#
# 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.core.cache import cache
from django.core.paginator import Paginator, EmptyPage
from django.db.models import Q
from django.template import Context, Template
from django.template import VariableDoesNotExist
from django.template import TemplateSyntaxError
from django.core.serializers.json import DjangoJSONEncoder

from orm.models import SrtSetting, Cve

import types
import json
import collections
import re
import shlex

from srtgui.tablefilter import TableFilterMap
from urllib.parse import unquote_plus

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


class NoFieldOrDataName(Exception):
    pass

# quick development/debugging support
from srtgui.api import _log

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 = []

        _log("ToasterTable:%s,%s" % (args,kwargs))

        # 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, request, *args, **kwargs):
        return super(ToasterTable, self).dispatch(request, *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

        # global variables
        context['report_id_list'] = ''

        # Number of visits to this view, as counted in the session variable.
        # Add documentation link
        context['srt_documentation_link'] = SrtSetting.objects.get(name='SRTOOL_DOCUMENATION_URL').value
        # Add optional local logo link
        context['srt_local_logo'] = SrtSetting.objects.get(name='SRTOOL_LOCAL_LOGO').value.split(',')

        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 put(self, *args, **kwargs):
        """ function to implement in the subclass which sets up
        the put method """
        _log("TABLE_PUT_SUPER")
        pass

    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 = unquote_plus(filter_value)
        except ValueError:
            return

        if "all" in action_name:
            return

        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)

    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)

        # HACK: Replace in case of manual page refresh submits URI encoded chars
        search_term = search_term.replace('%20',' ').replace('%22','"').replace('%27','"').replace('+',' ')
        search_queries = None
        next_op = 'AND'
        for st in shlex.split(search_term):
            queries = None
            if 'OR' == st:
                next_op = 'OR'
                continue
            if 'AND' == st:
                next_op = 'AND'
                continue
            for field in self.queryset.model.search_allowed_fields:
                if st.startswith('-'):
                    query = ~Q(**{field + '__icontains': st[1:]})
                else:
                    query = Q(**{field + '__icontains': st})
                if queries:
                    queries |= query
                else:
                    queries = query

            if search_queries:
                if 'OR' == next_op:
                    search_queries |= queries
                else:
                    search_queries &= queries
            else:
                search_queries = queries

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

    def apply_row_customization(self, row):
        """ function to implement in the subclass which supports
        row data customization in the respective table handler """
        return row

    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
        # (but keep quotes as dashes to support search string)
        cache_name = re.sub(r'["\']', "-", cache_name)
        cache_name = re.sub(r'[^A-Za-z0-9-]', "", cache_name)

        # Forcibly disable caching for all pages, since SRTool data is too dynamic
        if True or 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",
        }

        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']

                    try:
                        # Render the template given
                        required_data[col['static_data_name']] = \
                                self.render_static_data(
                                    col['static_data_template'], model_obj)
                    except (TemplateSyntaxError,
                            VariableDoesNotExist) as e:
                        logger.error("could not render template code"
                                        "%s %s %s",
                                        col['static_data_template'],
                                        e, self.__class__.__name__)
                        required_data[col['static_data_name']] =\
                            '<!--error-->'

                else:
                    # Traverse to any foreign 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)

        # apply any row data customization override before converted to JSON
        data = self.apply_row_customization(data)

        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 is None:
            # We got no search value so return empty reponse
            return response({'error': error, 'results': []})

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

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

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

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

        return response(data)

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

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