implement CommandNotFoundErrorHandler

2 files changed, 64 insertions, 0 deletions

diff --git a/bot/command_error_handlers/__init__.py b/bot/command_error_handlers/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/bot/command_error_handlers/__init__.py
diff --git a/bot/command_error_handlers/command_not_found.py b/bot/command_error_handlers/command_not_found.py
new file mode 100644
index 00000000..957b4d38
--- /dev/null
+++ b/bot/command_error_handlers/command_not_found.py
@@ -0,0 +1,64 @@
+from typing import NoReturn
+
+from discord import Embed, Interaction, errors
+from discord.ext import commands
+from pydis_core.utils.error_handling.commands import AbstractCommandErrorHandler
+from pydis_core.utils.logging import get_logger
+
+from bot.bot import Bot
+from bot.utils.commands import get_command_suggestions
+
+log = get_logger(__name__)
+
+DELETE_DELAY = 10
+QUESTION_MARK_ICON = "https://cdn.discordapp.com/emojis/512367613339369475.png"
+
+
+class CommandNotFoundErrorHandler(AbstractCommandErrorHandler):
+    """A handler for all CommandNotFound exceptions."""
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+    async def should_handle_error(self, error: errors.DiscordException) -> bool:
+        """A predicate that determines whether the error should be handled or not."""
+        return isinstance(error, commands.CommandNotFound)
+
+    async def handle_app_command_error(self, interaction: Interaction, error: errors.DiscordException) -> NoReturn:
+        """Handle error raised in the context of app commands."""
+        # CommandNotFound cannot happen with app commands, so there's nothing to do here
+        return
+
+    async def handle_text_command_error(self, context: commands.Context, error: errors.DiscordException) -> NoReturn:
+        """Handle error raised in the context of text commands."""
+        if not context.invoked_with.startswith("."):
+            await self.send_command_suggestion(context, context.invoked_with)
+
+    async def send_command_suggestion(self, ctx: commands.Context, command_name: str) -> None:
+        """Sends user similar commands if any can be found."""
+        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:
+                    log.debug(log_msg)
+                    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 = "\n".join(
+                misspelled_content.replace(command_name, cmd, 1) for cmd in command_suggestions
+            )
+            await ctx.send(embed=e, delete_after=DELETE_DELAY)