rewrite, use the rtex api instead of mpl

3 files changed, 63 insertions, 75 deletions

diff --git a/bot/exts/fun/latex/_latex_cog.py b/bot/exts/fun/latex/_latex_cog.py
index 0cd4c981..72d48b2a 100644
--- a/bot/exts/fun/latex/_latex_cog.py
+++ b/bot/exts/fun/latex/_latex_cog.py
@@ -1,13 +1,14 @@
-import asyncio
 import hashlib
 import re
-import sys
+import string
 from pathlib import Path
-from textwrap import dedent
+from typing import BinaryIO, Optional
 
 import discord
 from discord.ext import commands
 
+from bot.bot import Bot
+
 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)
@@ -18,35 +19,65 @@ FORMATTED_CODE_REGEX = re.compile(
     re.DOTALL | re.IGNORECASE,              # "." also matches newlines, case insensitive
 )
 
+LATEX_API_URL = "https://rtex.probablyaweb.site/api/v2"
+PASTEBIN_URL = "https://paste.pythondiscord.com"
+
 THIS_DIR = Path(__file__).parent
 CACHE_DIRECTORY = THIS_DIR / "cache"
 CACHE_DIRECTORY.mkdir(exist_ok=True)
+TEMPLATE = string.Template((THIS_DIR / "template.txt").read_text())
 
 
 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
 
 
-def _format_err(text: str) -> str:
-    # prevent escaping the codeblock by inserting a zero-width-joiner
-    text = text.replace("`", "`\u200d")
-    return dedent(
-        f"""
-        ```
-        {text}
-        ```
-        """
-    ).strip()
+class InvalidLatexError(Exception):
+    """Represents an error caused by invalid latex."""
+
+    def __init__(self, logs: str):
+        super().__init__(logs)
+        self.logs = logs
 
 
 class Latex(commands.Cog):
     """Renders latex."""
 
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+    async def _generate_image(self, query: str, out_file: BinaryIO) -> None:
+        """Make an API request and save the generated image to cache."""
+        payload = {"code": query, "format": "png"}
+        async with self.bot.http_session.post(LATEX_API_URL, data=payload, raise_for_status=True) as response:
+            response_json = await response.json()
+        if response_json["status"] != "success":
+            raise InvalidLatexError(logs=response_json["log"])
+        async with self.bot.http_session.get(
+            f"{LATEX_API_URL}/{response_json['filename']}",
+            data=payload,
+            raise_for_status=True
+        ) as response:
+            out_file.write(await response.read())
+
+    async def _upload_to_pastebin(self, text: str) -> Optional[str]:
+        """Uploads `text` to the paste service, returning the url if successful."""
+        try:
+            async with self.bot.http_session.post(
+                PASTEBIN_URL + "/documents",
+                data=text,
+                raise_for_status=True
+            ) as response:
+                response_json = await response.json()
+            if "key" in response_json:
+                return f"{PASTEBIN_URL}/{response_json['key']}.txt?noredirect"
+        except Exception:
+            # 400 (Bad Request) means there are too many characters
+            pass
+
     @commands.command()
     @commands.max_concurrency(1, commands.BucketType.guild, wait=True)
     async def latex(self, ctx: commands.Context, *, query: str) -> None:
@@ -56,18 +87,17 @@ class Latex(commands.Cog):
         image_path = CACHE_DIRECTORY / f"{query_hash}.png"
         async with ctx.typing():
             if not image_path.exists():
-                proc = await asyncio.subprocess.create_subprocess_exec(
-                    sys.executable,
-                    "_renderer.py",
-                    query,
-                    image_path.relative_to(THIS_DIR),
-                    cwd=THIS_DIR,
-                    stderr=asyncio.subprocess.PIPE
-                )
-                return_code = await proc.wait()
-                if return_code != 0:
+                try:
+                    with open(image_path, "wb") as out_file:
+                        await self._generate_image(TEMPLATE.substitute(text=query), out_file)
+                except InvalidLatexError as err:
+                    logs_paste_url = await self._upload_to_pastebin(err.logs)
+                    embed = discord.Embed(title="Failed to render input.")
+                    if logs_paste_url:
+                        embed.description = f"[View Logs]({logs_paste_url})"
+                    else:
+                        embed.description = "Couldn't upload logs."
+                    await ctx.send(embed=embed)
                     image_path.unlink()
-                    err = (await proc.stderr.read()).decode()
-                    raise commands.BadArgument(_format_err(err))
-
+                    return
             await ctx.send(file=discord.File(image_path, "latex.png"))
diff --git a/bot/exts/fun/latex/_renderer.py b/bot/exts/fun/latex/_renderer.py
deleted file mode 100644
index fb72b94c..00000000
--- a/bot/exts/fun/latex/_renderer.py
+++ /dev/null
@@ -1,47 +0,0 @@
-import sys
-from pathlib import Path
-from typing import BinaryIO
-
-import matplotlib.pyplot as plt
-
-# 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",
-    }
-)
-
-
-def render(text: str, file_handle: BinaryIO) -> None:
-    """
-    Saves rendered image in `file_handle`.
-
-    In case the input is invalid latex, it prints the error to `stderr`.
-    """
-    fig = plt.figure()
-    fig.text(0, 1, text, horizontalalignment="left", verticalalignment="top")
-    try:
-        plt.savefig(file_handle, bbox_inches="tight", dpi=600)
-    except ValueError as err:
-        # get rid of traceback, keeping just the latex error
-        sys.exit(err)
-
-
-def main() -> None:
-    """
-    Renders a latex query and saves the output in a specified file.
-
-    Expects two command line arguments: the query and the path to the output file.
-    """
-    query = sys.argv[1]
-    out_file_path = Path(sys.argv[2])
-    with open(out_file_path, "wb") as out_file:
-        render(query, out_file)
-
-
-if __name__ == "__main__":
-    main()
diff --git a/bot/exts/fun/latex/template.txt b/bot/exts/fun/latex/template.txt
new file mode 100644
index 00000000..a20cc279
--- /dev/null
+++ b/bot/exts/fun/latex/template.txt
@@ -0,0 +1,5 @@
+\documentclass{article}
+\begin{document}
+    \pagenumbering{gobble}
+    $text
+\end{document}