#
# ex:ts=4:sw=4:sts=4:et
# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
#
# BitBake Toaster Implementation
#
# Copyright (C) 2015        Intel Corporation
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

from django.views.generic import View, TemplateView
from django.views.decorators.cache import cache_control
from django.shortcuts import HttpResponse
from django.http import HttpResponseBadRequest
from django.core import serializers
from django.core.cache import cache
from django.core.paginator import Paginator, EmptyPage
from django.db.models import Q
from orm.models import Project, ProjectLayer, Layer_Version
from django.template import Context, Template
from django.core.serializers.json import DjangoJSONEncoder
from django.core.exceptions import FieldError
from django.conf.urls import url, patterns

import types
import json
import collections
import operator
import re

try:
    from urllib import unquote_plus
except ImportError:
    from urllib.parse import unquote_plus

import logging
logger = logging.getLogger("toaster")

from toastergui.tablefilter import TableFilterMap


class NoFieldOrDataName(Exception):
    pass

class ToasterTable(TemplateView):
    def __init__(self, *args, **kwargs):
        super(ToasterTable, self).__init__()
        if 'template_name' in kwargs:
            self.template_name = kwargs['template_name']
        self.title = "Table"
        self.queryset = None
        self.columns = []

        # map from field names to Filter instances
        self.filter_map = TableFilterMap()

        self.total_count = 0
        self.static_context_extra = {}
        self.empty_state = "Sorry - no data found"
        self.default_orderby = ""

    # prevent HTTP caching of table data
    @cache_control(must_revalidate=True,
                   max_age=0, no_store=True, no_cache=True)
    def dispatch(self, *args, **kwargs):
        return super(ToasterTable, self).dispatch(*args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super(ToasterTable, self).get_context_data(**kwargs)
        context['title'] = self.title
        context['table_name'] =  type(self).__name__.lower()
        context['empty_state'] = self.empty_state

        return context

    def get(self, request, *args, **kwargs):
        if request.GET.get('format', None) == 'json':

            self.setup_queryset(*args, **kwargs)
            # Put the project id into the context for the static_data_template
            if 'pid' in kwargs:
                self.static_context_extra['pid'] = kwargs['pid']

            cmd = request.GET.get('cmd', None)
            if cmd and 'filterinfo' in cmd:
                data = self.get_filter_info(request, **kwargs)
            else:
                # If no cmd is specified we give you the table data
                data = self.get_data(request, **kwargs)

            return HttpResponse(data, content_type="application/json")

        return super(ToasterTable, self).get(request, *args, **kwargs)

    def get_filter_info(self, request, **kwargs):
        self.setup_filters(**kwargs)

        search = request.GET.get("search", None)
        if search:
            self.apply_search(search)

        name = request.GET.get("name", None)
        table_filter = self.filter_map.get_filter(name)
        return json.dumps(table_filter.to_json(self.queryset),
                          indent=2,
                          cls=DjangoJSONEncoder)

    def setup_columns(self, *args, **kwargs):
        """ function to implement in the subclass which sets up
        the columns """
        pass

    def setup_filters(self, *args, **kwargs):
        """ function to implement in the subclass which sets up the
        filters """
        pass

    def setup_queryset(self, *args, **kwargs):
        """ function to implement in the subclass which sets up the
        queryset"""
        pass

    def add_filter(self, table_filter):
        """Add a filter to the table.

        Args:
            table_filter: Filter instance
        """
        self.filter_map.add_filter(table_filter.name, table_filter)

    def add_column(self, title="", help_text="",
                   orderable=False, hideable=True, hidden=False,
                   field_name="", filter_name=None, static_data_name=None,
                   static_data_template=None):
        """Add a column to the table.

