Adding video link preview cog

main.py

 Author: Ian Albert (@rocketsoup)
 Date: 2021-11-11
 """
-import asyncio
+import sys
 
-from config import CONFIG
-from rocketbot.bot import start_bot
-from rocketbot.utils import bot_log
+MIN_PYTHON_VERSION = (3, 10, 0)
+if sys.version_info < MIN_PYTHON_VERSION:
+	ver = sys.version_info
+	raise RuntimeError(f'rocketbot requires Python {MIN_PYTHON_VERSION[0]}.{MIN_PYTHON_VERSION[1]}.{MIN_PYTHON_VERSION[2]} '
+		f'or greater. Detected {ver[0]}.{ver[1]}.{ver[2]}.')
+
+import asyncio  # noqa: E402
+
+from config import CONFIG  # noqa: E402
+from rocketbot.bot import start_bot  # noqa: E402
+from rocketbot.utils import bot_log  # noqa: E402
 
 CURRENT_CONFIG_VERSION = 4
 if (CONFIG.get('__config_version') or 0) < CURRENT_CONFIG_VERSION:

requirements.txt

 discord.py == 2.6.4
+yt-dlp == 2026.02.04

rocketbot/bot.py

 	from rocketbot.cogs.patterncog import PatternCog
 	from rocketbot.cogs.urlspamcog import URLSpamCog
 	from rocketbot.cogs.usernamecog import UsernamePatternCog
+	from rocketbot.cogs.videopreviewcog import VideoPreviewCog
 
 	bot_log(None, None, 'Bot initializing...')
 
 	await rocketbot.add_cog(PatternCog(rocketbot))
 	await rocketbot.add_cog(URLSpamCog(rocketbot))
 	await rocketbot.add_cog(UsernamePatternCog(rocketbot))
+	await rocketbot.add_cog(VideoPreviewCog(rocketbot))
 
 	await rocketbot.start(CONFIG['client_token'], reconnect=True)
 	print('\nBot aborted')

