#!/usr/bin/python2.5

#

# Copyright 2008 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

# 

#   http://www.apache.org/licenses/LICENSE-2.0

# 

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Helpers functions for displaying views.

"""

__authors__ = [

  '"Sverre Rabbelier" <sverer@rabbelier.nl>',

  ]

from django import http

from django.utils.translation import ugettext_lazy

import soc.logic

import soc.logic.dicts

import soc.logic.out_of_band

import soc.views.helper.lists

import soc.views.helper.responses

import soc.views.out_of_band

from soc.logic import dicts

from soc.logic import models

from soc.views import simple

from soc.views import helper

from soc.views.helper import access

class View:

  """Views for entity classes.

  The View class functions specific to Entity classes by relying

  on the the child-classes to define the following fields:

  self._logic: the logic singleton for this entity

  """

  DEF_SUBMIT_MSG_PARAM_NAME = 's'

  DEF_SUBMIT_MSG_PROFILE_SAVED = 0

  DEF_CREATE_NEW_ENTITY_MSG = ugettext_lazy(

      ' You can create a new %(entity_type_lower)s by visiting'

      ' <a href="%(create)s">Create '

      'a New %(entity_type)s</a> page.')

  def __init__(self, params=None, rights=None):

    """

    Args:

      rights: This dictionary should be filled with the access check

        functions that should be called, it will be modified in-place.

      params: This dictionary should be filled with the parameters

        specific to this entity, required fields are:

        name: the name of the entity (names should have sentence-style caps) 

        name_short: the short form name of the name ('org' vs 'organization')

        name_plural: the plural form of the name

        edit_form: the class of the Django form to be used when editing

        create_form: the class of the Django form to be used when creating

        edit_template: the Django template to be used for editing

        public_template: the Django template to be used as public page 

        list_template: the Django template to be used as list page

        lists_template: the Django templates to search for the list page

        delete_redirect: the Django template to redirect to on delete

        create_redirect: the Django template to redirect to after creation

        save_message: the message to display when the entity is saved

        edit_params: the params to use when editing

    """

    new_rights = {}

    new_rights['any_access'] = [access.checkIsLoggedIn]

    self._rights = dicts.merge(rights, new_rights)

    self._params = params

  def public(self, request, page=None, **kwargs):

    """Displays the public page for the entity specified by **kwargs

    Args:

      request: the standard Django HTTP request object

      page: a soc.logic.site.page.Page object which is abstraction

        that combines a Django view with sidebar menu info

      kwargs: the Key Fields for the specified entity

    """

    try:

      self.checkAccess('edit', request)

    except soc.views.out_of_band.AccessViolationResponse, alt_response:

      return alt_response.response()

    # create default template context for use with any templates

    context = helper.responses.getUniversalContext(request)

    context['page'] = page

    entity = None

    try:

      entity = self._logic.getIfFields(**kwargs)

    except soc.logic.out_of_band.ErrorResponse, error:

      template = self._params['public_template']

      return simple.errorResponse(request, page, error, template, context)

    if not entity:

      #TODO: Change this into a proper redirect

      return http.HttpResponseRedirect('/')

    context['entity'] = entity

    context['entity_type'] = self._params['name']

    template = self._params['public_template']

    return helper.responses.respond(request, template, context)

  def create(self, request, page=None, **kwargs):

    """Displays the create page for this entity type

    Args:

      request: the standard Django HTTP request object

      page: a soc.logic.site.page.Page object which is abstraction

        that combines a Django view with sidebar menu info

      kwargs: not used for create()

    """

    # Create page is an edit page with no key fields

    kwargs = {}

    fields = self._logic.getKeyFieldNames()

    for field in fields:

      kwargs[field] = None

    return self.edit(request, page=page, **kwargs)

  def edit(self, request, page=None, **kwargs):

    """Displays the public page for the entity specified by **kwargs

    Args:

      request: the standard Django HTTP request object

      page: a soc.logic.site.page.Page object which is abstraction

        that combines a Django view with sidebar menu info

      kwargs: The Key Fields for the specified entity

    """

    try:

      self.checkAccess('edit', request)

    except soc.views.out_of_band.AccessViolationResponse, alt_response:

      return alt_response.response()

    context = helper.responses.getUniversalContext(request)

    context['page'] = page

    entity = None

    try:

      entity = self._logic.getIfFields(**kwargs)

    except soc.logic.out_of_band.ErrorResponse, error:

      template = self._params['public_template']

      error.message = error.message + self.DEF_CREATE_NEW_ENTITY_MSG % {

          'entity_type_lower' : self._params['name'].lower(),

          'entity_type' : self._params['name'],

          'create' : self._params['create_redirect']

          }

      return simple.errorResponse(request, page, error, template, context)

    if request.method == 'POST':

      return self.editPost(request, entity, context)

    else:

      return self.editGet(request, entity, context)

  def editPost(self, request, entity, context):

    """Same as edit, but on POST

    """

    if entity:

      form = self._params['edit_form'](request.POST)

    else:

      form = self._params['create_form'](request.POST)

    if not form.is_valid():

      return self._constructResponse(request, entity, context, form)

    fields = self.collectCleanedFields(form)

    self._editPost(request, entity, fields)

    keys = self._logic.getKeyFieldNames()

    values = self._logic.getKeyValuesFromFields(fields)

    kwargs = dicts.zip(keys, values)

    entity = self._logic.updateOrCreateFromFields(fields, **kwargs)

    if not entity:

      return http.HttpResponseRedirect('/')

    params = self._params['edit_params']

    suffix = self._logic.getKeySuffix(entity)

