#!/usr/bin/env python

import sys, os, sets
import ldap, ldap.dn, ldap.filter, ldif
import Backend, Config

SCOPE_BASE = "0"
SCOPE_ONE = "1"
SCOPE_SUB = "2"

class Lookups:
	def __init__(self, url, binddn, password):
		self.url = url
		self.ldap = None
		self.binddn = binddn
		self.password = password


	def __connect(self, force = False):
		if self.ldap:
			if not force:
				return
			self.ldap.unbind()
		self.ldap = ldap.initialize(self.url)
		try:
			self.ldap.simple_bind_s(self.binddn, self.password)
		except ldap.LDAPError, ex:
			raise Backend.Error(Backend.OPERATIONS_ERROR,
			                    "Couldn't do internal authenticate: %s" % ex.args[0]["desc"])

	def read(self, dn, filtstr = "(objectClass=*)", attrs = None, retries = 1):
		try:
			self.__connect()
			results = self.ldap.search_s(dn, ldap.SCOPE_BASE, filtstr, attrs, 0)

			if not results:
				return None
			(dn, entry) = results[0]
			return entry

		except ldap.SERVER_DOWN, ex:
			if retries <= 0:
				raise sys.exc_type, sys.exc_value, sys.exc_traceback
			self.__connect(True)
			return self.read(dn, filtstr, attrs, retries - 1)

	def search(self, base, filtstr, attrs = [], retries = 1):
		try:
			self.__connect()
			return self.ldap.search_s(base, ldap.SCOPE_SUBTREE, filtstr, attrs, 0)

		except ldap.SERVER_DOWN, ex:
			if retries <= 0:
				raise sys.exc_type, sys.exc_value, sys.exc_traceback
			self.__connect(True)
			return self.search(base, filtstr, attrs, retries - 1)

	def modify(self, dn, mods, retries = 1):
		try:
			self.__connect()
			self.ldap.modify_s(dn, mods)

		except ldap.SERVER_DOWN, ex:
			if retries <= 0:
				raise sys.exc_type, sys.exc_value, sys.exc_traceback
			self.__connect(True)
			self.modify(dn, mods, retries - 1)

class Storage:

	def __init__(self, filename = None):
		self.filename = filename
		self.entries = { }
		self.load()

	def load(self):
		if not self.filename:
			return
		if not os.path.exists(self.filename):
			return
		input = open(self.filename, 'r')
		reader = ldif.LDIFRecordList(input)
		reader.parse()
		input.close()
		self.entries = { }
		for (dn, entry) in reader.all_records:
			self.entries[dn] = entry

	def save(self):
		if not self.filename:
			return
		output = open(self.filename, 'w')
		print >> output, "# Overwritten automatically, do not edit\n"

		writer = ldif.LDIFWriter(output)
		for (dn, entry) in self.entries.items():
			if (entry):
				writer.unparse(dn, entry)
		output.close()

	def __entry_for_dn(self, dn):
		if not self.entries.has_key(dn):
			self.entries[dn] = { }
		return self.entries[dn]

	def store(self, dn, attribute, value):
		if value is None:
			return
		entry = self.__entry_for_dn(dn)
		if not entry.has_key(attribute):
			entry[attribute] = [ ]
		if value not in entry[attribute]:
			entry[attribute].append(value)

	def remove(self, dn, attribute, value = None):
		entry = self.__entry_for_dn(dn)
		if entry.has_key(attribute):
			if value is None:
				del entry[attribute]
			elif value in entry[attribute]:
				entry[attribute] = [val for val in entry[attribute] if val != value]

	def has(self, dn, attribute, value = None):
		entry = self.__entry_for_dn(dn)
		if not entry.has_key(attribute):
			return False
		if value is None:
			return True
		return value in entry[attribute]

	def retrieve(self, dn, attribute):
		entry = self.__entry_for_dn(dn)
		if not entry.has_key(attribute):
			return [ ]
		return entry[attribute][:] # copy

