from django.db import models
from django.conf import settings

from core.models import BaseModel
from core.media import (
    delete_image_derivatives_by_name,
    get_image_previous_name,
    safe_process_public_image,
)


class Gallery(BaseModel):
    title = models.CharField(max_length=200)
    description = models.TextField(blank=True)
    image = models.ImageField(upload_to='gallery/')
    uploaded_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='gallery_images')
    alt_text = models.CharField(max_length=200, blank=True)
    file_size = models.PositiveIntegerField(null=True, blank=True)
    width = models.PositiveIntegerField(null=True, blank=True)
    height = models.PositiveIntegerField(null=True, blank=True)
    is_public = models.BooleanField(default=True)

    class Meta:
        ordering = ['-created_at']
        verbose_name_plural = "Gallery Images"

    def __str__(self):
        return self.title

    def save(self, *args, **kwargs):
        previous_image_name = get_image_previous_name(self, "image")
        current_image_name = self.image.name if self.image else None
        image_changed = previous_image_name != current_image_name

        super().save(*args, **kwargs)

        if image_changed and previous_image_name:
            delete_image_derivatives_by_name(
                self.image.storage if self.image else None,
                previous_image_name,
                "gallery",
                delete_original=True,
            )

        if not self.image:
            if image_changed:
                Gallery.objects.filter(pk=self.pk).update(file_size=None, width=None, height=None)
            return

        if getattr(self, "_defer_image_processing", False):
            return

        if image_changed:
            result = safe_process_public_image(self.image, "gallery")
            if result:
                Gallery.objects.filter(pk=self.pk).update(
                    file_size=result.file_size,
                    width=result.width,
                    height=result.height,
                )
                self.file_size = result.file_size
                self.width = result.width
                self.height = result.height

    @property
    def file_size_mb(self):
        """Return file size in MB"""
        if self.file_size:
            return round(self.file_size / (1024 * 1024), 2)
        return 0

    @property
    def markdown_url(self):
        """Return URL for use in markdown"""
        return f"![{self.alt_text or self.title}]({settings.BACKEND_ROOT}{self.image.url})"