lodel2_mirror/EditorialModel/model.py

#-*- coding: utf-8 -*-

## @file editorialmodel.py
# Manage instance of an editorial model

from EditorialModel.migrationhandler.dummy import DummyMigrationHandler
from EditorialModel.backend.dummy_backend import EmBackendDummy
from EditorialModel.classes import EmClass
from EditorialModel.fieldgroups import EmFieldGroup
from EditorialModel.fields import EmField
from EditorialModel.types import EmType
from EditorialModel.exceptions import EmComponentCheckError, EmComponentNotExistError, MigrationHandlerChangeError
import hashlib


## Manages the Editorial Model
class Model(object):

    components_class = [EmClass, EmType, EmFieldGroup, EmField]

    ## Constructor
    #
    # @param backend unknown: A backend object instanciated from one of the classes in the backend module
    def __init__(self, backend, migration_handler=None):
        self.migration_handler = DummyMigrationHandler() if migration_handler is None else migration_handler
        self.backend = backend
        self._components = {'uids': {}, 'EmClass': [], 'EmType': [], 'EmField': [], 'EmFieldGroup': []}
        self.load()

    def __hash__(self):
        components_dump = ""
        for _, comp in self._components['uids'].items():
            components_dump += str(hash(comp))
        hashstring = hashlib.new('sha512')
        hashstring.update(components_dump.encode('utf-8'))
        return int(hashstring.hexdigest(), 16)

    def __eq__(self, other):
        return self.__hash__() == other.__hash__()

    @staticmethod
    ## Given a name return an EmComponent child class
    # @param class_name str : The name to identify an EmComponent class
    # @return A python class or False if the class_name is not a name of an EmComponent child class
    def emclass_from_name(class_name):
        for cls in Model.components_class:
            if cls.__name__ == class_name:
                return cls
        return False

    @staticmethod
    ## Given a python class return a name
    # @param cls : The python class we want the name
    # @return A class name as string or False if cls is not an EmComponent child class
    def name_from_emclass(em_class):
        if em_class not in Model.components_class:
            return False
        return em_class.__name__

    ## Loads the structure of the Editorial Model
    #
    # Gets all the objects contained in that structure and creates a dict indexed by their uids
    # @todo Change the thrown exception when a components check fails
    # @throw ValueError When a component class don't exists
    def load(self):
        datas = self.backend.load()
        for uid, kwargs in datas.items():
            #Store and delete the EmComponent class name from datas
            cls_name = kwargs['component']
            del kwargs['component']
            cls = self.emclass_from_name(cls_name)
            if cls:
                kwargs['uid'] = uid
                # create a dict for the component and one indexed by uids, store instanciated component in it
                self._components['uids'][uid] = cls(self, **kwargs)
                self._components[cls_name].append(self._components['uids'][uid])
            else:
                raise ValueError("Unknow EmComponent class : '" + cls_name + "'")

        #Sorting by rank
        for component_class in Model.components_class:
            self.sort_components(component_class)

        #Check integrity
        for uid, component in self._components['uids'].items():
            try:
                component.check()
            except EmComponentCheckError as exception_object:
                raise EmComponentCheckError("The component with uid %d is not valid. Check returns the following error : \"%s\"" % (uid, str(exception_object)))
            #Everything is done. Indicating that the component initialisation is over
            component.init_ended()

    ## Saves data using the current backend
    def save(self):
        return self.backend.save(self)

    ## Given a EmComponent child class return a list of instances
    # @param cls EmComponent : A python class
    # @return a list of instances or False if the class is not an EmComponent child
    def components(self, cls):
        key_name = self.name_from_emclass(cls)
        return False if key_name is False else self._components[key_name]

    ## Return an EmComponent given an uid
    # @param uid int : An EmComponent uid
    # @return The corresponding instance or False if uid don't exists
    def component(self, uid):
        return False if uid not in self._components['uids'] else self._components['uids'][uid]

    ## Sort components by rank in Model::_components
    # @param emclass pythonClass : The type of components to sort
    # @throw AttributeError if emclass is not valid
    def sort_components(self, component_class):
        if component_class not in self.components_class:
            raise AttributeError("Bad argument emclass : '" + component_class + "', excpeting one of " + str(self.components_class))

        self._components[self.name_from_emclass(component_class)] = sorted(self.components(component_class), key=lambda comp: comp.rank)

