Add cog for turning math expressions into LaTeX (#18)

* Add cog for turning math expressions into LaTeX

Note that this does NOT require eval, and does NOT evaluate the expression,
and is therefore 100% safe

* Fix whitespace

* Fix import order

Signed-off-by: Martmists <[email protected]>

* Enable loading of math cog

Signed-off-by: Martmists <[email protected]>

* Change size from 300 to 150

* Fix requested issues

Signed-off-by: Martmists <[email protected]>

* forgot setup()

Signed-off-by: Martmists <[email protected]>

* Fix spaces being ignored

Signed-off-by: Martmists <[email protected]>

* Use latex2png instead

Signed-off-by: Martmists <[email protected]>

* Allow ` to be used in expressions to not make it look odd

Signed-off-by: Martmists <[email protected]>

* Add safe calc

Signed-off-by: Martmists <[email protected]>

* Fix flake8

Signed-off-by: Martmists <[email protected]>

* Update math.py

* Fix

Signed-off-by: Martmists <[email protected]>

4 files changed, 103 insertions, 0 deletions

diff --git a/.snekrc b/.snekrc
new file mode 100644
index 000000000..9f582f477
--- /dev/null
+++ b/.snekrc
@@ -0,0 +1,6 @@
+[all]
+linters = flake8, safety, dodgy
+
+[flake8]
+max-line-length=120
+application_import_names=bot
diff --git a/bot/__main__.py b/bot/__main__.py
index 88991ac53..e04aaef5c 100644
--- a/bot/__main__.py
+++ b/bot/__main__.py
@@ -33,6 +33,7 @@ bot.load_extension("bot.cogs.cogs")
 bot.load_extension("bot.cogs.clickup")
 bot.load_extension("bot.cogs.deployment")
 bot.load_extension("bot.cogs.eval")
+bot.load_extension("bot.cogs.math")
 bot.load_extension("bot.cogs.fun")
 bot.load_extension("bot.cogs.tags")
 bot.load_extension("bot.cogs.verification")
diff --git a/bot/cogs/math.py b/bot/cogs/math.py
new file mode 100644
index 000000000..94024e8ae
--- /dev/null
+++ b/bot/cogs/math.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+
+from io import BytesIO
+from re import search
+
+
+from aiohttp import ClientSession
+
+from discord import File
+from discord.ext.commands import command
+
+from sympy import latex
+from sympy.parsing.sympy_parser import parse_expr
+
+
+LATEX_URL = "http://latex2png.com"
+
+
+class Math:
+    def __init__(self, bot):
+        self.bot = bot
+
+    @command()
+    async def latexify(self, ctx, *, expr: str):
+        fixed_expr = expr.replace('^', '**').strip('`').replace("__", "")
+        try:
+            parsed = parse_expr(fixed_expr, evaluate=False)
+
+        except SyntaxError:
+            await ctx.send("Invalid expression!")
+
+        else:
+            ltx = latex(parsed)
+
+            data = {
+                "latex": ltx,
+                "res": 300,
+                "color": 808080
+            }
+
+            async with ClientSession() as session:
+                async with session.post(LATEX_URL, data=data) as resp:
+                    html = await resp.text()
+
+                name = search(r'hist\.request\.basename = "(?P<url>[^"]+)"', html).group('url')
+
+                async with session.get(f"{LATEX_URL}/output/{name}.png") as resp:
+                    bytes_img = await resp.read()
+
+            file = File(fp=BytesIO(bytes_img), filename="latex.png")
+
+            await ctx.send(file=file)
+
+    @command()
+    async def calc(self, ctx, *, expr: str):
+        fixed_expr = expr.replace('^', '**').strip('`')
+
+        if any(x in fixed_expr for x in ("**", "__")):
+            return await ctx.send(
+                "You used an expression that has been disabled for security, our apologies")
+
+        try:
+            parsed = parse_expr(fixed_expr, evaluate=False)
+            result = parsed.doit()
+
+        except SyntaxError:
+            await ctx.send("Invalid expression!")
+
+        else:
+            ltx = latex(result)
+
+            data = {
+                "latex": ltx,
+                "res": 300,
+                "color": 808080
+            }
+
+            async with ClientSession() as session:
+                async with session.post(LATEX_URL, data=data) as resp:
+                    html = await resp.text()
+
+                name = search(r'hist\.request\.basename = "(?P<url>[^"]+)"', html).group('url')
+
+                async with session.get(f"{LATEX_URL}/output/{name}.png") as resp:
+                    bytes_img = await resp.read()
+
+            file = File(fp=BytesIO(bytes_img), filename="latex.png")
+
+            await ctx.send(file=file)
+
+
+def setup(bot):
+    bot.add_cog(Math(bot))
diff --git a/requirements.txt b/requirements.txt
index 9e191988d..941d7f2b6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 https://github.com/Rapptz/discord.py/archive/rewrite.zip#egg=discord.py[voice]
 dulwich
 multidict
+sympy