import sys, threading, types

from MiscUtils.NamedValueAccess import NamedValueAccess
from MiscUtils import NoDefault
from MiddleKit.Core.ObjRefAttr import ObjRefAttr
from MiddleKit.Core.ListAttr import ListAttr
import ObjectStore

try: # for Python < 2.2
	object
except NameError:
	class object:
		pass
try: # for Python < 2.3
	True, False
except NameError:
	True, False = 1, 0


class MiddleObject(object, NamedValueAccess):
	"""Superclass for the MiddleKit objects.

	MiddleObject is the abstract superclass of objects that are manipulated
	at runtime by MiddleKit. For any objects that you expect to pull out of
	a database via MiddleKit, their classes must inherit MiddleObject.

	MiddleObjects have a serial number which persists in the database
	and is unique for the object across all timelines. In other words,
	serial numbers do not get reused.

	A serial number of 0 is not valid for persistence, so if a MiddleObject
	has such a serial number, you will know that it was not created from
	the database and it has not yet been committed to the database (upon
	which time it will receive a valid serial number).

	Normally we simply prefix data attributes with '_', but here we
	prefix them with '_mk_'. Part of the reason is to provide an extra
	degree of protection for subclasses from current and future attribute
	names used for MiddleKit's own internal book keeping purposes. Although
	users of MiddleKit subclass MiddleObject, they only need to have
	a limited understanding of it. Also, in __setattr__ we skip the
	change-detection bookkeeping on '_mk_*' attributes.

	"""

	_mk_isDeleted = False


	## Init ##

	def __init__(self):
		self.__dict__['_mk_initing'] = True
		self._mk_store           = None
		self._mk_changedAttrs    = None
		self._mk_serialNum       = 0
		self._mk_key             = None
		self._mk_changed         = False
		self._mk_initing         = False
		self._mk_inStore         = False

	 # cache the various setFoo methods first by qualified class name
	_mk_setCache = {}
	# get a reentrant lock for accessing the persistent store
	_mk_cacheLock = threading.RLock()


	## Read Store ##

	def readStoreData(self, store, row):
		"""Read data from the persistent store.

		Invoked by the store in order for this object to read data from the
		persistent store. Could be invoked multiple times for the same object
		in order to "refresh the attributes" from the persistent store.

		"""
		self._mk_cacheLock.acquire()
		try:
			if self._mk_store:
				assert self._mk_store is store, \
					'Cannot refresh data from a different store.'
				if self._mk_changed and not self._mk_initing:
					assert store.setting('AllowRefreshOfChangedObject', False), (
						"attempted to refresh changed object %s.%d\nchanges=%r\n"
						"Your app needs to call store.saveChanges() before doing"
						" anything which can cause objects to be refreshed from the"
						" database (i.e. calling store.deleteObject()), otherwise"
						" your changes will be lost." % (self.klass().name(),
							self.serialNum(), self._mk_changedAttrs))
			else:
				self.setStore(store)
			assert not self._mk_isDeleted, 'Cannot refresh a deleted object.'
			if store.setting('UseBigIntObjRefColumns', False):
				fullClassName = self.__class__.__module__ + '.' + self.__class__.__name__
				cache = self._mk_setCache.setdefault(fullClassName, [])
				if not cache:
					allAttrs = self.klass().allDataAttrs()
					# @@ 2000-10-29 ce: next line is major hack: hasSQLColumn()
					attrs = [attr for attr in allAttrs if attr.hasSQLColumn()]
					attrNames = [attr.name() for attr in attrs]
					assert len(attrNames) + 1 == len(row) # +1 because row has serialNumber
					for name in attrNames:
						setMethodName = 'set' + name[0].upper() + name[1:]
						setMethod = getattr(self.__class__, setMethodName, '_'+name)
						cache.append(setMethod)

