import json
from urllib.parse import quote

from django.conf import settings
from django.contrib.auth import get_user_model
from django.core.exceptions import PermissionDenied
from django.db import transaction
from django.db.models import Prefetch, Q
from django.http import HttpResponse, JsonResponse
from django.shortcuts import get_object_or_404, redirect
from django.urls import reverse
from django.utils import timezone
from django.utils.functional import cached_property
from django.utils.html import format_html
from django.utils.translation import gettext as _
from django.views.generic.base import View

from wagtail.actions.publish_page_revision import PublishPageRevisionAction
from wagtail.admin import messages
from wagtail.admin.action_menu import PageActionMenu
from wagtail.admin.mail import send_notification
from wagtail.admin.models import EditingSession
from wagtail.admin.telepath import JSContext
from wagtail.admin.ui.autosave import AutosaveIndicator
from wagtail.admin.ui.components import MediaContainer
from wagtail.admin.ui.editing_sessions import EditingSessionsModule
from wagtail.admin.ui.side_panels import (
    ChecksSidePanel,
    CommentsSidePanel,
    PageStatusSidePanel,
    PreviewSidePanel,
)
from wagtail.admin.utils import get_valid_next_url_from_request
from wagtail.admin.views.generic import HookResponseMixin, JsonPostResponseMixin
from wagtail.admin.views.generic.base import WagtailAdminTemplateMixin
from wagtail.exceptions import PageClassNotFoundError
from wagtail.locks import BasicLock, ScheduledForPublishLock, WorkflowLock
from wagtail.models import (
    COMMENTS_RELATION_NAME,
    Comment,
    CommentReply,
    Page,
    PageSubscription,
    Revision,
    WorkflowState,
    get_default_page_content_type,
)
from wagtail.utils.timestamps import render_timestamp


class EditView(
    WagtailAdminTemplateMixin, HookResponseMixin, JsonPostResponseMixin, View
):
    partials_template_name = "wagtailadmin/pages/edit_partials.html"

    def get_page_title(self):
        return _("Editing %(page_type)s") % {
            "page_type": self.page_class.get_verbose_name()
        }

    def get_page_subtitle(self):
        return self.page.get_admin_display_title()

    def get_template_names(self):
        if self.page.alias_of_id:
            return ["wagtailadmin/pages/edit_alias.html"]
        elif self.hydrate_create_view:
            return [self.partials_template_name]
        else:
            return ["wagtailadmin/pages/edit.html"]

    def add_save_confirmation_message(self):
        if self.is_reverting:
            message = _(
                "Page '%(page_title)s' has been replaced "
                "with version from %(previous_revision_datetime)s."
            ) % {
                "page_title": self.page.get_admin_display_title(),
                "previous_revision_datetime": render_timestamp(
                    self.previous_revision.created_at
                ),
            }
        else:
            message = _("Page '%(page_title)s' has been updated.") % {
                "page_title": self.page.get_admin_display_title()
            }

        messages.success(self.request, message)

    def get_commenting_changes(self):
        """
        Finds comments that have been changed during this request.

        Returns a tuple of 5 lists:
         - New comments
         - Deleted comments
         - Resolved comments
         - Edited comments
         - Replied comments (dict containing the instance and list of replies)
        """
        # Get changes
        comments_formset = self.form.formsets["comments"]
        new_comments = comments_formset.new_objects
        deleted_comments = comments_formset.deleted_objects

        # Assume any changed comments that are resolved were only just resolved
        resolved_comments = []
        edited_comments = []
        for changed_comment, changed_fields in comments_formset.changed_objects:
            if changed_comment.resolved_at and "resolved" in changed_fields:
                resolved_comments.append(changed_comment)

            if "text" in changed_fields:
                edited_comments.append(changed_comment)

        new_replies = []
        deleted_replies = []
        edited_replies = []
        for comment_form in comments_formset.forms:
            # New
            replies = getattr(comment_form.formsets["replies"], "new_objects", [])
            if replies:
                new_replies.append((comment_form.instance, replies))

