Help command fix, normalize suggestions for unknown commands (#1064)

Co-authored-by: Xithrius <[email protected]>

3 files changed, 61 insertions, 33 deletions

diff --git a/bot/exts/core/error_handler.py b/bot/exts/core/error_handler.py
index 983632ba..4578f734 100644
--- a/bot/exts/core/error_handler.py
+++ b/bot/exts/core/error_handler.py
@@ -1,4 +1,3 @@
-import difflib
 import logging
 import math
 import random
@@ -11,6 +10,7 @@ from sentry_sdk import push_scope
 
 from bot.bot import Bot
 from bot.constants import Channels, Colours, ERROR_REPLIES, NEGATIVE_REPLIES, RedirectOutput
+from bot.utils.commands import get_command_suggestions
 from bot.utils.decorators import InChannelCheckFailure, InMonthCheckFailure
 from bot.utils.exceptions import APIError, MovedCommandError, UserNotPlayingError
 
@@ -158,31 +158,32 @@ class CommandErrorHandler(commands.Cog):
 
     async def send_command_suggestion(self, ctx: commands.Context, command_name: str) -> None:
         """Sends user similar commands if any can be found."""
-        raw_commands = []
-        for cmd in self.bot.walk_commands():
-            if not cmd.hidden:
-                raw_commands += (cmd.name, *cmd.aliases)
-        if similar_command_data := difflib.get_close_matches(command_name, raw_commands, 1):
-            similar_command_name = similar_command_data[0]
-            similar_command = self.bot.get_command(similar_command_name)
-
-            if not similar_command:
-                return
-
-            log_msg = "Cancelling attempt to suggest a command due to failed checks."
-            try:
-                if not await similar_command.can_run(ctx):
+        command_suggestions = []
+        if similar_command_names := get_command_suggestions(list(self.bot.all_commands.keys()), command_name):
+            for similar_command_name in similar_command_names:
+                similar_command = self.bot.get_command(similar_command_name)
+
+                if not similar_command:
+                    continue
+
+                log_msg = "Cancelling attempt to suggest a command due to failed checks."
+                try:
+                    if not await similar_command.can_run(ctx):
+                        log.debug(log_msg)
+                        continue
+                except commands.errors.CommandError as cmd_error:
                     log.debug(log_msg)
-                    return
-            except commands.errors.CommandError as cmd_error:
-                log.debug(log_msg)
-                await self.on_command_error(ctx, cmd_error)
-                return
+                    await self.on_command_error(ctx, cmd_error)
+                    continue
+
+                command_suggestions.append(similar_command_name)
 
             misspelled_content = ctx.message.content
             e = Embed()
             e.set_author(name="Did you mean:", icon_url=QUESTION_MARK_ICON)
-            e.description = misspelled_content.replace(command_name, similar_command_name, 1)
+            e.description = "\n".join(
+                misspelled_content.replace(command_name, cmd, 1) for cmd in command_suggestions
+            )
             await ctx.send(embed=e, delete_after=RedirectOutput.delete_delay)
 
 
diff --git a/bot/exts/core/help.py b/bot/exts/core/help.py
index f9b3513f..b5df70ca 100644
--- a/bot/exts/core/help.py
+++ b/bot/exts/core/help.py
@@ -3,16 +3,16 @@ import asyncio
 import itertools
 import logging
 from contextlib import suppress
-from typing import NamedTuple, Union
+from typing import NamedTuple, Optional, Union
 
 from discord import Colour, Embed, HTTPException, Message, Reaction, User
 from discord.ext import commands
 from discord.ext.commands import CheckFailure, Cog as DiscordCog, Command, Context
-from rapidfuzz import process
 
 from bot import constants
 from bot.bot import Bot
 from bot.constants import Emojis
+from bot.utils.commands import get_command_suggestions
 from bot.utils.pagination import FIRST_EMOJI, LAST_EMOJI, LEFT_EMOJI, LinePaginator, RIGHT_EMOJI
 
 DELETE_EMOJI = Emojis.trashcan
@@ -41,14 +41,18 @@ class HelpQueryNotFound(ValueError):
     """
     Raised when a HelpSession Query doesn't match a command or cog.
 
-    Contains the custom attribute of ``possible_matches``.
-    Instances of this object contain a dictionary of any command(s) that were close to matching the
-    query, where keys are the possible matched command names and values are the likeness match scores.
+    Params:
+    possible_matches: list of similar command names.
+    parent_command: parent command of an invalid subcommand. Only available when an invalid subcommand
+                    has been passed.
     """
 
-    def __init__(self, arg: str, possible_matches: dict = None):
+    def __init__(
+            self, arg: str, possible_matches: Optional[list[str]] = None, *, parent_command: Optional[Command] = None
+    ) -> None:
         super().__init__(arg)
         self.possible_matches = possible_matches
+        self.parent_command = parent_command
 
 
 class HelpSession:
@@ -153,12 +157,17 @@ class HelpSession:
 
         Will pass on possible close matches along with the `HelpQueryNotFound` exception.
         """
-        # Combine command and cog names
-        choices = list(self._bot.all_commands) + list(self._bot.cogs)
+        # Check if parent command is valid in case subcommand is invalid.
+        if " " in query:
+            parent, *_ = query.split()
+            parent_command = self._bot.get_command(parent)
+
+            if parent_command:
+                raise HelpQueryNotFound('Invalid Subcommand.', parent_command=parent_command)
 
-        result = process.extract(query, choices, score_cutoff=90)
+        similar_commands = get_command_suggestions(list(self._bot.all_commands.keys()), query)
 
-        raise HelpQueryNotFound(f'Query "{query}" not found.', dict(result))
+        raise HelpQueryNotFound(f'Query "{query}" not found.', similar_commands)
 
     async def timeout(self, seconds: int = 30) -> None:
         """Waits for a set number of seconds, then stops the help session."""
@@ -507,13 +516,20 @@ class Help(DiscordCog):
         try:
             await HelpSession.start(ctx, *commands)
         except HelpQueryNotFound as error:
+
+            # Send help message of parent command if subcommand is invalid.
+            if cmd := error.parent_command:
+                await ctx.send(str(error))
+                await self.new_help(ctx, cmd.qualified_name)
+                return
+
             embed = Embed()
             embed.colour = Colour.red()
             embed.title = str(error)
 
             if error.possible_matches:
-                matches = "\n".join(error.possible_matches.keys())
-                embed.description = f"**Did you mean:**\n`{matches}`"
+                matches = "\n".join(error.possible_matches)
+                embed.description = f"**Did you mean:**\n{matches}"
 
             await ctx.send(embed=embed)
 
diff --git a/bot/utils/commands.py b/bot/utils/commands.py
new file mode 100644
index 00000000..7c04a25a
--- /dev/null
+++ b/bot/utils/commands.py
@@ -0,0 +1,11 @@
+from typing import Optional
+
+from rapidfuzz import process
+
+
+def get_command_suggestions(
+        all_commands: list[str], query: str, *, cutoff: int = 60, limit: int = 3
+) -> Optional[list]:
+    """Get similar command names."""
+    results = process.extract(query, all_commands, score_cutoff=cutoff, limit=limit)
+    return [result[0] for result in results]