				assert len(cache) + 1 == len(row)
				self._mk_initing = True
				if self._mk_serialNum == 0:
					self.setSerialNum(row[0])
				else:
					assert self._mk_serialNum == row[0]
				# Set all of our attributes with setFoo() or by assigning to _foo
				for i in xrange(len(cache)):
					value = row[i+1]
					setter = cache[i]
					setter(self, value)
			else:
				self._mk_initing = True
				if self._mk_serialNum == 0:
					self.setSerialNum(row[0])
				else:
					assert self._mk_serialNum == row[0]
				allAttrs = self.klass().allDataAttrs()
				i = 1
				for attr in allAttrs:
					i = attr.readStoreDataRow(self, row, i)

			self._mk_initing = False
			self._mk_inStore = True
			self._mk_changed = False # setting the values above will have caused this to be set; clear it now
		finally:
			self._mk_cacheLock.release()
		return self


	## Debug Info ##

	def __repr__(self):
		return self.debugStr()

	_debugKeys = 'serialNum'.split()

	def debugStr(self):
		out = [self.__class__.__name__, '(', '0x%x' % id(self)]
		sep = ', '
		for key in self._debugKeys:
			out.append(sep)
			out.append(key)
			out.append('=')
			try:
				out.append(repr(self.valueForName(key)))
			except Exception, exc:
				from MiscUtils.Funcs import excstr
				out.append('('+excstr(exc)+')')
		out.append(')')
		out = ''.join(out)
		return out


	## Serial numbers ##

	def serialNum(self):
		return self._mk_serialNum

	def setSerialNum(self, value):
		"""Set the serial number of the object and invalidates the object's key.

		There are some restrictions: Once the serial number is a positive value,
		indicating a legitimate value from the object store, it cannot be set
		to anything else. Also, if the serial number is negative, indicating
		a temporary serial number for new objects that haven't been committed
		to the database, it can only be set to a positive value.

		"""
		assert type(value) in (type(0), type(0L)), \
			"Type is: %r, value is: %r" % (type(value), value)
		if self._mk_serialNum < 0:
			assert value > 0
		else:
			assert self._mk_serialNum == 0
		self._mk_serialNum = value
		self._mk_key = None

	# for people who capitalize the attributes in their model:
	SerialNum = serialNum


	## Change ##

	def isChanged(self):
		return self._mk_changed

	def setChanged(self, flag):
		self._mk_changed = flag


	## In Store ##

	def isInStore(self):
		return self._mk_inStore

	def isNew(self):
		"""Check if this is a new object.

		Returns true if the object was newly created (whether added to the
		store or not). Objects fetched from the database will return false.

		"""
		return self._mk_serialNum < 1

	def isDeleted(self):
		return self._mk_isDeleted


	## Keys ##

	def key(self):
		"""Return the object's key as needed and used by the ObjectStore.

		Will return None if setKey() was never invoked, or not invoked
		after a setSerialNum().

		"""
		return self._mk_key

	def setKey(self, key):
		"""Set the object's key.

		Restrictions: Cannot set the key twice.

		"""
		assert self._mk_serialNum >= 1, \
			"Cannot make keys for objects that haven't been persisted yet."
		assert self._mk_key is None
		self._mk_key = key


	## Misc utility ##

	def refetch(self):
		"""Refetch the object's attributes from the store.

		Only works for non-changed objects from a store.
		@@ not covered by test suite yet

		"""
		assert self.isInStore()
		assert not self.isChanged()
		result = self.store().fetchObject(self.__class__, self.serialNum())
		assert result is self, \
			'expecting result to be self. self=%r, result=%r' % (self, result)

	def allAttrs(self, includeUnderscoresInKeys=True):
		"""Return a dictionary mapping the names of attributes to their values.

		Only attributes defined in the MiddleKit object model are included.
		An example return value might be
			{ '_x': 1, '_y': 1 },
		or if includeUnderscoresInKeys is false,
			{ 'x': 1, 'y': 1 }.

		"""
		allAttrs = {}
		allAttrDefs = self.klass().allAttrs()
		for attrDef in allAttrDefs:
			if includeUnderscoresInKeys:
				key = attrName = '_'+attrDef.name()
			else:
				key = attrDef.name()
				attrName = '_' + key
			allAttrs[key] = getattr(self, attrName)
		return allAttrs

	def removeObjectFromListAttrs(self, object):
		"""Remove object from any list attributes that this instance might have.

