# -*- coding: utf-8; -*-
################################################################################
#
#  Rattail -- Retail Software Framework
#  Copyright © 2010-2017 Lance Edgar
#
#  This file is part of Rattail.
#
#  Rattail is free software: you can redistribute it and/or modify it under the
#  terms of the GNU General Public License as published by the Free Software
#  Foundation, either version 3 of the License, or (at your option) any later
#  version.
#
#  Rattail 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
#  Rattail.  If not, see <http://www.gnu.org/licenses/>.
#
################################################################################
"""
Base views for maintaining "new-style" batches.

.. note::
   This is all still somewhat experimental.
"""

from __future__ import unicode_literals, absolute_import

import os
import datetime
import logging
from cStringIO import StringIO

import six
from sqlalchemy import orm

from rattail.db import model, Session as RattailSession
from rattail.threads import Thread
from rattail.csvutil import UnicodeDictWriter
from rattail.util import load_object

import formalchemy as fa
from pyramid import httpexceptions
from pyramid.renderers import render_to_response
from pyramid.response import FileResponse
from pyramid_simpleform import Form
from webhelpers2.html import HTML, tags

from tailbone import forms, newgrids as grids
from tailbone.db import Session
from tailbone.views import MasterView
from tailbone.forms.renderers.batch import FileFieldRenderer
from tailbone.progress import SessionProgress


log = logging.getLogger(__name__)


class BatchMasterView(MasterView):
    """
    Base class for all "batch master" views.
    """
    default_handler_spec = None
    has_rows = True
    rows_deletable = True
    rows_downloadable = True
    refreshable = True
    refresh_after_create = False
    edit_with_rows = False
    cloneable = False

    def __init__(self, request):
        super(BatchMasterView, self).__init__(request)
        self.handler = self.get_handler()

    def get_handler(self):
        """
        Returns a `BatchHandler` instance for the view.  All (?) custom batch
        views should define a default handler class; however this may in all
        (?)  cases be overridden by config also.  The specific setting required
        to do so will depend on the 'key' for the type of batch involved, e.g.
        assuming the 'vendor_catalog' batch:

        .. code-block:: ini

           [rattail.batch]
           vendor_catalog.handler = myapp.batch.vendorcatalog:CustomCatalogHandler

        Note that the 'key' for a batch is generally the same as its primary
        table name, although technically it is whatever value returns from the
        ``batch_key`` attribute of the main batch model class.
        """
        key = self.model_class.batch_key
        spec = self.rattail_config.get('rattail.batch', '{}.handler'.format(key),
                                       default=self.default_handler_spec)
        if spec:
            return load_object(spec)(self.rattail_config)
        return self.batch_handler_class(self.rattail_config)

    def template_kwargs_view(self, **kwargs):
        batch = kwargs['instance']
        kwargs['batch'] = batch
        kwargs['handler'] = self.handler
        kwargs['execute_title'] = self.get_execute_title(batch)
        kwargs['execute_enabled'] = self.executable(batch)
        if kwargs['execute_enabled'] and self.has_execution_options:
            kwargs['rendered_execution_options'] = self.render_execution_options(batch)
        return kwargs

    def template_kwargs_index(self, **kwargs):
        kwargs['execute_enabled'] = self.executable()
        if kwargs['execute_enabled'] and self.has_execution_options:
            kwargs['rendered_execution_options'] = self.render_execution_options()
        return kwargs

    def render_execution_options(self, batch=None):
        if batch is None:
            batch = self.model_class
        form = self.make_execution_options_form(batch)
        kwargs = {
            'batch': batch,
            'form': forms.FormRenderer(form),
        }
        kwargs = self.get_exec_options_kwargs(**kwargs)
        return self.render('exec_options', kwargs)

    def get_exec_options_kwargs(self, **kwargs):
        return kwargs

    def get_instance_title(self, batch):
        return batch.id_str or unicode(batch)

    def _preconfigure_grid(self, g):
        """
        Apply some commonly-useful pre-configuration to the main batch grid.
        """
        g.joiners['created_by'] = lambda q: q.join(model.User,
                                                   model.User.uuid == self.model_class.created_by_uuid)
        g.joiners['executed_by'] = lambda q: q.outerjoin(model.User,
                                                         model.User.uuid == self.model_class.executed_by_uuid)

        g.filters['id'].label = "Batch ID"
        g.filters['executed'].default_active = True
        g.filters['executed'].default_verb = 'is_null'

