import os
import hashlib
import mimetypes

from django import forms
from django.core.exceptions import ValidationError
from django.core.files.storage import default_storage

from university.models import UserOnlineExam, OnlineExamEvent, OnlineExam, Upload


class AdminMessageForm(forms.Form):

    comment = forms.CharField(required=True, max_length=64)

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

    def clean(self):
        if self.user_online_exam.status != UserOnlineExam.STATUS_UNDERWAY:
            self.add_error('', '考试状态错误，只有考试进行中才能使用该功能')
        return self.cleaned_data

    def send_warning_message(self):
        comment = self.cleaned_data.get('comment', '')
        OnlineExamEvent.objects.create(
            user=self.user_online_exam.user,
            online_exam=self.user_online_exam.online_exam,
            user_online_exam=self.user_online_exam,
            event_type=OnlineExamEvent.EVENT_ADMIN_WARING_MESSAGE,
            comment=comment
        )
        self.user_online_exam.send_warning_ws_message(comment)

    def send_force_submit(self):
        comment = self.cleaned_data.get('comment', '')
        self.user_online_exam.is_force_submitted = True
        self.user_online_exam.force_submit_reason = comment
        self.user_online_exam.save(update_fields=['is_force_submitted', 'force_submit_reason'])

        OnlineExamEvent.objects.create(
            user=self.user_online_exam.user,
            online_exam=self.user_online_exam.online_exam,
            user_online_exam=self.user_online_exam,
            event_type=OnlineExamEvent.EVENT_ADMIN_FORCE_SUBMIT,
            comment=comment
        )
        self.user_online_exam.send_admin_force_submit_ws_message(comment)


class OnlineExamEditForm(forms.ModelForm):

    def clean(self):
        if self._errors:
            return
        start_at = self.cleaned_data.get('start_at')
        end_at = self.cleaned_data.get('end_at')
        registration_deadline = self.cleaned_data.get('registration_deadline')
        if start_at >= end_at:
            self.add_error('start_at', '开始时间不能晚于结束时间')
        if registration_deadline >= start_at:
            self.add_error('registration_deadline', '报名截止时间不能晚于开始时间')
        return self.cleaned_data

    class Meta:
        model = OnlineExam
        fields = [
            'name', 'short_description', 'detailed_description', 'rules',
            'registration_deadline', 'start_at', 'end_at', 'allowed_cheating_times',
            'alert_wechat_webhook'
        ]


class OnlineExamUploadCertForm(forms.Form):

    file = forms.FileField()

    def __init__(self, user_online_exam, *args, **kwargs):
        self.user_online_exam = user_online_exam
        return super(OnlineExamUploadCertForm, self).__init__(*args, **kwargs)

    def clean_file(self):
        file = self.cleaned_data.get('file')
        if file:
            try:
                file._size
            except Exception:
                pass
            else:
                if file._size > 3 * 1 << 20:
                    raise ValidationError('文件大小超过限制')
        return file

    def save(self):
        file_obj = self.cleaned_data.get('file')
        if file_obj:
            content_hash = hashlib.sha1(file_obj.read()).hexdigest()
            content_type, _temp = mimetypes.guess_type(file_obj.name, strict=False)
            file_path = self.generate_filepath_by_hash(content_hash)
            _temp, file_extension = os.path.splitext(file_obj.name)
            if file_extension:
                file_path += file_extension
            file_obj.seek(0)
            file_path = default_storage.save(file_path, file_obj)
            upload = Upload.objects.create(
                user=self.user_online_exam.user,
                original_filename=file_obj.name,
                filesize=file_obj.size,
                path=file_path,
                sha1=content_hash,
                extension=content_type,
                is_private=True
            )
            self.user_online_exam.cert = upload
            self.user_online_exam.save(update_fields=['cert'])

    def generate_filepath_by_hash(self, file_hash):
        return '{}/{}/{}'.format(
            file_hash[0],
            file_hash[1],
            file_hash
        )