from __future__ import unicode_literals

from django import forms
from django.core.exceptions import ValidationError
from django.forms.formsets import formset_factory
from django.utils.module_loading import import_string
from django.utils.translation import ugettext_lazy as _

from .models import MetadataType
from .settings import (
    setting_available_functions, setting_available_models,
    setting_available_validators
)


class MetadataForm(forms.Form):

    def clean_value(self):
        metadata_type = MetadataType.objects.get(pk=self.cleaned_data['id'])

        if metadata_type.validation:
            validator = import_string(metadata_type.validation)()

            try:
                # If it is a parsing function we should get a value
                # If it is a validation function we get nothing on success
                result = validator.validate(self.cleaned_data['value'])
            except Exception as exception:
                # If it is a validation function and an exception is raise
                # we wrap that into a new ValidationError exception
                # If the function exception is a ValidationError itself the
                # error messages will be in a 'messages' property, so we
                # contatenate them.
                # Otherwise we extract whatever single message the exception
                # included.
                try:
                    message = ', '.join(exception.messages)
                except AttributeError:
                    message = unicode(exception)

                raise ValidationError(_('Invalid value: %(message)s'), params={'message': message}, code='invalid')
            else:
                # Return the result if it was a parsing function
                # If it was a validation function and passed correctly we return
                # the original input value
                return result or self.cleaned_data['value']
        else:
            # If a validator was never specified we return the original value
            return self.cleaned_data['value']

    def __init__(self, *args, **kwargs):
        super(MetadataForm, self).__init__(*args, **kwargs)

        # Set form fields initial values
        if 'initial' in kwargs:
            self.metadata_type = kwargs['initial'].pop('metadata_type', None)
            required = kwargs['initial'].pop('required', False)
            required_string = ''

            if required:
                self.fields['value'].required = True
                required_string = ' (%s)' % _('Required')
            else:
                self.fields['value'].required = False

            self.fields['name'].initial = '%s%s' % ((self.metadata_type.label if self.metadata_type.label else self.metadata_type.name), required_string)
            self.fields['id'].initial = self.metadata_type.pk

            if self.metadata_type.lookup:
                try:
                    choices = eval(self.metadata_type.lookup, setting_available_models.value)
                    self.fields['value'] = forms.ChoiceField(label=self.fields['value'].label)
                    choices = zip(choices, choices)
                    if not required:
                        choices.insert(0, ('', '------'))
                    self.fields['value'].choices = choices
                    self.fields['value'].required = required
                except Exception as exception:
                    self.fields['value'].initial = exception
                    self.fields['value'].widget = forms.TextInput(attrs={'readonly': 'readonly'})

            if self.metadata_type.default:
                try:
                    self.fields['value'].initial = eval(self.metadata_type.default, setting_available_functions.value)
                except Exception as exception:
                    self.fields['value'].initial = exception

    id = forms.CharField(label=_('ID'), widget=forms.HiddenInput)

    name = forms.CharField(label=_('Name'), required=False, widget=forms.TextInput(attrs={'readonly': 'readonly'}))
    value = forms.CharField(label=_('Value'), required=False)
    update = forms.BooleanField(initial=True, label=_('Update'), required=False)

MetadataFormSet = formset_factory(MetadataForm, extra=0)


class AddMetadataForm(forms.Form):
    metadata_type = forms.ModelChoiceField(queryset=MetadataType.objects.all(), label=_('Metadata type'))

    def __init__(self, *args, **kwargs):
        document_type = kwargs.pop('document_type')
        super(AddMetadataForm, self).__init__(*args, **kwargs)
        self.fields['metadata_type'].queryset = document_type.metadata.all()


class MetadataRemoveForm(MetadataForm):
    update = forms.BooleanField(initial=False, label=_('Remove'), required=False)

    def __init__(self, *args, **kwargs):
        super(MetadataRemoveForm, self).__init__(*args, **kwargs)
        self.fields.pop('value')


MetadataRemoveFormSet = formset_factory(MetadataRemoveForm, extra=0)


class MetadataTypeForm(forms.ModelForm):
    class Meta:
        fields = ('name', 'label', 'default', 'lookup', 'validation')
        model = MetadataType