1 files changed, 265 insertions, 0 deletions
diff --git a/bot/exts/utils/extensions.py b/bot/exts/utils/extensions.py
new file mode 100644
index 00000000..c449a727
--- /dev/null
+++ b/bot/exts/utils/extensions.py
@@ -0,0 +1,265 @@
+import functools
+import logging
+import typing as t
+from enum import Enum
+
+from discord import Colour, Embed
+from discord.ext import commands
+from discord.ext.commands import Context, group
+
+from bot import exts
+from bot.bot import SeasonalBot as Bot
+from bot.constants import Emojis, MODERATION_ROLES, Roles, URLs
+from bot.utils.checks import with_role_check
+from bot.utils.extensions import EXTENSIONS, unqualify
+from bot.utils.pagination import LinePaginator
+
+log = logging.getLogger(__name__)
+
+
+UNLOAD_BLACKLIST = {f"{exts.__name__}.utils.extensions", f"{exts.__name__}.moderation.modlog"}
+BASE_PATH_LEN = len(exts.__name__.split("."))
+
+
+class Action(Enum):
+    """Represents an action to perform on an extension."""
+
+    # Need to be partial otherwise they are considered to be function definitions.
+    LOAD = functools.partial(Bot.load_extension)
+    UNLOAD = functools.partial(Bot.unload_extension)
+    RELOAD = functools.partial(Bot.reload_extension)
+
+
+class Extension(commands.Converter):
+    """
+    Fully qualify the name of an extension and ensure it exists.
+
+    The * and ** values bypass this when used with the reload command.
+    """
+
+    async def convert(self, ctx: Context, argument: str) -> str:
+        """Fully qualify the name of an extension and ensure it exists."""
+        # Special values to reload all extensions
+        if argument == "*" or argument == "**":
+            return argument
+
+        argument = argument.lower()
+
+        if argument in EXTENSIONS:
+            return argument
+        elif (qualified_arg := f"{exts.__name__}.{argument}") in EXTENSIONS:
+            return qualified_arg
+
+        matches = []
+        for ext in EXTENSIONS:
+            if argument == unqualify(ext):
+                matches.append(ext)
+
+        if len(matches) > 1:
+            matches.sort()
+            names = "\n".join(matches)
+            raise commands.BadArgument(
+                f":x: `{argument}` is an ambiguous extension name. "
+                f"Please use one of the following fully-qualified names.```\n{names}```"
+            )
+        elif matches:
+            return matches[0]
+        else:
+            raise commands.BadArgument(f":x: Could not find the extension `{argument}`.")
+
+
+class Extensions(commands.Cog):
+    """Extension management commands."""
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+
+    @group(name="extensions", aliases=("ext", "exts", "c", "cogs"), invoke_without_command=True)
+    async def extensions_group(self, ctx: Context) -> None:
+        """Load, unload, reload, and list loaded extensions."""
+        await ctx.send_help(ctx.command)
+
+    @extensions_group.command(name="load", aliases=("l",))
+    async def load_command(self, ctx: Context, *extensions: Extension) -> None:
+        r"""
+        Load extensions given their fully qualified or unqualified names.
+
+        If '\*' or '\*\*' is given as the name, all unloaded extensions will be loaded.
+        """  # noqa: W605
+        if not extensions:
+            await ctx.send_help(ctx.command)
+            return
+
+        if "*" in extensions or "**" in extensions:
+            extensions = set(EXTENSIONS) - set(self.bot.extensions.keys())
+
+        msg = self.batch_manage(Action.LOAD, *extensions)
+        await ctx.send(msg)
+
+    @extensions_group.command(name="unload", aliases=("ul",))
+    async def unload_command(self, ctx: Context, *extensions: Extension) -> None:
+        r"""
+        Unload currently loaded extensions given their fully qualified or unqualified names.
+
+        If '\*' or '\*\*' is given as the name, all loaded extensions will be unloaded.
+        """  # noqa: W605
+        if not extensions:
+            await ctx.send_help(ctx.command)
+            return
+
+        blacklisted = "\n".join(UNLOAD_BLACKLIST & set(extensions))
+
+        if blacklisted:
+            msg = f":x: The following extension(s) may not be unloaded:```{blacklisted}```"
+        else:
+            if "*" in extensions or "**" in extensions:
+                extensions = set(self.bot.extensions.keys()) - UNLOAD_BLACKLIST
+
+            msg = self.batch_manage(Action.UNLOAD, *extensions)
+
+        await ctx.send(msg)
+
+    @extensions_group.command(name="reload", aliases=("r",), root_aliases=("reload",))
+    async def reload_command(self, ctx: Context, *extensions: Extension) -> None:
+        r"""
+        Reload extensions given their fully qualified or unqualified names.
+
+        If an extension fails to be reloaded, it will be rolled-back to the prior working state.
+
+        If '\*' is given as the name, all currently loaded extensions will be reloaded.
+        If '\*\*' is given as the name, all extensions, including unloaded ones, will be reloaded.
