from __future__ import unicode_literals
from django import forms
from django.db import models
from django.utils.text import capfirst
from django.utils.translation import ugettext_lazy as _
from haystack import connections
from haystack.constants import DEFAULT_ALIAS
from haystack.query import SearchQuerySet, EmptySearchQuerySet

try:
    from django.utils.encoding import smart_text
except ImportError:
    from django.utils.encoding import smart_unicode as smart_text


def model_choices(using=DEFAULT_ALIAS):
    choices = [("%s.%s" % (m._meta.app_label, m._meta.module_name), capfirst(smart_text(m._meta.verbose_name_plural))) for m in connections[using].get_unified_index().get_indexed_models()]
    return sorted(choices, key=lambda x: x[1])


class SearchForm(forms.Form):
    q = forms.CharField(required=False, label=_('Search'))

    def __init__(self, *args, **kwargs):
        self.searchqueryset = kwargs.pop('searchqueryset', None)
        self.load_all = kwargs.pop('load_all', False)

        if self.searchqueryset is None:
            self.searchqueryset = SearchQuerySet()

        super(SearchForm, self).__init__(*args, **kwargs)

    def no_query_found(self):
        """
        Determines the behavior when no query was found.

        By default, no results are returned (``EmptySearchQuerySet``).

        Should you want to show all results, override this method in your
        own ``SearchForm`` subclass and do ``return self.searchqueryset.all()``.
        """
        return EmptySearchQuerySet()

    def search(self):
        if not self.is_valid():
            return self.no_query_found()

        if not self.cleaned_data.get('q'):
            return self.no_query_found()

        sqs = self.searchqueryset.auto_query(self.cleaned_data['q'])

        if self.load_all:
            sqs = sqs.load_all()

        return sqs

    def get_suggestion(self):
        if not self.is_valid():
            return None

        return self.searchqueryset.spelling_suggestion(self.cleaned_data['q'])


class HighlightedSearchForm(SearchForm):
    def search(self):
        return super(HighlightedSearchForm, self).search().highlight()


class FacetedSearchForm(SearchForm):
    def __init__(self, *args, **kwargs):
        self.selected_facets = kwargs.pop("selected_facets", [])
        super(FacetedSearchForm, self).__init__(*args, **kwargs)

    def search(self):
        sqs = super(FacetedSearchForm, self).search()

        # We need to process each facet to ensure that the field name and the
        # value are quoted correctly and separately:
        for facet in self.selected_facets:
            if ":" not in facet:
                continue

            field, value = facet.split(":", 1)

            if value:
                sqs = sqs.narrow(u'%s:"%s"' % (field, sqs.query.clean(value)))

        return sqs


class ModelSearchForm(SearchForm):
    def __init__(self, *args, **kwargs):
        super(ModelSearchForm, self).__init__(*args, **kwargs)
        self.fields['models'] = forms.MultipleChoiceField(choices=model_choices(), required=False, label=_('Search In'), widget=forms.CheckboxSelectMultiple)

    def get_models(self):
        """Return an alphabetical list of model classes in the index."""
        search_models = []

        if self.is_valid():
            for model in self.cleaned_data['models']:
                search_models.append(models.get_model(*model.split('.')))

        return search_models

    def search(self):
        sqs = super(ModelSearchForm, self).search()
        return sqs.models(*self.get_models())


class HighlightedModelSearchForm(ModelSearchForm):
    def search(self):
        return super(HighlightedModelSearchForm, self).search().highlight()


class FacetedModelSearchForm(ModelSearchForm):
    selected_facets = forms.CharField(required=False, widget=forms.HiddenInput)

    def search(self):
        sqs = super(FacetedModelSearchForm, self).search()

        if hasattr(self, 'cleaned_data') and self.cleaned_data['selected_facets']:
            sqs = sqs.narrow(self.cleaned_data['selected_facets'])

        return sqs.models(*self.get_models())