    ## Return a new uid
    # @return a new uid
    def new_uid(self):
        used_uid = [int(uid) for uid in self._components['uids'].keys()]
        return sorted(used_uid)[-1] + 1 if len(used_uid) > 0 else 1

    ## Create a component from a component type and datas
    #
    # @note if datas does not contains a rank the new component will be added last
    # @note datas['rank'] can be an integer or two specials strings 'last' or 'first'
    # @param component_type str : a component type ( component_class, component_fieldgroup, component_field or component_type )
    # @param datas dict : the options needed by the component creation
    # @throw ValueError if datas['rank'] is not valid (too big or too small, not an integer nor 'last' or 'first' )
    # @todo Handle a raise from the migration handler
    def create_component(self, component_type, datas, uid=None):

        em_obj = self.emclass_from_name(component_type)

        rank = 'last'
        if 'rank' in datas:
            rank = datas['rank']
            del datas['rank']

        datas['uid'] = uid if uid else self.new_uid()
        em_component = em_obj(self, **datas)

        em_component.rank = em_component.get_max_rank() + 1 #  Inserting last by default

        self._components['uids'][em_component.uid] = em_component
        self._components[component_type].append(em_component)

        if rank != 'last':
            em_component.set_rank(1 if rank == 'first' else rank)

        #everything done, indicating that initialisation is over
        em_component.init_ended()

        #register the creation in migration handler
        try:
            self.migration_handler.register_change(self, em_component.uid, None, em_component.attr_dump)
        except MigrationHandlerChangeError as exception_object:
            #Revert the creation
            self.components(em_component.__class__).remove(em_component)
            del self._components['uids'][em_component.uid]
            raise exception_object

        self.migration_handler.register_model_state(self, hash(self))

        return em_component

    ## Delete a component
    # @param uid int : Component identifier
    # @throw EmComponentNotExistError
    # @todo unable uid check
    # @todo Handle a raise from the migration handler
    def delete_component(self, uid):
        #register the deletion in migration handler
        self.migration_handler.register_change(self, uid, self.component(uid).attr_dump, None)

        em_component = self.component(uid)
        if not em_component:
            raise EmComponentNotExistError()
        if em_component.delete_check():
            self._components[self.name_from_emclass(em_component.__class__)].remove(em_component)
            del self._components['uids'][uid]
        #Register the new EM state
        self.migration_handler.register_model_state(self, hash(self))
        return True

    ## Changes the current backend
    #
    # @param backend unknown: A backend object
    def set_backend(self, backend):
        self.backend = backend

    ## Returns a list of all the EmClass objects of the model
    def classes(self):
        return list(self._components[self.name_from_emclass(EmClass)])

    ## Use a new migration handler, re-apply all the ME to this handler
    #
    # @param new_mh MigrationHandler: A migration_handler object
    # @warning : if a relational-attribute field (with 'rel_field_id') comes before it's relational field (with 'rel_to_type_id'), this will blow up
    def migrate_handler(self, new_mh):
        new_me = Model(EmBackendDummy(), new_mh)
        relations = {'fields_list': [], 'superiors_list': []}

        # re-create component one by one, in components_class[] order
        for cls in self.components_class:
            for component in self.components(cls):
                component_type = self.name_from_emclass(cls)
                component_dump = component.attr_dump
                del component_dump['model'], component_dump['_inited']
                # Save relations between component to apply them later
                for relation in relations.keys():
                    if relation in component_dump and component_dump[relation]:
                        relations[relation].append((component.uid, component_dump[relation]))
                        del component_dump[relation]
                new_me.create_component(component_type, component_dump, component.uid)

        # apply selected field  to types
        for fields_list in relations['fields_list']:
            uid, fields = fields_list
            for field_id in fields:
                new_me.component(uid).select_field(new_me.component(field_id))

        # add superiors to types
        # TODO: debug, this add a superior to all types !
        for superiors_list in relations['superiors_list']:
            uid, sup_list = superiors_list
            for nature, superior_uid in sup_list.items():
                new_me.component(uid).add_superior(new_me.component(superior_uid), nature)

        self.migration_handler = new_mh