from django import http

from django.db import models

from django.contrib.databrowse.datastructures import EasyModel

from django.contrib.databrowse.sites import DatabrowsePlugin

from django.shortcuts import render_to_response

from django.utils.text import capfirst

from django.utils.encoding import smart_str, force_unicode

from django.utils.safestring import mark_safe

import urllib

class FieldChoicePlugin(DatabrowsePlugin):

    def __init__(self, field_filter=None):

        # If field_filter is given, it should be a callable that takes a

        # Django database Field instance and returns True if that field should

        # be included. If field_filter is None, that all fields will be used.

        self.field_filter = field_filter

    def field_dict(self, model):

        """

        Helper function that returns a dictionary of all fields in the given

        model. If self.field_filter is set, it only includes the fields that

        match the filter.

        """

        if self.field_filter:

            return dict([(f.name, f) for f in model._meta.fields if self.field_filter(f)])

        else:

            return dict([(f.name, f) for f in model._meta.fields if not f.rel and not f.primary_key and not f.unique and not isinstance(f, (models.AutoField, models.TextField))])

    def model_index_html(self, request, model, site):

        fields = self.field_dict(model)

        if not fields:

            return u''

        return mark_safe(u'<p class="filter"><strong>View by:</strong> %s</p>' % \

            u', '.join(['<a href="fields/%s/">%s</a>' % (f.name, force_unicode(capfirst(f.verbose_name))) for f in fields.values()]))

    def urls(self, plugin_name, easy_instance_field):

        if easy_instance_field.field in self.field_dict(easy_instance_field.model.model).values():

            field_value = smart_str(easy_instance_field.raw_value)

            return [mark_safe(u'%s%s/%s/%s/' % (

                easy_instance_field.model.url(),

                plugin_name, easy_instance_field.field.name,

                urllib.quote(field_value, safe='')))]

    def model_view(self, request, model_databrowse, url):

        self.model, self.site = model_databrowse.model, model_databrowse.site

        self.fields = self.field_dict(self.model)

        # If the model has no fields with choices, there's no point in going

        # further.

        if not self.fields:

            raise http.Http404('The requested model has no fields.')

        if url is None:

            return self.homepage_view(request)

        url_bits = url.split('/', 1)

        if self.fields.has_key(url_bits[0]):

            return self.field_view(request, self.fields[url_bits[0]], *url_bits[1:])

        raise http.Http404('The requested page does not exist.')

    def homepage_view(self, request):

        easy_model = EasyModel(self.site, self.model)

        field_list = self.fields.values()

        field_list.sort(lambda x, y: cmp(x.verbose_name, y.verbose_name))

        return render_to_response('databrowse/fieldchoice_homepage.html', {'root_url': self.site.root_url, 'model': easy_model, 'field_list': field_list})

    def field_view(self, request, field, value=None):

        easy_model = EasyModel(self.site, self.model)

        easy_field = easy_model.field(field.name)

        if value is not None:

            obj_list = easy_model.objects(**{field.name: value})

            return render_to_response('databrowse/fieldchoice_detail.html', {'root_url': self.site.root_url, 'model': easy_model, 'field': easy_field, 'value': value, 'object_list': obj_list})

        obj_list = [v[field.name] for v in self.model._default_manager.distinct().order_by(field.name).values(field.name)]

        return render_to_response('databrowse/fieldchoice_list.html', {'root_url': self.site.root_url, 'model': easy_model, 'field': easy_field, 'object_list': obj_list})