		This is used if the object is deleted, so we don't have dangling references.

		"""
		for attr in self.klass().allAttrs():
			if isinstance(attr, ListAttr):
				listName = '_' + attr.name()
				list = getattr(self, listName)
				if list is not None and object in list:
					delattr(self, listName)
					setattr(self, listName, None)

	def updateReferencingListAttrs(self):
		"""Update all referencing list attributes.

		Checks through all object references, and asks each referenced
		object to remove us from any list attributes that they might have.

		"""
		for attr in self.klass().allAttrs():
			if isinstance(attr, ObjRefAttr):
				value = getattr(self, '_' + attr.name())
				if value is not None:
					if isinstance(value, (types.InstanceType, MiddleObject)):
						value.removeObjectFromListAttrs(self)
					elif type(value) is types.LongType:
						obj = self.store().objRefInMem(value)
						if obj:
							obj.removeObjectFromListAttrs(self)

	def referencedAttrsAndObjects(self):
		"""Get all referenced attributes and objects.

		Returns a list of tuples of (attr, object) for all objects
		that this object references.

		"""
		t = []
		for attr in self.klass().allDataAttrs():
			if isinstance(attr, ObjRefAttr):
				obj = self.valueForAttr(attr)
				if obj:
					t.append((attr, obj))
			elif isinstance(attr, ListAttr):
				for obj in self.valueForAttr(attr):
					t.append((attr, obj))
		return t

	def referencingObjectsAndAttrs(self):
		"""Get all referencing attributes and objects.

		Returns a list of tuples of (object, attr) for all objects that have
		ObjRefAttrs that reference this object.

		"""
		referencingObjectsAndAttrs = []
		selfSqlObjRef = self.sqlObjRef()
		for backObjRefAttr in self.klass().backObjRefAttrs():
			objects = self.store().fetchObjectsOfClass(backObjRefAttr.klass(),
				**self.referencingObjectsAndAttrsFetchKeywordArgs(backObjRefAttr))
			for object in objects:
				assert object.valueForAttr(backObjRefAttr) is self
				referencingObjectsAndAttrs.append((object, backObjRefAttr))
		return referencingObjectsAndAttrs

	def referencingObjectsAndAttrsFetchKeywordArgs(self, backObjRefAttr):
		"""Get keyword arguments for referencingObjectsAndAttrs().

		Used by referencingObjectsAndAttrs() to reduce the load on the
		persistent store. Specific object stores replace this as appropriate.

		"""
		return {'refreshAttrs': True}


	## Debugging ##

	def dumpAttrs(self, out=None, verbose=False):
		"""Print the attributes of the object.

		If verbose is false (the default), then the only MiddleKit specific
		attribute that gets printed is _mk_serialNum.

		"""
		if out is None:
			out = sys.stdout
		out.write('%s %x\n' % (self.__class__.__name__, id(self)))
		keys = dir(self)
		keys.sort()
		keyWidth = max([len(key) for key in keys])
		for key in keys:
			if verbose:
				dump = True
			else:
				dump = not key.startswith('_mk_') or key == '_mk_serialNum'
			if dump:
				name = key.ljust(keyWidth)
				out.write('%s = %s\n' % (name, getattr(self, key)))
		out.write('\n')


	## Misc access ##

	def store(self):
		return self._mk_store

	def setStore(self, store):
		assert not self._mk_store, \
			'The store was previously set and cannot be set twice.'
		self._mk_store = store
		self._mk_inStore = True


	## Sneaky MiddleKit stuff ##

	def klass(self):
		"""Return the MiddleKit class definition for this object.

		These definitions are instances of MiddleKit.Core.Klass and
		come from the MiddleKit model. Be sure the MiddleKit model
		is loaded. See the docs for more details.

