from __future__ import unicode_literals

import glob
import gzip
import os
import warnings
import zipfile
from optparse import make_option

from django.apps import apps
from django.conf import settings
from django.core import serializers
from django.core.management.base import BaseCommand, CommandError
from django.core.management.color import no_style
from django.db import (connections, router, transaction, DEFAULT_DB_ALIAS,
      IntegrityError, DatabaseError)
from django.utils import lru_cache
from django.utils.encoding import force_text
from django.utils.functional import cached_property
from django.utils._os import upath
from itertools import product

try:
    import bz2
    has_bz2 = True
except ImportError:
    has_bz2 = False


class Command(BaseCommand):
    help = 'Installs the named fixture(s) in the database.'
    args = "fixture [fixture ...]"

    option_list = BaseCommand.option_list + (
        make_option('--database', action='store', dest='database',
            default=DEFAULT_DB_ALIAS, help='Nominates a specific database to load '
                'fixtures into. Defaults to the "default" database.'),
        make_option('--ignorenonexistent', '-i', action='store_true', dest='ignore',
            default=False, help='Ignores entries in the serialized data for fields'
                                ' that do not currently exist on the model.'),
    )

    def handle(self, *fixture_labels, **options):

        self.ignore = options.get('ignore')
        self.using = options.get('database')

        if not len(fixture_labels):
            raise CommandError(
                "No database fixture specified. Please provide the path "
                "of at least one fixture in the command line.")

        self.verbosity = int(options.get('verbosity'))

        with transaction.commit_on_success_unless_managed(using=self.using):
            self.loaddata(fixture_labels)

        # Close the DB connection -- unless we're still in a transaction. 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.
        if transaction.get_autocommit(self.using):
            connections[self.using].close()

    def loaddata(self, fixture_labels):
        connection = connections[self.using]

        # Keep a count of the installed objects and fixtures
        self.fixture_count = 0
        self.loaded_object_count = 0
        self.fixture_object_count = 0
        self.models = set()

        self.serialization_formats = serializers.get_public_serializer_formats()
        self.compression_formats = {
            None: open,
            'gz': gzip.GzipFile,
            'zip': SingleZipReader
        }
        if has_bz2:
            self.compression_formats['bz2'] = bz2.BZ2File

        with connection.constraint_checks_disabled():
            for fixture_label in fixture_labels:
                self.load_label(fixture_label)

        # Since we disabled constraint checks, we must manually check for
        # any invalid keys that might have been added
        table_names = [model._meta.db_table for model in self.models]
        try:
            connection.check_constraints(table_names=table_names)
        except Exception as e:
            e.args = ("Problem installing fixtures: %s" % e,)
            raise

        # If we found even one object in a fixture, we need to reset the
        # database sequences.
        if self.loaded_object_count > 0:
            sequence_sql = connection.ops.sequence_reset_sql(no_style(), self.models)
            if sequence_sql:
                if self.verbosity >= 2:
                    self.stdout.write("Resetting sequences\n")
                cursor = connection.cursor()
                for line in sequence_sql:
                    cursor.execute(line)
                cursor.close()

        if self.verbosity >= 1:
            if self.fixture_object_count == self.loaded_object_count:
                self.stdout.write("Installed %d object(s) from %d fixture(s)" %
                    (self.loaded_object_count, self.fixture_count))
            else:
                self.stdout.write("Installed %d object(s) (of %d) from %d fixture(s)" %
                    (self.loaded_object_count, self.fixture_object_count, self.fixture_count))

    def load_label(self, fixture_label):
        """
        Loads fixtures files for a given label.
        """
        for fixture_file, fixture_dir, fixture_name in self.find_fixtures(fixture_label):
            _, ser_fmt, cmp_fmt = self.parse_name(os.path.basename(fixture_file))
            open_method = self.compression_formats[cmp_fmt]
            fixture = open_method(fixture_file, 'r')
            try:
                self.fixture_count += 1
                objects_in_fixture = 0
                loaded_objects_in_fixture = 0
                if self.verbosity >= 2:
                    self.stdout.write("Installing %s fixture '%s' from %s." %
                        (ser_fmt, fixture_name, humanize(fixture_dir)))

                objects = serializers.deserialize(ser_fmt, fixture,
                    using=self.using, ignorenonexistent=self.ignore)

                for obj in objects:
                    objects_in_fixture += 1
                    if router.allow_migrate(self.using, obj.object.__class__):
                        loaded_objects_in_fixture += 1
                        self.models.add(obj.object.__class__)
                        try:
                            obj.save(using=self.using)
                        except (DatabaseError, IntegrityError) as e:
                            e.args = ("Could not load %(app_label)s.%(object_name)s(pk=%(pk)s): %(error_msg)s" % {
                                'app_label': obj.object._meta.app_label,
                                'object_name': obj.object._meta.object_name,
                                'pk': obj.object.pk,
                                'error_msg': force_text(e)
                            },)
                            raise

                self.loaded_object_count += loaded_objects_in_fixture
                self.fixture_object_count += objects_in_fixture
            except Exception as e:
                if not isinstance(e, CommandError):
                    e.args = ("Problem installing fixture '%s': %s" % (fixture_file, e),)
                raise
            finally:
                fixture.close()

