from wagtail.models import Locale, Page

from books.models.module import Module
from books.models.topic import Topic

from core.logger import get_logger

logger = get_logger(__name__)


class AlreadyTranslatedException(Exception):
    pass


class ModuleDoesNotExistException(Exception):
    pass


# todo: make this a django command
# todo: add language to translate to as an argument
# todo: write a test maybe
def convert_page_to_translation(slug: str, original_slug: str, language_code="en"):
    """
    Migrate a module and its children to a new locale and links it to
    its translation in the original locale.

    @param slug: the slug of the module to migrate
    @param original_slug: the slug of the module in the original locale
    """
    try:
        module = Module.objects.get(slug=slug)
        original = Module.objects.get(slug=original_slug)
        if original.translation_key == module.translation_key:
            raise AlreadyTranslatedException
    except Module.DoesNotExist:
        raise ModuleDoesNotExistException
    locale, _ = Locale.objects.get_or_create(language_code=language_code)
    logger.debug("Starting conversion")
    topic: Topic = module.get_parent()
    try:
        logger.debug("Getting existing topic translation")
        translated_topic = topic.get_translation(locale)
    except Page.DoesNotExist:
        logger.debug("Creating topic translation")
        translated_topic = topic.copy_for_translation(locale)
        revision = translated_topic.latest_revision
        translated_topic.publish(revision)

    module.locale = locale
    if original is not None:
        translation_key = original.translation_key
        module.translation_key = translation_key
    module.save()
    chapters = module.get_children()
    for chapter in chapters:
        chapter.locale = locale
        chapter.save()
        content_blocks = chapter.get_children()
        for content_block in content_blocks:
            content_block.locale = locale
            content_block.save()

    module.move(translated_topic, "last-child")

    return f"Converted page {slug} to be the {language_code} translation of {original_slug}"