1 files changed, 94 insertions, 0 deletions
diff --git a/bot/exts/evergreen/latex.py b/bot/exts/evergreen/latex.py
new file mode 100644
index 00000000..c4a8597c
--- /dev/null
+++ b/bot/exts/evergreen/latex.py
@@ -0,0 +1,94 @@
+import asyncio
+import hashlib
+import pathlib
+import re
+from concurrent.futures import ThreadPoolExecutor
+from io import BytesIO
+
+import discord
+import matplotlib.pyplot as plt
+from discord.ext import commands
+
+# configure fonts and colors for matplotlib
+plt.rcParams.update(
+    {
+        "font.size": 16,
+        "mathtext.fontset": "cm",  # Computer Modern font set
+        "mathtext.rm": "serif",
+        "figure.facecolor": "36393F",  # matches Discord's dark mode background color
+        "text.color": "white",
+    }
+)
+
+FORMATTED_CODE_REGEX = re.compile(
+    r"(?P<delim>(?P<block>```)|``?)"        # code delimiter: 1-3 backticks; (?P=block) only matches if it's a block
+    r"(?(block)(?:(?P<lang>[a-z]+)\n)?)"    # if we're in a block, match optional language (only letters plus newline)
+    r"(?:[ \t]*\n)*"                        # any blank (empty or tabs/spaces only) lines before the code
+    r"(?P<code>.*?)"                        # extract all code inside the markup
+    r"\s*"                                  # any more whitespace before the end of the code markup
+    r"(?P=delim)",                          # match the exact same delimiter from the start again
+    re.DOTALL | re.IGNORECASE,              # "." also matches newlines, case insensitive
+)
+
+CACHE_DIRECTORY = pathlib.Path("_latex_cache")
+CACHE_DIRECTORY.mkdir(exist_ok=True)
+
+
+class Latex(commands.Cog):
+    """Renders latex."""
+
+    @staticmethod
+    def _render(text: str, filepath: pathlib.Path) -> BytesIO:
+        """
+        Return the rendered image if latex compiles without errors, otherwise raise a BadArgument Exception.
+
+        Saves rendered image to cache.
+        """
+        fig = plt.figure()
+        rendered_image = BytesIO()
+        fig.text(0, 1, text, horizontalalignment="left", verticalalignment="top")
+
+        try:
+            plt.savefig(rendered_image, bbox_inches="tight", dpi=600)
+        except ValueError as e:
+            raise commands.BadArgument(str(e))
+
+        rendered_image.seek(0)
+
+        with open(filepath, "wb") as f:
+            f.write(rendered_image.getbuffer())
+
+        return rendered_image
+
+    @staticmethod
+    def _prepare_input(text: str) -> str:
+        text = text.replace(r"\\", "$\n$")  # matplotlib uses \n for newlines, not \\
+
+        if match := FORMATTED_CODE_REGEX.match(text):
+            return match.group("code")
+        else:
+            return text
+
+    @commands.command()
+    @commands.max_concurrency(1, commands.BucketType.guild, wait=True)
+    async def latex(self, ctx: commands.Context, *, text: str) -> None:
+        """Renders the text in latex and sends the image."""
+        text = self._prepare_input(text)
+        query_hash = hashlib.md5(text.encode()).hexdigest()
+        image_path = CACHE_DIRECTORY.joinpath(f"{query_hash}.png")
+        async with ctx.typing():
+            if image_path.exists():
+                await ctx.send(file=discord.File(image_path))
+                return
+
+            with ThreadPoolExecutor() as pool:
+                image = await asyncio.get_running_loop().run_in_executor(
+                    pool, self._render, text, image_path
+                )
+
+            await ctx.send(file=discord.File(image, "latex.png"))
+
+
+def setup(bot: commands.Bot) -> None:
+    """Load the Latex Cog."""
+    bot.add_cog(Latex(bot))