            # Deleted
            replies = getattr(comment_form.formsets["replies"], "deleted_objects", [])
            if replies:
                deleted_replies.append((comment_form.instance, replies))

            # Edited
            replies = getattr(comment_form.formsets["replies"], "changed_objects", [])
            replies = [
                reply for reply, changed_fields in replies if "text" in changed_fields
            ]
            if replies:
                edited_replies.append((comment_form.instance, replies))

        return {
            "new_comments": new_comments,
            "deleted_comments": deleted_comments,
            "resolved_comments": resolved_comments,
            "edited_comments": edited_comments,
            "new_replies": new_replies,
            "deleted_replies": deleted_replies,
            "edited_replies": edited_replies,
        }

    def send_commenting_notifications(self, changes):
        """
        Sends notifications about any changes to comments to anyone who is subscribed.
        """
        relevant_comment_ids = []
        relevant_comment_ids.extend(
            comment.pk for comment in changes["resolved_comments"]
        )
        relevant_comment_ids.extend(
            comment.pk for comment, replies in changes["new_replies"]
        )

        # Skip if no changes were made
        # Note: We don't email about edited comments so ignore those here
        if (
            not changes["new_comments"]
            and not changes["deleted_comments"]
            and not changes["resolved_comments"]
            and not changes["new_replies"]
        ):
            return

        # Get global page comment subscribers
        subscribers = PageSubscription.objects.filter(
            page=self.page, comment_notifications=True
        ).select_related("user")
        global_recipient_users = [
            subscriber.user
            for subscriber in subscribers
            if subscriber.user != self.request.user
        ]

        # Get subscribers to individual threads
        replies = CommentReply.objects.filter(comment_id__in=relevant_comment_ids)
        comments = Comment.objects.filter(id__in=relevant_comment_ids)
        thread_users = (
            get_user_model()
            .objects.exclude(pk=self.request.user.pk)
            .exclude(pk__in=subscribers.values_list("user_id", flat=True))
            .filter(
                Q(comment_replies__comment_id__in=relevant_comment_ids)
                | Q(**{("%s__pk__in" % COMMENTS_RELATION_NAME): relevant_comment_ids})
            )
            .prefetch_related(
                Prefetch("comment_replies", queryset=replies),
                Prefetch(COMMENTS_RELATION_NAME, queryset=comments),
            )
        )

        # Skip if no recipients
        if not (global_recipient_users or thread_users):
            return
        thread_users = [
            (
                user,
                set(
                    list(user.comment_replies.values_list("comment_id", flat=True))
                    + list(
                        getattr(user, COMMENTS_RELATION_NAME).values_list(
                            "pk", flat=True
                        )
                    )
                ),
            )
            for user in thread_users
        ]
        mailed_users = set()

        for current_user, current_threads in thread_users:
            # We are trying to avoid calling send_notification for each user for performance reasons
            # so group the users receiving the same thread notifications together here
            if current_user in mailed_users:
                continue
            users = [current_user]
            mailed_users.add(current_user)
            for user, threads in thread_users:
                if user not in mailed_users and threads == current_threads:
                    users.append(user)
                    mailed_users.add(user)
            send_notification(
                users,
                "updated_comments",
                {
                    "page": self.page,
                    "editor": self.request.user,
                    "new_comments": [
                        comment
                        for comment in changes["new_comments"]
                        if comment.pk in threads
                    ],
                    "resolved_comments": [
                        comment
                        for comment in changes["resolved_comments"]
                        if comment.pk in threads
                    ],
                    "deleted_comments": [],
                    "replied_comments": [
                        {
                            "comment": comment,
                            "replies": replies,
                        }
                        for comment, replies in changes["new_replies"]
                        if comment.pk in threads
                    ],
                },
            )

        return send_notification(
            global_recipient_users,
            "updated_comments",
            {
                "page": self.page,
                "editor": self.request.user,
                "new_comments": changes["new_comments"],
                "resolved_comments": changes["resolved_comments"],
                "deleted_comments": changes["deleted_comments"],
                "replied_comments": [
                    {
                        "comment": comment,
                        "replies": replies,
                    }
                    for comment, replies in changes["new_replies"]
                ],
            },
        )

