misskey/packages/backend/src/mfm/to-html.ts

import { JSDOM } from 'jsdom';
import * as mfm from 'mfm-js';
import config from '@/config/index';
import { intersperse } from '@/prelude/array';
import { IMentionedRemoteUsers } from '@/models/entities/note';

export function toHtml(nodes: mfm.MfmNode[] | null, mentionedRemoteUsers: IMentionedRemoteUsers = []) {
	if (nodes == null) {
		return null;
	}

	const { window } = new JSDOM('');

	const doc = window.document;

	function appendChildren(children: mfm.MfmNode[], targetElement: any): void {
		if (children) {
			for (const child of children.map(x => (handlers as any)[x.type](x))) targetElement.appendChild(child);
		}
	}

	const handlers: { [K in mfm.MfmNode['type']]: (node: mfm.NodeType<K>) => any } = {
		bold(node) {
			const el = doc.createElement('b');
			appendChildren(node.children, el);
			return el;
		},

		small(node) {
			const el = doc.createElement('small');
			appendChildren(node.children, el);
			return el;
		},

		strike(node) {
			const el = doc.createElement('del');
			appendChildren(node.children, el);
			return el;
		},

		italic(node) {
			const el = doc.createElement('i');
			appendChildren(node.children, el);
			return el;
		},

		fn(node) {
			const el = doc.createElement('i');
			appendChildren(node.children, el);
			return el;
		},

		blockCode(node) {
			const pre = doc.createElement('pre');
			const inner = doc.createElement('code');
			inner.textContent = node.props.code;
			pre.appendChild(inner);
			return pre;
		},

		center(node) {
			const el = doc.createElement('div');
			appendChildren(node.children, el);
			return el;
		},

		emojiCode(node) {
			return doc.createTextNode(`\u200B:${node.props.name}:\u200B`);
		},

		unicodeEmoji(node) {
			return doc.createTextNode(node.props.emoji);
		},

		hashtag(node) {
			const a = doc.createElement('a');
			a.href = `${config.url}/tags/${node.props.hashtag}`;
			a.textContent = `#${node.props.hashtag}`;
			a.setAttribute('rel', 'tag');
			return a;
		},

		inlineCode(node) {
			const el = doc.createElement('code');
			el.textContent = node.props.code;
			return el;
		},

		mathInline(node) {
			const el = doc.createElement('code');
			el.textContent = node.props.formula;
			return el;
		},

		mathBlock(node) {
			const el = doc.createElement('code');
			el.textContent = node.props.formula;
			return el;
		},

		link(node) {
			const a = doc.createElement('a');
			a.href = node.props.url;
			appendChildren(node.children, a);
			return a;
		},

		mention(node) {
			const a = doc.createElement('a');
			const { username, host, acct } = node.props;
			const remoteUserInfo = mentionedRemoteUsers.find(remoteUser => remoteUser.username === username && remoteUser.host === host);
			a.href = remoteUserInfo ? (remoteUserInfo.url ? remoteUserInfo.url : remoteUserInfo.uri) : `${config.url}/${acct}`;
			a.className = 'u-url mention';
			a.textContent = acct;
			return a;
		},

		quote(node) {
			const el = doc.createElement('blockquote');
			appendChildren(node.children, el);
			return el;
		},

		text(node) {
			const el = doc.createElement('span');
			const nodes = node.props.text.split(/\r\n|\r|\n/).map(x => doc.createTextNode(x));

			for (const x of intersperse<FIXME | 'br'>('br', nodes)) {
				el.appendChild(x === 'br' ? doc.createElement('br') : x);
			}

			return el;
		},

		url(node) {
			const a = doc.createElement('a');
			a.href = node.props.url;
			a.textContent = node.props.url;
			return a;
		},

		search(node) {
			const a = doc.createElement('a');
			a.href = `https://www.google.com/search?q=${node.props.query}`;
			a.textContent = node.props.content;
			return a;
		}
	};

	appendChildren(nodes, doc.body);

	return `<p>${doc.body.innerHTML}</p>`;
}