  | 30 ++++++++++++++
 .../Tags/util/matchAndRenderTagFromString.ts  | 39 ++++++++++++++++++-
 .../src/plugins/Tags/util/onMessageCreate.ts  |  6 ++-
 4 files changed, 76 insertions(+), 4 deletions(-)
 create mode 100644 backend/src/plugins/Tags/util/fuzzySearch.ts

diff --git a/backend/src/plugins/Tags/commands/TagCreateCmd.ts b/backend/src/plugins/Tags/commands/TagCreateCmd.ts
index aba519d5..855adc38 100644
--- a/backend/src/plugins/Tags/commands/TagCreateCmd.ts
+++ b/backend/src/plugins/Tags/commands/TagCreateCmd.ts
@@ -17,6 +17,11 @@ export const TagCreateCmd = tagsCmd({
     const prefix = pluginData.config.get().prefix;
 
     if (args.alias) {
+      const existingTag = await pluginData.state.tagAliases.find(args.body);
+      if (existingTag) {
+        sendErrorMessage(pluginData, msg.channel, `You cannot create an alias of an alias`);
+        return;
+      }
       await pluginData.state.tagAliases.createOrUpdate(args.tag, args.body, msg.author.id);
       sendSuccessMessage(pluginData, msg.channel, `Alias set! Use it with: \`${prefix}${args.tag}\``);
       return;
diff --git a/backend/src/plugins/Tags/util/fuzzySearch.ts b/backend/src/plugins/Tags/util/fuzzySearch.ts
new file mode 100644
index 00000000..de6c5821
--- /dev/null
+++ b/backend/src/plugins/Tags/util/fuzzySearch.ts
@@ -0,0 +1,30 @@
+// https://rosettacode.org/wiki/Levenshtein_distance#JavaScript
+
+function levenshtein(a: string, b: string): number {
+  let t: number[] = [];
+  let u: number[] = [];
+  const m = a.length;
+  const n = b.length;
+  if (!m) {
+    return n;
+  }
+  if (!n) {
+    return m;
+  }
+  for (let j = 0; j <= n; j++) {
+    t[j] = j;
+  }
+  for (let i = 1; i <= m; i++) {
+    let j: number;
+    // tslint:disable-next-line:ban-comma-operator
+    for (u = [i], j = 1; j <= n; j++) {
+      u[j] = a[i - 1] === b[j - 1] ? t[j - 1] : Math.min(t[j - 1], t[j], u[j - 1]) + 1;
+    }
+    t = u;
+  }
+  return u[n];
+}
+
+export function distance(str: string, t: string): number {
+  return levenshtein(str, t);
+}
diff --git a/backend/src/plugins/Tags/util/matchAndRenderTagFromString.ts b/backend/src/plugins/Tags/util/matchAndRenderTagFromString.ts
index e5ad7319..cc1e90a7 100644
--- a/backend/src/plugins/Tags/util/matchAndRenderTagFromString.ts
+++ b/backend/src/plugins/Tags/util/matchAndRenderTagFromString.ts
@@ -1,9 +1,12 @@
-import { GuildMember } from "discord.js";
+import { GuildMember, Snowflake, TextChannel } from "discord.js";
 import escapeStringRegexp from "escape-string-regexp";
 import { GuildPluginData } from "knub";
 import { ExtendedMatchParams } from "knub/dist/config/PluginConfigManager";
+
 import { StrictMessageContent } from "../../../utils";
 import { TagsPluginType, TTagCategory } from "../types";
+
+import { distance } from "./fuzzySearch";
 import { renderTagFromString } from "./renderTagFromString";
 
 interface BaseResult {
@@ -93,7 +96,39 @@ export async function matchAndRenderTagFromString(
   const dynamicTag = await pluginData.state.tags.find(tagName);
 
   if (!aliasedTag && !dynamicTag) {
-    return null;
+    // fuzzy search the list of aliases and tags to see if there's a match and
+    // inform the user
+    const tags = await pluginData.state.tags.all();
+    const aliases = await pluginData.state.tagAliases.all();
+    let lowest: [number, [string]] = [999999, [""]];
+    tags.forEach((tag) => {
+      const tagname = tag?.tag;
+      const dist = distance(tagname, tagName);
+      if (dist < lowest[0]) {
+        lowest = [dist, [`**${tagname}**`]];
+      } else if (dist === lowest[0]) {
+        lowest[1].push(`**${tagname}**`);
+      }
+    });
+    aliases.forEach((alias) => {
+      const aliasname = alias?.alias;
+      const dist = distance(aliasname, tagName);
+      if (dist < lowest[0]) {
+        lowest = [dist, [`**${aliasname}**`]];
+      } else if (dist === lowest[0]) {
+        lowest[1].push(`**${aliasname}**`);
+      }
+    });
+    if (lowest[0] > 6) return null;
+    const content: StrictMessageContent = {
+      content: `Did you mean:\n${lowest[1].join("\n")}`,
+    };
+    return {
+      renderedContent: content,
+      tagName: "",
+      category: null,
+      categoryName: null,
+    };
   }
 
   const tagBody = aliasedTag?.body ?? dynamicTag?.body;
diff --git a/backend/src/plugins/Tags/util/onMessageCreate.ts b/backend/src/plugins/Tags/util/onMessageCreate.ts
index 052c6395..a7429f28 100644
--- a/backend/src/plugins/Tags/util/onMessageCreate.ts
+++ b/backend/src/plugins/Tags/util/onMessageCreate.ts
@@ -1,14 +1,16 @@
 import { Snowflake, TextChannel } from "discord.js";
 import { GuildPluginData } from "knub";
 import { erisAllowedMentionsToDjsMentionOptions } from "src/utils/erisAllowedMentionsToDjsMentionOptions";
+
 import { SavedMessage } from "../../../data/entities/SavedMessage";
 import { LogType } from "../../../data/LogType";
 import { convertDelayStringToMS, resolveMember, tStrictMessageContent } from "../../../utils";
 import { messageIsEmpty } from "../../../utils/messageIsEmpty";
 import { validate } from "../../../validatorUtils";
-import { TagsPluginType } from "../types";
-import { matchAndRenderTagFromString } from "./matchAndRenderTagFromString";
 import { LogsPlugin } from "../../Logs/LogsPlugin";
+import { TagsPluginType } from "../types";
+
+import { matchAndRenderTagFromString } from "./matchAndRenderTagFromString";
 
 export async function onMessageCreate(pluginData: GuildPluginData<TagsPluginType>, msg: SavedMessage) {
   if (msg.is_bot) return;