        Args:
            title (str): Title for the table header
            help_text (str): Optional help text to describe the column
            orderable (bool): Whether the column can be ordered.
                We order on the field_name.
            hideable (bool): Whether the user can hide the column
            hidden (bool): Whether the column is default hidden
            field_name (str or list): field(s) required for this column's data
            static_data_name (str, optional): The column's main identifier
                which will replace the field_name.
            static_data_template(str, optional): The template to be rendered
                as data
        """

        self.columns.append({'title': title,
                             'help_text': help_text,
                             'orderable': orderable,
                             'hideable': hideable,
                             'hidden': hidden,
                             'field_name': field_name,
                             'filter_name': filter_name,
                             'static_data_name': static_data_name,
                             'static_data_template': static_data_template})

    def set_column_hidden(self, title, hidden):
        """
        Set the hidden state of the column to the value of hidden
        """
        for col in self.columns:
            if col['title'] == title:
                col['hidden'] = hidden
                break

    def set_column_hideable(self, title, hideable):
        """
        Set the hideable state of the column to the value of hideable
        """
        for col in self.columns:
            if col['title'] == title:
                col['hideable'] = hideable
                break

    def render_static_data(self, template, row):
        """Utility function to render the static data template"""

        context = {
          'extra': self.static_context_extra,
          'data': row,
        }

        context = Context(context)
        template = Template(template)

        return template.render(context)

    def apply_filter(self, filters, filter_value, **kwargs):
        """
        Apply a filter submitted in the querystring to the ToasterTable

        filters: (str) in the format:
          '<filter name>:<action name>'
        filter_value: (str) parameters to pass to the named filter

        <filter name> and <action name> are used to look up the correct filter
        in the ToasterTable's filter map; the <action params> are set on
        TableFilterAction* before its filter is applied and may modify the
        queryset returned by the filter
        """
        self.setup_filters(**kwargs)

        try:
            filter_name, action_name = filters.split(':')
            action_params = urllib.unquote_plus(filter_value)
        except ValueError:
            return

        if "all" in action_name:
            return

        try:
            table_filter = self.filter_map.get_filter(filter_name)
            action = table_filter.get_action(action_name)
            action.set_filter_params(action_params)
            self.queryset = action.filter(self.queryset)
        except KeyError:
            # pass it to the user - programming error here
            raise

    def apply_orderby(self, orderby):
        # Note that django will execute this when we try to retrieve the data
        self.queryset = self.queryset.order_by(orderby)

    def apply_search(self, search_term):
        """Creates a query based on the model's search_allowed_fields"""

        if not hasattr(self.queryset.model, 'search_allowed_fields'):
            raise Exception("Search fields aren't defined in the model %s"
                            % self.queryset.model)

        search_queries = None
        for st in search_term.split(" "):
            queries = None
            for field in self.queryset.model.search_allowed_fields:
                query = Q(**{field + '__icontains': st})
                if queries:
                    queries |= query
                else:
                    queries = query

            if search_queries:
               search_queries &= queries
            else:
               search_queries = queries

        self.queryset = self.queryset.filter(search_queries)

    def get_data(self, request, **kwargs):
        """
        Returns the data for the page requested with the specified
        parameters applied

        filters: filter and action name, e.g. "outcome:build_succeeded"
        filter_value: value to pass to the named filter+action, e.g. "on"
        (for a toggle filter) or "2015-12-11,2015-12-12"
        (for a date range filter)
        """

        page_num = request.GET.get("page", 1)
        limit = request.GET.get("limit", 10)
        search = request.GET.get("search", None)
        filters = request.GET.get("filter", None)
        filter_value = request.GET.get("filter_value", "on")
        orderby = request.GET.get("orderby", None)
        nocache = request.GET.get("nocache", None)

        # Make a unique cache name
        cache_name = self.__class__.__name__

        for key, val in request.GET.items():
            if key == 'nocache':
                continue
            cache_name = cache_name + str(key) + str(val)

        for key, val in kwargs.items():
            cache_name = cache_name + str(key) + str(val)