		"""
		return self._mk_klass # If you get AttributeError, then the MK model wasn't loaded.

	def addReferencedObjectsToStore(self, store):
		"""Adds all MK objects referenced by this object to the store."""
		assert store
		values = [self.valueForAttr(attr) for attr in self.klass().allDataRefAttrs()]
		for value in values:
			if isinstance(value, MiddleObject):
				store.addObject(value)
			elif isinstance(value, types.ListType):
				for obj in value:
					if isinstance(obj, MiddleObject):
						store.addObject(obj)


	## Accessing attributes by name ##

	def valueForKey(self, attrName, default=NoDefault):
		"""Get value of a named attribute for a given key.

		Returns the value of the named attribute by invoking its "get"
		accessor method. You can use this when you want a value whose
		name is determined at runtime.

		It also insulates you from the naming convention used for the
		accessor methods as defined in Attr.pyGetName(). For example, the
		test suites use this instead of directly invoking the "get" methods.

		If the attribute is not found, this method will look for any
		Python attribute or method that matches.

		If a value is still not found, the default argument is returned
		if specified, otherwise LookupError is raised with the attrName.

		"""
		attr = self.klass().lookupAttr(attrName, None)
		if attr:
			return self.valueForAttr(attr, default)
		else:
			value = getattr(self, attrName, NoDefault)
			if value is not NoDefault:
				if callable(value):
					value = value()
				return value
			if default is NoDefault:
				raise LookupError, attrName
			else:
				return default

	def setValueForKey(self, attrName, value):
		"""Set value of a named attribute for a given key.

		Sets the value of the named attribute by invoking its "set"
		accessor method. You can use this when you want a value whose
		name is determined at runtime.

		It also insulates you from the naming convention used for the
		accessor methods as defined in Attr.pySetName(). For example, the
		test suites use this instead of directly invoking the "set" methods.

		If the required set method is not found, a LookupError is raised
		with the attrName.

		"""
		try:
			attr = self.klass().lookupAttr(attrName)
		except KeyError:
			method = None
		else:
			pySetName = attr.pySetName()
			method = getattr(self, pySetName, None)
		if method is None:
			attrs = self.klass().allAttrs()
			attrs = [a.name() for a in attrs]
			attrs.sort()
			attrs = ','.join(attrs)
			raise LookupError, \
				'%s, class=%s, all attrs=%s' % (attrName, self.__class__, attrs)
		return method(value)

	def valueForAttr(self, attr, default=NoDefault):
		getMethod = self.klass()._getMethods.get(attr.name(), None)
		if getMethod is None:
			pyGetName = attr.pyGetName()
			getMethod = getattr(self.klass().pyClass(), pyGetName, None)
			if getMethod is None:
				getMethod = False # indicates that the search was already done
			self.klass()._getMethods[attr.name()] = getMethod
		if getMethod:
			return getMethod(self)
		else:
			if default is NoDefault:
				raise LookupError, attr['Name']
			else:
				return default

	def setValueForAttr(self, attr, value):
		return self.setValueForKey(attr['Name'], value)


	## Problems ##

	def objRefErrorWasRaised(self, error, sourceKlassName, sourceAttrName):
		"""Invoked by getter methods when ObjRefErrors are raised.

		Prints very useful information to stdout.
		Override if you wish other actions to be taken.
		The value returned is used for the obj ref (defaults to None).

		"""
		klassId, objSerialNum = error.args
		try:
			rep = repr(self)
		except Exception, e:
			rep = '(exception during repr: %s: %s)' % (e.__class__.__name__, e)
		try:
			klassName = self.store().klassForId(klassId).name()
		except Exception, e:
			klassName = '%i (exception during klassName fetch: %s: %s)' % (
				klassId, e.__class__.__name__, e)
		sys.stdout.flush()
		sys.stderr.flush()
		print ('WARNING: MiddleKit: In object %(rep)s, attribute'
			' %(sourceKlassName)s.%(sourceAttrName)s dangles with value'
			' %(klassName)s.%(objSerialNum)s' % locals())
		sys.stdout.flush()
		return None


	# @@ 2001-07-10 ce: the old names
	#attr = valueForKey
	#setAttr = setValueForKey

	# @@ 2001-04-29 ce: This is for backwards compatibility only:
	# We can take out after the post 0.5.x version (e.g., 0.6 or 1.0)
	# or after 4 months, whichever comes later.
	_get = valueForKey
	_set = setValueForKey

	def clone(self, memo=None, depthAttr=None):
		"""Clone middle object(s) generically.

