117 lines
3.2 KiB
TypeScript
117 lines
3.2 KiB
TypeScript
import type { Emoji } from 'masto'
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import type { Node } from 'ultrahtml'
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import { TEXT_NODE, parse, render, walkSync } from 'ultrahtml'
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const decoder = document.createElement('textarea')
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function decode(text: string) {
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decoder.innerHTML = text
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return decoder.value
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}
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/**
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* Parse raw HTML form Mastodon server to AST,
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* with interop of custom emojis and inline Markdown syntax
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*/
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export function parseMastodonHTML(html: string, customEmojis: Record<string, Emoji> = {}) {
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let processed = html
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// custom emojis
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.replace(/:([\w-]+?):/g, (_, name) => {
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const emoji = customEmojis[name]
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if (emoji)
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return `<img src="${emoji.url}" alt=":${name}:" class="custom-emoji" data-emoji-id="${name}" />`
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return `:${name}:`
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})
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// handle code blocks
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.replace(/>(```|~~~)(\w*)([\s\S]+?)\1/g, (_1, _2, lang, raw) => {
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const code = htmlToText(raw)
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const classes = lang ? ` class="language-${lang}"` : ''
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return `><pre><code${classes}>${code}</code></pre>`
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})
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walkSync(parse(processed), (node) => {
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if (node.type !== TEXT_NODE)
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return
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const replacements = [
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[/\*\*\*(.*?)\*\*\*/g, '<b><em>$1</em></b>'],
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[/\*\*(.*?)\*\*/g, '<b>$1</b>'],
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[/\*(.*?)\*/g, '<em>$1</em>'],
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[/~~(.*?)~~/g, '<del>$1</del>'],
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[/`([^`]+?)`/g, '<code>$1</code>'],
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[/&[^;]+;/g, (val: string) => decode(val)],
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] as any
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for (const [re, replacement] of replacements) {
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for (const match of node.value.matchAll(re)) {
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if (node.loc) {
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const start = match.index! + node.loc[0].start
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const end = start + match[0].length + node.loc[0].start
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processed = processed.slice(0, start) + match[0].replace(re, replacement) + processed.slice(end)
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}
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else {
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processed = processed.replace(match[0], match[0].replace(re, replacement))
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}
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}
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}
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})
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return parse(processed)
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}
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export async function convertMastodonHTML(html: string, customEmojis: Record<string, Emoji> = {}) {
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const tree = parseMastodonHTML(html, customEmojis)
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return await render(tree)
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}
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export function htmlToText(html: string) {
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const tree = parse(html)
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return (tree.children as Node[]).map(n => treeToText(n)).join('').trim()
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}
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export function treeToText(input: Node): string {
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let pre = ''
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let body = ''
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let post = ''
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if (input.type === TEXT_NODE)
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return input.value
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if (input.name === 'br')
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return '\n'
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if (['p', 'pre'].includes(input.name))
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pre = '\n'
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if (input.name === 'code') {
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if (input.parent?.name === 'pre') {
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const lang = input.attributes.class?.replace('language-', '')
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pre = `\`\`\`${lang || ''}\n`
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post = '\n```'
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}
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else {
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pre = '`'
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post = '`'
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}
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}
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else if (input.name === 'b' || input.name === 'strong') {
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pre = '**'
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post = '**'
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}
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else if (input.name === 'i' || input.name === 'em') {
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pre = '*'
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post = '*'
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}
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else if (input.name === 'del') {
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pre = '~~'
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post = '~~'
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}
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if ('children' in input)
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body = (input.children as Node[]).map(n => treeToText(n)).join('')
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if (input.name === 'img' && input.attributes.class?.includes('custom-emoji'))
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return `:${input.attributes['data-emoji-id']}:`
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return pre + body + post
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}
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