        # No special chars allowed in the cache name apart from dash
        cache_name = re.sub(r'[^A-Za-z0-9-]', "", cache_name)

        if nocache:
            cache.delete(cache_name)

        data = cache.get(cache_name)

        if data:
            logger.debug("Got cache data for table '%s'" % self.title)
            return data

        self.setup_columns(**kwargs)

        if search:
            self.apply_search(search)
        if filters:
            self.apply_filter(filters, filter_value, **kwargs)
        if orderby:
            self.apply_orderby(orderby)

        paginator = Paginator(self.queryset, limit)

        try:
            page = paginator.page(page_num)
        except EmptyPage:
            page = paginator.page(1)

        data = {
            'total': self.queryset.count(),
            'default_orderby': self.default_orderby,
            'columns': self.columns,
            'rows': [],
            'error': "ok",
        }

        try:
            for model_obj in page.object_list:
                # Use collection to maintain the order
                required_data = collections.OrderedDict()

                for col in self.columns:
                    field = col['field_name']
                    if not field:
                        field = col['static_data_name']
                    if not field:
                        raise NoFieldOrDataName("Must supply a field_name or"
                                                "static_data_name for column"
                                                "%s.%s" %
                                                (self.__class__.__name__, col)
                                                )

                    # Check if we need to process some static data
                    if "static_data_name" in col and col['static_data_name']:
                        # Overwrite the field_name with static_data_name
                        # so that this can be used as the html class name
                        col['field_name'] = col['static_data_name']

                        # Render the template given
                        required_data[col['static_data_name']] = \
                            self.render_static_data(
                                col['static_data_template'], model_obj)
                    else:
                        # Traverse to any foriegn key in the field
                        # e.g. recipe__layer_version__name
                        model_data = None

                        if "__" in field:
                            for subfield in field.split("__"):
                                if not model_data:
                                    # The first iteration is always going to
                                    # be on the actual model object instance.
                                    # Subsequent ones are on the result of
                                    # that. e.g. forieng key objects
                                    model_data = getattr(model_obj,
                                                         subfield)
                                else:
                                    model_data = getattr(model_data,
                                                         subfield)

                        else:
                            model_data = getattr(model_obj,
                                                 col['field_name'])

                        # We might have a model function as the field so
                        # call it to return the data needed
                        if isinstance(model_data, types.MethodType):
                            model_data = model_data()

                        required_data[col['field_name']] = model_data

                data['rows'].append(required_data)

        except FieldError:
            # pass  it to the user - programming-error here
            raise

        data = json.dumps(data, indent=2, cls=DjangoJSONEncoder)
        cache.set(cache_name, data, 60*30)

        return data



class ToasterTypeAhead(View):
    """ A typeahead mechanism to support the front end typeahead widgets """
    MAX_RESULTS = 6

    class MissingFieldsException(Exception):
        pass

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

    def get(self, request, *args, **kwargs):
        def response(data):
            return HttpResponse(json.dumps(data,
                                           indent=2,
                                           cls=DjangoJSONEncoder),
                                content_type="application/json")

        error = "ok"

        search_term = request.GET.get("search", None)
        if search_term == None:
            # We got no search value so return empty reponse
            return response({'error' : error , 'results': []})

        try:
            prj = Project.objects.get(pk=kwargs['pid'])
        except KeyError:
            prj = None

        results = self.apply_search(search_term, prj, request)[:ToasterTypeAhead.MAX_RESULTS]

        if len(results) > 0:
            try:
                self.validate_fields(results[0])
            except MissingFieldsException as e:
                error = e

        data = { 'results' : results,
                'error' : error,
               }

        return response(data)

    def validate_fields(self, result):
        if 'name' in result == False or 'detail' in result == False:
            raise MissingFieldsException("name and detail are required fields")

    def apply_search(self, search_term, prj):
        """ Override this function to implement search. Return an array of
        dictionaries with a minium of a name and detail field"""
        pass