rocketbot/cogs/videopreviewcog.py

+import asyncio
+import json
+import re
+import subprocess
+
+from discord import Message
+from discord.ext.commands import Cog
+
+from rocketbot.cogs.basecog import BaseCog
+from rocketbot.cogsetting import CogSetting
+from rocketbot.utils import (
+	blockquote_markdown,
+	format_bytes,
+	suppress_markdown_url_previews,
+)
+
+
+def filter_video_format(format: dict) -> bool:
+	if format.get('resolution') == 'audio only':
+		return False
+	if format.get('format_note') == 'DASH audio':
+		return False
+	return True
+
+def rank_video_format(format: dict) -> tuple:
+	content = 0
+	if format.get('resolution') == 'audio only':
+		content = 1
+	elif format.get('format_note') == 'DASH audio':
+		content = 1
+	elif format.get('format_note') == 'DASH video':
+		content = 2
+	else:
+		content = 3  # both I guess! multiplexed formats don't seem clearly labeled
+	res = (format.get('width') or 0) + (format.get('height') or 0)
+	return (content, res)
+
+class MessageLink:
+	url: str
+	spoiler: bool = False
+	link_type: str = 'unknown'
+
+	def __init__(self, url: str, link_type: str, spoiler: bool = False):
+		self.url = url
+		self.link_type = link_type
+		self.spoiler = spoiler
+
+class VideoPreviewCog(BaseCog, name='Video Link Previews'):
+	SETTING_ENABLED = CogSetting(
+		'enabled',
+		bool,
+		default_value=False,
+		brief='Video link previews',
+		description='Whether links to certain social media videos should show previews.',
+	)
+	SETTING_INSTAGRAM = CogSetting(
+		'instagram',
+		bool,
+		default_value=False,
+		brief='whether to show video previews for Instagram links',
+		description='For both regular posts and reels',
+	)
+	SETTING_FACEBOOK = CogSetting(
+		'facebook',
+		bool,
+		default_value=False,
+		brief='whether to show video previews for Facebook links',
+	)
+	SETTING_TWITTER = CogSetting(
+		'twitter',
+		bool,
+		default_value=False,
+		brief='whether to show video previews for Twitter links',
+	)
+
+	REGEX_INSTAGRAM_POST = r'https?:\/\/(?:www\.)?instagram\.com\/(?:p|reel)\/[a-zA-Z0-9_-]+\/?'
+	REGEX_FACEBOOK_POST = r'https?:\/\/(?:www\.)?facebook\.com\/share\/[rv]\/[a-zA-Z0-9_-]+\/?'
+	REGEX_TWITTER_POST = r'https?:\/\/(?:twitter|x)\.com\/[a-zA-Z0-9_-]+/status/[0-9]+'
+
+	REGEX_SPOILERS = '\|\|.+\|\|'
+
+	# Best video and best audio, mp4 format with m4a audio
+	FORMATS = 'bv*[ext=mp4]+ba[ext=m4a]/' \
+		'b[ext=mp4]/' \
+		'bv*[ext=mp4]+ba[ext=m4a]/' \
+		'b[ext=mp4]/' \
+		'bv*+ba/' \
+		'b'
+
+	def __init__(self, bot):
+		super().__init__(
+			bot,
+			config_prefix='linkpreview',
+			short_description='Manages video link preview behavior.',
+		)
+		Self = VideoPreviewCog
+		self.add_setting(Self.SETTING_ENABLED)
+		self.add_setting(Self.SETTING_INSTAGRAM)
+		self.add_setting(Self.SETTING_FACEBOOK)
+		self.add_setting(Self.SETTING_TWITTER)
+
+	@Cog.listener()
+	async def on_message(self, message: Message):
+		"""Event listener"""
+		if message.author is None or \
+				message.author.bot or \
+				message.guild is None or \
+				message.channel is None or \
+				message.content is None:
+			return
+		if not self.get_guild_setting(message.guild, self.SETTING_ENABLED):
+			return
+		links = self._get_previewable_links(message)
+		if len(links) == 0:
+			return
+		await self._wait_for_preview(message, links)
+
+
+		# TODO: Make this just link to the raw video file if possible (yt-dlp --get-url)
+
+	def _get_previewable_links(self, message: Message) -> list[MessageLink]:
+		Self = VideoPreviewCog
+		links: list[MessageLink] = []
+		content: str = message.content
+		has_spoilers = re.match(Self.REGEX_SPOILERS, content) is not None
+		if self.get_guild_setting(message.guild, Self.SETTING_INSTAGRAM):
+			for link in re.findall(Self.REGEX_INSTAGRAM_POST, content):
+				links.append(MessageLink(link, 'instagram', has_spoilers))
+		if self.get_guild_setting(message.guild, Self.SETTING_FACEBOOK):
+			for link in re.findall(Self.REGEX_FACEBOOK_POST, content):
+				links.append(MessageLink(link, 'facebook', has_spoilers))
+		if self.get_guild_setting(message.guild, Self.SETTING_TWITTER):
+			for link in re.findall(Self.REGEX_TWITTER_POST, content):
+				links.append(MessageLink(link, 'twitter', has_spoilers))
+		# TODO: Custom patterns
+		return links
+
+	async def _wait_for_preview(self, message: Message, links: list[MessageLink]):
+		await asyncio.sleep(3)
+		# Look for embeds already showing the video
+		self.log(message.guild, "Checking message for embeds")
+		for embed in message.embeds:
+			if embed.video.url:
+				# If there's any video, skip downloading any previews
+				self.log(message.guild, "Message already has a video. Skipping this message.")
+				return
+		await self._fetch_previews(message, links)
+
+	async def _fetch_previews(self, message: Message, links: list[MessageLink]):
+		promises = []
+		for link in links:
+			promises.append(self._fetch_preview(message, link))
+		await asyncio.gather(*promises)
+
+	async def _fetch_preview(self, message: Message, link: MessageLink):
+		result = subprocess.run(
+			[
+				'yt-dlp',
+				'--skip-download',
+				'--dump-single-json',
+				link.url,
+			],
+			stdout=subprocess.PIPE,
+			stderr=subprocess.PIPE,
+			universal_newlines=True
+		)
+		if result.returncode != 0:
+			self.log(message.guild, "Fetching link info JSON failed. Skipping preview.")
+			self.log(message.guild, result.stderr)
+			return
+		try:
+			info: dict = json.loads(result.stdout)
+		except Exception as e:
+			self.log(message.guild, f"Error parsing info.json. Skipping preview. {e}")
+			return
+		description = info.get('description') or ''
+		formats: list[dict] = info.get('formats') or []
+		self.log(message.guild, f"Found {len(formats)} formats")
+		formats = list(filter(filter_video_format, formats))
+		self.log(message.guild, f"Filtered to {len(formats)} formats")
+		sorted_formats: list[dict] = sorted(formats, key=rank_video_format, reverse=True)
+		if len(sorted_formats) == 0:
+			self.log(message.guild, f"No eligible formats for URL {link.url}")
+			return
+		best_format: dict = sorted_formats[0]
+		self.log(message.guild, f"Best format is id {best_format.get('format_id')}")
+		video_url: str = best_format.get('url')
+		link_description: str = "video"
+		if (best_format.get('width') or 0) > 0 and (best_format.get('height') or 0) > 0:
+			link_description += f", {best_format.get('width')}×{best_format.get('height')}"
+		if (best_format.get('filesize') or 0) > 0:
+			link_description += f", {format_bytes(best_format.get('filesize'))}"
+		elif (best_format.get('filesize_approx') or 0) > 0:
+			link_description += f", {format_bytes(best_format.get('filesize_approx'))}"
+		content = "Hmm, video preview didn't load. Let's try this."
+		if len(description) > 0:
+			content += "\n\n" + blockquote_markdown(suppress_markdown_url_previews(description)) + "\n"
+		if link.spoiler:
+			content += f"\n||[{link_description}]({video_url})||"
+		else:
+			content += f"\n[{link_description}]({video_url})"
+		await message.reply(
+			content,
+			mention_author=False
+		)

rocketbot/utils.py

 	"""Indents a block of Markdown by one level."""
 	return '    ' + (markdown.replace('\n', '\n    '))
 
+def suppress_markdown_url_previews(markdown: str) -> str:
+	"""Finds URLs in markdown and encloses them in <...> to suppress the preview."""
+	return re.sub(r'(?<!<)(https?://\S+)(?!>)', '<\\1>', markdown)
+
+def format_bytes(size: int) -> str:
+	"""Formats s size in bytes to a human readable description (e.g. "3.2 KiB")"""
+	if size < 0:
+		size = 0
+	kib = 1024
+	mib = kib * kib
+	gib = mib * kib
+	if size < kib:
+		return f"{size:,} bytes"
+	if size < 10 * kib:
+		return f"{size/kib:,.1f} KiB"
+	if size < mib:
+		return f"{size/kib:,.0f} KiB"
+	if size < 10 * mib:
+		return f"{size/mib:,.1f} MiB"
+	if size < gib:
+		return f"{size/mib:,.0f} MiB"
+	if size < 10 * gib:
+		return f"{size/gib:,.1f} GiB"
+	return f"{size/gib:,.0f} GiB"
+
 MOD_PERMISSIONS: Permissions = Permissions(Permissions.manage_messages.flag)
 
 class TimeDeltaTransformer(Transformer):