from datetime import timedelta

import django_filters
from django import forms
from django.core.exceptions import PermissionDenied
from django.core.paginator import Paginator
from django.shortcuts import get_object_or_404
from django.template.response import TemplateResponse
from django.utils.decorators import method_decorator
from django.utils.translation import gettext as _

from wagtail.admin.auth import user_has_any_page_permission, user_passes_test
from wagtail.admin.filters import DateRangePickerWidget, WagtailFilterSet
from wagtail.admin.views.reports import ReportView
from wagtail.log_actions import registry as log_action_registry
from wagtail.models import (
    Page,
    PageLogEntry,
    Revision,
    TaskState,
    UserPagePermissionsProxy,
    WorkflowState,
)


class PageHistoryReportFilterSet(WagtailFilterSet):
    action = django_filters.ChoiceFilter(
        label=_("Action"),
        choices=log_action_registry.get_choices,
    )
    hide_commenting_actions = django_filters.BooleanFilter(
        label=_("Hide commenting actions"),
        method="filter_hide_commenting_actions",
        widget=forms.CheckboxInput,
    )
    user = django_filters.ModelChoiceFilter(
        label=_("User"),
        field_name="user",
        queryset=lambda request: PageLogEntry.objects.all().get_users(),
    )
    timestamp = django_filters.DateFromToRangeFilter(
        label=_("Date"), widget=DateRangePickerWidget
    )

    def filter_hide_commenting_actions(self, queryset, name, value):
        if value:
            queryset = queryset.exclude(action__startswith="wagtail.comments")
        return queryset

    class Meta:
        model = PageLogEntry
        fields = ["action", "user", "timestamp", "hide_commenting_actions"]


def workflow_history(request, page_id):
    page = get_object_or_404(Page, id=page_id)

    user_perms = UserPagePermissionsProxy(request.user)
    if not user_perms.for_page(page).can_edit():
        raise PermissionDenied

    workflow_states = WorkflowState.objects.filter(page=page).order_by("-created_at")

    paginator = Paginator(workflow_states, per_page=20)
    workflow_states = paginator.get_page(request.GET.get("p"))

    return TemplateResponse(
        request,
        "wagtailadmin/pages/workflow_history/index.html",
        {
            "page": page,
            "workflow_states": workflow_states,
        },
    )


def workflow_history_detail(request, page_id, workflow_state_id):
    page = get_object_or_404(Page, id=page_id)

    user_perms = UserPagePermissionsProxy(request.user)
    if not user_perms.for_page(page).can_edit():
        raise PermissionDenied

    workflow_state = get_object_or_404(WorkflowState, page=page, id=workflow_state_id)

    # Get QuerySet of all revisions that have existed during this workflow state
    # It's possible that the page is edited while the workflow is running, so some
    # tasks may be repeated. All tasks that have been completed no matter what
    # revision needs to be displayed on this page.
    page_revisions = Revision.page_revisions.filter(
        object_id=str(page.id),
        id__in=TaskState.objects.filter(workflow_state=workflow_state).values_list(
            "page_revision_id", flat=True
        ),
    ).order_by("-created_at")

    # Now get QuerySet of tasks completed for each revision
    task_states_by_revision_task = [
        (
            page_revision,
            {
                task_state.task: task_state
                for task_state in TaskState.objects.filter(
                    workflow_state=workflow_state, page_revision=page_revision
                )
            },
        )
        for page_revision in page_revisions
    ]

    # Make sure task states are always in a consistent order
    # In some cases, they can be completed in a different order to what they are defined
    tasks = workflow_state.workflow.tasks.all()
    task_states_by_revision = [
        (page_revision, [task_states_by_task.get(task, None) for task in tasks])
        for page_revision, task_states_by_task in task_states_by_revision_task
    ]

    # Generate timeline
    completed_task_states = (
        TaskState.objects.filter(workflow_state=workflow_state)
        .exclude(finished_at__isnull=True)
        .exclude(status=TaskState.STATUS_CANCELLED)
    )

    timeline = [
        {
            "time": workflow_state.created_at,
            "action": "workflow_started",
            "workflow_state": workflow_state,
        }
    ]

    if workflow_state.status not in (
        WorkflowState.STATUS_IN_PROGRESS,
        WorkflowState.STATUS_NEEDS_CHANGES,
    ):
        last_task = completed_task_states.order_by("finished_at").last()
        if last_task:
            timeline.append(
                {
                    "time": last_task.finished_at + timedelta(milliseconds=1),
                    "action": "workflow_completed",
                    "workflow_state": workflow_state,
                }
            )

    for page_revision in page_revisions:
        timeline.append(
            {
                "time": page_revision.created_at,
                "action": "page_edited",
                "revision": page_revision,
            }
        )

    for task_state in completed_task_states:
        timeline.append(
            {
                "time": task_state.finished_at,
                "action": "task_completed",
                "task_state": task_state,
            }
        )

    timeline.sort(key=lambda t: t["time"])
    timeline.reverse()

    return TemplateResponse(
        request,
        "wagtailadmin/pages/workflow_history/detail.html",
        {
            "page": page,
            "workflow_state": workflow_state,
            "tasks": tasks,
            "task_states_by_revision": task_states_by_revision,
            "timeline": timeline,
        },
    )


class PageHistoryView(ReportView):
    template_name = "wagtailadmin/pages/history.html"
    title = _("Page history")
    header_icon = "history"
    paginate_by = 20
    filterset_class = PageHistoryReportFilterSet

    @method_decorator(user_passes_test(user_has_any_page_permission))
    def dispatch(self, request, *args, **kwargs):
        self.page = get_object_or_404(Page, id=kwargs.pop("page_id")).specific

        return super().dispatch(request, *args, **kwargs)

    def get_context_data(self, *args, object_list=None, **kwargs):
        context = super().get_context_data(*args, object_list=object_list, **kwargs)
        context["page"] = self.page
        context["subtitle"] = self.page.get_admin_display_title()
        context["page_latest_revision"] = self.page.get_latest_revision()

        return context

    def get_queryset(self):
        return PageLogEntry.objects.filter(page=self.page).select_related(
            "revision", "user", "user__wagtail_userprofile"
        )