	def list_attributes(self, dn):
		entry = self.__entry_for_dn(dn)
		return entry.keys()[:] # copy

	def list_dns(self):
		return self.entries.keys()[:] # copy

	def exists(self, dn):
		return dn in self.entries.keys()

	def delete(self, dn):
		if self.entries.has_key(dn):
			del self.entries[dn]


class Static:
    def __init__(self, func):
        self.__call__ = func

class Tags:
	def __init__(self, database, tags):
		self.database = database
		self.tags = tags

	def __refresh(self, force = False):
		if not force and self.tags is not None:
			return
		try:
			results = self.database.lookups.search(self.database.search_base,
			                                       "(%s=*)" % self.database.tag_attribute,
			                                       [self.database.tag_attribute])

			tags = { }
			for (dn, entry) in results:
				for attr in entry.values():
					for value in attr:
						tags[value] = self.database.dn_attribute
			self.tags = tags

		except ldap.LDAPError, ex:
			raise Backend.Error(Backend.OPERATIONS_ERROR,
			                    "Couldn't search ldap for keys: %s" % ex.args[0]["desc"])

	def __len__(self):
		self.__refresh()
		return len(self.tags)
	def __getitem__(self, k):
		self.__refresh()
		return self.tags[k]
	def __setitem__(self, k):
		assert False
	def __delitem__(self, k):
		assert False
	def __contains__(self, k):
		self.__refresh()
		return k in self.tags
	def __iter__(self):
		self.__refresh()
		return iter(self.tags)
	def items(self):
		self.__refresh()
		return self.tags.items()


	def from_dn(dn):
		try:
			parsed = ldap.dn.str2dn(dn)
		except ValueError:
			raise Backend.Error(Backend.Error.PROTOCOL_ERROR, "invalid dn: %s" % dn)
		return Tags.from_parsed_dn(parsed)
	from_dn = Static(from_dn)

	def from_parsed_dn(parsed):
		tags = { }
		for (typ, val, num) in parsed[0]:
			tags[val] = typ
		return Tags(None, tags)
	from_parsed_dn = Static(from_parsed_dn)

	def from_database(database):
		return Tags(database, None)
	from_database = Static(from_database)


def parse_dn(dn):
	try:
		return ldap.dn.str2dn(dn)
	except:
		raise Backend.Error(Backend.PROTOCOL_ERROR, "Invalid dn: %s" % dn)

def is_parsed_dn_parent(dn, parent):
	if len(dn) != len(parent) + 1:
		return False
	# Go backwards and validate each parent
	for i in range(-1, -1 - len(parent)):
		if dn[i] != parent[i]:
			return False
	return True

class Database(Backend.Database):
	def __init__(self, suffix):
		Backend.Database.__init__(self, suffix)

		self.rootdn = Config.require("ldap-root")
		self.search_base = Config.require("ldap-base")
		self.lookups = Lookups(Config.require("ldap-host"), self.rootdn,
		                       Config.require("ldap-password"))
		self.suffix_dn = parse_dn(self.suffix)

		self.dn_attribute = Config.require("rdn-attribute")
		self.object_class = Config.require("ref-objectclass")
		self.ref_attribute = Config.require("ref-attribute")
		self.key_attribute = Config.require("key-attribute")
		self.access_attribute = Config.require("access-attribute")
		self.tag_attribute = Config.require("tag-attribute")

		filename = Config.option("storage-file")
		self.storage = Storage(filename)


	def __search_tag_keys(self, tags):

		if not len(tags):
			return []

		# Build up a filter
		filter = [ldap.filter.filter_format("(%s=%s)", (self.tag_attribute, tag)) for tag in tags]
		if len(filter) > 1:
			filter = "(&" + "".join(filter) + ")"
		else:
			filter = filter[0]

		try:
			# Search for all those guys
			results = self.lookups.search(self.search_base, filter, [ self.key_attribute ])

		except ldap.LDAPError, ex:
			raise Backend.Error(Backend.OPERATIONS_ERROR,
			                    "Couldn't search ldap for tags: %s" % ex.args[0]["desc"])

		return [entry[self.key_attribute][0] for (dn, entry) in results if entry[self.key_attribute]]


	def __search_key_dns(self, key):

