add add command

a lot of this is from Emoji Connoisseur

bot.py

@@ -4,20 +4,24 @@
 import discord
 from discord.ext import commands
 
-with open('config.py') as f:
-	config = eval(f.read(), {})
-
 class Bot(commands.AutoShardedBot):
-    def __init__(self, **kwargs):
-        super().__init__(command_prefix=commands.when_mentioned, **kwargs)
-        for cog in config['cogs']:
-               self.load_extension(cog)
+	def __init__(self, **kwargs):
+		super().__init__(command_prefix=commands.when_mentioned, **kwargs)
 
-    async def on_ready(self):
-        print('Logged on as {0} (ID: {0.id})'.format(self.user))
+		with open('config.py') as f:
+			self.config = eval(f.read(), {})
+
+		for cog in self.config['cogs']:
+			   self.load_extension(cog)
+
+	def run(self):
+		super().run(self.config['tokens'].pop('discord'))
+
+	async def on_ready(self):
+		print('Logged on as {0} (ID: {0.id})'.format(self.user))
 
 
 bot = Bot()
 
 if __name__ == '__main__':
-	bot.run(config['tokens'].pop('discord'))
+	bot.run()

cogs/emoji.py

@@ -1,16 +1,212 @@
 #!/usr/bin/env python3
 # encoding: utf-8
 
+import io
+import imghdr
+import asyncio
+import logging
+import traceback
+import contextlib
+
+logger = logging.getLogger(__name__)
+
+try:
+	from wand.image import Image
+except ImportError:
+	logger.warn('failed to import wand.image. Image manipulation functions will be unavailable.')
+	Image = None
+
+import aiohttp
+import discord
 from discord.ext import commands
 
+import utils
+from utils import errors
+
 class Emoji:
 	def __init__(self, bot):
 		self.bot = bot
-
+		self.http = aiohttp.ClientSession(loop=self.bot.loop, read_timeout=30, headers={
+			'User-Agent':
+				self.bot.config['user_agent'] + ' '
+				+ self.bot.http.user_agent
+		})
 	async def __local_check(self, context):
 		return (
 			context.guild
 			and context.author.guild_permissions.manage_emojis)
 