            # Warn if the fixture we loaded contains 0 objects.
            if objects_in_fixture == 0:
                warnings.warn(
                    "No fixture data found for '%s'. (File format may be "
                    "invalid.)" % fixture_name,
                    RuntimeWarning
                )

    @lru_cache.lru_cache(maxsize=None)
    def find_fixtures(self, fixture_label):
        """
        Finds fixture files for a given label.
        """
        fixture_name, ser_fmt, cmp_fmt = self.parse_name(fixture_label)
        databases = [self.using, None]
        cmp_fmts = list(self.compression_formats.keys()) if cmp_fmt is None else [cmp_fmt]
        ser_fmts = serializers.get_public_serializer_formats() if ser_fmt is None else [ser_fmt]

        if self.verbosity >= 2:
            self.stdout.write("Loading '%s' fixtures..." % fixture_name)

        if os.path.isabs(fixture_name):
            fixture_dirs = [os.path.dirname(fixture_name)]
            fixture_name = os.path.basename(fixture_name)
        else:
            fixture_dirs = self.fixture_dirs
            if os.path.sep in fixture_name:
                fixture_dirs = [os.path.join(dir_, os.path.dirname(fixture_name))
                                for dir_ in fixture_dirs]
                fixture_name = os.path.basename(fixture_name)

        suffixes = ('.'.join(ext for ext in combo if ext)
                for combo in product(databases, ser_fmts, cmp_fmts))
        targets = set('.'.join((fixture_name, suffix)) for suffix in suffixes)

        fixture_files = []
        for fixture_dir in fixture_dirs:
            if self.verbosity >= 2:
                self.stdout.write("Checking %s for fixtures..." % humanize(fixture_dir))
            fixture_files_in_dir = []
            for candidate in glob.iglob(os.path.join(fixture_dir, fixture_name + '*')):
                if os.path.basename(candidate) in targets:
                    # Save the fixture_dir and fixture_name for future error messages.
                    fixture_files_in_dir.append((candidate, fixture_dir, fixture_name))

            if self.verbosity >= 2 and not fixture_files_in_dir:
                self.stdout.write("No fixture '%s' in %s." %
                                  (fixture_name, humanize(fixture_dir)))

            # Check kept for backwards-compatibility; it isn't clear why
            # duplicates are only allowed in different directories.
            if len(fixture_files_in_dir) > 1:
                raise CommandError(
                    "Multiple fixtures named '%s' in %s. Aborting." %
                    (fixture_name, humanize(fixture_dir)))
            fixture_files.extend(fixture_files_in_dir)

        if fixture_name != 'initial_data' and not fixture_files:
            # Warning kept for backwards-compatibility; why not an exception?
            warnings.warn("No fixture named '%s' found." % fixture_name)

        return fixture_files

    @cached_property
    def fixture_dirs(self):
        """
        Return a list of fixture directories.

        The list contains the 'fixtures' subdirectory of each installed
        application, if it exists, the directories in FIXTURE_DIRS, and the
        current directory.
        """
        dirs = []
        for app_config in apps.get_app_configs():
            d = os.path.join(app_config.path, 'fixtures')
            if os.path.isdir(d):
                dirs.append(d)
        dirs.extend(list(settings.FIXTURE_DIRS))
        dirs.append('')
        dirs = [upath(os.path.abspath(os.path.realpath(d))) for d in dirs]
        return dirs

    def parse_name(self, fixture_name):
        """
        Splits fixture name in name, serialization format, compression format.
        """
        parts = fixture_name.rsplit('.', 2)

        if len(parts) > 1 and parts[-1] in self.compression_formats:
            cmp_fmt = parts[-1]
            parts = parts[:-1]
        else:
            cmp_fmt = None

        if len(parts) > 1:
            if parts[-1] in self.serialization_formats:
                ser_fmt = parts[-1]
                parts = parts[:-1]
            else:
                raise CommandError(
                    "Problem installing fixture '%s': %s is not a known "
                    "serialization format." % (''.join(parts[:-1]), parts[-1]))
        else:
            ser_fmt = None

        name = '.'.join(parts)

        return name, ser_fmt, cmp_fmt


class SingleZipReader(zipfile.ZipFile):

    def __init__(self, *args, **kwargs):
        zipfile.ZipFile.__init__(self, *args, **kwargs)
        if len(self.namelist()) != 1:
            raise ValueError("Zip-compressed fixtures must contain one file.")

    def read(self):
        return zipfile.ZipFile.read(self, self.namelist()[0])


def humanize(dirname):
    return "'%s'" % dirname if dirname else 'absolute path'
