mtcute/packages/html-parser/src/index.ts

435 lines
14 KiB
TypeScript

import { Parser } from 'htmlparser2'
import Long from 'long'
import type { InputText, MessageEntity, TextWithEntities, tl } from '@mtcute/client'
const MENTION_REGEX = /^tg:\/\/user\?id=(\d+)(?:&hash=(-?[0-9a-fA-F]+)(?:&|$)|&|$)/
/**
* Escape a string to be safely used in HTML.
*
* > **Note**: this function is in most cases not needed, as `html` function
* > handles all `string`s passed to it automatically as plain text.
*/
function escape(str: string, quote = false): string {
str = str.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;')
if (quote) str = str.replace(/"/g, '&quot;')
return str
}
function parse(
strings: TemplateStringsArray | string,
...sub: (InputText | MessageEntity | boolean | number | undefined | null)[]
): TextWithEntities {
const stacks: Record<string, tl.Mutable<tl.TypeMessageEntity>[]> = {}
const entities: tl.TypeMessageEntity[] = []
let plainText = ''
let pendingText = ''
function processPendingText(tagEnd = false) {
if (!pendingText.length) return
if (!stacks.pre?.length) {
pendingText = pendingText.replace(/[^\S\u00A0]+/gs, ' ')
if (tagEnd) pendingText = pendingText.trimEnd()
if (!plainText.length || plainText.match(/\s$/)) {
pendingText = pendingText.trimStart()
}
}
for (const ents of Object.values(stacks)) {
for (const ent of ents) {
ent.length += pendingText.length
}
}
plainText += pendingText
pendingText = ''
}
const parser = new Parser({
onopentag(name, attribs) {
name = name.toLowerCase()
processPendingText()
// ignore tags inside pre (except pre)
if (name !== 'pre' && stacks.pre?.length) return
let entity: tl.TypeMessageEntity
switch (name) {
case 'br':
plainText += '\n'
return
case 'b':
case 'strong':
entity = {
_: 'messageEntityBold',
offset: plainText.length,
length: 0,
}
break
case 'i':
case 'em':
entity = {
_: 'messageEntityItalic',
offset: plainText.length,
length: 0,
}
break
case 'u':
entity = {
_: 'messageEntityUnderline',
offset: plainText.length,
length: 0,
}
break
case 's':
case 'del':
case 'strike':
entity = {
_: 'messageEntityStrike',
offset: plainText.length,
length: 0,
}
break
case 'blockquote':
entity = {
_: 'messageEntityBlockquote',
offset: plainText.length,
length: 0,
}
break
case 'code':
entity = {
_: 'messageEntityCode',
offset: plainText.length,
length: 0,
}
break
case 'pre':
entity = {
_: 'messageEntityPre',
offset: plainText.length,
length: 0,
language: attribs.language ?? '',
}
break
case 'spoiler':
case 'tg-spoiler':
entity = {
_: 'messageEntitySpoiler',
offset: plainText.length,
length: 0,
}
break
case 'emoji':
case 'tg-emoji': {
const id = attribs.id || attribs['emoji-id']
if (!id || !id.match(/^-?\d+$/)) return
entity = {
_: 'messageEntityCustomEmoji',
offset: plainText.length,
length: 0,
documentId: Long.fromString(id),
}
break
}
case 'a': {
let url = attribs.href
if (!url) return
const mention = MENTION_REGEX.exec(url)
if (mention) {
const id = parseInt(mention[1])
const accessHash = mention[2]
if (accessHash) {
entity = {
_: 'inputMessageEntityMentionName',
offset: plainText.length,
length: 0,
userId: {
_: 'inputUser',
userId: id,
accessHash: Long.fromString(accessHash, false, 16),
},
}
} else {
entity = {
_: 'messageEntityMentionName',
offset: plainText.length,
length: 0,
userId: id,
}
}
} else {
if (url.match(/^\/\//)) url = 'http:' + url
entity = {
_: 'messageEntityTextUrl',
offset: plainText.length,
length: 0,
url,
}
}
break
}
default:
return
}
if (!(name in stacks)) {
stacks[name] = []
}
stacks[name].push(entity)
},
onclosetag(name: string) {
processPendingText(true)
name = name.toLowerCase()
// ignore tags inside pre (except pre)
if (name !== 'pre' && stacks.pre?.length) return
const entity = stacks[name]?.pop()
if (!entity) return // unmatched close tag
// ignore nested pre-s
if (name !== 'pre' || !stacks.pre?.length) {
entities.push(entity)
}
},
ontext(data) {
pendingText += data
},
})
if (typeof strings === 'string') strings = [strings] as unknown as TemplateStringsArray
sub.forEach((it, idx) => {
parser.write(strings[idx])
if (typeof it === 'boolean' || !it) return
if (typeof it === 'string' || typeof it === 'number') {
pendingText += it
} else {
// TextWithEntities or MessageEntity
const text = it.text
const innerEntities = 'raw' in it ? [it.raw] : it.entities
processPendingText()
const baseOffset = plainText.length
pendingText += text
if (innerEntities) {
for (const ent of innerEntities) {
entities.push({ ...ent, offset: ent.offset + baseOffset })
}
}
}
})
