implement ?tex command and add rTeX server option

CHANGELOG.md

@@ -5,7 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 
 ## [Unreleased]
-
+### Added
+- `?tex` command to render a LaTeX expression.
+- Configuration option to use another rTeX instance for `?tex`.
 
 ## [2.6.0] - 2021-03-18
 ### Added

exts/tex.py

@@ -0,0 +1,65 @@
+"""
+TeX extension for qrm
+---
+Copyright (C) 2021 thxo
+
+This file is part of qrm2 and is released under the terms of
+the GNU General Public License, version 2.
+"""
+
+import aiohttp
+from io import BytesIO
+from urllib.parse import urljoin
+
+import discord
+import discord.ext.commands as commands
+
+import common as cmn
+import data.options as opt
+
+
+class TexCog(commands.Cog):
+    def __init__(self, bot: commands.Bot):
+        self.bot = bot
+        self.session = aiohttp.ClientSession(connector=bot.qrm.connector)
+        self.rtex_instance = getattr(opt, "rtex_instance", "https://rtex.probablyaweb.site/")
+        with open(cmn.paths.resources / "template.1.tex") as latex_template:
+            self.template = latex_template.read()
+
+    @commands.command(name="tex", aliases=["latex"], category=cmn.cat.fun)
+    async def tex(self, ctx: commands.Context, *, expr: str):
+        """Renders a LaTeX expression."""
+        payload = {
+            "format": "png",
+            "code": self.template.replace("#CONTENT#", expr),
+            "quality": 50
+        }
+
+        with ctx.typing():
+            # ask rTeX to render our expression
+            async with self.session.post(urljoin(self.rtex_instance, "api/v2"), json=payload) as r:
+                if r.status != 200:
+                    raise cmn.BotHTTPError(r)
+
+                render_result = await r.json()
+                if render_result["status"] != "success":
+                    embed = cmn.embed_factory(ctx)
+                    embed.title = "LaTeX Rendering Failed!"
+                    embed.description = render_result.get("description", "Unknown error")
+                    embed.colour = cmn.colours.bad
+                    await ctx.send(embed=embed)
+                    return
+
+            # if rendering went well, download the file given in the response
+            async with self.session.get(urljoin(self.rtex_instance, "api/v2/" + render_result["filename"])) as r:
+                png_buffer = BytesIO(await r.read())
+
+            embed = cmn.embed_factory(ctx)
+            embed.title = "LaTeX Expression"
+            embed.description = "Rendered by [rTeX](https://rtex.probablyaweb.site/)."
+            embed.set_image(url="attachment://tex.png")
+            await ctx.send(file=discord.File(png_buffer, "tex.png"), embed=embed)
+
+
+def setup(bot: commands.Bot):
+    bot.add_cog(TexCog(bot))

templates/data/options.py

@@ -41,6 +41,7 @@ exts = [
     "morse",
     "qrz",
     "study",
+    "tex",
     "weather",
     "dbconv",
     "propagation",
@@ -86,3 +87,6 @@ msg_reacts = {}
 
 # A :pika: emote's ID, None for no emote :c
 pika = 658733876176355338
+
+# Base URL to a deployment of rTeX, which performs LaTeX rendering.
+rtex_instance = "https://rtex.probablyaweb.site/"