import os
from pathlib import Path
from django.db import models
from django.db.models import signals
from django.conf import settings
from django.core.exceptions import ValidationError
from django.core.files.base import ContentFile
from django.dispatch import receiver
from django.urls import reverse
from django.utils import timezone
from PIL import Image
from io import BytesIO


def image_upload(instance, filename):
    op_id = instance.op.id if instance.op else instance.id
    now = timezone.now()
    now_sec = now.strftime("%s.%f")
    ext = Path(filename).suffix.lower()
    if ext in (".jpeg", ".jpg"):
        ext = ".jpg"

    if ext not in (".jpg", ".png", ".gif"):
        raise Exception("File type invalid")

    return f"{instance.board.url}/{now_sec}{ext}"


def thumbs_upload(instance, filename):
    op_id = instance.op.id if instance.op else instance.id
    now = timezone.now()
    now_sec = now.strftime("%s.%f")
    ext = Path(filename).suffix.lower()
    return f"{instance.board.url}/{now_sec}t{ext}"


class Board(models.Model):
    # The short URL name for the board
    url = models.CharField(max_length=255, null=False, blank=False, unique=True)
    # Human-readable name for the board
    name = models.CharField(max_length=255, null=False, blank=False)

    @property
    def threads(self):
        return Post.objects.filter(board=self, op=None)


class Post(models.Model):
    # Board that this post was made on
    board = models.ForeignKey("Board", on_delete=models.CASCADE)
    # Thread that this is a part of
    op = models.ForeignKey(
        "self", null=True, on_delete=models.CASCADE, related_name="all_replies"
    )
    # Post that this is replying to
    reply = models.ForeignKey(
        "self", null=True, on_delete=models.CASCADE, related_name="replies"
    )
    # User's supplied name for this post
    name = models.CharField(max_length=255, null=True, blank=True)
    # User's supplied subject for this post
    subject = models.CharField(max_length=255, null=True, blank=True)
    # Text of this post
    text = models.TextField(max_length=10000, null=False, blank=True)
    # The IP address of the user that made this post
    ip = models.GenericIPAddressField()
    # Creation time
    created = models.DateTimeField(auto_now_add=True)
    # Last bump time
    last_bump = models.DateTimeField(auto_now_add=True)
    # Image
    image = models.ImageField(
        upload_to=image_upload,
        null=True,
        blank=True,
        width_field="image_width",
        height_field="image_height",
    )
    # Thumbnail
    thumbnail = models.ImageField(upload_to=thumbs_upload, editable=False, null=True)
    # Original image name
    original_image_name = models.CharField(max_length=255, null=True)
    # Image width and height
    image_width = models.IntegerField(null=True)
    image_height = models.IntegerField(null=True)

    def save(self, *args, **kwargs):
        if self.image:
            self.original_image_name = Path(self.image.name).parts[-1]
            self.__make_thumbnail()
        super(Post, self).save(*args, **kwargs)

    def __make_thumbnail(self):
        image = Image.open(self.image)
        image.thumbnail(settings.THUMB_SIZE, Image.ANTIALIAS)

        image_path = Path(self.image.name)
        thumb_path = Path(image_path.stem + "t" + image_path.suffix)

        ext = thumb_path.suffix.lower()
        if ext in (".jpg", ".jpeg"):
            FTYPE = "JPEG"
        elif ext == ".gif":
            FTYPE = "GIF"
        elif ext == ".png":
            FTYPE = "PNG"
        else:
            raise Exception("File type invalid")

        thumb_temp = BytesIO()
        image.save(thumb_temp, FTYPE)
        thumb_temp.seek(0)

        # save=False stops recursion
        self.thumbnail.save(thumb_path, ContentFile(thumb_temp.read()), save=False)
        thumb_temp.close()

    def get_absolute_url(self):
        if self.op is None:
            return reverse(
                "board:post_detail", kwargs={"url": self.board.url, "id": self.id}
            )
        else:
            return (
                reverse(
                    "board:post_detail",
                    kwargs={"url": self.board.url, "id": self.op.id},
                )
                + f"#p{self.id}"
            )

    def clean(self):
        if self.image and self.image.size > settings.MAX_UPLOAD_SIZE:
            raise ValidationError(
                "Image supplied is too large. Maximum image size is %(max)s",
                params={"max": settings.MAX_UPLOAD_SIZE},
            )


@receiver(signals.post_save, sender=Post)
def post_created(sender, instance, created, **kwargs):
    if created and instance.op:
        instance.op.last_bump = timezone.now()
        instance.op.save()


@receiver(signals.post_delete, sender=Post)
def post_deleted(sender, instance, **kwargs):
    if instance.image and Path(instance.image.path).is_file():
        os.remove(instance.image.path)
    if instance.thumbnail and Path(instance.thumbnail.path).is_file():
        os.remove(instance.thumbnail.path)