		# Build up a filter
		filter = ldap.filter.filter_format("(%s=%s)", (self.key_attribute, key))

		try:
			# Do the actual search
			results = self.lookups.search(self.search_base, filter)

		except ldap.LDAPError, ex:
			raise Backend.Error(Backend.OPERATIONS_ERROR,
			                    "Couldn't search ldap for keys: %s" % ex.args[0]["desc"])

		return [dn for (dn, entry) in results if dn]


	def __build_root_entry(self, tags):
		attrs = {
			"objectClass" : [ "top" ],
			"hasSubordinates" : [  ]
		}

		for (typ, val, num) in self.suffix_dn[0]:
			if not attrs.has_key(typ):
				attrs[typ] = [ ]
			attrs[typ].append(val)

		attrs["hasSubordinates"].append(tags and "TRUE" or "FALSE")
		return (self.suffix, attrs)


	def __build_pivot_entry(self, tags, keys):
		attrs = {
			self.ref_attribute : [ ],
			"objectClass" : [ self.object_class ],
			"hasSubordinates" : [ "FALSE" ]
		}

		# Build up a DN, and relevant attrs
		rdn = []
		for tag, typ in tags.items():
			rdn.append((typ, tag, 1))
			if not attrs.has_key(typ):
				attrs[typ] = [ ]
			attrs[typ].append(tag)
		dn = [ rdn ]
		dn.extend(self.suffix_dn)
		dn = ldap.dn.dn2str(dn)

		for key in keys:
			attrs[self.ref_attribute].append(key)

		return (dn, attrs)


	def __build_storage_entry(self, parsed_dn, keys):
		attrs = {
			self.ref_attribute : [ ]
		}

		# Build up DN relevant attrs
		for (typ, val, num) in parsed_dn[0]:
			if not attrs.has_key(typ):
				attrs[typ] = [ ]
			attrs[typ].append(val)

		for key in keys:
			attrs[self.ref_attribute].append(key)

		# All other storage attributes retrieved later if necessary
		return (ldap.dn.dn2str(parsed_dn), attrs)


	def __complete_results(self, args, entries):
		# TODO: Support sizelimit
		# TODO: Support a filter

		# Only return the attribute names?
		only_names = (args["attrsonly"] == "1")
		which_attrs = args["attrs"]
		all_attrs = (which_attrs == "all" or
		             which_attrs == "*" or
		             which_attrs == "+")
		which_attrs = which_attrs.split(" ")

		# Convert results from our map to a list with (dn, entry) tuples
		results = [ ]

		for (dn, entry) in entries.items():

			# Retrieve extra value names
			extra = self.storage.list_attributes(dn)

			# Only return attribute names
			if only_names:
				for attr in extra:
					entry[attr] = [ "" ]
				for attr in entry:
					entry[attr] = [ "" ]

			# Return extra attribute names and values
			else:
				for attr in extra:
					values = self.storage.retrieve(dn, attr)
					if entry.has_key(attr):
						entry[attr].extend(values)
					else:
						entry[attr] = values
					# Remove all duplicates
					entry[attr] = list(set(entry[attr]))

			# Limit to the attributes requested
			if not all_attrs:
				for attr in entry.keys():
					if attr not in which_attrs:
						del entry[attr]

			results.append((dn, entry))

		return results


	def search(self, dn, args):
		results = { }
		parsed = parse_dn(dn)

