# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, you can obtain one at http://mozilla.org/MPL/2.0/.
from django import forms
from django.core.exceptions import ValidationError
from django.template.defaultfilters import filesizeformat


class PublicKeyFileField(forms.FileField):
    """
    Custom Django for file field that only accepts SSH public keys.

    The cleaned data is the public key as a string.
    """
    def clean(self, data, initial=None):
        uploaded_file = super(PublicKeyFileField, self).clean(data, initial)
        if uploaded_file.size > 100000:
            raise ValidationError(
                'File size must be at most 100kB, actual size is {}'.format(
                    filesizeformat(uploaded_file.size)
                )
            )
        contents = uploaded_file.read()
        if not contents.startswith('ssh-rsa AAAAB3'):
            raise ValidationError(
                'Invalid public key (a public key should start with \'ssh-rsa AAAAB3\')'
            )
        return contents


class CreatedByFormMixin(object):
    """
    Custom Django form mixin that takes a user object and if the provided
    model form instance has a primary key checks if the given user
    matches the "created_by" field.
    """
    def __init__(self, user, *args, **kwargs):
        self.created_by = user
        super(CreatedByFormMixin, self).__init__(*args, **kwargs)

    def clean(self):
        """
        only allow deleting clusters that one created
        """
        super(CreatedByFormMixin, self).clean()
        if self.instance.id and self.created_by != self.instance.created_by:
            raise forms.ValidationError(
                'Access denied to the data of another user'
            )