path: root/portato/plugin.py

# -*- coding: utf-8 -*-
#
# File: portato/plugin.py
# This file is part of the Portato-Project, a graphical portage-frontend.
#
# Copyright (C) 2007 René 'Necoro' Neumann
# This is free software.  You may redistribute copies of it under the terms of
# the GNU General Public License version 2.
# There is NO WARRANTY, to the extent permitted by law.
#
# Written by René 'Necoro' Neumann <necoro@necoro.net>

import os, os.path
from xml.dom.minidom import parse

from constants import PLUGIN_DIR
from helper import debug, flatten

class ParseException (Exception):
	pass

def error (reason, p):
	reason = "("+reason+")"
	debug("Malformed plugin:", p, reason, minus=1, error = 1)

class Menu:
	"""A single <menu>-element."""
	def __init__ (self, plugin, label, call):
		"""Constructor.

		@param plugin: the plugin this menu belongs to
		@type plugin: Plugin
		@param label: the label to show
		@type label: string
		@param call: the function to call relative to the import statement
		@type call: string

		@raises ParseException: on parsing errors"""

		if not label:
			raise ParseException, "label attribute missing"

		if not call:
			raise ParseException, "call attribute missing"

		self.label = label
		self.plugin = plugin

		if self.plugin.needs_import(): # get import
			imp = self.plugin.get_import()
			try:
				mod = __import__(imp, globals(), locals(), [call])
			except ImportError:
				raise ParseException, imp+" cannot be imported"

			try:
				self.call = eval("mod."+call) # build function
			except AttributeError:
				raise ParseException, call+" cannot be imported"
		else:
			try:
				self.call = eval(call)
			except AttributeError:
				raise ParseException, call+" cannot be imported"

class Connect:
	"""A single <connect>-element."""

	def __init__ (self, hook, type, depend_plugin):
		"""Constructor.

		@param hook: the parent Hook
		@type hook: Hook
		@param type: the type of the connect ("before", "after", "override")
		@type type: string
		@param depend_plugin: a plugin we are dependant on
		@type depend_plugin: string or None
		
		@raises ParseException: on parsing errors"""

		if not type in ["before", "after", "override"]:
			raise ParseException, "Unknown connect type %s" % type

		self.type = type
		self.hook = hook
		self.depend_plugin = depend_plugin

	def is_before_type (self):
		return self.type == "before"

	def is_after_type (self):
		return self.type == "after"

	def is_override_type (self):
		return self.type == "override"

class Hook:
	"""A single <hook>-element."""

	def __init__ (self, plugin, hook, call):
		"""Constructor.

		@param plugin: the parent Plugin
		@type plugin: Plugin
		@param hook: the hook to add to
		@type hook: string
		@param call: the call to make
		@type call: string

		@raises ParseException: on parsing errors"""

		if not hook: 
			raise ParseException, "hook attribute missing"

		if not call: 
			raise ParseException, "call attribute missing"
		
		self.plugin = plugin
		self.hook = hook
		self.call = call
		self.connects = []

	def parse_connects (self, connects):
		"""This gets a list of <connect>-elements and parses them.
		
		@param connects: the list of <connect>'s
		@type connects: NodeList
		
		@raises ParseException: on parsing errors"""
		
		if not connects:
			raise ParseException, "No connect elements in hook"

		for c in connects:
			type = c.getAttribute("type")
			if type == '': 
				type = "before"

			# get dep_plugin if available
			dep_plugin = None
			if c.hasChildNodes():
				nodes = c.childNodes
				if len(nodes) > 1:
					raise ParseException, "Malformed connect"
				
				if nodes[0].nodeType != nodes[0].TEXT_NODE:
					raise ParseException, "Malformed connect"

				dep_plugin = nodes[0].nodeValue.strip()

			connect = Connect(self, type, dep_plugin)
			self.connects.append(connect)
		
class Plugin:
	"""A complete plugin."""

	def __init__ (self, file, name, author):
		"""Constructor.

		@param file: the file name of the plugin.xml
		@type file: string
		@param name: the name of the plugin
		@type name: string
		@param author: the author of the plugin
		@type author: string"""

		self.file = file
		self.name = name
		self.author = author
		self._import = None
		self.hooks = []
		self.menus = []

	def parse_hooks (self, hooks):
		"""Gets a list of <hook>-elements and parses them.

		@param hooks: the list of elements
		@type hooks: NodeList
		
		@raises ParseException: on parsing errors"""

		for h in hooks:
			hook = Hook(self, h.getAttribute("hook"), h.getAttribute("call"))
			hook.parse_connects(h.getElementsByTagName("connect"))
			self.hooks.append(hook)

	def parse_menus (self, menus):
		"""Gets a list of <menu>-elements and parses them.