		# Arguments sent
		scope = args["scope"] or SCOPE_BASE

		# Start at the root
		if parsed == self.suffix_dn:
			tags = Tags.from_database(self)
			if scope == SCOPE_BASE or scope == SCOPE_SUB:
				(dn, entry) = self.__build_root_entry(tags)
				results[dn] = entry
			if scope == SCOPE_ONE or scope == SCOPE_SUB:
				# Process each tag individually, by default
				for (tag, typ) in tags.items():
					ctags = { tag : typ }
					keys = self.__search_tag_keys(ctags)
					(child, entry) = self.__build_pivot_entry(ctags, keys)
					results[child] = entry
				# Process all extra storage items
				for child in self.storage.list_dns():
					if child not in results:
						cparsed = parse_dn(child)
						ctags = Tags.from_parsed_dn(cparsed)
						keys = self.__search_tag_keys(ctags)
						(child, entry) = self.__build_storage_entry(parse_dn(child), keys)
						results[child] = entry

		# Something in the database
		elif self.storage.exists(dn):
			if scope == SCOPE_BASE or scope == SCOPE_SUB:
				tags = Tags.from_parsed_dn(parsed)
				keys = self.__search_tag_keys(tags)
				(dn, entry) = self.__build_storage_entry(parsed, keys)
				results[dn] = entry

		# Start at a tag
		elif is_parsed_dn_parent(parsed, self.suffix_dn):
			if scope == SCOPE_BASE or scope == SCOPE_SUB:
				tags = Tags.from_parsed_dn(parsed)
				keys = self.__search_tag_keys(tags)
				if keys:
					(dn, entry) = self.__build_pivot_entry(tags, keys)
					results[dn] = entry


		# We don't have that base
		else:
			raise Backend.Error(Backend.NO_SUCH_OBJECT, "DN '%s' does not exist" % dn)

		return self.__complete_results(args, results)


	def __build_key_mods(self, key, tags, op, mods):
		dns = self.__search_key_dns(key)
		if not dns:
			raise Backend.Error(Backend.CONSTRAINT_VIOLATION,
			                    "Cannot find an entry for %s '%s'" % (self.key_attribute, key))
		for dn in dns:
			if not mods.has_key(dn):
				mods[dn] = (key, [])
			for tag in tags:
				mods[dn][1].append((op, self.tag_attribute, tag))


	def __check_write_access(self, dn):
		if self.binddn == self.rootdn:
			return True
		return self.storage.has(dn, self.access_attribute, self.binddn)


	def add(self, dn, entry):

		parsed = parse_dn(dn)
		tags = Tags.from_parsed_dn(parsed)

		if parsed == self.suffix_dn:
			raise Backend.Error(Backend.ALREADY_EXISTS, "This entry already exists: %s" % dn)
		if not is_parsed_dn_parent(parsed, self.suffix_dn):
			raise Backend.Error(Backend.NO_SUCH_OBJECT, "Parent of '%s' does not exist or is not a valid place for an entry" % dn)
		if self.storage.exists(dn):
			raise Backend.Error(Backend.ALREADY_EXISTS, "This entry already exists: %s" % dn)
		if len(self.__search_tag_keys(tags)):
			raise Backend.Error(Backend.ALREADY_EXISTS, "This entry already exists: %s" % dn)

		# Everyone has implicit access to create a new group

		# Convert into a modify change set
		mods = []
		for (attr, values) in entry.items():
			for value in values:
				mods.append((ldap.MOD_ADD, attr, value))

		# Add an access attribute for the creator
		if self.binddn and not self.access_attribute in entry :
			mods.append((ldap.MOD_ADD, self.access_attribute, self.binddn))

		# Make the actual changes
		self.__change(parsed, mods, tags)

		# Save extra attributes to storage
		self.storage.save()


	def delete(self, dn, args):
		parsed = parse_dn(dn)
		tags = Tags.from_parsed_dn(parsed)

		if parsed == self.suffix_dn:
			raise Backend.Error(Backend.NOT_ALLOWED_ON_NONLEAF, "Cannot delete the root entry: %s" % dn)
		if not is_parsed_dn_parent(parsed, self.suffix_dn):
			raise Backend.Error(Backend.NO_SUCH_OBJECT, "Entry does not exist: %s" % dn)

		if not self.__check_write_access(dn):
			raise Backend.Error(Backend.INSUFFICIENT_ACCESS, "Access denied to delete entry: %s" % dn)

		mods = []
		mods.append((ldap.MOD_DELETE, self.ref_attribute, None))

