Tooltron

from collections import deque

import datetime

import os

import re

import sys

from django.core.exceptions import ImproperlyConfigured

from django.db import models

from django.conf import settings

from django.utils import importlib

from south import exceptions

from south.migration.utils import depends, dfs, flatten, get_app_label

from south.orm import FakeORM

from south.utils import memoize, ask_for_it_by_name, datetime_utils

from south.migration.utils import app_label_to_app_module

def all_migrations(applications=None):

    """

    Returns all Migrations for all `applications` that are migrated.

    """

    if applications is None:

        applications = models.get_apps()

    for model_module in applications:

        # The app they've passed is the models module - go up one level

        app_path = ".".join(model_module.__name__.split(".")[:-1])

        app = ask_for_it_by_name(app_path)

        try:

            yield Migrations(app)

        except exceptions.NoMigrations:

            pass

def application_to_app_label(application):

    "Works out the app label from either the app label, the app name, or the module"

    if isinstance(application, basestring):

        app_label = application.split('.')[-1]

    else:

        app_label = application.__name__.split('.')[-1]

    return app_label

class MigrationsMetaclass(type):

    """

    Metaclass which ensures there is only one instance of a Migrations for

    any given app.

    """

    def __init__(self, name, bases, dict):

        super(MigrationsMetaclass, self).__init__(name, bases, dict)

        self.instances = {}

    def __call__(self, application, **kwds):

        app_label = application_to_app_label(application)

        # If we don't already have an instance, make one

        if app_label not in self.instances:

            self.instances[app_label] = super(MigrationsMetaclass, self).__call__(app_label_to_app_module(app_label), **kwds)

        return self.instances[app_label]

    def _clear_cache(self):

        "Clears the cache of Migration objects."

        self.instances = {}

class Migrations(list):

    """

    Holds a list of Migration objects for a particular app.

    """

    __metaclass__ = MigrationsMetaclass

    if getattr(settings, "SOUTH_USE_PYC", False):

        MIGRATION_FILENAME = re.compile(r'(?!__init__)' # Don't match __init__.py

                                        r'[0-9a-zA-Z_]*' # Don't match dotfiles, or names with dots/invalid chars in them

                                        r'(\.pyc?)?$')     # Match .py or .pyc files, or module dirs

    else:

        MIGRATION_FILENAME = re.compile(r'(?!__init__)' # Don't match __init__.py

                                        r'[0-9a-zA-Z_]*' # Don't match dotfiles, or names with dots/invalid chars in them

                                        r'(\.py)?$')       # Match only .py files, or module dirs

    def __init__(self, application, force_creation=False, verbose_creation=True):

        "Constructor. Takes the module of the app, NOT its models (like get_app returns)"

        self._cache = {}

        self.set_application(application, force_creation, verbose_creation)

    def create_migrations_directory(self, verbose=True):

        "Given an application, ensures that the migrations directory is ready."

        migrations_dir = self.migrations_dir()

        # Make the directory if it's not already there

        if not os.path.isdir(migrations_dir):

            if verbose:

                print "Creating migrations directory at '%s'..." % migrations_dir

            os.mkdir(migrations_dir)

        # Same for __init__.py

        init_path = os.path.join(migrations_dir, "__init__.py")

        if not os.path.isfile(init_path):

            # Touch the init py file

            if verbose:

                print "Creating __init__.py in '%s'..." % migrations_dir

            open(init_path, "w").close()

    def migrations_dir(self):

        """

        Returns the full path of the migrations directory.

        If it doesn't exist yet, returns where it would exist, based on the

        app's migrations module (defaults to app.migrations)

        """

        module_path = self.migrations_module()

        try:

            module = importlib.import_module(module_path)

        except ImportError:

            # There's no migrations module made yet; guess!

            try:

                parent = importlib.import_module(".".join(module_path.split(".")[:-1]))

            except ImportError:

                # The parent doesn't even exist, that's an issue.

                raise exceptions.InvalidMigrationModule(

                    application = self.application.__name__,

                    module = module_path,

                )

            else:

                # Good guess.

                return os.path.join(os.path.dirname(parent.__file__), module_path.split(".")[-1])

        else:

            # Get directory directly

            return os.path.dirname(module.__file__)

    def migrations_module(self):

        "Returns the module name of the migrations module for this"

        app_label = application_to_app_label(self.application)

        if hasattr(settings, "SOUTH_MIGRATION_MODULES"):

            if app_label in settings.SOUTH_MIGRATION_MODULES:

                # There's an override.

                return settings.SOUTH_MIGRATION_MODULES[app_label]

        return self._application.__name__ + '.migrations'

    def get_application(self):

        return self._application

    def set_application(self, application, force_creation=False, verbose_creation=True):

        """

        Called when the application for this Migrations is set.