+	@commands.command()
+	async def add(self, context, *args):
+		"""Adds an emoji to this server."""
+		try:
+			name, url = self.parse_add_command_args(context, args)
+		except commands.BadArgument as exception:
+			return await context.send(exception)
+
+		async with context.typing():
+			message = await self.add_safe(context.guild, name, url, context.message.author.id)
+		await context.send(message)
+
+	@classmethod
+	def parse_add_command_args(cls, context, args):
+		if context.message.attachments:
+			return cls.parse_add_command_attachment(context, args)
+
+		elif len(args) == 1:
+			match = utils.emote.RE_CUSTOM_EMOTE.match(args[0])
+			if match is None:
+				raise commands.BadArgument(
+					'Error: I expected a custom emote as the first argument, '
+					'but I got something else. '
+					"If you're trying to add an emote using an image URL, "
+					'you need to provide a name as the first argument, like this:\n'
+					'`{}add NAME_HERE URL_HERE`'.format(context.prefix))
+			else:
+				animated, name, id = match.groups()
+				url = utils.emote.url(id, animated=animated)
+
+			return name, url
+
+		elif len(args) >= 2:
+			name = args[0]
+			match = utils.emote.RE_CUSTOM_EMOTE.match(args[1])
+			if match is None:
+				url = utils.strip_angle_brackets(args[1])
+			else:
+				url = utils.emote.url(match.group('id'))
+
+			return name, url
+
+		elif not args:
+			raise commands.BadArgument('Your message had no emotes and no name!')
+
+	@staticmethod
+	def parse_add_command_attachment(context, args):
+		attachment = context.message.attachments[0]
+		# as far as i can tell, this is how discord replaces filenames when you upload an emote image
+		name = ''.join(args) if args else attachment.filename.split('.')[0].replace(' ', '')
+		url = attachment.url
+
+		return name, url
+
+	async def add_safe(self, guild, name, url, author_id):
+		"""Try to add an emote. Returns a string that should be sent to the user."""
+		try:
+			emote = await self.add_from_url(guild, name, url, author_id)
+		except discord.HTTPException as ex:
+			logger.error(traceback.format_exc())
+			return (
+				'An error occurred while creating the emote:\n'
+				+ utils.format_http_exception(ex))
+		except asyncio.TimeoutError:
+			return 'Error: retrieving the image took too long.'
+		except ValueError:
+			return 'Error: Invalid URL.'
+		else:
+			return f'Emote {emote} successfully created.'
+
+	async def add_from_url(self, guild, name, url, author_id):
+		image_data = await self.fetch_emote(url)
+		emote = await self.create_emote_from_bytes(guild, name, author_id, image_data)
+
+		return emote
+
+	async def fetch_emote(self, url):
+		# credits to @Liara#0001 (ID 136900814408122368) for most of this part
+		# https://gitlab.com/Pandentia/element-zero/blob/47bc8eeeecc7d353ec66e1ef5235adab98ca9635/element_zero/cogs/emoji.py#L217-228
+		async with self.http.head(url, timeout=5) as response:
+			if response.reason != 'OK':
+				raise errors.HTTPException(response.status)
+			if response.headers.get('Content-Type') not in ('image/png', 'image/jpeg', 'image/gif'):
+				raise errors.InvalidImageError
+
+		async with self.http.get(url) as response:
+			if response.reason != 'OK':
+				raise errors.HTTPException(response.status)
+			return io.BytesIO(await response.read())
+
+	async def create_emote_from_bytes(self, guild, name, author_id, image_data: io.BytesIO):
+		# resize_until_small is normally blocking, because wand is.
+		# run_in_executor is magic that makes it non blocking somehow.
+		# also, None as the executor arg means "use the loop's default executor"
+		image_data = await self.bot.loop.run_in_executor(None, self.resize_until_small, image_data)
+		return await guild.create_custom_emoji(
+			name=name,
+			image=image_data.read(),
+			reason=f'Created by {utils.format_user(self.bot, author_id)}')
+
+	@staticmethod
+	def is_animated(image_data: bytes):
+		"""Return whether the image data is animated, or raise InvalidImageError if it's not an image."""
+		type = imghdr.what(None, image_data)
+		if type == 'gif':
+			return True
+		elif type in ('png', 'jpeg'):
+			return False
+		else:
+			raise errors.InvalidImageError
+
+	@classmethod
+	def size(cls, data: io.BytesIO):
+		"""return the size, in bytes, of the data a BytesIO object represents"""
+		with cls.preserve_position(data):
+			data.seek(0, io.SEEK_END)
+			return data.tell()
+
+	class preserve_position(contextlib.AbstractContextManager):
+		def __init__(self, fp):
+			self.fp = fp
+			self.old_pos = fp.tell()
+
+		def __exit__(self, *excinfo):
+			self.fp.seek(self.old_pos)
+
+	@classmethod
+	def resize_until_small(cls, image_data: io.BytesIO):
+		"""If the image_data is bigger than 256KB, resize it until it's not"""
+		# It's important that we only attempt to resize the image when we have to,
+		# ie when it exceeds the Discord limit of 256KiB.
+		# Apparently some <256KiB images become larger when we attempt to resize them,
+		# so resizing sometimes does more harm than good.
+		max_resolution = 128  # pixels
+		size = cls.size(image_data)
+		while size > 256 * 2**10 and max_resolution >= 32:  # don't resize past 32x32 or 256KiB
+			logger.debug('image size too big (%s bytes)', size)
+			logger.debug('attempting resize to %s*%s pixels', max_resolution, max_resolution)
+			image_data = cls.thumbnail(image_data, (max_resolution, max_resolution))
+			size = cls.size(image_data)
+			max_resolution //= 2
+		return image_data
+
+	@classmethod
+	def thumbnail(cls, image_data: io.BytesIO, max_size=(128, 128)):
+		"""Resize an image in place to no more than max_size pixels, preserving aspect ratio."""
+		# Credit to @Liara#0001 (ID 136900814408122368)
+		# https://gitlab.com/Pandentia/element-zero/blob/47bc8eeeecc7d353ec66e1ef5235adab98ca9635/element_zero/cogs/emoji.py#L243-247
+		image = Image(blob=image_data)
+		image.resize(*cls.scale_resolution((image.width, image.height), max_size))
+		# we create a new buffer here because there's wand errors otherwise.
+		# specific error:
+		# MissingDelegateError: no decode delegate for this image format `' @ error/blob.c/BlobToImage/353
+		out = io.BytesIO()
+		image.save(file=out)
+		out.seek(0)
+		return out
+
+	@staticmethod
+	def scale_resolution(old_res, new_res):
+		# https://stackoverflow.com/a/6565988
+		"""Resize a resolution, preserving aspect ratio. Returned w,h will be <= new_res"""
+		old_width, old_height = old_res
+		new_width, new_height = new_res
+		old_ratio = old_width / old_height
+		new_ratio = new_width / new_height
+		if new_ratio > old_ratio:
+			return (old_width * new_height//old_height, new_height)
+		return new_width, old_height * new_width//old_width
+
+
+
 def setup(bot):
 	bot.add_cog(Emoji(bot))