        # TODO: in some cases grid has no sorters yet..e.g. when building query for bulk-delete
        if hasattr(g, 'sorters'):
            g.sorters['created_by'] = g.make_sorter(model.User.username)
            g.sorters['executed_by'] = g.make_sorter(model.User.username)

        g.default_sortkey = 'created'
        g.default_sortdir = 'desc'

        g.id.set(label="ID", renderer=forms.renderers.BatchIDFieldRenderer)
        g.created_by.set(label="Created by", renderer=forms.renderers.UserFieldRenderer)
        g.cognized_by.set(renderer=forms.renderers.UserFieldRenderer)
        g.rowcount.set(label="Rows")
        g.status_code.set(label="Status", renderer=StatusRenderer(self.model_class.STATUS))
        g.executed_by.set(label="Executed by", renderer=forms.renderers.UserFieldRenderer)

    def configure_grid(self, g):
        """
        Apply final configuration to the main batch grid.  Custom batch views
        are encouraged to override this method.
        """
        g.configure(
            include=[
                g.id,
                g.created,
                g.created_by,
                g.rowcount,
                g.executed,
                g.executed_by,
            ],
            readonly=True)

    def _preconfigure_fieldset(self, fs):
        """
        Apply some commonly-useful pre-configuration to the main batch
        fieldset.
        """
        fs.id.set(label="Batch ID", readonly=True, renderer=forms.renderers.BatchIDFieldRenderer)

        fs.created.set(readonly=True)
        fs.created_by.set(label="Created by", renderer=forms.renderers.UserFieldRenderer,
                          readonly=True)
        fs.cognized_by.set(label="Cognized by", renderer=forms.renderers.UserFieldRenderer)
        fs.rowcount.set(label="Row Count")
        fs.status_code.set(label="Status", renderer=StatusRenderer(self.model_class.STATUS))
        fs.executed_by.set(label="Executed by", renderer=forms.renderers.UserFieldRenderer)
        fs.notes.set(renderer=fa.TextAreaFieldRenderer, size=(80, 10))

        if self.creating and self.request.user:
            batch = fs.model
            batch.created_by_uuid = self.request.user.uuid

    def configure_fieldset(self, fs):
        """
        Apply final configuration to the main batch fieldset.  Custom batch
        views are encouraged to override this method.
        """
        if self.creating:
            fs.configure()

        else:
            batch = fs.model
            if batch.executed:
                fs.configure(
                    include=[
                        fs.id,
                        fs.created,
                        fs.created_by,
                        fs.executed,
                        fs.executed_by,
                    ])
            else:
                fs.configure(
                    include=[
                        fs.id,
                        fs.created,
                        fs.created_by,
                    ])

    def _postconfigure_fieldset(self, fs):
        if self.creating:
            unwanted = [
                'id',
                'rowcount',
                'created',
                'created_by',
                'cognized',
                'cognized_by',
                'executed',
                'executed_by',
                'purge',
                'data_rows',
            ]
            for field in unwanted:
                if field in fs.render_fields:
                    delattr(fs, field)
        else:
            batch = fs.model
            if not batch.executed:
                unwanted = [
                    'executed',
                    'executed_by',
                ]
                for field in unwanted:
                    if field in fs.render_fields:
                        delattr(fs, field)

    def add_file_field(self, fs, name, **kwargs):
        kwargs.setdefault('value', lambda b: getattr(b, 'filename_{}'.format(name)))
        if 'renderer' not in kwargs:
            batch = fs.model
            storage_path = self.rattail_config.batch_filedir(self.handler.batch_key)
            download_url = self.get_action_url('download', batch, _query={'file': name})
            kwargs['renderer'] = FileFieldRenderer.new(self,
                                                       storage_path=storage_path,
                                                       download_url=download_url)
        fs.append(fa.Field(name, **kwargs))

    def save_create_form(self, form):
        self.before_create(form)

        with Session.no_autoflush:

            # transfer form data to batch instance
            form.fieldset.sync()
            batch = form.fieldset.model

            # current user is batch creator
            batch.created_by = self.request.user or self.late_login_user()

            # destroy initial batch and re-make using handler
            kwargs = self.get_batch_kwargs(batch)
            Session.expunge(batch)
            batch = self.handler.make_batch(Session(), **kwargs)

        Session.flush()

        # TODO: this needs work yet surely...
        # if batch has input data file, let handler properly establish that
        filename = getattr(batch, 'filename', None)
        if filename:
            path = os.path.join(self.upload_dir, filename)
            self.handler.set_input_file(batch, path)
            os.remove(path)

        # return this object to replace the original
        return batch

    def get_batch_kwargs(self, batch, mobile=False):
        """
        Return a kwargs dict for use with ``self.handler.make_batch()``, using
        the given batch as a template.
        """
        kwargs = {}
        if batch.created_by:
            kwargs['created_by'] = batch.created_by
        elif batch.created_by_uuid:
            kwargs['created_by_uuid'] = batch.created_by_uuid
        kwargs['notes'] = batch.notes
        if hasattr(batch, 'filename'):
            kwargs['filename'] = batch.filename
        return kwargs

    # TODO: deprecate / remove this (is it used at all now?)
    def init_batch(self, batch):
        """
        Initialize a new batch.  Derived classes can override this to
        effectively provide default values for a batch, etc.  This method is
        invoked after a batch has been fully prepared for insertion to the
        database, but before the push to the database occurs.

