from random import shuffle
import re

from django.core.exceptions import ValidationError
from django.forms import Form, CharField, EmailField, Textarea, ChoiceField, BooleanField
import sshpubkeys as ssh

from .models import Townie, SSH_TYPE_CHOICES
from common.forms import CaptchaField, throttler

submission_throttle = {}
throttle_submission = throttler(submission_throttle)


USERNAME_RE = re.compile(r'[a-z][a-z0-9_]+')
USERNAME_MIN_LENGTH = 4
DISPLAY_NAME_RE = re.compile(r"[a-zA-Z0-9_\-']+")
DISPLAY_MIN_LENGTH = 2


def validate_username(username):
    if len(username) < USERNAME_MIN_LENGTH:
        raise ValidationError('Username too short.')
    if not USERNAME_RE.match(username):
        raise ValidationError('Username must be all lowercase, start with a letter, and only use the _ special character')
    duplicate = Townie.objects.filter(username=username).count()
    if duplicate > 0:
        raise ValidationError('Username already in use :(')


def validate_displayname(display_name):
    if len(display_name) < DISPLAY_MIN_LENGTH:
        raise ValidationError('Display name too short.')
    if not DISPLAY_NAME_RE.match(display_name):
        raise ValidationError("Valid characters: a-z, A-Z, 0-9, -, _, and '.")

def validate_pubkey(pubkey):
    # TODO see if I can get the type out
    key = ssh.SSHKey(pubkey, strict_mode=False, skip_option_parsing=True)
    try:
        key.parse()
    except ssh.InvalidKeyException as e:
        raise ValidationError('Could not validate key: {}'.format(e))
    except NotImplementedError as e:
        raise ValidationError('Invalid key type')
    except Exception as e:
        raise ValidationError('unknown error: {}'.format(e))


class TownieForm(Form):
    username = CharField(
        validators=(validate_username,),
        help_text='lowercase and no spaces. underscore ok',
        label='username')
    email = EmailField(
        help_text='only used to message you about your account and nothing else.',
        label='e-mail')
    displayname = CharField(
        validators=(validate_displayname,),
        help_text='100% optional. pseudonyms welcome.',
        label='display name',
        required=False)
    reasons = CharField(
        widget=Textarea,
        required=False,
        label='what interests you about tilde.town?',
        help_text='This is a totally optional place for you to tell us what excites you about getting a ~ account. This is mainly just so we can all feel warm fuzzies.')
    captcha = CaptchaField()
    pubkey = CharField(
        widget=Textarea,
        validators=(validate_pubkey,),
        label='SSH public key',
        help_text='if this is not a thing you are familiar with, that\'s okay! check out <a href="https://tilde.town/~wiki/ssh.html">our guide</a> to learn how to get one of these.')
    pubkey_type = ChoiceField(
        choices=SSH_TYPE_CHOICES,
        label='SSH public key type',
        help_text="unless you know what you're doing you can leave this be.")
    aup = BooleanField(
        label='i super agree to our acceptable use policy',
        help_text='please read our <a href="https://tilde.town/~wiki/conduct.html">code of conduct</a> and click this box if you agree.')

    def clean(self):
        result = super().clean()
        if self.errors:
            raise ValidationError('oops, looks like there were some problems below.')
        throttle_submission(self.cleaned_data['email'])
        return result