import base64
import hashlib
from io import BytesIO
from django import forms
from django.core.exceptions import ValidationError
from django.core.files.storage import default_storage
from django.utils.translation import ugettext_lazy as _
from django.utils import timezone

from university.models import UserOnlineExam, UserOnlineExamFace, Upload
from university.file_storage.utils import generate_random_file_path
from university.tasks.online_exam import async_validate_examinee_id_face


class ExamineeInfoForm(forms.Form):

    name = forms.CharField(required=True, max_length=64)
    chinese_id_number = forms.CharField(required=True, max_length=64)

    def __init__(self, user, user_online_exam, *args, **kwargs):
        self.user = user
        self.user_online_exam = user_online_exam
        super(ExamineeInfoForm, self).__init__(*args, **kwargs)

    def clean_chinese_id_number(self):
        chinese_id_number = self.cleaned_data.get('chinese_id_number')
        if chinese_id_number:
            # TODO
            if not (15 <= len(chinese_id_number) <= 18):
                raise ValidationError(_('invalid chinese ID number'))
        return chinese_id_number

    def save(self):
        self.user_online_exam.examinee_name = self.cleaned_data.get('name')
        self.user_online_exam.examinee_chinese_id = self.cleaned_data.get('chinese_id_number')
        self.user_online_exam.save(update_fields=['examinee_name', 'examinee_chinese_id'])

        identity_face = self.user_online_exam.identity_face
        identity_face.status = UserOnlineExamFace.STATUS_PENDING
        identity_face.save(update_fields=['status'])
        async_validate_examinee_id_face.delay(identity_face.id)


class FaceIdentificationForm(forms.Form):

    image = forms.CharField(required=True)

    def __init__(self, user, user_online_exam, *args, **kwargs):
        self.user_online_exam = user_online_exam
        self.user = user
        super(FaceIdentificationForm, self).__init__(*args, **kwargs)

    def clean_image(self):
        image = self.cleaned_data.get('image')
        if image:
            if len(image) > (6 * 1 << 20):
                raise ValidationError('文件大小超过限制')

            if not image.startswith('data:image/'):
                raise ValidationError('图片格式错误, 格式应类似于: data:image/jpeg;base64,/9j/4AA....')
        return image

    def save(self):
        image = self.cleaned_data.get('image')
        content_type, base64string = image.split(':', 1)[1].split(';', 1)
        file_suffix = content_type.split('/')[1]
        base64string = base64string.split(',', 1)[1]
        img = base64.b64decode(base64string)
        content_hash = hashlib.sha1(img).hexdigest()
        file_obj = BytesIO()
        file_obj.write(img)
        file_obj.seek(0)
        file_path = '{}.{}'.format(generate_random_file_path(), file_suffix)
        default_storage.save(file_path, file_obj)
        upload = Upload.objects.create(
            user=self.user,
            original_filename=file_path,
            filesize=len(img),
            path=file_path,
            sha1=content_hash,
            extension=content_type,
            is_private=True
        )
        exam_face = UserOnlineExamFace.objects.create(
            user=self.user,
            online_exam=self.user_online_exam.online_exam,
            user_online_exam=self.user_online_exam,
            face=upload,
            face_type=UserOnlineExamFace.FACE_TYPE_IDENTITY
        )

        if self.user_online_exam.status == UserOnlineExam.STATUS_WAIT:
            self.user_online_exam.identity_face = exam_face
            self.user_online_exam.status = UserOnlineExam.STATUS_UNDERWAY
            self.user_online_exam.start_at = timezone.now()
            self.user_online_exam.save()

        async_validate_examinee_id_face.delay(exam_face.id)


class ExamineeCaptureForm(forms.Form):

    image = forms.CharField(required=True)

    def __init__(self, user, *args, **kwargs):
        self.user = user
        super(ExamineeCaptureForm, self).__init__(*args, **kwargs)

    def clean_image(self):
        image = self.cleaned_data.get('image')
        if image:
            if len(image) > (6 * 1 << 20):
                raise ValidationError('文件大小超过限制')

            if not image.startswith('data:image/'):
                raise ValidationError('图片格式错误, 格式应类似于: data:image/jpeg;base64,/9j/4AA....')
        return image