        Note that the return value of this function matters; if it is boolean
        false then the batch will not be persisted at all, and the user will be
        redirected to the "create batch" page.
        """
        return True

    def redirect_after_create(self, batch):
        if self.handler.should_populate(batch):
            return self.redirect(self.get_action_url('prefill', batch))
        elif self.refresh_after_create:
            return self.redirect(self.get_action_url('refresh', batch))
        else:
            return self.redirect(self.get_action_url('view', batch))

    # TODO: some of this at least can go to master now right?
    def edit(self):
        """
        Don't allow editing a batch which has already been executed.
        """
        self.editing = True
        batch = self.get_instance()
        if batch.executed:
            return self.redirect(self.get_action_url('view', batch))

        if self.edit_with_rows:
            grid = self.make_row_grid(batch=batch)

            # If user just refreshed the page with a reset instruction, issue a
            # redirect in order to clear out the query string.
            if self.request.GET.get('reset-to-default-filters') == 'true':
                return self.redirect(self.request.current_route_url(_query=None))

            if self.request.params.get('partial'):
                self.request.response.content_type = b'text/html'
                self.request.response.text = grid.render_grid()
                return self.request.response

        form = self.make_form(batch)
        if self.request.method == 'POST':
            if form.validate():
                self.save_edit_form(form)
                self.request.session.flash("{} has been updated: {}".format(
                    self.get_model_title(), self.get_instance_title(batch)))
                return self.redirect_after_edit(batch)

        context = {
            'instance': batch,
            'instance_title': self.get_instance_title(batch),
            'instance_deletable': self.deletable_instance(batch),
            'form': form,
            'batch': batch,
            'execute_title': self.get_execute_title(batch),
            'execute_enabled': self.executable(batch),
        }

        if self.edit_with_rows:
            context['rows_grid'] = grid
        if context['execute_enabled'] and self.has_execution_options:
            context['rendered_execution_options'] = self.render_execution_options(batch)

        return self.render_to_response('edit', context)

    def rows_creatable_for(self, batch):
        """
        Only allow creating new rows on a batch if it hasn't yet been executed.
        """
        return not batch.executed

    def create_row(self):
        """
        Only allow creating a new row if the batch hasn't yet been executed.
        """
        batch = self.get_instance()
        if batch.executed:
            self.request.session.flash("You cannot add new rows to a batch which has been executed")
            return self.redirect(self.get_action_url('view', batch))
        return super(BatchMasterView, self).create_row()

    def make_default_row_grid_tools(self, batch):
        if self.rows_creatable and not batch.executed:
            permission_prefix = self.get_permission_prefix()
            if self.request.has_perm('{}.create_row'.format(permission_prefix)):
                link = tags.link_to("Create a new {}".format(self.get_row_model_title()),
                                    self.get_action_url('create_row', batch))
                return HTML.tag('p', c=link)

    def make_batch_row_grid_tools(self, batch):
        if self.rows_bulk_deletable and not batch.executed and self.request.has_perm('{}.delete_rows'.format(self.get_permission_prefix())):
            url = self.request.route_url('{}.delete_rows'.format(self.get_route_prefix()), uuid=batch.uuid)
            return HTML.tag('p', c=tags.link_to("Delete all rows matching current search", url))

    def make_row_grid_tools(self, batch):
        return (self.make_default_row_grid_tools(batch) or '') + (self.make_batch_row_grid_tools(batch) or '')

    def redirect_after_edit(self, batch):
        """
        If refresh flag is set, do that; otherwise go (back) to view/edit page.
        """
        if self.request.params.get('refresh') == 'true':
            return self.redirect(self.get_action_url('refresh', batch))
        if self.edit_with_rows:
            return self.redirect(self.get_action_url('edit', batch))
        return self.redirect(self.get_action_url('view', batch))

    def delete_instance(self, batch):
        """
        Delete all data (files etc.) for the batch.
        """
        if hasattr(batch, 'delete_data'):
            batch.delete_data(self.rattail_config)
        del batch.data_rows[:]
        super(BatchMasterView, self).delete_instance(batch)

    def get_fallback_templates(self, template, mobile=False):
        if mobile:
            return [
                '/mobile/newbatch/{}.mako'.format(template),
                '/mobile/master/{}.mako'.format(template),
            ]
        return [
            '/newbatch/{}.mako'.format(template),
            '/master/{}.mako'.format(template),
        ]

    def editable_instance(self, batch):
        return not bool(batch.executed)

    def executable(self, batch=None):
        return self.handler.executable(batch)

    def batch_refreshable(self, batch):
        """
        Return a boolean indicating whether the given batch should allow a
        refresh operation.
        """
        # TODO: deprecate/remove this?
        if not self.refreshable:
            return False

