# -*- coding: utf-8 -*-
"""
      Title: Dumpscript management command
    Project: Hardytools (queryset-refactor version)
     Author: Will Hardy (http://willhardy.com.au)
       Date: June 2008
      Usage: python manage.py dumpscript appname > scripts/scriptname.py
  $Revision: 217 $

Description:
    Generates a Python script that will repopulate the database using objects.
    The advantage of this approach is that it is easy to understand, and more
    flexible than directly populating the database, or using XML.

    * It also allows for new defaults to take effect and only transfers what is
      needed.
    * If a new database schema has a NEW ATTRIBUTE, it is simply not
      populated (using a default value will make the transition smooth :)
    * If a new database schema REMOVES AN ATTRIBUTE, it is simply ignored
      and the data moves across safely (I'm assuming we don't want this
      attribute anymore.
    * Problems may only occur if there is a new model and is now a required
      ForeignKey for an existing model. But this is easy to fix by editing the
      populate script. Half of the job is already done as all ForeingKey
      lookups occur though the locate_object() function in the generated script.

Improvements:
    See TODOs and FIXMEs scattered throughout :-)

"""

import datetime
import sys

import django
import six
# conditional import, force_unicode was renamed in Django 1.5
from django.contrib.contenttypes.models import ContentType
from django.core.exceptions import ObjectDoesNotExist
from django.db.models import (
    AutoField, BooleanField, DateField, DateTimeField, FileField, ForeignKey,
)

from django_extensions.management.utils import signalcommand
from django_extensions.compat import (
    list_app_labels, get_model_compat, get_models_for_app
)
from django_extensions.compat import CompatibilityBaseCommand as BaseCommand

try:
    from django.utils.encoding import smart_unicode, force_unicode  # NOQA
except ImportError:
    from django.utils.encoding import smart_text as smart_unicode, force_text as force_unicode  # NOQA


def orm_item_locator(orm_obj):
    """
    This function is called every time an object that will not be exported is required.
    Where orm_obj is the referred object.
    We postpone the lookup to locate_object() which will be run on the generated script

    """

    the_class = orm_obj._meta.object_name
    original_class = the_class
    pk_name = orm_obj._meta.pk.name
    original_pk_name = pk_name
    pk_value = getattr(orm_obj, pk_name)

    while hasattr(pk_value, "_meta") and hasattr(pk_value._meta, "pk") and hasattr(pk_value._meta.pk, "name"):
        the_class = pk_value._meta.object_name
        pk_name = pk_value._meta.pk.name
        pk_value = getattr(pk_value, pk_name)

    clean_dict = make_clean_dict(orm_obj.__dict__)

    for key in clean_dict:
        v = clean_dict[key]
        if v is not None and not isinstance(v, (six.string_types, six.integer_types, float, datetime.datetime)):
            clean_dict[key] = six.u("%s" % v)

    output = """ importer.locate_object(%s, "%s", %s, "%s", %s, %s ) """ % (
        original_class, original_pk_name,
        the_class, pk_name, pk_value, clean_dict
    )
    return output


class Command(BaseCommand):
    help = 'Dumps the data as a customised python script.'
    args = '[appname ...]'

    def add_arguments(self, parser):
        parser.add_argument(
            '--autofield', action='store_false', dest='skip_autofield',
            default=True, help='Include Autofields (like pk fields)')

    @signalcommand
    def handle(self, *app_labels, **options):

        # Get the models we want to export
        models = get_models(app_labels)

        # A dictionary is created to keep track of all the processed objects,
        # so that foreign key references can be made using python variable names.
        # This variable "context" will be passed around like the town bicycle.
        context = {}

        # Create a dumpscript object and let it format itself as a string
        script = Script(
            models=models,
            context=context,
            stdout=self.stdout,
            stderr=self.stderr,
            options=options,
        )
        self.stdout.write(str(script))
        self.stdout.write("\n")


def get_models(app_labels):
    """ Gets a list of models for the given app labels, with some exceptions.
        TODO: If a required model is referenced, it should also be included.
        Or at least discovered with a get_or_create() call.
    """

    # These models are not to be output, e.g. because they can be generated automatically
    # TODO: This should be "appname.modelname" string
    EXCLUDED_MODELS = (ContentType, )

    models = []

    # If no app labels are given, return all
    if not app_labels:
        for app_label in list_app_labels():
            models += [m for m in get_models_for_app(app_label)
                       if m not in EXCLUDED_MODELS]
        return models

    # Get all relevant apps
    for app_label in app_labels:
        # If a specific model is mentioned, get only that model
        if "." in app_label:
            app_label, model_name = app_label.split(".", 1)
            models.append(get_model_compat(app_label, model_name))
        # Get all models for a given app
        else:
            models += [m for m in get_models_for_app(app_label)
                       if m not in EXCLUDED_MODELS]

    return models


class Code(object):
    """ A snippet of python script.
        This keeps track of import statements and can be output to a string.
        In the future, other features such as custom indentation might be included
        in this class.
    """

    def __init__(self, indent=-1, stdout=None, stderr=None):

        if not stdout:
            stdout = sys.stdout
        if not stderr:
            stderr = sys.stderr

