From 4393095af4d4f0487e456ebd30d08ad6b69f0919 Mon Sep 17 00:00:00 2001
From: brecert <11599528+Brecert@users.noreply.github.com>
Date: Fri, 26 Jul 2019 19:44:26 -0400
Subject: [PATCH] increase emoji-parsing performance

---
 .../markdown-it-plugins/replaceCustomEmoji.js | 62 ++++++++++++-------
 1 file changed, 41 insertions(+), 21 deletions(-)

diff --git a/src/utils/markdown-it-plugins/replaceCustomEmoji.js b/src/utils/markdown-it-plugins/replaceCustomEmoji.js
index b810514..bcf4d71 100644
--- a/src/utils/markdown-it-plugins/replaceCustomEmoji.js
+++ b/src/utils/markdown-it-plugins/replaceCustomEmoji.js
@@ -3,39 +3,52 @@ import config from "@/config.js";
 /* 58: ':' */
 /* 60: '<' */
 /* 62: '>' */
+/* example: '<:cat_1:1hvDmIdozFp2vTTkEIsO-wBHPaYRkGmlP>' */
 
-function render_custom_emoji(tokens, idx) {
-	return ':3'
+function skipUntil(state, pos, code) {
+  for (let max = state.src.length; pos < max; pos++) {
+    if (state.src.charCodeAt(pos) === code) { break; }
+  }
+  return pos;
 }
 
-function parseUntil(state, fromPos, until) {
+// old
+function parseUntil(state, fromPos, until, maxLength = 16) {
 	let max = state.posMax
 	let found = false
-
+	let pos = state.pos + fromPos
 	let oldPos = state.pos
-	// let start = nameStart + 1
-	state.pos = fromPos
 	let end = -1
 
-	while(state.pos++ < max) {
-		let marker = state.src.charCodeAt(state.pos)
+
+	while(pos < max &&  pos - oldPos < maxLength) {
+		let marker = state.src.charCodeAt(pos)
 		if(marker === until) {
 			found = true;
 			break;
 		}
+
+		// state.md.inline.skipToken(state);
+
+		pos += 1
 	}
 
 	if(found) {
-		end = state.pos
+		end = pos
 	}
 
-	state.pos = oldPos
-
 	return end
 }
 
+function render_custom_emoji(tokens, idx) {
+	return ''
+}
+
+
 function parseEmojiName(state, nameStart) {
-	return parseUntil(state, nameStart, 58)
+	// return parseUntil(state, nameStart, 58)
+
+	return skipUntil(state, nameStart, 58)
 }
 
 function replace_custom_emoji(state, silent) {
@@ -53,8 +66,10 @@ function replace_custom_emoji(state, silent) {
 	let nameStart = pos + 1
 	let nameEnd = parseEmojiName(state, nameStart)
 
+	// console.log(nameEnd, parseUntil(state,nameStart,58))
+
 	// parser failed to find another ':', so it's not a valid emoji
-	if(nameEnd < 0 || nameEnd - nameStart <= 1) { return false; }
+	if(nameEnd > max || nameEnd < 0 || nameEnd - nameStart <= 1) { return false; }
 
 	let emojiName = state.src.slice(nameStart, nameEnd)
 	
@@ -62,9 +77,9 @@ function replace_custom_emoji(state, silent) {
 
 	// parse until '>'
 	let idStart = pos
-	let idEnd = parseUntil(state, idStart, 62)
+	let idEnd = skipUntil(state, pos, 62);
 
-	if(idEnd < 0 || idEnd - idStart <= 1) { return false; }
+	if(idEnd > max || idEnd < 0 || idEnd - idStart <= 1) { return false; }
 
 	let emojiID = state.src.slice(idStart, idEnd)
 
@@ -72,20 +87,25 @@ function replace_custom_emoji(state, silent) {
 		state.pos = idStart
 		state.posMax = idEnd
 
-		let token = state.push('custom_emoji_open', 'img', 1);
-		token.attrs = [[ 'src', `${config.domain}/files/${emojiID}` ]]
-
-		// state.md.inline.tokenize(state)
+		let token = state.push('custom_emoji', 'img', 0);
+		token.attrs = [[ 'src', `${config.domain}/files/${emojiID}` ], [ 'alt', emojiName ]]
 	}
 
 	state.pos = idEnd + 1
 	state.posMax = max
 	return true
 }
+
 export default function custom_emoji_plugin(md, opts) {
-	md.renderer.rules.custom_emoji_open = (tokens, idx) => { 
+	md.renderer.rules.custom_emoji = (tokens, idx) => { 
 		let token = tokens[idx]
-		return `<${md.utils.escapeHtml(token.tag)} class="emoji" src=${md.utils.escapeHtml(token.attrs.find(([name]) => name === 'src')[1])} />` 
+
+		// todo: better escaping method,
+		// 			 even if this is good and covers most cases, there may be edge cases where DOMPurify may be better
+		let src = md.utils.escapeHtml(token.attrs.find(([name]) => name === 'src')[1])
+		let alt = md.utils.escapeHtml(token.attrs.find(([name]) => name === 'alt')[1])
+
+		return `<${md.utils.escapeHtml(token.tag)} class="emoji" title=${alt} alt=${alt} src=${src} />` 
 	}
 
 	md.inline.ruler.push('custom_emoji', replace_custom_emoji)