config.example.py

@@ -14,4 +14,6 @@
 			'botsfordiscord.com': None,
 		},
 	},
+
+	'user_agent': 'EmojiManagerBot (https://github.com/bmintz/emoji-manager-bot)',
 }

utils/__init__.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+
+from .misc import *
+from . import emote
+from . import errors

utils/emote.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+
+import re
+
+"""
+various utilities related to custom emotes
+"""
+
+"""Matches :foo: and ;foo; but not :foo;. Used for emotes in text."""
+RE_EMOTE = re.compile(r'(:|;)(?P<name>\w{2,32})\1|(?P<newline>\n)', re.ASCII)
+
+"""Matches only custom server emotes."""
+RE_CUSTOM_EMOTE = re.compile(r'<(?P<animated>a?):(?P<name>\w{2,32}):(?P<id>\d{17,})>', re.ASCII)
+
+def url(id, *, animated: bool = False):
+	"""Convert an emote ID to the image URL for that emote."""
+	extension = 'gif' if animated else 'png'
+	return f'https://cdn.discordapp.com/emojis/{id}.{extension}?v=1'

utils/errors.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+
+from discord.ext.commands import CommandError
+
+
+class EmojiManagerError(CommandError):
+	"""Generic error with the bot. This can be used to catch all bot errors."""
+	pass
+
+
+class HTTPException(EmojiManagerError):
+	"""The server did not respond with an OK status code."""
+	def __init__(self, status):
+		super().__init__(f'URL error: server returned error code {status}')
+
+
+class EmojiNotFoundError(EmojiManagerError):
+	"""An emoji with that name was not found"""
+	def __init__(self, name):
+		super().__init__(f'An emoji called `{name}` does not exist in this server.')
+
+
+class InvalidImageError(EmojiManagerError):
+	"""The image is not a GIF, PNG, or JPG"""
+	def __init__(self):
+		super().__init__('The image supplied was not a GIF, PNG, or JPG.')
+
+
+class NoMoreSlotsError(EmojiManagerError):
+	"""Raised in case all slots of a particular type (static/animated) are full"""
+	def __init__(self):
+		super().__init__('No more backend slots available.')
+
+
+class PermissionDeniedError(EmojiManagerError):
+	"""Raised when a user tries to modify an emoji without the Manage Emojis permission"""
+	def __init__(self, name):
+		super().__init__(f"You're not authorized to modify `{name}`.")
+
+
+class DiscordError(Exception):
+	"""Usually raised when the client cache is being baka"""
+	def __init__(self):
+		super().__init__('Discord seems to be having issues right now, please try again later.')

utils/misc.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+
+import discord
+
+"""various utilities for use within the bot"""
+
+"""Emotes used to indicate success/failure. You can obtain these from the discordbots.org guild,
+but I uploaded them to my test server
+so that both the staging and the stable versions of the bot can use them"""
+SUCCESS_EMOTES = ('<:error:416845770239508512>', '<:success:416845760810844160>')
+
+def format_user(bot, id, *, mention=False):
+	"""Format a user ID for human readable display."""
+	user = bot.get_user(id)
+	if user is None:
+		return f'Unknown user with ID {id}'
+	# not mention: @null byte#8191 (140516693242937345)
+	# mention: <@140516693242937345> (null byte#8191)
+	# this allows people to still see the username and discrim
+	# if they don't share a server with that user
+	if mention:
+		return f'{user.mention} (@{user})'
+	else:
+		return f'@{user} ({user.id})'
+
+def format_http_exception(exception: discord.HTTPException):
+	"""Formats a discord.HTTPException for relaying to the user.
+	Sample return value:
+
+	BAD REQUEST (status code: 400):
+	Invalid Form Body
+	In image: File cannot be larger than 256 kb.
+	"""
+	return (
+		f'{exception.response.reason} (status code: {exception.response.status}):'
+		f'\n{exception.text}')
+
+def strip_angle_brackets(string):
+	"""Strip leading < and trailing > from a string.
+	Useful if a user sends you a url like <this> to avoid embeds, or to convert emotes to reactions."""
+	if string.startswith('<') and string.endswith('>'):
+		return string[1:-1]
+	return string