import re
import os

from django.db.models.signals import post_save, pre_save, pre_delete, \
    post_delete
from django.dispatch import receiver
from django.utils import timezone

from boards import thumbs
from boards.mdx_neboard import get_parser

from boards.models import Post, GlobalId, Attachment
from boards.models.attachment.viewers import FILE_TYPES_IMAGE
from boards.models.post import REGEX_NOTIFICATION, REGEX_REPLY,\
        REGEX_GLOBAL_REPLY
from boards.models.post.manager import post_import_deps
from boards.models.user import Notification
from neboard.settings import MEDIA_ROOT


THUMB_SIZES = ((200, 150),)


@receiver(post_save, sender=Post)
def connect_replies(instance, **kwargs):
    if not kwargs['update_fields']:
        for reply_number in re.finditer(REGEX_REPLY, instance.get_raw_text()):
            post_id = reply_number.group(1)

            try:
                referenced_post = Post.objects.get(id=post_id)

                if not referenced_post.referenced_posts.filter(
                        id=instance.id).exists():
                    referenced_post.referenced_posts.add(instance)
                    referenced_post.last_edit_time = instance.pub_time
                    referenced_post.build_refmap()
                    referenced_post.save(update_fields=['refmap', 'last_edit_time'])
            except Post.DoesNotExist:
                pass


@receiver(post_save, sender=Post)
@receiver(post_import_deps, sender=Post)
def connect_global_replies(instance, **kwargs):
    if not kwargs['update_fields']:
        for reply_number in re.finditer(REGEX_GLOBAL_REPLY, instance.get_raw_text()):
            key_type = reply_number.group(1)
            key = reply_number.group(2)
            local_id = reply_number.group(3)

            try:
                global_id = GlobalId.objects.get(key_type=key_type, key=key,
                        local_id=local_id)
                referenced_post = Post.objects.get(global_id=global_id)
                referenced_post.referenced_posts.add(instance)
                referenced_post.last_edit_time = instance.pub_time
                referenced_post.build_refmap()
                referenced_post.save(update_fields=['refmap', 'last_edit_time'])
            except (GlobalId.DoesNotExist, Post.DoesNotExist):
                pass


@receiver(post_save, sender=Post)
def connect_notifications(instance, **kwargs):
    if not kwargs['update_fields']:
        for reply_number in re.finditer(REGEX_NOTIFICATION, instance.get_raw_text()):
            user_name = reply_number.group(1).lower()
            Notification.objects.get_or_create(name=user_name, post=instance)


@receiver(pre_save, sender=Post)
@receiver(post_import_deps, sender=Post)
def parse_text(instance, **kwargs):
    instance._text_rendered = get_parser().parse(instance.get_raw_text())


@receiver(pre_delete, sender=Post)
def delete_attachments(instance, **kwargs):
    for attachment in instance.attachments.all():
        attachment_refs_count = attachment.attachment_posts.count()
        if attachment_refs_count == 1:
            attachment.delete()


@receiver(post_delete, sender=Post)
def update_thread_on_delete(instance, **kwargs):
    thread = instance.get_thread()
    thread.last_edit_time = timezone.now()
    thread.save()


@receiver(post_delete, sender=Post)
def delete_global_id(instance, **kwargs):
    if instance.global_id and instance.global_id.id:
        instance.global_id.delete()


@receiver(post_save, sender=Attachment)
def generate_thumb(instance, **kwargs):
    if instance.mimetype in FILE_TYPES_IMAGE:
        for size in THUMB_SIZES:
            (w, h) = size
            split = instance.file.name.rsplit('.', 1)
            thumb_name = '%s.%sx%s.%s' % (split[0], w, h, split[1])

            if not instance.file.storage.exists(thumb_name):
                # you can use another thumbnailing function if you like
                thumb_content = thumbs.generate_thumb(instance.file, size, split[1])

                thumb_name_ = instance.file.storage.save(thumb_name, thumb_content)

                if not thumb_name == thumb_name_:
                    raise ValueError(
                        'There is already a file named %s' % thumb_name_)


@receiver(pre_delete, sender=Post)
def rebuild_refmap(instance, **kwargs):
    for referenced_post in instance.refposts.all():
        referenced_post.build_refmap(excluded_ids=[instance.id])
        referenced_post.save(update_fields=['refmap'])


@receiver(post_delete, sender=Attachment)
def delete_file(instance, **kwargs):
    if instance.is_internal():
        file = MEDIA_ROOT + instance.file.name
        try:
            os.remove(file)
        except FileNotFoundError:
            pass
        if instance.mimetype in FILE_TYPES_IMAGE:
            for size in THUMB_SIZES:
                file_name_parts = instance.file.name.split('.')
                thumb_file = MEDIA_ROOT + '{}.{}x{}.{}'.format(file_name_parts[0], size[0], size[1], file_name_parts[1])
                try:
                    os.remove(thumb_file)
                except FileNotFoundError:
                    pass