        # (this is how it should be done i think..)
        if callable(self.handler.refreshable):
            return self.handler.refreshable(batch)

        # TODO: deprecate/remove this
        return self.handler.refreshable and not batch.executed

    @property
    def has_execution_options(self):
        return bool(self.execution_options_schema)

    # TODO
    execution_options_schema = None

    def make_execution_options_form(self, batch=None):
        """
        Return a proper Form for execution options.
        """
        if batch is None:
            batch = self.model_class
        defaults = {}
        for field in self.execution_options_schema.fields:
            key = 'batch.{}.execute_option.{}'.format(batch.batch_key, field)
            value = self.request.session.get(key)
            if value:
                defaults[field] = value
        return Form(self.request, schema=self.execution_options_schema,
                    defaults=defaults or None)

    def get_execute_title(self, batch):
        if hasattr(self.handler, 'get_execute_title'):
            return self.handler.get_execute_title(batch)
        return "Execute this batch"

    def prefill(self):
        """
        View which will attempt to prefill all data for the batch.  What
        exactly this means will depend on the type of batch etc.
        """
        batch = self.get_instance()
        route_prefix = self.get_route_prefix()
        permission_prefix = self.get_permission_prefix()

        # showing progress requires a separate thread; start that first
        progress_key = '{}.prefill'.format(route_prefix)
        progress = SessionProgress(self.request, progress_key)
        thread = Thread(target=self.prefill_thread, args=(batch.uuid, progress))
        thread.start()

        # Send user to progress page.
        kwargs = {
            'key': progress_key,
            'cancel_url': self.get_action_url('view', batch),
            'cancel_msg': "Batch prefill was canceled.",
        }

        # TODO: This seems hacky...it exists for (only) one specific scenario.
        if not self.request.has_perm('{}.view'.format(permission_prefix)):
            kwargs['cancel_url'] = self.request.route_url('{}.create'.format(route_prefix))

        return self.render_progress(kwargs)

    def prefill_thread(self, batch_uuid, progress):
        """
        Thread target for prefilling batch data with progress indicator.
        """
        # mustn't use tailbone web session here
        session = RattailSession()
        batch = session.query(self.model_class).get(batch_uuid)
        try:
            self.handler.populate(batch, progress=progress)
            self.handler.refresh_batch_status(batch)
        except Exception as error:
            session.rollback()
            log.warning("batch pre-fill failed: {}".format(batch), exc_info=True)
            session.close()
            if progress:
                progress.session.load()
                progress.session['error'] = True
                progress.session['error_msg'] = "Batch pre-fill failed: {} {}".format(error.__class__.__name__, error)
                progress.session.save()
            return

        session.commit()
        session.refresh(batch)
        session.close()

        # finalize progress
        if progress:
            progress.session.load()
            progress.session['complete'] = True
            progress.session['success_url'] = self.get_action_url('view', batch)
            progress.session.save()

    def refresh(self):
        """
        View which will attempt to refresh all data for the batch.  What
        exactly this means will depend on the type of batch etc.
        """
        batch = self.get_instance()
        route_prefix = self.get_route_prefix()
        permission_prefix = self.get_permission_prefix()

        # TODO: deprecate / remove this
        cognizer = self.request.user
        if not cognizer:
            uuid = self.request.session.pop('late_login_user', None)
            cognizer = Session.query(model.User).get(uuid) if uuid else None

        # TODO: refresh should probably always imply/use progress
        # If handler doesn't declare the need for progress indicator, things
        # are nice and simple.
        if not getattr(self.handler, 'show_progress', True):
            self.refresh_data(Session, batch, cognizer=cognizer)
            self.request.session.flash("Batch data has been refreshed.")

            # TODO: This seems hacky...it exists for (only) one specific scenario.
            if not self.request.has_perm('{}.view'.format(permission_prefix)):
                return self.redirect(self.request.route_url('{}.create'.format(route_prefix)))

            return self.redirect(self.get_action_url('view', batch))

        # Showing progress requires a separate thread; start that first.
        key = '{}.refresh'.format(self.model_class.__tablename__)
        progress = SessionProgress(self.request, key)
        # success_url = self.request.route_url('vendors.scangenius.create') if not self.request.user else None
        
        # TODO: This seems hacky...it exists for (only) one specific scenario.
        success_url = None
        if not self.request.user:
            success_url = self.request.route_url('{}.create'.format(route_prefix))
            
        thread = Thread(target=self.refresh_thread, args=(batch.uuid, progress,
                                                          cognizer.uuid if cognizer else None,
                                                          success_url))
        thread.start()

        # Send user to progress page.
        kwargs = {
            'key': key,
            'cancel_url': self.get_action_url('view', batch),
            'cancel_msg': "Batch refresh was canceled.",
            }

