from django.db import models
from django.forms import ModelForm, CharField, TextInput
import random


class Link(models.Model):
    id = models.CharField(primary_key=True, max_length=12)
    url = models.URLField(max_length=2048)
    created_at = models.DateTimeField(auto_now_add=True)
    clicks = models.IntegerField(default=0)
    ip = models.GenericIPAddressField(null=True)

    def __unicode__(self):
        return self.url

    def generate_unique_id(self, length=8):
        attempts = 0
        id = random_id(length)
        try:
            while Link.objects.get(id=id) and attempts < 10:
                attempts = attempts + 1
                id = random_id()
        except:
            pass
        return id

    def save(self, *args, **kwargs):
        if not self.pk:
            self.id = self.generate_unique_id()
        super(Link, self).save(*args, **kwargs)


class LinkForm(ModelForm):
    url = CharField(widget=TextInput(attrs={
                    'class': 'u-full-width',
                    'placeholder': 'Paste the link you want to shorten'}),
                    label='')

    class Meta:
        model = Link
        fields = ['url']


def random_id(length):
    rand = ''
    for i in range(0, length):
        rand += int_to_char(random.randint(0, 61))
    return rand


def int_to_char(int):
    if(int < 10):
        char = chr(int + 48)
    elif(int < 36):
        char = chr(int + 55)
    else:
        char = chr(int + 61)
    return char