        self.indent = indent
        self.stdout = stdout
        self.stderr = stderr

    def __str__(self):
        """ Returns a string representation of this script.
        """
        if self.imports:
            self.stderr.write(repr(self.import_lines))
            return flatten_blocks([""] + self.import_lines + [""] + self.lines, num_indents=self.indent)
        else:
            return flatten_blocks(self.lines, num_indents=self.indent)

    def get_import_lines(self):
        """ Takes the stored imports and converts them to lines
        """
        if self.imports:
            return ["from %s import %s" % (value, key) for key, value in self.imports.items()]
        else:
            return []
    import_lines = property(get_import_lines)


class ModelCode(Code):
    """ Produces a python script that can recreate data for a given model class. """

    def __init__(self, model, context=None, stdout=None, stderr=None, options=None):
        super(ModelCode, self).__init__(indent=0, stdout=stdout, stderr=stderr)
        self.model = model
        if context is None:
            context = {}
        self.context = context
        self.options = options
        self.instances = []

    def get_imports(self):
        """ Returns a dictionary of import statements, with the variable being
            defined as the key.
        """
        return {self.model.__name__: smart_unicode(self.model.__module__)}
    imports = property(get_imports)

    def get_lines(self):
        """ Returns a list of lists or strings, representing the code body.
            Each list is a block, each string is a statement.
        """
        code = []

        for counter, item in enumerate(self.model._default_manager.all()):
            instance = InstanceCode(instance=item, id=counter + 1, context=self.context, stdout=self.stdout, stderr=self.stderr, options=self.options)
            self.instances.append(instance)
            if instance.waiting_list:
                code += instance.lines

        # After each instance has been processed, try again.
        # This allows self referencing fields to work.
        for instance in self.instances:
            if instance.waiting_list:
                code += instance.lines

        return code

    lines = property(get_lines)


class InstanceCode(Code):
    """ Produces a python script that can recreate data for a given model instance. """

    def __init__(self, instance, id, context=None, stdout=None, stderr=None, options=None):
        """ We need the instance in question and an id """

        super(InstanceCode, self).__init__(indent=0, stdout=stdout, stderr=stderr)
        self.imports = {}

        self.options = options
        self.instance = instance
        self.model = self.instance.__class__
        if context is None:
            context = {}
        self.context = context
        self.variable_name = "%s_%s" % (self.instance._meta.db_table, id)
        self.skip_me = None
        self.instantiated = False

        self.waiting_list = list(self.model._meta.fields)

        self.many_to_many_waiting_list = {}
        for field in self.model._meta.many_to_many:
            self.many_to_many_waiting_list[field] = list(getattr(self.instance, field.name).all())

    def get_lines(self, force=False):
        """ Returns a list of lists or strings, representing the code body.
            Each list is a block, each string is a statement.

            force (True or False): if an attribute object cannot be included,
            it is usually skipped to be processed later. With 'force' set, there
            will be no waiting: a get_or_create() call is written instead.
        """
        code_lines = []

        # Don't return anything if this is an instance that should be skipped
        if self.skip():
            return []

        # Initialise our new object
        # e.g. model_name_35 = Model()
        code_lines += self.instantiate()

        # Add each field
        # e.g. model_name_35.field_one = 1034.91
        #      model_name_35.field_two = "text"
        code_lines += self.get_waiting_list()

        if force:
            # TODO: Check that M2M are not affected
            code_lines += self.get_waiting_list(force=force)

        # Print the save command for our new object
        # e.g. model_name_35.save()
        if code_lines:
            code_lines.append("%s = importer.save_or_locate(%s)\n" % (self.variable_name, self.variable_name))

        code_lines += self.get_many_to_many_lines(force=force)

        return code_lines
    lines = property(get_lines)

    def skip(self):
        """ Determine whether or not this object should be skipped.
            If this model instance is a parent of a single subclassed
            instance, skip it. The subclassed instance will create this
            parent instance for us.

            TODO: Allow the user to force its creation?
        """

        if self.skip_me is not None:
            return self.skip_me

        def get_skip_version():
            """ Return which version of the skip code should be run

                Django's deletion code was refactored in r14507 which
                was just two days before 1.3 alpha 1 (r14519)
            """
            if not hasattr(self, '_SKIP_VERSION'):
                version = django.VERSION
                # no, it isn't lisp. I swear.
                self._SKIP_VERSION = (
                    version[0] > 1 or (  # django 2k... someday :)
                        version[0] == 1 and (  # 1.x
                            version[1] >= 4 or  # 1.4+
                            version[1] == 3 and not (  # 1.3.x
                                (version[3] == 'alpha' and version[1] == 0)
                            )
                        )
                    )
                ) and 2 or 1  # NOQA
            return self._SKIP_VERSION

        if get_skip_version() == 1:
            try:
                # Django trunk since r7722 uses CollectedObjects instead of dict
                from django.db.models.query import CollectedObjects
                sub_objects = CollectedObjects()
            except ImportError:
                # previous versions don't have CollectedObjects
                sub_objects = {}
            self.instance._collect_sub_objects(sub_objects)
            sub_objects = sub_objects.keys()

        elif get_skip_version() == 2:
            from django.db.models.deletion import Collector
            from django.db import router
            cls = self.instance.__class__
            using = router.db_for_write(cls, instance=self.instance)
            collector = Collector(using=using)
            collector.collect([self.instance], collect_related=False)