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"""
Simple HTML -> Telegram entity parser.
"""
from collections import deque
from html import escape
from html.parser import HTMLParser
from typing import Iterable, Tuple, List
from ..helpers import add_surrogate, del_surrogate, within_surrogate, strip_text
from ..tl import TLObject
from ..tl.types import (
MessageEntityBold, MessageEntityItalic, MessageEntityCode,
MessageEntityPre, MessageEntityEmail, MessageEntityUrl,
MessageEntityTextUrl, MessageEntityMentionName,
MessageEntityUnderline, MessageEntityStrike, MessageEntityBlockquote,
MessageEntityCustomEmoji, TypeMessageEntity
)
class HTMLToTelegramParser(HTMLParser):
def __init__(self):
super().__init__()
self.text = ''
self.entities = []
self._building_entities = {}
self._open_tags = deque()
self._open_tags_meta = deque()
def handle_starttag(self, tag, attrs):
self._open_tags.appendleft(tag)
self._open_tags_meta.appendleft(None)
attrs = dict(attrs)
EntityType = None
args = {}
if tag == 'strong' or tag == 'b':
EntityType = MessageEntityBold
elif tag == 'em' or tag == 'i':
EntityType = MessageEntityItalic
elif tag == 'u':
EntityType = MessageEntityUnderline
elif tag == 'del' or tag == 's':
EntityType = MessageEntityStrike
elif tag == 'blockquote':
EntityType = MessageEntityBlockquote
elif tag == 'code':
try:
# If we're in the middle of a <pre> tag, this <code> tag is
# probably intended for syntax highlighting.
#
# Syntax highlighting is set with
# <code class='language-...'>codeblock</code>
# inside <pre> tags
pre = self._building_entities['pre']
try:
pre.language = attrs['class'][len('language-'):]
except KeyError:
pass
except KeyError:
EntityType = MessageEntityCode
elif tag == 'pre':
EntityType = MessageEntityPre
args['language'] = ''
elif tag == 'a':
try:
url = attrs['href']
except KeyError:
return
if url.startswith('mailto:'):
url = url[len('mailto:'):]
EntityType = MessageEntityEmail
else:
if self.get_starttag_text() == url:
EntityType = MessageEntityUrl
else:
EntityType = MessageEntityTextUrl
args['url'] = del_surrogate(url)
url = None
self._open_tags_meta.popleft()
self._open_tags_meta.appendleft(url)
elif tag == 'tg-emoji':
try:
emoji_id = int(attrs['emoji-id'])
except (KeyError, ValueError):
return
EntityType = MessageEntityCustomEmoji
args['document_id'] = emoji_id
if EntityType and tag not in self._building_entities:
self._building_entities[tag] = EntityType(
offset=len(self.text),
# The length will be determined when closing the tag.
length=0,
**args)
def handle_data(self, text):
previous_tag = self._open_tags[0] if len(self._open_tags) > 0 else ''
if previous_tag == 'a':
url = self._open_tags_meta[0]
if url:
text = url
for tag, entity in self._building_entities.items():
entity.length += len(text)
self.text += text
def handle_endtag(self, tag):
try:
self._open_tags.popleft()
self._open_tags_meta.popleft()
except IndexError:
pass
entity = self._building_entities.pop(tag, None)
if entity:
self.entities.append(entity)
def parse(html: str) -> Tuple[str, List[TypeMessageEntity]]:
"""
Parses the given HTML message and returns its stripped representation
plus a list of the MessageEntity's that were found.
:param html: the message with HTML to be parsed.
:return: a tuple consisting of (clean message, [message entities]).
"""
if not html:
return html, []
parser = HTMLToTelegramParser()
parser.feed(add_surrogate(html))
text = strip_text(parser.text, parser.entities)
parser.entities.reverse()
parser.entities.sort(key=lambda entity: entity.offset)
return del_surrogate(text), parser.entities
ENTITY_TO_FORMATTER = {
MessageEntityBold: ('<strong>', '</strong>'),
MessageEntityItalic: ('<em>', '</em>'),
MessageEntityCode: ('<code>', '</code>'),
MessageEntityUnderline: ('<u>', '</u>'),
MessageEntityStrike: ('<del>', '</del>'),
MessageEntityBlockquote: ('<blockquote>', '</blockquote>'),
MessageEntityPre: lambda e, _: (
"<pre>\n"
" <code class='language-{}'>\n"
" ".format(e.language), "{}\n"
" </code>\n"
"</pre>"
),
MessageEntityEmail: lambda _, t: ('<a href="mailto:{}">'.format(t), '</a>'),
MessageEntityUrl: lambda _, t: ('<a href="{}">'.format(t), '</a>'),
MessageEntityTextUrl: lambda e, _: ('<a href="{}">'.format(escape(e.url)), '</a>'),
MessageEntityMentionName: lambda e, _: ('<a href="tg://user?id={}">'.format(e.user_id), '</a>'),
MessageEntityCustomEmoji: lambda e, _: ('<tg-emoji emoji-id="{}">'.format(e.document_id), '</tg-emoji>'),
}
def unparse(text: str, entities: Iterable[TypeMessageEntity]) -> str:
"""
Performs the reverse operation to .parse(), effectively returning HTML
given a normal text and its MessageEntity's.
:param text: the text to be reconverted into HTML.
:param entities: the MessageEntity's applied to the text.
:return: a HTML representation of the combination of both inputs.
"""
if not text:
return text
elif not entities:
return escape(text)
if isinstance(entities, TLObject):
entities = (entities,)
text = add_surrogate(text)
insert_at = []
for i, entity in enumerate(entities):
s = entity.offset
e = entity.offset + entity.length
delimiter = ENTITY_TO_FORMATTER.get(type(entity), None)
if delimiter:
if callable(delimiter):
delimiter = delimiter(entity, text[s:e])
insert_at.append((s, i, delimiter[0]))
insert_at.append((e, -i, delimiter[1]))
insert_at.sort(key=lambda t: (t[0], t[1]))
next_escape_bound = len(text)
while insert_at:
# Same logic as markdown.py
at, _, what = insert_at.pop()
while within_surrogate(text, at):
at += 1
text = text[:at] + what + escape(text[at:next_escape_bound]) + text[next_escape_bound:]
next_escape_bound = at
text = escape(text[:next_escape_bound]) + text[next_escape_bound:]
return del_surrogate(text)
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