		You may or may not want objects referenced by ObjRefAttr or ListAttr
		attributes to be cloned in addition to the object itself. You can
		control this by adding a "Copy" column in your Classes.csv file, and
		set the value for each attribute which may reference another object.

		The possible values for "Copy" are:
		'deep': referenced objects will be cloned and references to them will be set
		'shallow' (default): the cloned object references the same object as the original
		'none': the attribute in the cloned object is set to 'None'

		Clone will call itself recursively to copy references deeply, and
		gracefully handles recursive references (where a referenced object
		may have already been cloned). In this case only one clone is created,
		not two cloned instances of the same original.

		If you want a mapping from original to cloned objects, pass in an empty
		dict for the memo argument.  It will be filled in during the clone
		operation, such that the keys are the original object instances and
		the values are the corresponding clones.

		The parameter depthAttr may be set to a column name which, if set, will
		take precedence over the value in the 'Copy' column for that attribute.

		"""

		def copyAttrValue(source, dest, attr, memo, depthAttr):
			if depthAttr and attr.has_key(depthAttr):
				copymode = attr[depthAttr]
			else:
				copymode = attr.get('Copy', 'shallow')

			if copymode == 'deep' and isinstance(attr, ObjRefAttr):
				# clone the value of an attribute from the source object,
				# and set it in the attribute of the dest object
				value = getattr(source, attr.pyGetName())()
				if value:
					clonedvalue = value.clone(memo, depthAttr)
				else:
					clonedvalue = None
				retvalue = getattr(dest, attr.pySetName())(clonedvalue)
			elif copymode == 'none':
				# Shouldn't set attribute to None explicitly since attribute may have
				# isRequired=True
				# besides, the object will initialize all attributes to None anyways
				pass
			else:
				# copy the value of an attribute from the source object
				# to the dest object
				# print 'copying value of ' + attr.name()
				value = getattr(source, attr.pyGetName())()
				retvalue = getattr(dest, attr.pySetName())(value)

		if memo is None:
			# print 'Initializing memo'
			memo = {}

		# if we've already cloned this object, return the clone
		if memo.has_key(self):
			return memo[self]

		# make an instance of ourselves
		copy = self.__class__()
		#print 'cloning %s %s as %s' % ( self.klass().name(), str(self), str(copy) )

		memo[self] = copy

		# iterate over our persistent attributes
		for attr in self.klass().allDataAttrs():
			if isinstance(attr, ListAttr):
				valuelist = getattr(self, attr.pyGetName())()
				setmethodname = "addTo" + attr.name()[0].upper() + attr.name()[1:]
				setmethod = getattr(copy, setmethodname)

				# if cloning to create an extension object, we might want to copy fewer subobjects
				copymode = attr['Copy']
				if depthAttr and attr.has_key(depthAttr):
					copymode = attr[depthAttr]

				if copymode == 'deep':
					backrefname = attr.backRefAttrName()
					setrefname = "set" + backrefname[0].upper() + backrefname[1:]
					for value in valuelist:
						# clone the value
						valcopy = value.clone(memo, depthAttr)

						# set the value's back ref to point to self
						setrefmethod = getattr(valcopy, setrefname)
						backrefattr = valcopy.klass().lookupAttr(backrefname)
						setrefmethod(None)

						# add the value to the list
						retval = setmethod(valcopy)
				elif attr['Copy'] == 'none':
					# leave the list empty
					pass
				else:
					pass
			else:
				copyAttrValue(self, copy, attr, memo, depthAttr)

		return copy