    def log_commenting_changes(self, changes, revision):
        """
        Generates log entries for any changes made to comments or replies.
        """
        for comment in changes["new_comments"]:
            comment.log_create(page_revision=revision, user=self.request.user)

        for comment in changes["edited_comments"]:
            comment.log_edit(page_revision=revision, user=self.request.user)

        for comment in changes["resolved_comments"]:
            comment.log_resolve(page_revision=revision, user=self.request.user)

        for comment in changes["deleted_comments"]:
            comment.log_delete(page_revision=revision, user=self.request.user)

        for comment, replies in changes["new_replies"]:
            for reply in replies:
                reply.log_create(page_revision=revision, user=self.request.user)

        for comment, replies in changes["edited_replies"]:
            for reply in replies:
                reply.log_edit(page_revision=revision, user=self.request.user)

        for comment, replies in changes["deleted_replies"]:
            for reply in replies:
                reply.log_delete(page_revision=revision, user=self.request.user)

    def get_edit_message_button(self):
        return messages.button(self.get_edit_url(), _("Edit"))

    def get_view_draft_message_button(self):
        return messages.button(
            reverse("wagtailadmin_pages:view_draft", args=(self.page.id,)),
            _("View draft"),
            new_window=False,
        )

    def get_view_live_message_button(self):
        return messages.button(self.page.url, _("View live"), new_window=False)

    def get_compare_with_live_message_button(self):
        return messages.button(
            reverse(
                "wagtailadmin_pages:revisions_compare",
                args=(self.page.id, "live", self.latest_revision.id),
            ),
            _("Compare with live version"),
        )

    def get_page_for_status(self):
        if self.page.live and self.page.has_unpublished_changes:
            # Page status needs to present the version of the page containing the correct live URL
            return self.real_page_record.specific
        else:
            return self.page

    def get_object(self):
        return self.real_page_record.get_latest_revision_as_object()

    def get_edit_url(self):
        return reverse("wagtailadmin_pages:edit", args=(self.page.id,))

    def dispatch(self, request, page_id, **kwargs):
        self.real_page_record = get_object_or_404(
            Page.objects.prefetch_workflow_states(), id=page_id
        )
        self.latest_revision = self.real_page_record.get_latest_revision()
        self.scheduled_revision = self.real_page_record.scheduled_revision
        self.page_content_type = self.real_page_record.cached_content_type
        self.page_class = self.real_page_record.specific_class

        if self.page_class is None:
            raise PageClassNotFoundError(
                f"The page '{self.real_page_record}' cannot be edited because the "
                f"model class used to create it ({self.page_content_type.app_label}."
                f"{self.page_content_type.model}) can no longer be found in the codebase. "
                "This usually happens as a result of switching between git "
                "branches without running migrations to trigger the removal of "
                "unused ContentTypes. To edit the page, you will need to switch "
                "back to a branch where the model class is still present."
            )

        self.revision_id = kwargs.get("revision_id")
        self.is_reverting = bool(self.revision_id)
        self.previous_revision = None
        if self.is_reverting:
            self.previous_revision = get_object_or_404(
                self.real_page_record.revisions, id=self.revision_id
            )
        self.page = self.get_object()
        self.parent = self.page.get_parent()
        self.scheduled_page = self.real_page_record.get_scheduled_revision_as_object()

        self.page_perms = self.page.permissions_for_user(self.request.user)
        self.lock = self.page.get_lock()
        self.locked_for_user = self.lock is not None and self.lock.for_user(
            self.request.user
        )

        if not self.page_perms.can_edit():
            raise PermissionDenied

        self.next_url = get_valid_next_url_from_request(self.request)

        response = self.run_hook("before_edit_page", self.request, self.page)
        if response:
            if self.expects_json_response and not self.response_is_json(response):
                # Hook response is not suitable for a JSON response, so construct our own error response
                return self.json_error_response(
                    "blocked_by_hook",
                    _("Request to edit %(model_name)s was blocked by hook.")
                    % {"model_name": Page._meta.verbose_name},
                )
            else:
                return response

