import datetime
import logging

from django import forms
from django.forms import ModelForm
from django.utils import timezone

from web.algorithm import VerhoeffAlgorithm
from web.forms.forms import DATEPICKER_DATE_ATTRS
from web.models import VoucherType, VoucherTypePrice, Voucher
from web.models.constants import VOUCHER_STATUS_NEW, VOUCHER_STATUS_USED

logger = logging.getLogger(__name__)


class VoucherTypeForm(ModelForm):
    class Meta:
        model = VoucherType
        exclude = ['study']


class VoucherTypePriceForm(ModelForm):
    start_date = forms.DateField(label="Start date",
                                 widget=forms.DateInput(DATEPICKER_DATE_ATTRS, "%Y-%m-%d")
                                 )
    end_date = forms.DateField(label="End date",
                               widget=forms.DateInput(DATEPICKER_DATE_ATTRS, "%Y-%m-%d")
                               )

    class Meta:
        model = VoucherTypePrice
        exclude = ['voucher_type']


class VoucherForm(ModelForm):
    class Meta:
        model = Voucher
        fields = '__all__'

    def __init__(self, *args, **kwargs):
        voucher_types = kwargs.pop('voucher_types', VoucherType.objects.all())
        super(VoucherForm, self).__init__(*args, **kwargs)

        self.fields['voucher_type'].queryset = voucher_types

        self.fields['number'].widget.attrs['readonly'] = True
        self.fields['number'].required = False

        self.fields['issue_date'].widget.attrs['readonly'] = True
        self.fields['issue_date'].required = False
        self.fields['expiry_date'].widget.attrs['readonly'] = True
        self.fields['expiry_date'].required = False
        self.fields['use_date'].widget.attrs['readonly'] = True
        instance = getattr(self, 'instance', None)
        if instance and instance.pk:
            self.fields['voucher_type'].widget.attrs['readonly'] = True
            if instance.status != VOUCHER_STATUS_NEW:
                self.fields['status'].widget.attrs['readonly'] = True
                self.fields['feedback'].widget.attrs['readonly'] = True
                self.fields['usage_partner'].widget.attrs['readonly'] = True

    def clean(self):
        if self.cleaned_data["status"] == VOUCHER_STATUS_USED and not self.cleaned_data["usage_partner"]:
            self.add_error('usage_partner', "Partner must be defined for used voucher")
        if self.cleaned_data["status"] != VOUCHER_STATUS_USED and self.cleaned_data["usage_partner"]:
            self.add_error('status', "Status must be used for voucher with defined partner")

    def save(self, commit=True):
        instance = super(VoucherForm, self).save(commit=False)
        if not instance.id:
            instance.issue_date = timezone.now()
            instance.expiry_date = instance.issue_date + datetime.timedelta(days=92)
            max_id = str(0).zfill(5)
            if Voucher.objects.all().count() > 0:
                max_id = str(Voucher.objects.latest('id').id).zfill(5)
            instance.number = max_id + VerhoeffAlgorithm.calculate_verhoeff_check_sum(max_id)
        if instance.status == VOUCHER_STATUS_USED and not instance.use_date:
            instance.use_date = timezone.now()

        if commit:
            instance.save()