        Imports the migrations module object, and throws a paddy if it can't.

        """

        self._application = application

        if not hasattr(application, 'migrations'):

            try:

                module = importlib.import_module(self.migrations_module())

                self._migrations = application.migrations = module

            except ImportError:

                if force_creation:

                    self.create_migrations_directory(verbose_creation)

                    module = importlib.import_module(self.migrations_module())

                    self._migrations = application.migrations = module

                else:

                    raise exceptions.NoMigrations(application)

        self._load_migrations_module(application.migrations)

    application = property(get_application, set_application)

    def _load_migrations_module(self, module):

        self._migrations = module

        filenames = []

        dirname = self.migrations_dir()

        for f in os.listdir(dirname):

            if self.MIGRATION_FILENAME.match(os.path.basename(f)):

                full_path = os.path.join(dirname, f)

                # If it's a .pyc file, only append if the .py isn't already around

                if f.endswith(".pyc") and (os.path.isfile(full_path[:-1])):

                    continue

                # If it's a module directory, only append if it contains __init__.py[c].

                if os.path.isdir(full_path):

                    if not (os.path.isfile(os.path.join(full_path, "__init__.py")) or \

                      (getattr(settings, "SOUTH_USE_PYC", False) and \

                      os.path.isfile(os.path.join(full_path, "__init__.pyc")))):

                        continue

                filenames.append(f)

        filenames.sort()

        self.extend(self.migration(f) for f in filenames)

    def migration(self, filename):

        name = Migration.strip_filename(filename)

        if name not in self._cache:

            self._cache[name] = Migration(self, name)

        return self._cache[name]

    def __getitem__(self, value):

        if isinstance(value, basestring):

            return self.migration(value)

        return super(Migrations, self).__getitem__(value)

    def _guess_migration(self, prefix):

        prefix = Migration.strip_filename(prefix)

        matches = [m for m in self if m.name().startswith(prefix)]

        if len(matches) == 1:

            return matches[0]

        elif len(matches) > 1:

            raise exceptions.MultiplePrefixMatches(prefix, matches)

        else:

            raise exceptions.UnknownMigration(prefix, None)

    def guess_migration(self, target_name):

        if target_name == 'zero' or not self:

            return

        elif target_name is None:

            return self[-1]

        else:

            return self._guess_migration(prefix=target_name)

    def app_label(self):

        return self._application.__name__.split('.')[-1]

    def full_name(self):

        return self._migrations.__name__

    @classmethod

    def calculate_dependencies(cls, force=False):

        "Goes through all the migrations, and works out the dependencies."

        if getattr(cls, "_dependencies_done", False) and not force:

            return

        for migrations in all_migrations():

            for migration in migrations:

                migration.calculate_dependencies()

        cls._dependencies_done = True

    @staticmethod

    def invalidate_all_modules():

        "Goes through all the migrations, and invalidates all cached modules."

        for migrations in all_migrations():

            for migration in migrations:

                migration.invalidate_module()

    def next_filename(self, name):

        "Returns the fully-formatted filename of what a new migration 'name' would be"

        highest_number = 0

        for migration in self:

            try:

                number = int(migration.name().split("_")[0])

                highest_number = max(highest_number, number)

            except ValueError:

                pass

        # Work out the new filename

        return "%04i_%s.py" % (

            highest_number + 1,

            name,

        )

class Migration(object):

    """

    Class which represents a particular migration file on-disk.

    """

    def __init__(self, migrations, filename):

        """

        Returns the migration class implied by 'filename'.

