from enum import StrEnum
from pathlib import Path

from django.conf import settings
from django.core.validators import FileExtensionValidator
from django.db import models
from django.db.models.signals import post_delete
from django.dispatch import receiver


class FontStyle(StrEnum):
    SANS_SERIF = "sans-serif"
    SERIF = "serif"
    MONOSPACE = "monospace"


class BackgroundColor(StrEnum):
    WHITE = "#ffffff"
    SEPIA = "#f4e4c1"
    DARK = "#1a1a2e"
    GREEN = "#c7edcc"


class Book(models.Model):
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="books",
    )
    title = models.CharField(max_length=512)
    author = models.CharField(max_length=256, blank=True, default="")
    file = models.FileField(
        upload_to="books/%Y/%m/%d/",
        validators=[FileExtensionValidator(allowed_extensions=["epub", "pdf"])],
    )
    cover_image = models.ImageField(upload_to="covers/%Y/%m/%d/", blank=True, null=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-created_at"]
        indexes = [
            models.Index(fields=["user", "-created_at"]),
        ]

    def __str__(self) -> str:
        return self.title

    def filename(self) -> str:
        return Path(self.file.name).name


@receiver(post_delete, sender=Book)
def _auto_delete_file_on_delete(sender: type[Book], instance: Book, **kwargs: object) -> None:
    """Delete the uploaded file when the Book record is deleted."""
    if instance.file:
        instance.file.delete(save=False)
    if instance.cover_image:
        instance.cover_image.delete(save=False)


class ReadingProgress(models.Model):
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="reading_progress",
    )
    book = models.OneToOneField(
        Book,
        on_delete=models.CASCADE,
        related_name="reading_progress",
    )
    current_position = models.FloatField(default=0.0)
    """Position in the book as a percentage (0.0 to 100.0)"""
    last_page = models.IntegerField(default=0)
    """Last page/paragraph index for granular tracking"""
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        verbose_name_plural = "reading progress"
        unique_together = [("user", "book")]

    def __str__(self) -> str:
        return f"{self.book.title} — {self.current_position:.1f}%"


class ReadingSettings(models.Model):
    user = models.OneToOneField(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="reading_settings",
    )
    font_size = models.IntegerField(default=18)
    """Font size in pixels (min 12, max 36)"""
    font_style = models.CharField(
        max_length=20,
        choices=[(s.value, s.name.replace("_", " ").title()) for s in FontStyle],
        default=FontStyle.SANS_SERIF.value,
    )
    background_color = models.CharField(
        max_length=7,
        choices=[(c.value, c.name.title()) for c in BackgroundColor],
        default=BackgroundColor.WHITE.value,
    )
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        verbose_name_plural = "reading settings"

    def __str__(self) -> str:
        return f"Settings for {self.user}"