+        """  # noqa: W605
+        if not extensions:
+            await ctx.send_help(ctx.command)
+            return
+
+        if "**" in extensions:
+            extensions = EXTENSIONS
+        elif "*" in extensions:
+            extensions = set(self.bot.extensions.keys()) | set(extensions)
+            extensions.remove("*")
+
+        msg = self.batch_manage(Action.RELOAD, *extensions)
+
+        await ctx.send(msg)
+
+    @extensions_group.command(name="list", aliases=("all",))
+    async def list_command(self, ctx: Context) -> None:
+        """
+        Get a list of all extensions, including their loaded status.
+
+        Grey indicates that the extension is unloaded.
+        Green indicates that the extension is currently loaded.
+        """
+        embed = Embed(colour=Colour.blurple())
+        embed.set_author(
+            name="Extensions List",
+            url=URLs.github_bot_repo,
+            icon_url=URLs.bot_avatar
+        )
+
+        lines = []
+        categories = self.group_extension_statuses()
+        for category, extensions in sorted(categories.items()):
+            # Treat each category as a single line by concatenating everything.
+            # This ensures the paginator will not cut off a page in the middle of a category.
+            category = category.replace("_", " ").title()
+            extensions = "\n".join(sorted(extensions))
+            lines.append(f"**{category}**\n{extensions}\n")
+
+        log.debug(f"{ctx.author} requested a list of all cogs. Returning a paginated list.")
+        await LinePaginator.paginate(lines, ctx, embed, max_size=700, empty=False)
+
+    def group_extension_statuses(self) -> t.Mapping[str, str]:
+        """Return a mapping of extension names and statuses to their categories."""
+        categories = {}
+
+        for ext in EXTENSIONS:
+            if ext in self.bot.extensions:
+                status = Emojis.status_online
+            else:
+                status = Emojis.status_offline
+
+            path = ext.split(".")
+            if len(path) > BASE_PATH_LEN + 1:
+                category = " - ".join(path[BASE_PATH_LEN:-1])
+            else:
+                category = "uncategorised"
+
+            categories.setdefault(category, []).append(f"{status}  {path[-1]}")
+
+        return categories
+
+    def batch_manage(self, action: Action, *extensions: str) -> str:
+        """
+        Apply an action to multiple extensions and return a message with the results.
+
+        If only one extension is given, it is deferred to `manage()`.
+        """
+        if len(extensions) == 1:
+            msg, _ = self.manage(action, extensions[0])
+            return msg
+
+        verb = action.name.lower()
+        failures = {}
+
+        for extension in extensions:
+            _, error = self.manage(action, extension)
+            if error:
+                failures[extension] = error
+
+        emoji = ":x:" if failures else ":ok_hand:"
+        msg = f"{emoji} {len(extensions) - len(failures)} / {len(extensions)} extensions {verb}ed."
+
+        if failures:
+            failures = "\n".join(f"{ext}\n    {err}" for ext, err in failures.items())
+            msg += f"\nFailures:```{failures}```"
+
+        log.debug(f"Batch {verb}ed extensions.")
+
+        return msg
+
+    def manage(self, action: Action, ext: str) -> t.Tuple[str, t.Optional[str]]:
+        """Apply an action to an extension and return the status message and any error message."""
+        verb = action.name.lower()
+        error_msg = None
+
+        try:
+            action.value(self.bot, ext)
+        except (commands.ExtensionAlreadyLoaded, commands.ExtensionNotLoaded):
+            if action is Action.RELOAD:
+                # When reloading, just load the extension if it was not loaded.
+                return self.manage(Action.LOAD, ext)
+
+            msg = f":x: Extension `{ext}` is already {verb}ed."
+            log.debug(msg[4:])
+        except Exception as e:
+            if hasattr(e, "original"):
+                e = e.original
+
+            log.exception(f"Extension '{ext}' failed to {verb}.")
+
+            error_msg = f"{e.__class__.__name__}: {e}"
+            msg = f":x: Failed to {verb} extension `{ext}`:\n```{error_msg}```"
+        else:
+            msg = f":ok_hand: Extension successfully {verb}ed: `{ext}`."
+            log.debug(msg[10:])
+
+        return msg, error_msg
+
+    # This cannot be static (must have a __func__ attribute).
+    def cog_check(self, ctx: Context) -> bool:
+        """Only allow moderators and core developers to invoke the commands in this cog."""
+        return with_role_check(ctx, *MODERATION_ROLES, Roles.core_developers)
+
+    # This cannot be static (must have a __func__ attribute).
+    async def cog_command_error(self, ctx: Context, error: Exception) -> None:
+        """Handle BadArgument errors locally to prevent the help command from showing."""
+        if isinstance(error, commands.BadArgument):
+            await ctx.send(str(error))
+            error.handled = True
+
+
+def setup(bot: Bot) -> None:
+    """Load the Extensions cog."""
+    bot.add_cog(Extensions(bot))