commands: add plugin loading/unloading/reloading support

Closes #5.

plugins/commands.py

@@ -2,6 +2,8 @@
 import sys
 import os
 from time import ctime
+import itertools
+import gc
 
 sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 import utils
@@ -203,3 +205,107 @@ def echo(irc, source, args):
 
     Echoes the text given."""
     irc.msg(irc.called_by, ' '.join(args))
+
+def load(irc, source, args):
+    """<plugin name>.
+
+    Loads a plugin from the plugin folder."""
+    utils.checkAuthenticated(irc, source, allowOper=False)
+    try:
+        name = args[0]
+    except IndexError:
+        irc.msg(irc.called_by, "Error: Not enough arguments. Needs 1: plugin name.")
+        return
+    try:
+        world.plugins[name] = pl = __import__(name)
+    except ImportError as e:
+        if str(e) == ('No module named %r' % name):
+            log.exception('Failed to load plugin %r: The plugin could not be found.', name)
+        else:
+            log.exception('Failed to load plugin %r: ImportError.', name)
+        raise
+    else:
+        if hasattr(pl, 'main'):
+            log.debug('Calling main() function of plugin %r', pl)
+            pl.main(irc)
+    irc.msg(irc.called_by, "Loaded plugin %r." % name)
+utils.add_cmd(load)
+
+def unload(irc, source, args):
+    """<plugin name>.
+
+    Unloads a currently loaded plugin."""
+    utils.checkAuthenticated(irc, source, allowOper=False)
+    try:
+        name = args[0]
+    except IndexError:
+        irc.msg(irc.called_by, "Error: Not enough arguments. Needs 1: plugin name.")
+        return
+    if name == 'commands':
+        irc.msg(irc.called_by, "Error: Cannot unload the commands plugin!")
+        return
+    elif name in world.plugins:
+        pl = world.plugins[name]
+        log.debug('sys.getrefcount of plugin %s is %s', pl, sys.getrefcount(pl))
+        # Remove any command functions set by the plugin.
+        for cmdname, cmdfuncs in world.commands.copy().items():
+            log.debug('cmdname=%s, cmdfuncs=%s', cmdname, cmdfuncs)
+            for cmdfunc in cmdfuncs:
+                log.debug('__module__ of cmdfunc %s is %s', cmdfunc, cmdfunc.__module__)
+                if cmdfunc.__module__ == name:
+                    log.debug('Removing %s from world.commands[%s]', cmdfunc, cmdname)
+                    world.commands[cmdname].remove(cmdfunc)
+                    # If the cmdfunc list is empty, remove it.
+                    if not cmdfuncs:
+                        log.debug("Removing world.commands[%s] (it's empty now)", cmdname)
+                        del world.commands[cmdname]
+
+        # Remove any command hooks set by the plugin.
+        for hookname, hookfuncs in world.hooks.copy().items():
+            for hookfunc in hookfuncs:
+                if hookfunc.__module__ == name:
+                    world.hooks[hookname].remove(hookfunc)
+                    # If the hookfuncs list is empty, remove it.
+                    if not hookfuncs:
+                        del world.hooks[hookname]
+
+        # Remove whois handlers too.
+        for f in world.whois_handlers:
+            if f.__module__ == name:
+                world.whois_handlers.remove(f)
+
+        # Call the die() function in the plugin, if present.
+        if hasattr(pl, 'die'):
+            try:
+                pl.die(irc)
+            except:  # But don't allow it to crash the server.
+                log.exception('(%s) Error occurred in die() of plugin %s, skipping...', irc.name, pl)
+
+        # Delete it from memory (hopefully).
+        del world.plugins[name]
+        if name in sys.modules:
+            del sys.modules[name]
+        if name in globals():
+            del globals()[name]
+
+        # Garbage collect.
+        gc.collect()
+
+        irc.msg(irc.called_by, "Unloaded plugin %r." % name)
+        return True  # We succeeded, make it clear (this status is used by reload() below)
+    else:
+        irc.msg(irc.called_by, "Unknown plugin %r." % name)
+utils.add_cmd(unload)
+
+@utils.add_cmd
+def reload(irc, source, args):
+    """<plugin name>.
+
+    Loads a plugin from the plugin folder."""
+    try:
+        name = args[0]
+    except IndexError:
+        irc.msg(irc.called_by, "Error: Not enough arguments. Needs 1: plugin name.")
+        return
+    if unload(irc, source, args):
+        load(irc, source, args)