        # TODO: This seems hacky...it exists for (only) one specific scenario.
        if not self.request.has_perm('{}.view'.format(permission_prefix)):
            kwargs['cancel_url'] = self.request.route_url('{}.create'.format(route_prefix))

        return self.render_progress(kwargs)

    def refresh_data(self, session, batch, cognizer=None, progress=None):
        """
        Instruct the batch handler to refresh all data for the batch.
        """
        # TODO: deprecate/remove this
        if hasattr(self.handler, 'refresh_data'):
            self.handler.refresh_data(session, batch, progress=progress)
            batch.cognized = datetime.datetime.utcnow()
            batch.cognized_by = cognizer or session.merge(self.request.user)

        else: # the future
            self.handler.refresh(batch, progress=progress)

    def refresh_thread(self, batch_uuid, progress=None, cognizer_uuid=None, success_url=None):
        """
        Thread target for refreshing batch data with progress indicator.
        """
        # Refresh data for the batch, with progress.  Note that we must use the
        # rattail session here; can't use tailbone because it has web request
        # transaction binding etc.
        session = RattailSession()
        batch = session.query(self.model_class).get(batch_uuid)
        cognizer = session.query(model.User).get(cognizer_uuid) if cognizer_uuid else None
        try:
            self.refresh_data(session, batch, cognizer=cognizer, progress=progress)
        except Exception as error:
            session.rollback()
            log.warning("refreshing data for batch failed: {}".format(batch), exc_info=True)
            session.close()
            if progress:
                progress.session.load()
                progress.session['error'] = True
                progress.session['error_msg'] = "Data refresh failed: {} {}".format(error.__class__.__name__, error)
                progress.session.save()
            return

        session.commit()
        session.refresh(batch)
        session.close()

        # Finalize progress indicator.
        if progress:
            progress.session.load()
            progress.session['complete'] = True
            progress.session['success_url'] = success_url or self.get_action_url('view', batch)
            progress.session.save()

    ########################################
    # batch rows
    ########################################

    def get_row_instance_title(self, row):
        return "Row {}".format(row.sequence)

    def _preconfigure_row_grid(self, g):

        g.filters['status_code'].label = "Status"
        g.filters['status_code'].set_value_renderer(grids.filters.EnumValueRenderer(self.model_row_class.STATUS))

        g.default_sortkey = 'sequence'

        g.sequence.set(label="Seq.")
        g.status_code.set(label="Status",
                          renderer=StatusRenderer(self.model_row_class.STATUS))


    hide_row_status_codes = []

    def get_row_data(self, batch):
        """
        Generate the base data set for a rows grid.
        """
        query = self.Session.query(self.model_row_class)\
                            .filter(self.model_row_class.batch == batch)\
                            .filter(self.model_row_class.removed == False)
        if self.hide_row_status_codes:
            query = query.filter(~self.model_row_class.status_code.in_(self.hide_row_status_codes))
        return query

    def row_editable(self, row):
        """
        Batch rows are editable only until batch has been executed.
        """
        return self.rows_editable and not row.batch.executed

    def row_edit_action_url(self, row, i):
        if self.row_editable(row):
            return self.get_row_action_url('edit', row)

    def row_deletable(self, row):
        """
        Batch rows are deletable only until batch has been executed.
        """
        return self.rows_deletable and not row.batch.executed

    def row_delete_action_url(self, row, i):
        if self.row_deletable(row):
            return self.get_row_action_url('delete', row)

    def _preconfigure_row_fieldset(self, fs):
        fs.sequence.set(readonly=True)
        fs.status_code.set(renderer=StatusRenderer(self.model_row_class.STATUS),
                           label="Status", readonly=True)
        fs.status_text.set(readonly=True)
        fs.removed.set(readonly=True)
        try:
            fs.product.set(readonly=True, renderer=forms.renderers.ProductFieldRenderer)
        except AttributeError:
            pass

    def configure_row_fieldset(self, fs):
        fs.configure()
        del fs.batch

    def template_kwargs_view_row(self, **kwargs):
        kwargs['batch_model_title'] = kwargs['parent_model_title']
        return kwargs

    def get_parent(self, row):
        return row.batch

    def delete_row(self):
        """
        "Delete" a row from the batch.  This sets the ``removed`` flag on the
        row but does not truly delete it.
        """
        row = self.Session.query(self.model_row_class).get(self.request.matchdict['uuid'])
        if not row:
            raise httpexceptions.HTTPNotFound()
        row.removed = True
        batch = row.batch
        self.handler.refresh_batch_status(batch)
        if batch.rowcount is not None:
            batch.rowcount -= 1
        return self.redirect(self.get_action_url('view', self.get_parent(row)))

