Feature: suggest command usage for misspelt commands

bot/exts/backend/error_handler.py

@@ -1,4 +1,5 @@
 import contextlib
+import difflib
 import logging
 import typing as t
 
@@ -8,7 +9,7 @@
 
 from bot.api import ResponseCodeError
 from bot.bot import Bot
-from bot.constants import Colours
+from bot.constants import Colours, Icons, MODERATION_ROLES
 from bot.converters import TagNameConverter
 from bot.errors import LockedResourceError
 from bot.utils.checks import InWhitelistCheckFailure
@@ -155,9 +156,46 @@ async def try_get_tag(self, ctx: Context) -> None:
         else:
             with contextlib.suppress(ResponseCodeError):
                 await ctx.invoke(tags_get_command, tag_name=tag_name)
+
+        if not any(role.id in MODERATION_ROLES for role in ctx.author.roles):
+            tags_cog = self.bot.get_cog("Tags")
+            command_name = ctx.invoked_with
+            sent = await tags_cog.display_tag(ctx, command_name)
+
+            if not sent:
+                await self.send_command_suggestion(ctx, command_name)
+
         # Return to not raise the exception
         return
 
+    async def send_command_suggestion(self, ctx: Context, command_name: str) -> None:
+        """Sends user similar commands if any can be found."""
+        # No similar tag found, or tag on cooldown -
+        # searching for a similar command
+        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)
+
+            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)
+                    return
+            except errors.CommandError as cmd_error:
+                log.debug(log_msg)
+                await self.on_command_error(ctx, cmd_error)
+                return
+
+            misspelled_content = ctx.message.content
+            e = Embed()
+            e.set_author(name="Did you mean:", icon_url=Icons.questionmark)
+            e.description = f"{misspelled_content.replace(command_name, similar_command_name, 1)}"
+            await ctx.send(embed=e, delete_after=10.0)
+
     async def handle_user_input_error(self, ctx: Context, e: errors.UserInputError) -> None:
         """
         Send an error message in `ctx` for UserInputError, sometimes invoking the help command too.

bot/exts/info/tags.py

@@ -182,10 +182,15 @@ async def search_tag_content_any_keyword(self, ctx: Context, *, keywords: Option
         matching_tags = self._get_tags_via_content(any, keywords or 'any', ctx.author)
         await self._send_matching_tags(ctx, keywords, matching_tags)
 
-    @tags_group.command(name='get', aliases=('show', 'g'))
-    async def get_command(self, ctx: Context, *, tag_name: TagNameConverter = None) -> None:
-        """Get a specified tag, or a list of all tags if no tag is specified."""
+    async def display_tag(self, ctx: Context, tag_name: str = None) -> bool:
+        """
+        If a tag is not found, display similar tag names as suggestions.
 
+        If a tag is not specified, display a paginated embed of all tags.
+
+        Tags are on cooldowns on a per-tag, per-channel basis. If a tag is on cooldown, display
+        nothing and return False.
+        """
         def _command_on_cooldown(tag_name: str) -> bool:
             """
             Check if the command is currently on cooldown, on a per-tag, per-channel basis.
@@ -212,7 +217,7 @@ def _command_on_cooldown(tag_name: str) -> bool:
                 f"{ctx.author} tried to get the '{tag_name}' tag, but the tag is on cooldown. "
                 f"Cooldown ends in {time_left:.1f} seconds."
             )
-            return
+            return False
 
         if tag_name is not None:
             temp_founds = self._get_tag(tag_name)
@@ -237,6 +242,7 @@ def _command_on_cooldown(tag_name: str) -> bool:
                     await ctx.send(embed=Embed.from_dict(tag['embed'])),
                     [ctx.author.id],
                 )
+                return True
             elif founds and len(tag_name) >= 3:
                 await wait_for_deletion(
                     await ctx.send(
@@ -247,6 +253,7 @@ def _command_on_cooldown(tag_name: str) -> bool:
                     ),
                     [ctx.author.id],
                 )
+                return True
 
         else:
             tags = self._cache.values()
@@ -255,6 +262,7 @@ def _command_on_cooldown(tag_name: str) -> bool:
                     description="**There are no tags in the database!**",
                     colour=Colour.red()
                 ))
+                return True
             else:
                 embed: Embed = Embed(title="**Current tags**")
                 await LinePaginator.paginate(
@@ -268,6 +276,14 @@ def _command_on_cooldown(tag_name: str) -> bool:
                     empty=False,
                     max_lines=15
                 )
+                return True
+
+        return False
+
+    @tags_group.command(name='get', aliases=('show', 'g'))
+    async def get_command(self, ctx: Context, *, tag_name: TagNameConverter = None) -> None:
+        """Get a specified tag, or a list of all tags if no tag is specified."""
+        await self.display_tag(ctx, tag_name)
 
 
 def setup(bot: Bot) -> None: