from ModelObject import ModelObject
from MiscUtils import NoDefault, StringTypes
from MiddleKit.Core.ListAttr import ListAttr
from MiddleKit.Core.ObjRefAttr import ObjRefAttr
from MiddleDict import MiddleDict

try: # for Python < 2.3
	True, False
except NameError:
	True, False = 1, 0

try:
	set
except NameError: # fallback for Python < 2.4
	try:
		from sets import Set as set
	except ImportError: # fallback for Python < 2.3
		from UserDict import UserDict as set


class Klass(MiddleDict, ModelObject):
	"""A Klass represents a class specification.

	It is consisting primarily of a name and a list of attributes.
	
	"""


	## Init ##

	def __init__(self, klassContainer, dict=None):
		"""Initialize a Klass definition with a raw dictionary.

		This is typically read from a file. The 'Class' field contains the name
		and can also contain the name of the superclass (like "Name : SuperName").
		Multiple inheritance is not yet supported.

		"""
		MiddleDict.__init__(self, {})
		self._klassContainer = klassContainer
		self._attrsList = []
		self._attrsByName = {}
		self._superklass = None
		self._subklasses = []
		self._pyClass = False   # False means never computed. None would mean computed, but not found.
		self._backObjRefAttrs = None
		self._allAttrs = None

		if dict is not None:
			self.readDict(dict)


	## Reading ##

	def readDict(self, dict):
		name = dict['Class']
		if '(' in name:
			assert ')' in name, 'Invalid class spec. Missing ).'
			self._name, rest = name.split('(')
			self._supername, rest = rest.split(')')
			assert rest.strip() == ''
			self._name = self._name.strip()
			self._supername = self._supername.strip()
		elif ':' in name:
			# deprecated: we used to use a C++-like syntax involving colons
			# instead of a Python-like syntax with parens
			parts = [part.strip() for part in name.split(':')]
			if len(parts) != 2:
				raise RuntimeError, 'Invalid class spec: %s' % string
			self._name, self._supername = parts
		else:
			self._name = name
			self._supername = dict.get('Super', 'MiddleObject')
		self._isAbstract = dict.get('isAbstract', False)

		# fill in dictionary (self) with the contents of the dict argument
		for key, value in dict.items():
			# @@ 2001-02-21 ce: should we always strip string fields? Probably.
			if type(value) in StringTypes and value.strip() == '':
				value = None
			self[key] = value


	def awakeFromRead(self, klasses):
		"""Perform further initialization.

		Invoked by Klasses after all basic Klass definitions have been read.

		"""
		assert self._klasses is klasses

		self._makeAllAttrs()
		# Python classes need to know their MiddleKit classes in
		# order for MiddleKit.Run.MiddleObject methods to work.
		# Invoking pyClass() makes that happen.
		self.pyClass()
		for attr in self.attrs():
			attr.awakeFromRead()

	def _makeAllAttrs(self):
		"""Make all attributes.

		Makes list attributes accessible via methods for the following:
			allAttrs - every attr of the klass including inherited and derived attributes
			allDataAttrs - every attr of the klass including inherited, but NOT derived
			allDataRefAttrs - same as allDataAttrs, but only obj refs and lists

		...and a dictionary attribute used by lookupAttr().

		Does nothing if called extra times.

		"""
		if self._allAttrs is not None:
			return

		klass = self
		klasses = []
		while 1:
			klasses.append(klass)
			klass = klass.superklass()
			if klass is None:
				break
		klasses.reverse()

		allAttrs = []
		allDataAttrs = []
		allDataRefAttrs = []
		for klass in klasses:
			attrs = klass.attrs()
			allAttrs.extend(attrs)
			for attr in attrs:
				if not attr.get('isDerived', False):
					allDataAttrs.append(attr)
					if isinstance(attr, ObjRefAttr) or isinstance(attr, ListAttr):
						allDataRefAttrs.append(attr)

		self._allAttrs = allAttrs
		self._allDataAttrs = allDataAttrs
		self._allDataRefAttrs = allDataRefAttrs

		# set up _allAttrsByName which is used by lookupAttr()
		self._allAttrsByName = {}
		for attr in allAttrs:
			self._allAttrsByName[attr.name()] = attr


	## Names ##

	def name(self):
		return self._name

	def supername(self):
		return self._supername


	## Id ##

	def id(self):
		"""Return the id of the class, which is an integer.

		Ids can be fundamental to storing object references in concrete object stores.
		This method will throw an exception if setId() was not previously invoked.

		"""
		return self._id

	def setId(self, id):
		if isinstance(id, set):
			# create an id that is a hash of the klass name
			# see Klasses.assignClassIds()
			allIds = id
			# the limit of 2 billion keeps the id easily in the range
			# of a 32 bit signed int without going negative
			limit = 2000000000
			id = abs(hash(self.name()) % limit)
			assert 0 < id < limit
			while id in allIds:
				# adjust for collision
				id += 1
			assert 0 < id < limit
			self._id = id
		else:
			self._id = id


	## Superklass ##

	def superklass(self):
		return self._superklass

	def setSuperklass(self, klass):
		assert self._superklass is None, "Can't set superklass twice."
		self._superklass = klass
		klass.addSubklass(self)


	## Ancestors ##

	def lookupAncestorKlass(self, name, default=NoDefault):
		"""Search for and return the ancestor klass with the given name.

		Raises an exception if no such klass exists, unless a default
		is specified (in which case it is returned).

		"""
		if self._superklass:
			if self._superklass.name() == name:
				return self._superklass
			else:
				return self._superklass.lookupAncestorKlass(name, default)
		else:
			if default is NoDefault:
				raise KeyError, name
			else:
				return default

	def isKindOfKlassNamed(self, name):
		"""Check whether the klass is from the given kind.

		Returns true if the klass is the same as, or inherits from,
		the klass with the given name.

		"""
		if self.name() == name:
			return True
		else:
			return self.lookupAncestorKlass(name, None) is not None


	## Subklasses ##

	def subklasses(self):
		return self._subklasses

	def addSubklass(self, klass):
		self._subklasses.append(klass)

	def descendants(self, init=1, memo=None):
		"""Return all descendant klasses of this klass."""
		if memo is None:
			memo = {}
		if memo.has_key(self):
			return
		memo[self] = None
		for k in self.subklasses():
			k.descendants(init=0, memo=memo)
		if init:
			del memo[self]
		return memo.keys()


	## Accessing attributes ##

	def addAttr(self, attr):
		self._attrsList.append(attr)
		self._attrsByName[attr.name()] = attr
		attr.setKlass(self)

	def attrs(self):
		"""Return a list of all the klass' attributes not including inheritance."""
		return self._attrsList

	def hasAttr(self, name):
		return self._attrsByName.has_key(name)

	def attr(self, name, default=NoDefault):
		"""Return the attribute with the given name.

		If no such attribute exists, an exception is raised unless a default
		was provided (which is then returned).

		"""
		if default is NoDefault:
			return self._attrsByName[name]
		else:
			return self._attrsByName.get(name, default)

	def lookupAttr(self, name, default=NoDefault):
		if self._allAttrs is None:
			# happens sometimes during awakeFromRead()
			self._makeAllAttrs()
		if default is NoDefault:
			return self._allAttrsByName[name]
		else:
			return self._allAttrsByName.get(name, default)

	def allAttrs(self):
		"""Returns a list of all attributes.

		This includes those attributes that are inherited and derived.
		The order is top down; that is, ancestor attributes come first.

		"""
		return self._allAttrs

	def allDataAttrs(self):
		"""Return a list of all data attributes.

		This includes those attributes that are inherited.
		The order is top down; that is, ancestor attributes come first.
		Derived attributes are not included in the list.

		"""
		return self._allDataAttrs

	def allDataRefAttrs(self):
		"""Return a list of all data referencing attributes.

		Returns a list of all data attributes that are obj refs or lists,
		including those that are inherited.

		"""
		return self._allDataRefAttrs


	## Klasses access ##

	def klasses(self):
		return self._klasses

	def setKlasses(self, klasses):
		"""Set the klasses object of the klass. This is the klass' owner."""
		self._klasses = klasses

	def model(self):
		return self._klasses.model()


	## Other access ##

	def isAbstract(self):
		return self._isAbstract

	def pyClass(self):
		"""Return the Python class that corresponds to this class.

