import os
import tarfile
import progressbar
import django.apps
from datetime import datetime
from django.core.management.base import BaseCommand
from django.utils.encoding import smart_str


class Command(BaseCommand):
    help = 'Backup item images'

    def add_arguments(self, parser):
        parser.add_argument(
            '--show-bar',
            action='store_true',
            dest='show_bar',
            default=False,
            help='Show progressbar'
        )
        parser.add_argument(
            '--print-paths',
            action='store_true',
            dest='print_paths',
            default=False,
            help='Print files paths'
        )

    def handle(self, *args, **options):
        backuper = BackupFiles(
            'project-name',
            show_bar=options['show_bar'],
            print_paths=options['print_paths']
        )
        archive_path = backuper.start()
        print(archive_path)


class BackupFiles(object):
    _media_folder_name = None

    def __init__(self,
                 project_name,
                 archive_folder='/tmp',
                 default_media_folder_name='media',
                 show_bar=False,
                 print_paths=False):
        self.show_bar = show_bar
        self.print_paths = print_paths

        self.project_name = project_name
        self.archive_folder = archive_folder
        self._default_media_folder_name = default_media_folder_name

    def start(self):
        archive_path = self._get_archive_path()
        tar = tarfile.open(archive_path, 'w:gz')

        files_path = []
        models_list = django.apps.apps.get_models()
        for model_class in models_list:
            for instance in model_class.objects.all():
                file_field_names = self._get_file_fields(instance)
                for field_name in file_field_names:
                    cur_path = self._get_file_field(instance, field_name)
                    if cur_path:
                        files_path.append(cur_path)

                        if self.print_paths:
                            message = '{}.{} {} :: {}'.format(
                                model_class._meta.app_label,
                                model_class._meta.model_name,
                                field_name,
                                cur_path['full_path']
                            )
                            print(message)

        bar = None
        if self.show_bar:
            bar = progressbar.ProgressBar(max_value=len(files_path)).start()

        for i, cur_path in enumerate(files_path):
            tar.add(
                cur_path['full_path'],
                arcname=cur_path['arc_name']
            )

            if bar:
                bar.update(i + 1)

        if bar:
            bar.finish()

        tar.close()

        return archive_path

    def _get_archive_path(self):
        file_name = '{}-{}-{}.tar.gz'.format(
            self.project_name,
            self.media_folder_name,
            datetime.now().strftime('%Y-%m-%d_%H-%M-%S')
        )
        archive_path = '{}/{}'.format(
            self.archive_folder,
            file_name
        )
        return archive_path

    @property
    def media_folder_name(self):
        if self._media_folder_name:
            return self._media_folder_name
        return self._default_media_folder_name

    @media_folder_name.setter
    def media_folder_name(self, value):
        self._media_folder_name = value

    @staticmethod
    def _get_file_fields(instance):
        names = []
        for field in instance._meta.fields:
            if field.get_internal_type() == 'FileField':
                names.append(field.name)
        return names

    def _get_file_field(self, instance, field_name):
        field = getattr(instance, field_name)
        if not field:
            return {}

        full_path = smart_str(field.path)
        arc_name = '{}/{}/{}'.format(
            self.media_folder_name,
            field.field.upload_to,
            os.path.basename(full_path)
        )
        return {
            'arc_name': arc_name,
            'full_path': full_path,
        }