med/media/management/commands/import_isbn.py

from argparse import FileType
from sys import stdin

from django.core.exceptions import ValidationError
from django.core.management import BaseCommand
from media.models import Comic, FutureMedium, Manga, Novel
from media.validators import isbn_validator


class Command(BaseCommand):
    def add_arguments(self, parser):
        parser.add_argument('--media-type',
                            type=str,
                            default='bd',
                            choices=[
                                'bd',
                                'manga',
                                'roman',
                            ],
                            help="Type of media to be "
                                 "imported.")
        parser.add_argument('input', nargs='?',
                            type=FileType('r'),
                            default=stdin,
                            help="ISBN to be imported.")

    def handle(self, *args, **options):
        type_str = options["media_type"]

        media_classes = [Comic, Manga, Novel, FutureMedium]

        file = options["input"]
        isbns = []
        for line in file:
            isbns.append(line[:-1])

        print("Registering", len(isbns), "ISBN")

        imported = 0
        not_imported = []

        for isbn in isbns:
            if not isbn:
                continue

            try:
                if not isbn_validator(isbn):
                    raise ValidationError(
                        "This ISBN is invalid for an unknown reason")
            except ValidationError as e:
                self.stderr.write(self.style.ERROR(
                    "The following ISBN is invalid:"
                    " {isbn}, reason: {reason}. Ignoring...".format(
                        isbn=isbn, reason=e.message)))

            isbn_exists = False
            for cl in media_classes:
                if cl.objects.filter(isbn=isbn).exists():
                    isbn_exists = True
                    medium = cl.objects.get(isbn=isbn)
                    self.stderr.write(self.style.WARNING(
                        ("Warning: ISBN {isbn} already exists, and is "
                         + "registered as type {type}: {name}. Ignoring...")
                        .format(isbn=isbn,
                                name=str(medium),
                                type=str(cl._meta.verbose_name))))
                    not_imported.append(medium)
                    break

            if isbn_exists:
                continue

            FutureMedium.objects.create(isbn=isbn, type=type_str)
            self.stdout.write(self.style.SUCCESS("ISBN {isbn} imported"
                                                 .format(isbn=isbn)))
            imported += 1

        self.stdout.write(self.style.SUCCESS("{count} media imported"
                                             .format(count=imported)))

        with open('not_imported_media.csv', 'w') as f:
            f.write("isbn|type|title\n")
            for medium in not_imported:
                if not hasattr(medium, 'title') or not medium.title:
                    medium.title = ''
                f.write(medium.isbn + "|"
                        + str(medium._meta.verbose_name)
                        + "|" + medium.title + "\n")

        self.stderr.write(self.style.WARNING(("{count} media already "
                                              + "imported").format(
            count=len(not_imported))))