from django import forms
from django.core.exceptions import ValidationError
from django.utils import timezone
from django.contrib.auth.models import Group

from university.models import UserCourse, User, GroupCourse


class AdminGrantUserCourseForm(forms.Form):

    user_id = forms.IntegerField(required=True)
    expires_at = forms.DateTimeField(required=True)

    def __init__(self, staff, course, *args, **kwargs):
        self.target_user = None
        self.staff = staff
        self.course = course
        super(AdminGrantUserCourseForm, self).__init__(*args, **kwargs)

    def clean_user_id(self):
        user_id = self.cleaned_data.get('user_id')
        if user_id:
            try:
                self.target_user = User.objects.get(id=user_id)
            except Exception:
                raise ValidationError('未找到该用户')
            if UserCourse.objects.filter(
                    user=self.target_user, course=self.course).exists():
                raise ValidationError('该用户已有权限')
        return user_id

    def clean_expires_at(self):
        expires_at = self.cleaned_data.get('expires_at')
        if expires_at and expires_at < timezone.now():
            raise ValidationError('不能晚于当前时间')
        return expires_at

    def save(self):
        UserCourse.objects.create(
            user=self.target_user,
            course=self.course,
            expires_at=self.cleaned_data.get('expires_at'),
            created_by=self.staff
        )


class AdminGrantGroupCourseForm(forms.Form):

    group_id = forms.IntegerField(required=True)

    def __init__(self, staff, course, *args, **kwargs):
        self.target_group = None
        self.staff = staff
        self.course = course
        super(AdminGrantGroupCourseForm, self).__init__(*args, **kwargs)

    def clean_group_id(self):
        group_id = self.cleaned_data.get('group_id')
        if group_id:
            try:
                self.target_group = Group.objects.get(id=group_id)
            except Exception:
                raise ValidationError('未找到该组')
            if GroupCourse.objects.filter(
                    group=self.target_group, course=self.course).exists():
                raise ValidationError('该组已有权限')
        return group_id

    def save(self):
        GroupCourse.objects.create(
            group=self.target_group,
            course=self.course,
            created_by=self.staff
        )