    # redirect to (possibly new) location of the entity

    # (causes 'Profile saved' message to be displayed)

    return helper.responses.redirectToChangedSuffix(

        request, suffix, suffix,

        params=params)

  def editGet(self, request, entity, context):

    """Same as edit, but on GET

    """

    suffix = self._logic.getKeySuffix(entity)

    # Remove the params from the request, this is relevant only if

    # someone bookmarked a POST page.

    is_self_referrer = helper.requests.isReferrerSelf(request, suffix=suffix)

    if request.GET.get(self.DEF_SUBMIT_MSG_PARAM_NAME):

      if (not entity) or (not is_self_referrer):

        return http.HttpResponseRedirect(request.path)

    if entity:

      # Note: no message will be displayed if parameter is not present

      context['notice'] = helper.requests.getSingleIndexedParamValue(

          request, self.DEF_SUBMIT_MSG_PARAM_NAME,

          values=self._params['save_message'])

      # populate form with the existing entity

      form = self._params['edit_form'](instance=entity)

      self._editGet(request, entity, form)

    else:

      form = self._params['create_form']()

    return self._constructResponse(request, entity, context, form)

  def list(self, request, page=None):

    """Displays the list page for the entity type

    Args:

      request: the standard Django HTTP request object

      page: a soc.logic.site.page.Page object which is abstraction

        that combines a Django view with sidebar menu info

    """

    try:

      self.checkAccess('list', request)

    except soc.views.out_of_band.AccessViolationResponse, alt_response:

      return alt_response.response()

    context = helper.responses.getUniversalContext(request)

    context['page'] = page

    offset, limit = helper.lists.cleanListParameters(

      offset=request.GET.get('offset'), limit=request.GET.get('limit'))

    # Fetch one more to see if there should be a 'next' link

    entities = self._logic.getForLimitAndOffset(limit + 1, offset=offset)

    context['pagination_form'] = helper.lists.makePaginationForm(request, limit)

    templates = self._params['lists_template']

    context = helper.lists.setList(request, context, entities, 

                                 offset, limit, templates)

    context['entity_type'] = self._params['name']

    context['entity_type_plural'] = self._params['name_plural']

    template = self._params['list_template']

    return helper.responses.respond(request, template, context)

  def delete(self, request, page=None, **kwargs):

    """Shows the delete page for the entity specified by kwargs

    Args:

      request: the standard Django HTTP request object

      page: a soc.logic.site.page.Page object which is abstraction

        that combines a Django view with sidebar menu info

      kwargs: The Key Fields for the specified entity

    """

    try:

      self.checkAccess('delete', request)

    except soc.views.out_of_band.AccessViolationResponse, alt_response:

      return alt_response.response()

    # create default template context for use with any templates

    context = helper.responses.getUniversalContext(request)

    context['page'] = page

    entity = None

    try:

      entity = self._logic.getIfFields(**kwargs)

    except soc.logic.out_of_band.ErrorResponse, error:

      template = self._params['edit_template']

      error.message = error.message + self.DEF_CREATE_NEW_ENTITY_MSG % {

          'entity_type_lower' : self._params['name'].lower(),

          'entity_type' : self._params['name'],

          'create' : self._params['create_redirect']

          }

      return simple.errorResponse(request, page, error, template, context)

    if not entity:

      #TODO: Create a proper error page for this

      return http.HttpResponseRedirect('/')

    if not self._logic.isDeletable(entity):

      # TODO: Update the notice area telling the user that they

      # can't delete the entity

      pass

    self._logic.delete(entity)

    redirect = self._params['delete_redirect']

    return http.HttpResponseRedirect(redirect)

  def _editPost(self, request, entity, fields):

    """Performs any required processing on the entity to post its edit page

    Args:

      request: the django request object

      entity:  the entity to create or update from POST contents

      fields: the new field values

    """

    raise NotImplementedError

  def _editGet(self, request, entity, form):

    """Performs any required processing on the form to get its edit page

    Args:

      request: the django request object

      entity: the entity to get

      form: the django form that will be used for the page

    """

    pass

  def checkUnspecified(self, access_type, request):

    """Checks whether an unspecified access_type should be allowed

    Args:

      access_type: the access type (such as 'list' or 'edit') that was

                   not present in the _rights dictionary when checking.

    """

    pass

  def _constructResponse(self, request, entity, context, form):

    """Updates the context and returns a response for the specified arguments

    Args:

      request: the django request object

      entity: the entity that is used

      context: the context to be used

      form: the form that will be used

    """

    suffix = self._logic.getKeySuffix(entity)

    context['form'] = form

    context['entity'] = entity

    context['entity_suffix'] = suffix

    context['entity_type'] = self._params['name']

    context['entity_type_plural'] = self._params['name_plural']

    context['entity_type_short'] = self._params['name_short']

    template = self._params['edit_template']

    return helper.responses.respond(request, template, context)

  def checkAccess(self, access_type, request):

    """Runs all the defined checks for the specified type

    Args:

      access_type: the type of request (such as 'list' or 'edit')

      request: the Django request object

    Returns:

      True: If all the required access checks have been made successfully

      False: If a check failed, in this case self._response will contain

             the response provided by the failed access check.

    """

    if access_type not in self._rights:

       # No checks defined, so do the 'generic check' and bail out

      self.checkUnspecified(access_type, request)

      return

    # Call each access checker

    for check in self._rights['any_access']:

      check(request)

    for check in self._rights[access_type]:

      check(request)

  def collectCleanedFields(self, form):

    """Collects all cleaned fields from form and returns them 

    Args:

      form: The form from which the cleaned fields should be collected

    """

    fields = {}

    for field, value in form.cleaned_data.iteritems():

      fields[field] = value

    return fields