    def bulk_delete_rows(self):
        """
        "Delete" all rows matching the current row grid view query.  This sets
        the ``removed`` flag on the rows but does not truly delete them.
        """
        query = self.get_effective_row_query()
        query.update({'removed': True}, synchronize_session=False)
        return self.redirect(self.get_action_url('view', self.get_instance()))

    def execute(self):
        """
        Execute a batch.  Starts a separate thread for the execution, and
        displays a progress indicator page.
        """
        batch = self.get_instance()
        if self.request.method == 'POST':

            kwargs = {}
            if self.has_execution_options:
                form = self.make_execution_options_form(batch)
                assert form.validate() # TODO
                kwargs.update(form.data)
                for key, value in form.data.iteritems():
                    # TODO: properly serialize option values?
                    self.request.session['batch.{}.execute_option.{}'.format(batch.batch_key, key)] = unicode(value)

            key = '{}.execute'.format(self.model_class.__tablename__)
            kwargs['progress'] = SessionProgress(self.request, key)
            thread = Thread(target=self.execute_thread, args=(batch.uuid, self.request.user.uuid), kwargs=kwargs)
            thread.start()

            return self.render_progress({
                'key': key,
                'cancel_url': self.get_action_url('view', batch),
                'cancel_msg': "Batch execution was canceled.",
            })

        self.request.session.flash("Sorry, you must POST to execute a batch.", 'error')
        return self.redirect(self.get_action_url('view', batch))

    def execute_error_message(self, error):
        return "Batch execution failed: {}: {}".format(type(error).__name__, error)

    def execute_thread(self, batch_uuid, user_uuid, progress=None, **kwargs):
        """
        Thread target for executing a batch with progress indicator.
        """
        # Execute the batch, with progress.  Note that we must use the rattail
        # session here; can't use tailbone because it has web request
        # transaction binding etc.
        session = RattailSession()
        batch = session.query(self.model_class).get(batch_uuid)
        user = session.query(model.User).get(user_uuid)
        try:
            result = self.handler.execute(batch, user=user, progress=progress, **kwargs)

        # If anything goes wrong, rollback and log the error etc.
        except Exception as error:
            session.rollback()
            log.exception("execution failed for batch: {}".format(batch))
            session.close()
            if progress:
                progress.session.load()
                progress.session['error'] = True
                progress.session['error_msg'] = self.execute_error_message(error)
                progress.session.save()

        # If no error, check result flag (false means user canceled).
        else:
            if result:
                batch.executed = datetime.datetime.utcnow()
                batch.executed_by = user
                session.commit()
                # TODO: this doesn't always work...?
                self.request.session.flash("{} has been executed: {}".format(
                    self.get_model_title(), batch.id_str))
            else:
                session.rollback()

            session.refresh(batch)
            success_url = self.get_execute_success_url(batch, result, **kwargs)
            session.close()

            if progress:
                progress.session.load()
                progress.session['complete'] = True
                progress.session['success_url'] = success_url
                progress.session.save()

    def get_execute_success_url(self, batch, result, **kwargs):
        return self.get_action_url('view', batch)

    def execute_results(self):
        """
        Execute all batches which are returned from the current index query.
        Starts a separate thread for the execution, and displays a progress
        indicator page.
        """
        if self.request.method == 'POST':

            kwargs = {}
            if self.has_execution_options:
                form = self.make_execution_options_form()
                if not form.validate():
                    raise RuntimeError("Execution options form did not validate")
                kwargs.update(form.data)

                # cache options to use as defaults next time
                for key, value in form.data.iteritems():
                    self.request.session['batch.{}.execute_option.{}'.format(self.model_class.batch_key, key)] = six.text_type(value)

            key = '{}.execute_results'.format(self.model_class.__tablename__)
            batches = self.get_effective_data()
            kwargs['progress'] = SessionProgress(self.request, key)
            thread = Thread(target=self.execute_results_thread, args=(batches, self.request.user.uuid), kwargs=kwargs)
            thread.start()

            return self.render_progress({
                'key': key,
                'cancel_url': self.get_index_url(),
                'cancel_msg': "Batch execution was canceled",
            })

        self.request.session.flash("Sorry, you must POST to execute batches", 'error')
        return self.redirect(self.get_index_url())

    def execute_results_thread(self, batches, user_uuid, progress=None, **kwargs):
        """
        Thread target for executing multiple batches with progress indicator.
        """
        session = RattailSession()
        batches = batches.with_session(session).all()
        user = session.query(model.User).get(user_uuid)
        try:
            result = self.handler.execute_many(batches, user=user, progress=progress, **kwargs)

        # If anything goes wrong, rollback and log the error etc.
        except Exception as error:
            session.rollback()
            log.exception("execution failed for batch results")
            session.close()
            if progress:
                progress.session.load()
                progress.session['error'] = True
                progress.session['error_msg'] = self.execute_error_message(error)
                progress.session.save()

