from datetime import datetime, timedelta

import shortuuid
from django.core.validators import MaxLengthValidator
from django.db import models
from django.urls import reverse
from django.utils import timezone
from django.utils.translation import gettext_lazy as _

from webtools import settings


class Paste(models.Model):
    """Paste object."""

    filename = models.CharField(max_length=255, default="")
    slug = models.SlugField(unique=True, editable=False)
    content = models.TextField(
        validators=[MaxLengthValidator(settings.PASTE["max_characters"])]
    )
    size = models.IntegerField(default=0, editable=False)
    paste_time = models.DateTimeField(auto_now_add=True)
    viewcount = models.IntegerField(default=0, editable=False)

    def compute_size(self):
        """Computes size."""
        self.size = len(self.content)

    def get_absolute_url(self):
        return reverse("short_paste", kwargs={"slug": self.slug})

    def incr_viewcount(self):
        """Increment view counter."""
        self.viewcount = self.viewcount + 1
        self.save()

    def __str__(self):
        excerpt = repr(self.content.split("\n")[0][:100]) + (
            "..." if len(self.content) > 100 else ""
        )
        return f"{self.slug} - {excerpt}"

    @classmethod
    def choose_prefix(cls, filenames):
        """Find a prefix free for all the given filenames.

        Such as <prefix>/filename is unused.
        """
        while True:
            uuid = shortuuid.uuid()
            for i in range(4, len(uuid) + 1):
                potential_uuid = uuid[:i]
                for filename in filenames:
                    slug = f"{potential_uuid}/{filename}"
                    if not any(cls.objects.filter(slug=slug) for filename in filenames):
                        return potential_uuid

    def choose_slug(self):
        while True:
            uuid = shortuuid.uuid()
            for i in range(4, len(uuid)):
                potential_uuid = uuid[:i]
                if not type(self).objects.filter(slug=potential_uuid):
                    self.slug = potential_uuid
                    return