		This request will even result in the Python class' module being
		imported if necessary. It will also set the Python class
		attribute _mk_klass which is used by MiddleKit.Run.MiddleObject.

		"""
		if self._pyClass == False:
			if self._klassContainer._model._havePythonClasses:
				self._pyClass = self._klassContainer._model.pyClassForName(self.name())
				assert self._pyClass.__name__ == self.name(), 'self.name()=%r, self._pyClass=%r' % (self.name(), self._pyClass)
				self._pyClass._mk_klass = self
			else:
				self._pyClass = None
		return self._pyClass

	def backObjRefAttrs(self):
		"""Return a list of all potentially referencing attributes.

		Returns a list of all ObjRefAttrs in the given object model that can
		potentially refer to this object. The list does NOT include attributes
		inherited from superclasses.

		"""
		if self._backObjRefAttrs is None:
			backObjRefAttrs = []
			# Construct targetKlasses = a list of this object's klass and all superklasses
			targetKlasses = {}
			super = self
			while super:
				targetKlasses[super.name()] = super
				super = super.superklass()
			# Look at all klasses in the model
			for klass in self._klassContainer._model.allKlassesInOrder():
				# find all ObjRefAttrs of klass that refer to one of our targetKlasses
				for attr in klass.attrs():
					if not attr.get('isDerived', False):
						if isinstance(attr, ObjRefAttr) and targetKlasses.has_key(attr.targetClassName()):
							backObjRefAttrs.append(attr)
			self._backObjRefAttrs = backObjRefAttrs
		return self._backObjRefAttrs

	def setting(self, name, default=NoDefault):
		"""Return the value of a particular configuration setting taken from the model."""
		return self._klassContainer.setting(name, default)


	## As string ##

	def asShortString(self):
		return '<Klass, %s, %x, %d attrs>' % (self._name, id(self), len(self._attrsList))

	def __str__(self):
		return self.asShortString()


	## As a dictionary key (for "set" purposes) ##

	def __hash__(self):
		return hash(self.name()) # | hash(self.model().name())

	def __cmp__(self, other):
		if other is None:
			return 1
		if not isinstance(other, Klass):
			return 1
		if self.model() is not other.model():
			value = cmp(self.model().name(), other.model().name())
			if value == 0:
				value = cmp(self.name(), other.name())
			return value
		return cmp(self.name(), other.name())


	## Warnings ##

	def printWarnings(self, out):
		for attr in self.attrs():
			attr.printWarnings(out)


	## Model support ##

	def willBuildDependencies(self):
		"""Preps the klass for buildDependencies()."""
		self._dependencies = []  # who self depends on
		self._dependents = []  # who depends on self

	def buildDependencies(self):
		"""Build dependencies of the klass.

		A klass' immediate dependencies are its ancestor classes (which may
		have auxilliary tables such as enums), the target klasses of all its
		obj ref attrs and their descendant classes.

		"""
		if self._dependents is not None:
			# already done
			pass
		klass = self.superklass()
		while klass is not None:
			self._dependencies.append(klass)
			klass._dependents.append(self)
			klass = klass.superklass()
		from MiddleKit.Core.ObjRefAttr import ObjRefAttr
		for attr in self.allAttrs():
			if isinstance(attr, ObjRefAttr):
				klass = attr.targetKlass()
				if klass is not self and attr.boolForKey('Ref', True):
					self._dependencies.append(klass)
					klass._dependents.append(self)
					for klass in klass.descendants():
						self._dependencies.append(klass)
						klass._dependents.append(self)

	def recordDependencyOrder(self, order, visited, indent=0):
		#print '%srecordDependencyOrder() for %s' % (' '*indent*4, self.name())
		if visited.has_key(self):
			return
		visited[self] = None # better use visited.add(self) in Python >= 2.3
		for klass in self._dependencies:
			klass.recordDependencyOrder(order, visited, indent+1)
		order.append(self)
