import sys
from types import ModuleType, ClassType

from MiscUtils.MixIn import MixIn
from MiscUtils import NoDefault


class ModelUser:


	## Init ##

	def __init__(self):
		self._model = None


	## Settings ##

	def setting(self, name, default=NoDefault):
		"""Return the given setting which is actually just taken from the model."""
		return self._model.setting(name, default)


	## Models ##

	def model(self):
		return self._model

	def setModel(self, model):
		assert model
		assert self._model is None, 'Can only set model once.'
		self._model = model
		self.modelWasSet()

	def readModelFileNamed(self, filename, modelClass=None, **keywords):
		assert self._model is None, 'Cannot re-read a model.'
		if modelClass is None:
			from MiddleKit.Core.Model import Model as modelClass
		self._model = modelClass(**keywords)
		self._model.read(filename)
		self.modelWasSet()

	def modelWasSet(self):
		"""Perform additional set up of the store after the model is set.

		Invoked by setModel() or readModelFileNamed() as a hook for taking
		action on this event. Invokes installMixIns().

		"""
		self.installMixIns()


	## Mix-ins ##

	def installMixIns(self, verbose=0):
		if verbose:
			print '>> installMixIns()'
			print 'class =', self.__class__

		modules = self.modulesForClass(self.__class__)
		if verbose:
			print 'modules =', ', '.join(modules)

		modules.reverse()  # so that mix-ins in subclasses override super
		modules = [sys.modules[m] for m in modules]

		for module in modules:
			assert type(module) is ModuleType
			self.installMixInsForModule(module, verbose)

		if verbose:
			print


	def installMixInsForModule(self, module, verbose=0):
		# @@ 2000-10-18 ce: perhaps MixIns should be applied to the actual
		# MiddleKit.Core class and not the custom one that possibly was
		# passed into model. This would help with "invoking super" which
		# may be a non-trivial operation in a mix-in of a generator module.
		coreClassNames = self._model.coreClassNames()
		if verbose:
			print '>>', module
		for name in dir(module):
			generatorThing = getattr(module, name)
			if type(generatorThing) is ClassType:
				# See if a class with the same name exists in MiddleKit.Core
				import MiddleKit.Core as Core
				if name in coreClassNames:
					baseClass = self._model.coreClass(name)
					if baseClass is not generatorThing:
						if verbose:
							print '>> mixing %s into %s' % (generatorThing, baseClass)
						assert type(baseClass) is ClassType
						assert type(generatorThing) is ClassType
						MixIn(baseClass, generatorThing, mixInSuperMethods=1)


	## Warning ##

	def warning(self, msg):
		"""Output a warning.

		Invoked by self for any kind of appropriate warning that doesn't
		warrant an exception being thrown. Preferably, this should be invoked
		from a method that is invoked when the "bad event" occurs. This allows
		subclasses to override that method and potentially customize the
		behavior, including providing more debugging information.

		This implementation writes the msg to stdout.

		"""
		print 'WARNING:', msg


	## Self utility ##

	def modulesForClass(self, pyClass, modules=None):
		"""Return the modules for the class.

		Returns a list of modules for pyClass, going up the chain of ancestor
		classes, stopping short before ModelUser. Utility method for installMixIns.

		"""
		if modules is None:
			modules = []
		className = pyClass.__name__
		if className != 'ModelUser':
			modules.append(pyClass.__module__)
			for baseClass in pyClass.__bases__:
				self.modulesForClass(baseClass, modules)
		return modules