        self.subscription, created = PageSubscription.objects.get_or_create(
            page=self.page,
            user=self.request.user,
            defaults={
                "comment_notifications": False,
            },
        )

        self.edit_handler = self.page_class.get_edit_handler()
        self.form_class = self.edit_handler.get_form_class()

        if getattr(settings, "WAGTAIL_WORKFLOW_ENABLED", True):
            # Retrieve current workflow state if set, default to last workflow state
            self.workflow_state = (
                self.page.current_workflow_state
                or self.page.workflow_states.order_by("created_at").last()
            )
        else:
            self.workflow_state = None

        if getattr(settings, "WAGTAIL_I18N_ENABLED", False):
            self.locale = self.page.locale
            self.translations = self.get_translations()
        else:
            self.locale = None
            self.translations = []

        if self.workflow_state:
            self.workflow_tasks = self.workflow_state.all_tasks_with_status()
        else:
            self.workflow_tasks = []

        self.has_unsaved_changes = False
        self.errors_debug = None
        self.autosave_interval = getattr(settings, "WAGTAIL_AUTOSAVE_INTERVAL", 500)
        self.autosave_enabled = self.autosave_interval > 0

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

    def get(self, request, *args, **kwargs):
        if self.lock:
            lock_message = self.lock.get_message(self.request.user)
            if lock_message:
                if isinstance(self.lock, BasicLock) and self.page_perms.can_unlock():
                    lock_message = format_html(
                        '{} <span class="buttons"><button type="button" class="button button-small button-secondary" data-action="w-action#post" data-controller="w-action" data-w-action-url-value="{}">{}</button></span>',
                        lock_message,
                        reverse("wagtailadmin_pages:unlock", args=(self.page.id,)),
                        _("Unlock"),
                    )

                if (
                    isinstance(self.lock, ScheduledForPublishLock)
                    and self.page_perms.can_unschedule()
                ):
                    lock_message = format_html(
                        '{} <span class="buttons"><button type="button" class="button button-small button-secondary" data-action="w-action#post" data-controller="w-action" data-w-action-url-value="{}">{}</button></span>',
                        lock_message,
                        reverse(
                            "wagtailadmin_pages:revisions_unschedule",
                            args=[self.page.id, self.scheduled_revision.pk],
                        ),
                        _("Cancel scheduled publish"),
                    )

                if (
                    not isinstance(self.lock, ScheduledForPublishLock)
                    and self.locked_for_user
                ):
                    messages.warning(self.request, lock_message, extra_tags="lock")
                else:
                    messages.info(self.request, lock_message, extra_tags="lock")

        self.form = self.form_class(
            instance=self.page,
            subscription=self.subscription,
            parent_page=self.parent,
            for_user=self.request.user,
        )

        return self.render_to_response(self.get_context_data())

    def add_cancel_workflow_confirmation_message(self):
        message = _("Workflow on page '%(page_title)s' has been cancelled.") % {
            "page_title": self.page.get_admin_display_title()
        }

        messages.success(
            self.request,
            message,
            buttons=[
                self.get_view_draft_message_button(),
                self.get_edit_message_button(),
            ],
        )

    @cached_property
    def is_cancelling_workflow(self):
        return (
            bool(self.request.POST.get("action-cancel-workflow"))
            and self.workflow_state
            and self.workflow_state.user_can_cancel(self.request.user)
        )

    @cached_property
    def hydrate_create_view(self):
        return bool(self.request.GET.get("_w_hydrate_create_view"))

    @cached_property
    def latest_revision_created_at(self):
        return self.latest_revision and self.latest_revision.created_at.isoformat()

    @cached_property
    def is_out_of_date(self):
        if not self.latest_revision:
            return False

        latest_revision_id = str(self.latest_revision.pk)

        # Two different sessions cannot have the same autosave revision, so if
        # autosave revision is present, it is either the latest or it is not.
        if overwrite_revision_id := self.request.POST.get("overwrite_revision_id"):
            return overwrite_revision_id != latest_revision_id