        """

        self.migrations = migrations

        self.filename = filename

        self.dependencies = set()

        self.dependents = set()

    def __str__(self):

        return self.app_label() + ':' + self.name()

    def __repr__(self):

        return u'<Migration: %s>' % unicode(self)

    def __eq__(self, other):

        return self.app_label() == other.app_label() and self.name() == other.name()

    def __hash__(self):

        return hash(str(self))

    def app_label(self):

        return self.migrations.app_label()

    @staticmethod

    def strip_filename(filename):

        return os.path.splitext(os.path.basename(filename))[0]

    def name(self):

        return self.strip_filename(os.path.basename(self.filename))

    def full_name(self):

        return self.migrations.full_name() + '.' + self.name()

    def migration(self):

        "Tries to load the actual migration module"

        full_name = self.full_name()

        try:

            migration = sys.modules[full_name]

        except KeyError:

            try:

                migration = __import__(full_name, {}, {}, ['Migration'])

            except ImportError, e:

                raise exceptions.UnknownMigration(self, sys.exc_info())

            except Exception, e:

                raise exceptions.BrokenMigration(self, sys.exc_info())

        # Override some imports

        migration._ = lambda x: x  # Fake i18n

        migration.datetime = datetime_utils

        return migration

    migration = memoize(migration)

    def migration_class(self):

        "Returns the Migration class from the module"

        return self.migration().Migration

    def migration_instance(self):

        "Instantiates the migration_class"

        return self.migration_class()()

    migration_instance = memoize(migration_instance)

    def previous(self):

        "Returns the migration that comes before this one in the sequence."

        index = self.migrations.index(self) - 1

        if index < 0:

            return None

        return self.migrations[index]

    previous = memoize(previous)

    def next(self):

        "Returns the migration that comes after this one in the sequence."

        index = self.migrations.index(self) + 1

        if index >= len(self.migrations):

            return None

        return self.migrations[index]

    next = memoize(next)

    def _get_dependency_objects(self, attrname):

        """

        Given the name of an attribute (depends_on or needed_by), either yields

        a list of migration objects representing it, or errors out.

        """

        for app, name in getattr(self.migration_class(), attrname, []):

            try:

                migrations = Migrations(app)

            except ImproperlyConfigured:

                raise exceptions.DependsOnUnmigratedApplication(self, app)

            migration = migrations.migration(name)

            try:

                migration.migration()

            except exceptions.UnknownMigration:

                raise exceptions.DependsOnUnknownMigration(self, migration)

            if migration.is_before(self) == False:

                raise exceptions.DependsOnHigherMigration(self, migration)

            yield migration

    def calculate_dependencies(self):

        """

        Loads dependency info for this migration, and stores it in itself

        and any other relevant migrations.

        """

        # Normal deps first

        for migration in self._get_dependency_objects("depends_on"):

            self.dependencies.add(migration)

            migration.dependents.add(self)

        # And reverse deps

        for migration in self._get_dependency_objects("needed_by"):

            self.dependents.add(migration)

            migration.dependencies.add(self)

        # And implicit ordering deps

        previous = self.previous()

        if previous:

            self.dependencies.add(previous)

            previous.dependents.add(self)

    def invalidate_module(self):

        """

        Removes the cached version of this migration's module import, so we

        have to re-import it. Used when south.db.db changes.

        """

        reload(self.migration())

        self.migration._invalidate()

    def forwards(self):

        return self.migration_instance().forwards

    def backwards(self):

        return self.migration_instance().backwards

    def forwards_plan(self):

        """

        Returns a list of Migration objects to be applied, in order.

        This list includes `self`, which will be applied last.

        """

        return depends(self, lambda x: x.dependencies)

    def _backwards_plan(self):

        return depends(self, lambda x: x.dependents)

    def backwards_plan(self):

        """

        Returns a list of Migration objects to be unapplied, in order.

        This list includes `self`, which will be unapplied last.

        """

        return list(self._backwards_plan())

    def is_before(self, other):

        if self.migrations == other.migrations:

            if self.filename < other.filename:

                return True

            return False

    def is_after(self, other):

        if self.migrations == other.migrations:

            if self.filename > other.filename:

                return True

            return False

    def prev_orm(self):

        if getattr(self.migration_class(), 'symmetrical', False):

            return self.orm()

        previous = self.previous()

        if previous is None:

            # First migration? The 'previous ORM' is empty.

            return FakeORM(None, self.app_label())

        return previous.orm()

    prev_orm = memoize(prev_orm)

    def orm(self):

        return FakeORM(self.migration_class(), self.app_label())

    orm = memoize(orm)

    def no_dry_run(self):

        migration_class = self.migration_class()

        try:

            return migration_class.no_dry_run

        except AttributeError:

            return False