parser.write(strings[strings.length - 1])
processPendingText(true)
return {
text: plainText.replace(/\u00A0/g, ' '),
entities,
}
}
/** Options passed to `html.unparse` */
export interface HtmlUnparseOptions {
/**
* Syntax highlighter to use when un-parsing `pre` tags with language
*/
syntaxHighlighter?: (code: string, language: string) => string
}
// internal function that uses recursion to correctly process nested & overlapping entities
function _unparse(
text: string,
entities: ReadonlyArray<tl.TypeMessageEntity>,
params: HtmlUnparseOptions,
entitiesOffset = 0,
offset = 0,
length = text.length,
): string {
if (!text) return text
if (!entities.length || entities.length === entitiesOffset) {
return escape(text)
.replace(/\n/g, '<br>')
.replace(/ {2,}/g, (match) => {
return '&nbsp;'.repeat(match.length)
})
}
const end = offset + length
const html: string[] = []
let lastOffset = 0
for (let i = entitiesOffset; i < entities.length; i++) {
const entity = entities[i]
if (entity.offset >= end) break
let entOffset = entity.offset
let length = entity.length
if (entOffset < 0) {
length += entOffset
entOffset = 0
}
let relativeOffset = entOffset - offset
if (relativeOffset > lastOffset) {
// add missing plain text
html.push(escape(text.substring(lastOffset, relativeOffset)))
} else if (relativeOffset < lastOffset) {
length -= lastOffset - relativeOffset
relativeOffset = lastOffset
}
if (length <= 0 || relativeOffset >= end || relativeOffset < 0) {
continue
}
let skip = false
const substr = text.substr(relativeOffset, length)
if (!substr) continue
const type = entity._
let entityText
if (type === 'messageEntityPre') {
entityText = substr
} else {
entityText = _unparse(substr, entities, params, i + 1, offset + relativeOffset, length)
}
switch (type) {
case 'messageEntityBold':
case 'messageEntityItalic':
case 'messageEntityUnderline':
case 'messageEntityStrike':
case 'messageEntityCode':
case 'messageEntityBlockquote':
case 'messageEntitySpoiler':
{
const tag = (
{
messageEntityBold: 'b',
messageEntityItalic: 'i',
messageEntityUnderline: 'u',
messageEntityStrike: 's',
messageEntityCode: 'code',
messageEntityBlockquote: 'blockquote',
messageEntitySpoiler: 'spoiler',
} as const
)[type]
html.push(`<${tag}>${entityText}</${tag}>`)
}
break
case 'messageEntityPre':
html.push(
`<pre${entity.language ? ` language="${entity.language}"` : ''}>${
params.syntaxHighlighter && entity.language ?
params.syntaxHighlighter(entityText, entity.language) :
entityText
}</pre>`,
)
break
case 'messageEntityEmail':
html.push(`<a href="mailto:${entityText}">${entityText}</a>`)
break
case 'messageEntityUrl':
html.push(`<a href="${entityText}">${entityText}</a>`)
break
case 'messageEntityTextUrl':
html.push(`<a href="${escape(entity.url, true)}">${entityText}</a>`)
break
case 'messageEntityMentionName':
html.push(`<a href="tg://user?id=${entity.userId}">${entityText}</a>`)
break
default:
skip = true
break
}
lastOffset = relativeOffset + (skip ? 0 : length)
}
html.push(escape(text.substr(lastOffset)))
return html.join('')
}
/**
* Add HTML formatting to the text given the plain text and entities contained in it.
*/
function unparse(input: InputText, options?: HtmlUnparseOptions): string {
if (typeof input === 'string') {
return _unparse(input, [], options ?? {})
}
return _unparse(input.text, input.entities ?? [], options ?? {})
}
// typedoc doesn't support this yet, so we'll have to do it manually
// https://github.com/TypeStrong/typedoc/issues/2436
export const html: {
/**
* Tagged template based HTML-to-entities parser function
*
* Additionally, `md` function has two static methods:
* - `html.escape` - escape a string to be safely used in HTML
* (should not be needed in most cases, as `html` function itself handles all `string`s
* passed to it automatically as plain text)
* - `html.unparse` - add HTML formatting to the text given the plain text and entities contained in it
*
* @example
* ```typescript
* const text = html`<b>${user.displayName}</b>`
* ```
*/
(
strings: TemplateStringsArray,
...sub: (InputText | MessageEntity | boolean | number | undefined | null)[]
): TextWithEntities
/**
* A variant taking a plain JS string as input
* and parsing it.
*
* Useful for cases when you already have a string
* (e.g. from some server) and want to parse it.
*
* @example
* ```typescript
* const string = '<b>hello</b>'
* const text = html(string)
* ```
*/
(string: string): TextWithEntities
escape: typeof escape
unparse: typeof unparse
} = Object.assign(parse, {
escape,
unparse,
})