add ![vw]ideoidea command

bot.py

@@ -1,10 +1,12 @@
 import argparse
-import asyncio
+import asyncio.subprocess
 import datetime
 import json
+import os.path
 import random
 import re
 import sys
+import tempfile
 import traceback
 from typing import Callable
 from typing import List
@@ -271,6 +273,55 @@ def cmd_settoday(match: Match[str]) -> Response:
     return SetTodayResponse(match, rest)
 
 
+async def check_call(*cmd: str) -> None:
+    proc = await asyncio.subprocess.create_subprocess_exec(
+        *cmd, stdout=asyncio.subprocess.DEVNULL,
+    )
+    await proc.communicate()
+    if proc.returncode != 0:
+        raise ValueError(cmd, proc.returncode)
+
+
+class VideoIdeaResponse(MessageResponse):
+    def __init__(self, match: Match[str], videoidea: str) -> None:
+        super().__init__(
+            match,
+            'added! https://github.com/asottile/scratch/wiki/anthony-explains-ideas',  # noqa: E501
+        )
+        self.videoidea = videoidea
+
+    async def __call__(self, config: Config) -> Optional[str]:
+        async def _git(*cmd: str) -> None:
+            await check_call('git', '-C', tmpdir, *cmd)
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            await _git(
+                'clone', '--depth=1', '--quiet',
+                'git@github.com:asottile/scratch.wiki', '.',
+            )
+            ideas_file = os.path.join(tmpdir, 'anthony-explains-ideas.md')
+            with open(ideas_file, 'rb+') as f:
+                f.seek(-1, os.SEEK_END)
+                c = f.read()
+                if c != b'\n':
+                    f.write(b'\n')
+                f.write(f'- {self.videoidea}\n'.encode())
+            await _git('add', '.')
+            await _git('commit', '-q', '-m', 'idea added by !videoidea')
+            await _git('push', '-q', 'origin', 'HEAD')
+        return await super().__call__(config)
+
+
+@handle_message('![wv]ideoidea')
+def cmd_videoidea(match: Match[str]) -> Response:
+    if match['user'] != match['channel']:
+        return MessageResponse(
+            match, 'https://www.youtube.com/watch?v=RfiQYRn7fBg',
+        )
+    _, _, rest = match['msg'].partition(' ')
+    return VideoIdeaResponse(match, rest)
+
+
 class UptimeResponse(Response):
     async def __call__(self, config: Config) -> Optional[str]:
         url = f'https://api.twitch.tv/helix/streams?user_login={config.channel}'  # noqa: E501