        # If no error, check result flag (false means user canceled).
        else:
            if result:
                now = datetime.datetime.utcnow()
                for batch in batches:
                    batch.executed = now
                    batch.executed_by = user
                session.commit()
                # TODO: this doesn't always work...?
                self.request.session.flash("{} {} were executed".format(
                    len(batches), self.get_model_title_plural()))
                success_url = self.get_execute_results_success_url(result, **kwargs)
            else:
                session.rollback()
                success_url = self.get_index_url()
            session.close()

            if progress:
                progress.session.load()
                progress.session['complete'] = True
                progress.session['success_url'] = success_url
                progress.session.save()

    def get_execute_results_success_url(self, result, **kwargs):
        return self.get_index_url()

    def csv(self):
        """
        Download batch data as CSV.
        """
        batch = self.get_instance()
        fields = self.get_csv_fields()
        data = StringIO()
        writer = UnicodeDictWriter(data, fields)
        writer.writeheader()
        for row in batch.data_rows:
            if not row.removed:
                writer.writerow(self.get_csv_row(row, fields))
        response = self.request.response
        response.text = data.getvalue().decode('utf_8')
        data.close()
        response.content_length = len(response.text)
        response.content_type = b'text/csv'
        response.content_disposition = b'attachment; filename=batch.csv'
        return response

    def get_csv_fields(self):
        """
        Return the list of fields to be written to CSV download.
        """
        fields = []
        mapper = orm.class_mapper(self.model_row_class)
        for prop in mapper.iterate_properties:
            if isinstance(prop, orm.ColumnProperty):
                if prop.key != 'removed' and not prop.key.endswith('uuid'):
                    fields.append(prop.key)
        return fields

    def get_csv_row(self, row, fields):
        """
        Return a dict for use when writing the row's data to CSV download.
        """
        csvrow = {}
        for field in fields:
            value = getattr(row, field)
            csvrow[field] = '' if value is None else unicode(value)
        return csvrow

    def clone(self):
        """
        Clone current batch as new batch
        """
        batch = self.get_instance()
        batch = self.handler.clone(batch, created_by=self.request.user)
        return self.redirect(self.get_action_url('view', batch))

    @classmethod
    def defaults(cls, config):
        cls._batch_defaults(config)
        cls._defaults(config)

    @classmethod
    def _batch_defaults(cls, config):
        route_prefix = cls.get_route_prefix()
        url_prefix = cls.get_url_prefix()
        permission_prefix = cls.get_permission_prefix()
        model_title = cls.get_model_title()
        model_title_plural = cls.get_model_title_plural()

        # TODO: currently must do this here (in addition to `_defaults()` or
        # else the perm group label will not display correctly...
        config.add_tailbone_permission_group(permission_prefix, model_title_plural, overwrite=False)

        # prefill row data
        config.add_route('{}.prefill'.format(route_prefix), '{}/{{uuid}}/prefill'.format(url_prefix))
        config.add_view(cls, attr='prefill', route_name='{}.prefill'.format(route_prefix),
                        permission='{}.create'.format(permission_prefix))

        # refresh batch data
        config.add_route('{}.refresh'.format(route_prefix), '{}/{{uuid}}/refresh'.format(url_prefix))
        config.add_view(cls, attr='refresh', route_name='{}.refresh'.format(route_prefix),
                        permission='{}.refresh'.format(permission_prefix))
        config.add_tailbone_permission(permission_prefix, '{}.refresh'.format(permission_prefix),
                                       "Refresh data for {}".format(model_title))

        # bulk delete rows
        if cls.rows_bulk_deletable:
            config.add_route('{}.delete_rows'.format(route_prefix), '{}/{{uuid}}/rows/delete'.format(url_prefix))
            config.add_view(cls, attr='bulk_delete_rows', route_name='{}.delete_rows'.format(route_prefix),
                            permission='{}.delete_rows'.format(permission_prefix))
            config.add_tailbone_permission(permission_prefix, '{}.delete_rows'.format(permission_prefix),
                                           "Bulk-delete data rows from {}".format(model_title))

        # execute batch
        config.add_route('{}.execute'.format(route_prefix), '{}/{{uuid}}/execute'.format(url_prefix))
        config.add_view(cls, attr='execute', route_name='{}.execute'.format(route_prefix),
                        permission='{}.execute'.format(permission_prefix))
        config.add_tailbone_permission(permission_prefix, '{}.execute'.format(permission_prefix),
                                       "Execute {}".format(model_title))

        # execute (multiple) batch results
        config.add_route('{}.execute_results'.format(route_prefix), '{}/execute-results'.format(url_prefix))
        config.add_view(cls, attr='execute_results', route_name='{}.execute_results'.format(route_prefix),
                        permission='{}.execute_multiple'.format(permission_prefix))
        config.add_tailbone_permission(permission_prefix, '{}.execute_multiple'.format(permission_prefix),
                                       "Execute multiple {}".format(model_title_plural))

