templateFormatter: return empty string for null/undefined variables; Tags: catch template syntax errors on tag creation; add mention() tag function

src/plugins/Tags.ts

@@ -1,4 +1,4 @@
-import { Plugin, decorators as d, IPluginOptions } from "knub";
+import { decorators as d, IPluginOptions } from "knub";
 import { Message, TextChannel } from "eris";
 import { errorMessage, successMessage } from "../utils";
 import { GuildTags } from "../data/GuildTags";
@@ -7,20 +7,9 @@ import { SavedMessage } from "../data/entities/SavedMessage";
 import moment from "moment-timezone";
 import humanizeDuration from "humanize-duration";
 import { ZeppelinPlugin } from "./ZeppelinPlugin";
-import { renderTemplate } from "../templateFormatter";
+import { parseTemplate, renderTemplate, TemplateParseError } from "../templateFormatter";
-import { escapeBacktickString } from "jest-snapshot/build/utils";
 import { GuildArchives } from "../data/GuildArchives";
 
-const TAG_FUNCTIONS = {
-  countdown(toDate) {
-    const now = moment();
-    const target = moment(toDate, "YYYY-MM-DD HH:mm:ss");
-    const diff = target.diff(now);
-    const result = humanizeDuration(diff, { largest: 2, round: true });
-    return diff >= 0 ? result : `${result} ago`;
-  },
-};
-
 interface ITagsPluginConfig {
   prefix: string;
   delete_with_command: boolean;
@@ -42,6 +31,8 @@ export class TagsPlugin extends ZeppelinPlugin<ITagsPluginConfig, ITagsPluginPer
   private onMessageCreateFn;
   private onMessageDeleteFn;
 
+  protected tagFunctions;
+
   getDefaultOptions(): IPluginOptions<ITagsPluginConfig, ITagsPluginPermissions> {
     return {
       config: {
@@ -77,6 +68,37 @@ export class TagsPlugin extends ZeppelinPlugin<ITagsPluginConfig, ITagsPluginPer
 
     this.onMessageDeleteFn = this.onMessageDelete.bind(this);
     this.savedMessages.events.on("delete", this.onMessageDeleteFn);
+
+    this.tagFunctions = {
+      countdown(toDate) {
+        if (typeof toDate !== "string") return "";
+
+        const now = moment();
+        const target = moment(toDate, "YYYY-MM-DD HH:mm:ss");
+        if (!target.isValid()) return "";
+
+        const diff = target.diff(now);
+        const result = humanizeDuration(diff, { largest: 2, round: true });
+        return diff >= 0 ? result : `${result} ago`;
+      },
+
+      mention: input => {
+        if (typeof input !== "string") return "";
+        if (input.match(/^<(@#)(!&)\d+>$/)) {
+          return input;
+        }
+
+        if (this.guild.members.has(input) || this.bot.users.has(input)) {
+          return `<@!${input}>`;
+        }
+
+        if (this.guild.channels.has(input) || this.bot.channelGuildMap[input]) {
+          return `<#${input}>`;
+        }
+
+        return input;
+      },
+    };
   }
 
   onUnload() {
@@ -118,6 +140,17 @@ export class TagsPlugin extends ZeppelinPlugin<ITagsPluginConfig, ITagsPluginPer
   @d.command("tag", "<tag:string> <body:string$>")
   @d.permission("create")
   async tagCmd(msg: Message, args: { tag: string; body: string }) {
+    try {
+      parseTemplate(args.body);
+    } catch (e) {
+      if (e instanceof TemplateParseError) {
+        msg.channel.createMessage(errorMessage(`Invalid tag syntax: ${e.message}`));
+        return;
+      } else {
+        throw e;
+      }
+    }
+
     await this.tags.createOrUpdate(args.tag, args.body, msg.author.id);
 
     const prefix = this.getConfig().prefix;
@@ -164,7 +197,7 @@ export class TagsPlugin extends ZeppelinPlugin<ITagsPluginConfig, ITagsPluginPer
     // Format the string
     body = await renderTemplate(body, {
       args: tagArgs,
-      ...TAG_FUNCTIONS,
+      ...this.tagFunctions,
     });
 
     const channel = this.guild.channels.get(msg.channel_id) as TextChannel;

src/templateFormatter.ts

@@ -94,9 +94,7 @@ export function parseTemplate(str: string): ParsedTemplate {
     inVar = false;
   };
 
-  let i = -1;
+  for (const [i, char] of chars.entries()) {
-  for (const char of chars) {
-    i++;
     if (inVar) {
       if (currentVar) {
         if (currentVar._state.inArg) {
@@ -130,7 +128,7 @@ export function parseTemplate(str: string): ParsedTemplate {
           } else if (char === '"') {
             // A double quote can start a string argument, but only if we haven't committed to some other type of argument already
             if (currentVar._state.currentArgType !== null) {
-              throw new TemplateParseError(`Unexpected char: ${char} at ${i}`);
+              throw new TemplateParseError(`Unexpected char ${char} at ${i}`);
             }
 
             currentVar._state.currentArgType = "string";
@@ -138,7 +136,7 @@ export function parseTemplate(str: string): ParsedTemplate {
           } else if (char.match(/\d/)) {
             // A number can start a string argument, but only if we haven't committed to some other type of argument already
             if (currentVar._state.currentArgType !== null) {
-              throw new TemplateParseError(`Unexpected char: ${char}`);
+              throw new TemplateParseError(`Unexpected char ${char} at ${i}`);
             }
 
             currentVar._state.currentArgType = "number";
@@ -153,7 +151,7 @@ export function parseTemplate(str: string): ParsedTemplate {
             currentVar._state.currentArg = newVar;
             currentVar = newVar;
           } else {
-            throw new TemplateParseError(`Unexpected char: ${char}`);
+            throw new TemplateParseError(`Unexpected char ${char} at ${i}`);
           }
         } else {
           if (char === "(") {
@@ -180,7 +178,7 @@ export function parseTemplate(str: string): ParsedTemplate {
         if (char === "}") {
           exitInjectedVar();
         } else {
-          throw new TemplateParseError(`Unexpected char: ${char}`);
+          throw new TemplateParseError(`Unexpected char ${char} at ${i}`);
         }
       }
     } else {
@@ -233,10 +231,11 @@ async function evaluateTemplateVariable(theVar: ITemplateVar, values) {
       }
     }
 
-    return value(...args);
+    const result = await value(...args);
+    return result == null ? "" : result;
   }
 
-  return value;
+  return value == null ? "" : value;
 }
 
 export async function renderParsedTemplate(parsedTemplate: ParsedTemplate, values: any) {