from __future__ import absolute_import, unicode_literals

from django.contrib import messages
from django.db import transaction
from django.http import Http404, HttpResponseRedirect
from django.shortcuts import get_object_or_404
from django.template import RequestContext
from django.urls import reverse, reverse_lazy
from django.utils.translation import ugettext_lazy as _

from mayan.apps.common.generics import (
    AddRemoveView, ConfirmView, FormView, SingleObjectCreateView,
    SingleObjectDeleteView, SingleObjectDetailView,
    SingleObjectDynamicFormCreateView, SingleObjectDynamicFormEditView,
    SingleObjectEditView, SingleObjectListView
)
from mayan.apps.common.mixins import ExternalObjectMixin
from mayan.apps.documents.events import event_document_type_edited
from mayan.apps.documents.models import DocumentType
from mayan.apps.documents.permissions import permission_document_type_edit
from mayan.apps.events.classes import EventType
from mayan.apps.events.models import StoredEventType

from ..classes import WorkflowAction
from ..events import event_workflow_edited
from ..forms import (
    WorkflowActionSelectionForm, WorkflowForm, WorkflowPreviewForm,
    WorkflowStateActionDynamicForm, WorkflowStateForm, WorkflowTransitionForm,
    WorkflowTransitionTriggerEventRelationshipFormSet
)
from ..icons import (
    icon_workflow_template_list, icon_workflow_state, icon_workflow_state_action,
    icon_workflow_transition, icon_workflow_transition_field
)
from ..links import (
    link_workflow_template_create, link_workflow_template_state_create,
    link_workflow_template_state_action_selection,
    link_workflow_template_transition_create,
    link_workflow_template_transition_field_create,
)
from ..models import (
    Workflow, WorkflowState, WorkflowStateAction, WorkflowTransition,
    WorkflowTransitionField
)
from ..permissions import (
    permission_workflow_create, permission_workflow_delete,
    permission_workflow_edit, permission_workflow_tools,
    permission_workflow_view,
)
from ..tasks import task_launch_all_workflows


class DocumentTypeWorkflowTemplatesView(AddRemoveView):
    main_object_permission = permission_document_type_edit
    main_object_model = DocumentType
    main_object_pk_url_kwarg = 'pk'
    secondary_object_model = Workflow
    secondary_object_permission = permission_workflow_edit
    list_available_title = _('Available workflows')
    list_added_title = _('Workflows assigned this document type')
    related_field = 'workflows'

    def get_actions_extra_kwargs(self):
        return {'_user': self.request.user}

    def get_extra_context(self):
        return {
            'object': self.main_object,
            'subtitle': _(
                'Removing a workflow from a document type will also '
                'remove all running instances of that workflow.'
            ),
            'title': _(
                'Workflows assigned the document type: %s'
            ) % self.main_object,
        }

    def action_add(self, queryset, _user):
        with transaction.atomic():
            event_document_type_edited.commit(
                actor=_user, target=self.main_object
            )

            for obj in queryset:
                self.main_object.workflows.add(obj)
                event_workflow_edited.commit(
                    action_object=self.main_object, actor=_user, target=obj
                )

    def action_remove(self, queryset, _user):
        with transaction.atomic():
            event_document_type_edited.commit(
                actor=_user, target=self.main_object
            )

            for obj in queryset:
                self.main_object.workflows.remove(obj)
                event_workflow_edited.commit(
                    action_object=self.main_object, actor=_user,
                    target=obj
                )
                obj.instances.filter(
                    document__document_type=self.main_object
                ).delete()


class WorkflowTemplateListView(SingleObjectListView):
    model = Workflow
    object_permission = permission_workflow_view

    def get_extra_context(self):
        return {
            'hide_object': True,
            'no_results_icon': icon_workflow_template_list,
            'no_results_main_link': link_workflow_template_create.resolve(
                context=RequestContext(request=self.request)
            ),
            'no_results_text': _(
                'Workflows store a series of states and keep track of the '
                'current state of a document. Transitions are used to change the '
                'current state to a new one.'
            ),
            'no_results_title': _(
                'No workflows have been defined'
            ),
            'title': _('Workflows'),
        }


class WorkflowTemplateCreateView(SingleObjectCreateView):
    extra_context = {'title': _('Create workflow')}
    form_class = WorkflowForm
    model = Workflow
    post_action_redirect = reverse_lazy(
        viewname='document_states:workflow_template_list'
    )
    view_permission = permission_workflow_create

    def get_save_extra_data(self):
        return {'_user': self.request.user}


class WorkflowTemplateDeleteView(SingleObjectDeleteView):
    model = Workflow
    object_permission = permission_workflow_delete
    post_action_redirect = reverse_lazy(
        viewname='document_states:workflow_template_list'
    )

    def get_extra_context(self):
        return {
            'title': _(
                'Delete workflow: %s?'
            ) % self.object,
        }


class WorkflowTemplateEditView(SingleObjectEditView):
    form_class = WorkflowForm
    model = Workflow
    object_permission = permission_workflow_edit
    post_action_redirect = reverse_lazy(
        viewname='document_states:workflow_template_list'
    )

    def get_extra_context(self):
        return {
            'title': _(
                'Edit workflow: %s'
            ) % self.object,
        }

    def get_save_extra_data(self):
        return {'_user': self.request.user}


class WorkflowTemplateDocumentTypesView(AddRemoveView):
    main_object_permission = permission_workflow_edit
    main_object_model = Workflow
    main_object_pk_url_kwarg = 'pk'
    secondary_object_model = DocumentType
    secondary_object_permission = permission_document_type_edit
    list_available_title = _('Available document types')
    list_added_title = _('Document types assigned this workflow')
    related_field = 'document_types'

    def get_actions_extra_kwargs(self):
        return {'_user': self.request.user}

    def get_extra_context(self):
        return {
            'object': self.main_object,
            'subtitle': _(
                'Removing a document type from a workflow will also '
                'remove all running instances of that workflow for '
                'documents of the document type just removed.'
            ),
            'title': _(
                'Document types assigned the workflow: %s'
            ) % self.main_object,
        }

    def action_add(self, queryset, _user):
        with transaction.atomic():
            event_workflow_edited.commit(
                actor=_user, target=self.main_object
            )

            for obj in queryset:
                self.main_object.document_types.add(obj)
                event_document_type_edited.commit(
                    action_object=self.main_object, actor=_user, target=obj
                )

    def action_remove(self, queryset, _user):
        with transaction.atomic():
            event_workflow_edited.commit(
                actor=_user, target=self.main_object
            )

            for obj in queryset:
                self.main_object.document_types.remove(obj)
                event_document_type_edited.commit(
                    action_object=self.main_object, actor=_user,
                    target=obj
                )
                self.main_object.instances.filter(
                    document__document_type=obj
                ).delete()


class WorkflowTemplatePreviewView(SingleObjectDetailView):
    form_class = WorkflowPreviewForm
    model = Workflow
    object_permission = permission_workflow_view
    pk_url_kwarg = 'pk'

    def get_extra_context(self):
        return {
            'hide_labels': True,
            'object': self.get_object(),
            'title': _('Preview of: %s') % self.get_object()
        }


class ToolLaunchWorkflows(ConfirmView):
    extra_context = {
        'title': _('Launch all workflows?'),
        'subtitle': _(
            'This will launch all workflows created after documents have '
            'already been uploaded.'
        )
    }
    view_permission = permission_workflow_tools

    def view_action(self):
        task_launch_all_workflows.apply_async()
        messages.success(
            message=_('Workflow launch queued successfully.'),
            request=self.request
        )