import logging
import os

from subprocess import Popen

from django.conf import settings

from ..models import Correspondent, Tag


def logger(message, group):
    logging.getLogger(__name__).debug(message, extra={"group": group})


def set_correspondent(sender, document=None, logging_group=None, **kwargs):

    # No sense in assigning a correspondent when one is already set.
    if document.correspondent:
        return

    # No matching correspondents, so no need to continue
    potential_correspondents = list(Correspondent.match_all(document.content))
    if not potential_correspondents:
        return

    potential_count = len(potential_correspondents)
    selected = potential_correspondents[0]
    if potential_count > 1:
        message = "Detected {} potential correspondents, so we've opted for {}"
        logger(
            message.format(potential_count, selected),
            logging_group
        )

    logger(
        'Assigning correspondent "{}" to "{}" '.format(selected, document),
        logging_group
    )

    document.correspondent = selected
    document.save(update_fields=("correspondent",))


def set_tags(sender, document=None, logging_group=None, **kwargs):

    current_tags = set(document.tags.all())
    relevant_tags = set(Tag.match_all(document.content)) - current_tags

    if not relevant_tags:
        return

    message = 'Tagging "{}" with "{}"'
    logger(
        message.format(document, ", ".join([t.slug for t in relevant_tags])),
        logging_group
    )

    document.tags.add(*relevant_tags)


def run_pre_consume_script(sender, filename, **kwargs):

    if not settings.PRE_CONSUME_SCRIPT:
        return

    Popen((settings.PRE_CONSUME_SCRIPT, filename)).wait()


def run_post_consume_script(sender, document, **kwargs):

    if not settings.POST_CONSUME_SCRIPT:
        return

    Popen((
        settings.POST_CONSUME_SCRIPT,
        str(document.id),
        document.file_name,
        document.source_path,
        document.thumbnail_path,
        document.download_url,
        document.thumbnail_url,
        str(document.correspondent),
        str(",".join(document.tags.all().values_list("slug", flat=True)))
    )).wait()


def cleanup_document_deletion(sender, instance, using, **kwargs):
    try:
        os.unlink(instance.source_path)
    except FileNotFoundError:
        pass  # The file's already gone, so we're cool with it.