        # download rows as CSV
        if cls.rows_downloadable:
            config.add_route('{}.csv'.format(route_prefix), '{}/{{uuid}}/csv'.format(url_prefix))
            config.add_view(cls, attr='csv', route_name='{}.csv'.format(route_prefix),
                            permission='{}.csv'.format(permission_prefix))
            config.add_tailbone_permission(permission_prefix, '{}.csv'.format(permission_prefix),
                                           "Download {} rows as CSV".format(model_title))

        # clone as new batch
        if cls.cloneable:
            config.add_route('{}.clone'.format(route_prefix), '{}/{{uuid}}/clone'.format(url_prefix))
            config.add_view(cls, attr='clone', route_name='{}.clone'.format(route_prefix),
                            permission='{}.clone'.format(permission_prefix))
            config.add_tailbone_permission(permission_prefix, '{}.clone'.format(permission_prefix),
                                           "Clone {} as new batch".format(model_title))


class FileBatchMasterView(BatchMasterView):
    """
    Base class for all file-based "batch master" views.
    """

    @property
    def upload_dir(self):
        """
        The path to the root upload folder, to be used as the ``storage_path``
        argument for the file field renderer.
        """
        uploads = os.path.join(
            self.rattail_config.require('rattail', 'batch.files'),
            'uploads')
        uploads = self.rattail_config.get('tailbone', 'batch.uploads',
                                          default=uploads)
        if not os.path.exists(uploads):
            os.makedirs(uploads)
        return uploads

    def preconfigure_grid(self, g):
        super(FileBatchMasterView, self).preconfigure_grid(g)
        g.created.set(label="Uploaded")
        g.created_by.set(label="Uploaded by")

    def _preconfigure_fieldset(self, fs):
        super(FileBatchMasterView, self)._preconfigure_fieldset(fs)
        fs.created.set(label="Uploaded")
        fs.created_by.set(label="Uploaded by")
        fs.filename.set(label="Data File", renderer=FileFieldRenderer.new(self))
        if self.editing:
            fs.filename.set(readonly=True)

    def configure_fieldset(self, fs):
        """
        Apply final configuration to the main batch fieldset.  Custom batch
        views are encouraged to override this method.
        """
        if self.creating:
            fs.configure(
                include=[
                    fs.filename,
                ])

        else:
            batch = fs.model
            if batch.executed:
                fs.configure(
                    include=[
                        fs.id,
                        fs.created,
                        fs.created_by,
                        fs.filename,
                        fs.executed,
                        fs.executed_by,
                    ])
            else:
                fs.configure(
                    include=[
                        fs.id,
                        fs.created,
                        fs.created_by,
                        fs.filename,
                    ])

    def download(self):
        """
        View for downloading the data file associated with a batch.
        """
        batch = self.get_instance()
        if not batch:
            raise httpexceptions.HTTPNotFound()
        path = batch.filepath(self.rattail_config)
        response = FileResponse(path, request=self.request)
        response.headers[b'Content-Length'] = str(os.path.getsize(path))
        filename = os.path.basename(batch.filename).encode('ascii', 'replace')
        response.headers[b'Content-Disposition'] = b'attachment; filename="{}"'.format(filename)
        return response

    @classmethod
    def defaults(cls, config):
        cls._filebatch_defaults(config)
        cls._batch_defaults(config)
        cls._defaults(config)

    @classmethod
    def _filebatch_defaults(cls, config):
        route_prefix = cls.get_route_prefix()
        url_prefix = cls.get_url_prefix()
        permission_prefix = cls.get_permission_prefix()
        model_title = cls.get_model_title()
        model_title_plural = cls.get_model_title_plural()

        # fix permission group title
        config.add_tailbone_permission_group(permission_prefix, model_title_plural)

        # download batch data file
        config.add_route('{}.download'.format(route_prefix), '{}/{{uuid}}/download'.format(url_prefix))
        config.add_view(cls, attr='download', route_name='{}.download'.format(route_prefix),
                        permission='{}.download'.format(permission_prefix))
        config.add_tailbone_permission(permission_prefix, '{}.download'.format(permission_prefix),
                                       "Download existing {} data file".format(model_title))


class StatusRenderer(forms.renderers.EnumFieldRenderer):
    """
    Custom renderer for ``status_code`` fields.  Adds ``status_text`` value as
    title attribute if it exists.
    """

    def render_readonly(self, **kwargs):
        value = self.raw_value
        if value is None:
            return ''
        status_code_text = self.enumeration.get(value, unicode(value))
        row = self.field.parent.model
        if row.status_text:
            return HTML.tag('span', title=row.status_text, c=status_code_text)
        return status_code_text