		@param menus: the list of elements
		@type menus: NodeList

		@raises ParseException: on parsing errors"""

		for m in menus:
			menu = Menu(self, m.getAttribute("label"), m.getAttribute("call"))
			self.menus.append(menu)
	
	def set_import (self, imports):
		"""This gets a list of imports and parses them - setting the import needed to call the plugin.

		@param imports: list of imports
		@type imports: NodeList
		
		@raises ParseException: on parsing errors"""

		if len(imports) > 1:
			raise ParseException, "More than one import statement."

		if imports[0].hasChildNodes():
			nodes = imports[0].childNodes
			
			if len(nodes) > 1:
				raise ParseException, "Malformed import"
			
			if nodes[0].nodeType != nodes[0].TEXT_NODE:
				raise ParseException, "Malformed import"

			self._import = nodes[0].nodeValue.strip()

			try: # try loading
				mod = __import__(self._import)
				del mod
			except ImportError:
				raise ParseException, self._import+" cannot be imported"
		else:
			raise ParseException, "Malformed import"

	def needs_import (self):
		"""Returns True if an import is required prior to calling the plugin.
		@rtype: bool"""
		return self._import is not None

	def get_import (self):
		"""Returns the module to import.
		@rtype: string"""
		return self._import

class PluginQueue:
	"""Class managing and loading the plugins."""

	def __init__ (self, frontend, load = True):
		"""Constructor.
		
		@param frontend: the frontend used
		@type frontend: string
		@param load: if False nothing is loaded
		@type load: bool"""

		self.frontend = frontend
		self.list = []
		self.hooks = {}
		if load:
			self._load()

	def get_plugin_data (self):
		return [(x.name, x.author) for x in self.list]

	def get_plugin_menus (self):
		return flatten([x.menus for x in self.list])

	def hook (self, hook, *hargs, **hkwargs):
		"""This is a method taking care of calling the plugins.
		
		B{Example}::
			
			@pluginQueue.hook("some_hook", data)
			def function (a, b, c):
				orig_call(b,c,data)
			
			def function (a, b, c):
				hook = pluginQueue.hook("some_hook", data)
				hook(orig_call)(b,c,data)

		@param hook: the name of the hook
		@type hook: string"""
			
		def call (cmd):
			"""Convienience function for calling a connect.
			@param cmd: the actual Connect
			@type cmd: Connect"""

			imp = ""
			if cmd.hook.plugin.needs_import(): # get import
				imp = cmd.hook.plugin.get_import()
				try:
					mod = __import__(imp, globals(), locals(), [cmd.hook.call])
				except ImportError:
					debug(imp,"cannot be imported", error = 1)
					return

				try:
					f = eval("mod."+cmd.hook.call) # build function
				except AttributeError:
					debug(cmd.hook.call,"cannot be imported", error = 1)
			else:
				try:
					f = eval(cmd.hook.call)
				except AttributeError:
					debug(cmd.hook.call,"cannot be imported", error = 1)

			return f(*hargs, **hkwargs) # call function

		def hook_decorator (func):
			"""This is the real decorator."""
			if hook in self.hooks:
				list = self.hooks[hook]
			else:
				list = ([],[],[])

			def wrapper (*args, **kwargs):
				
				ret = None

				# before
				for cmd in list[0]:
					debug("Accessing hook '%s' of plugin '%s' (before)" % (hook, cmd.hook.plugin.name))
					call(cmd)
				
				if list[1]: # override
					debug("Overriding hook '%s' with plugin '%s'" % (hook, list[1][0].hook.plugin.name))
					ret = call(list[1][0])
				else: # normal
					ret = func(*args, **kwargs)

				# after
				for cmd in list[2]:
					debug("Accessing hook '%s' of plugin '%s' (after)" % (hook, cmd.hook.plugin.name))
					call(cmd)

				return ret

			return wrapper

		return hook_decorator

	def _load (self):
		"""Load the plugins."""
		plugins = filter(lambda x: x.endswith(".xml"), os.listdir(PLUGIN_DIR))
		plugins = map(lambda x: os.path.join(PLUGIN_DIR, x), plugins)

		for p in plugins:
			doc = parse(p)
			
			try:
				try:
					list = doc.getElementsByTagName("plugin")
					if len(list) != 1:
						raise ParseException, "Number of plugin elements unequal to 1"
					
					elem = list[0]

					frontendOK = None
					for f in elem.getElementsByTagName("frontend"):
						if f.hasChildNodes():
							nodes = f.childNodes
							if len(nodes) > 1:
								raise ParseException, "Malformed frontend"
				
							if nodes[0].nodeType != nodes[0].TEXT_NODE:
								raise ParseException, "Malformed frontend"

							fValue = nodes[0].nodeValue.strip()