# coding=utf-8
"""
SyncData
========

Django command similar to 'loaddata' but also deletes.
After 'syncdata' has run, the database will have the same data as the fixture - anything
missing will of been added, anything different will of been updated,
and anything extra will of been deleted.
"""

import os
import sys
from contextlib import contextmanager
from functools import wraps

import six
from django.core.management.color import no_style
from django.db import connection, transaction

from django_extensions.management.utils import signalcommand
from django_extensions.compat import CompatibilityBaseCommand as BaseCommand

if hasattr(transaction, 'set_autocommit'):
    @contextmanager
    def _custom_transaction(using=None):
        transaction.set_autocommit(False)
        yield
        transaction.set_autocommit(True)
else:
    @contextmanager
    def _custom_transaction(using=None):
        transaction.commit_unless_managed()
        transaction.enter_transaction_management()
        transaction.managed(True)
        yield
        transaction.leave_transaction_management()


def custom_transaction(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        with _custom_transaction():
            return func(*args, **kwargs)
    return wrapper


class Command(BaseCommand):
    """ syncdata command """

    help = 'Makes the current database have the same data as the fixture(s), no more, no less.'
    args = "fixture [fixture ...]"

    def add_arguments(self, parser):
        parser.add_argument('--skip-remove', action='store_false',
                            dest='remove', default=True,
                            help='Avoid remove any object from db'),

    def remove_objects_not_in(self, objects_to_keep, verbosity):
        """
        Deletes all the objects in the database that are not in objects_to_keep.
        - objects_to_keep: A map where the keys are classes, and the values are a
         set of the objects of that class we should keep.
        """
        for class_ in objects_to_keep.keys():
            current = class_.objects.all()
            current_ids = set([x.pk for x in current])
            keep_ids = set([x.pk for x in objects_to_keep[class_]])

            remove_these_ones = current_ids.difference(keep_ids)
            if remove_these_ones:
                for obj in current:
                    if obj.pk in remove_these_ones:
                        obj.delete()
                        if verbosity >= 2:
                            print("Deleted object: %s" % six.u(obj))

            if verbosity > 0 and remove_these_ones:
                num_deleted = len(remove_these_ones)
                if num_deleted > 1:
                    type_deleted = six.u(class_._meta.verbose_name_plural)
                else:
                    type_deleted = six.u(class_._meta.verbose_name)

                print("Deleted %s %s" % (str(num_deleted), type_deleted))

    @signalcommand
    @custom_transaction
    def handle(self, *fixture_labels, **options):
        """ Main method of a Django command """
        from django.db.models import get_apps
        from django.core import serializers
        from django.conf import settings

        self.style = no_style()

        verbosity = int(options.get('verbosity', 1))
        show_traceback = options.get('traceback', False)

        # Keep a count of the installed objects and fixtures
        fixture_count = 0
        object_count = 0
        objects_per_fixture = []
        models = set()

        humanize = lambda dirname: dirname and "'%s'" % dirname or 'absolute path'

        # Get a cursor (even though we don't need one yet). This has
        # the side effect of initializing the test database (if
        # it isn't already initialized).
        cursor = connection.cursor()

        app_fixtures = [os.path.join(os.path.dirname(app.__file__), 'fixtures') for app in get_apps()]
        for fixture_label in fixture_labels:
            parts = fixture_label.split('.')
            if len(parts) == 1:
                fixture_name = fixture_label
                formats = serializers.get_public_serializer_formats()
            else:
                fixture_name, format = '.'.join(parts[:-1]), parts[-1]
                if format in serializers.get_public_serializer_formats():
                    formats = [format]
                else:
                    formats = []

            if formats:
                if verbosity > 1:
                    print("Loading '%s' fixtures..." % fixture_name)
            else:
                sys.stderr.write(self.style.ERROR("Problem installing fixture '%s': %s is not a known serialization format." % (fixture_name, format)))
                transaction.rollback()
                return

            if os.path.isabs(fixture_name):
                fixture_dirs = [fixture_name]
            else:
                fixture_dirs = app_fixtures + list(settings.FIXTURE_DIRS) + ['']

            for fixture_dir in fixture_dirs:
                if verbosity > 1:
                    print("Checking %s for fixtures..." % humanize(fixture_dir))

                label_found = False
                for format in formats:
                    if verbosity > 1:
                        print("Trying %s for %s fixture '%s'..." % (humanize(fixture_dir), format, fixture_name))
                    try:
                        full_path = os.path.join(fixture_dir, '.'.join([fixture_name, format]))
                        fixture = open(full_path, 'r')
                        if label_found:
                            fixture.close()
                            print(self.style.ERROR("Multiple fixtures named '%s' in %s. Aborting." % (fixture_name, humanize(fixture_dir))))
                            transaction.rollback()
                            return
                        else:
                            fixture_count += 1
                            objects_per_fixture.append(0)
                            if verbosity > 0:
                                print("Installing %s fixture '%s' from %s." % (format, fixture_name, humanize(fixture_dir)))
                            try:
                                objects_to_keep = {}
                                objects = serializers.deserialize(format, fixture)
                                for obj in objects:
                                    object_count += 1
                                    objects_per_fixture[-1] += 1

                                    class_ = obj.object.__class__
                                    if class_ not in objects_to_keep:
                                        objects_to_keep[class_] = set()
                                    objects_to_keep[class_].add(obj.object)

                                    models.add(class_)
                                    obj.save()

                                if options.get('remove'):
                                    self.remove_objects_not_in(objects_to_keep, verbosity)

                                label_found = True
                            except (SystemExit, KeyboardInterrupt):
                                raise
                            except Exception:
                                import traceback
                                fixture.close()
                                transaction.rollback()
                                if show_traceback:
                                    traceback.print_exc()
                                else:
                                    sys.stderr.write(self.style.ERROR("Problem installing fixture '%s': %s\n" % (full_path, traceback.format_exc())))
                                return
                            fixture.close()
                    except:
                        if verbosity > 1:
                            print("No %s fixture '%s' in %s." % (format, fixture_name, humanize(fixture_dir)))

        # If any of the fixtures we loaded contain 0 objects, assume that an
        # error was encountered during fixture loading.
        if 0 in objects_per_fixture:
            sys.stderr.write(
                self.style.ERROR("No fixture data found for '%s'. (File format may be invalid.)" % fixture_name))
            transaction.rollback()
            return

        # If we found even one object in a fixture, we need to reset the
        # database sequences.
        if object_count > 0:
            sequence_sql = connection.ops.sequence_reset_sql(self.style, models)
            if sequence_sql:
                if verbosity > 1:
                    print("Resetting sequences")
                for line in sequence_sql:
                    cursor.execute(line)

        transaction.commit()

        if object_count == 0:
            if verbosity > 1:
                print("No fixtures found.")
        else:
            if verbosity > 0:
                print("Installed %d object(s) from %d fixture(s)" % (object_count, fixture_count))

        # Close the DB connection. This is required as a workaround for an
        # edge case in MySQL: if the same connection is used to
        # create tables, load data, and query, the query can return
        # incorrect results. See Django #7572, MySQL #37735.
        connection.close()