Add command to list all messages used for random selection

bot.py

@@ -138,6 +138,22 @@ async def random_message_command(ctx: commands.Context, channel: Optional[discor
     await ctx.channel.send(embed=embed)
 
 
+@bot.command(name='collect_messages', brief='Lists all messages with the given filters')
+async def collect_messages_command(ctx: commands.Context, channel: Optional[discord.TextChannel] = None,
+                                   max_cnt: Optional[int] = 100, reaction_filter: Optional[str] = None):
+    typing = ctx.channel.trigger_typing()
+    if channel is None:
+        channel = ctx.channel
+    messages = async_filter(lambda m: _is_message_valid_for_selection(m, reaction_filter), channel.history(limit=max_cnt))
+    messages = [item async for item in messages]
+    embed = discord.Embed(
+        title="List of matching messages",
+        description='\n'.join([m.content for m in messages])
+    )
+    await typing
+    await ctx.channel.send(embed=embed)
+
+
 def _is_message_valid_for_selection(message: discord.Message, reaction_filter: Optional[str] = None) -> bool:
     if message.clean_content.strip() == '':
         return False