		# Make the actual changes
		self.__change(parsed, mods, tags)

		# Delete extra attributes from storage
		self.storage.delete(dn)
		self.storage.save()


	def modify(self, dn, mods):
		parsed = parse_dn(dn)
		tags = Tags.from_parsed_dn(parsed)

		if dn == self.suffix:
			raise Backend.Error(Backend.INSUFFICIENT_ACCESS, "Cannot modify root dn of pivot area: %s" % dn)
		if not is_parsed_dn_parent (parsed, self.suffix_dn):
			raise Backend.Error(Backend.NO_SUCH_OBJECT, "DN '%s' does not exist" % dn)

		if not self.__check_write_access(dn):
			raise Backend.Error(Backend.INSUFFICIENT_ACCESS, "Access denied to modify entry: %s" % dn)

		# Make the actual changes
		self.__change(parsed, mods, tags)

		# Save extra attributes to storage
		self.storage.save()


	def __change(self, parsed, mods, tags):

		add_keys = sets.Set()
		remove_keys = sets.Set()
		remove_all = False

		# Parse out all the adds and removes
		for (op, attr, value) in mods:

			# Process access attributes later
			if attr != self.ref_attribute:
				continue

			if op == ldap.MOD_ADD:
				if value:
					add_keys.add(value)
			elif op == ldap.MOD_REPLACE:
				remove_all = True
				if value:
					add_keys.add(value)
			elif op == ldap.MOD_DELETE:
				if value:
					remove_keys.add(value)
				else:
					remove_all = True
			else:
				continue

		# Remove all of the ref attribute
		if remove_all:
			for key in self.__search_tag_keys (tags):
				remove_keys.add(key)

		# Make them all unique, and non conflicting
		for key in add_keys.copy():
			if key in remove_keys:
				remove_keys.remove(key)
				add_keys.remove(key)

		# Change them to DNs, and build mods objects for each dn
		keys_and_mods_by_dn = { }
		for key in add_keys:
			self.__build_key_mods(key, tags, ldap.MOD_ADD, keys_and_mods_by_dn)
		for key in remove_keys:
			self.__build_key_mods(key, tags, ldap.MOD_DELETE, keys_and_mods_by_dn)


		# Now perform the actual actions, combining errors
		errors = []
		for (dn, (key, mod)) in keys_and_mods_by_dn.items():
			try:
				self.lookups.modify(dn, mod)
			except (ldap.TYPE_OR_VALUE_EXISTS, ldap.NO_SUCH_ATTRIBUTE):
				continue
			except ldap.NO_SUCH_OBJECT:
				errors.append(key)
			except ldap.LDAPError, ex:
				raise Backend.Error(Backend.OPERATIONS_ERROR,
				                    "Couldn't perform one of the modifications: %s" % ex.args[0]["desc"])

		# Send back errors
		if errors:
			raise Backend.Error(Backend.CONSTRAINT_VIOLATION,
			                    "Couldn't change %s for %s" % (self.key_attribute, ", ".join(errors)))

		# Process other attributes now
		dn = ldap.dn.dn2str(parsed)
		for (op, attr, value) in mods:
			if attr == self.ref_attribute:
				continue
			if op == ldap.MOD_ADD:
				self.storage.store(dn, attr, value)
			elif op == ldap.MOD_REPLACE:
				self.storage.remove(dn, attr)
				self.storage.add(dn, attr, value)
			elif op == ldap.MOD_DELETE:
				self.storage.remove(dn, attr, value)