        # Client has not made an autosave revision, check the loaded revision.
        if loaded_revision_id := self.request.POST.get("loaded_revision_id"):
            # If the loaded revision is not the latest revision, it is outdated.
            if loaded_revision_id != latest_revision_id:
                return True

            # It's pointing to the latest revision, but that revision may have
            # been overwritten by another session (via autosave) since the editor
            # loaded it. The created_at is strictly increasing, so assume the
            # loaded revision outdated if it doesn't match the latest created_at.
            return (
                self.request.POST.get("loaded_revision_created_at", "")
                != self.latest_revision_created_at
            )

        # Not enough information to deduce, assume it's up to date.
        return False

    def post(self, request, *args, **kwargs):
        # Don't allow POST requests if the page is an alias
        if self.page.alias_of_id:
            # Return 405 "Method Not Allowed" response
            return HttpResponse(status=405)

        # For autosave, we only want to save the page if there are no conflicts
        if self.expects_json_response and self.is_out_of_date:
            return self.json_error_response(
                "invalid_revision",
                _("Saving will overwrite a newer version."),
            )

        self.form = self.form_class(
            self.request.POST,
            self.request.FILES,
            instance=self.page,
            subscription=self.subscription,
            parent_page=self.parent,
            for_user=self.request.user,
        )

        if self.action_name == "save":
            self.form.defer_required_fields()

        if self.form.is_valid() and not self.locked_for_user:
            return self.form_valid(self.form)
        else:
            self.form.restore_required_fields()
            return self.form_invalid(self.form)

    def workflow_action_is_valid(self):
        self.workflow_action = self.request.POST["workflow-action-name"]
        available_actions = self.page.current_workflow_task.get_actions(
            self.page, self.request.user
        )
        available_action_names = [
            name for name, verbose_name, modal in available_actions
        ]
        return self.workflow_action in available_action_names

    @cached_property
    def action_name_and_method(self):
        if self.request.POST.get("action-publish") and self.page_perms.can_publish():
            return ("publish", self.publish_action)
        elif (
            self.request.POST.get("action-submit")
            and self.page_perms.can_submit_for_moderation()
        ):
            return ("submit", self.submit_action)
        elif (
            self.request.POST.get("action-restart-workflow")
            and self.page_perms.can_submit_for_moderation()
            and self.workflow_state
            and self.workflow_state.user_can_cancel(self.request.user)
        ):
            return ("restart_workflow", self.restart_workflow_action)
        elif (
            self.request.POST.get("action-workflow-action")
            and self.workflow_action_is_valid()
        ):
            return ("perform_workflow_action", self.perform_workflow_action)
        elif self.is_cancelling_workflow:
            return ("cancel_workflow", self.cancel_workflow_action)
        else:
            return ("save", self.save_action)

    @property
    def action_name(self):
        return self.action_name_and_method[0]

    @property
    def action_method(self):
        return self.action_name_and_method[1]

    def form_valid(self, form):
        self.has_content_changes = self.form.has_changed()
        return self.action_method()

    def save_action(self):
        try:
            with transaction.atomic():
                self.page = self.form.save(commit=not self.page.live)
                self.subscription.save()

                overwrite_revision_id = self.request.POST.get("overwrite_revision_id")
                if overwrite_revision_id:
                    try:
                        overwrite_revision = self.page.revisions.get(
                            pk=overwrite_revision_id
                        )
                    except Revision.DoesNotExist as e:
                        raise PermissionDenied(
                            "Cannot overwrite a revision that does not exist."
                        ) from e
                else:
                    overwrite_revision = None

                # Save revision
                revision = self.page.save_revision(
                    user=self.request.user,
                    log_action=True,  # Always log the new revision on edit
                    previous_revision=self.previous_revision,
                    overwrite_revision=overwrite_revision,
                    clean=False,
                )
        except PermissionDenied as e:
            # The revision passed to overwrite_revision was not valid
            if self.expects_json_response:
                return self.json_error_response("invalid_revision", str(e))
            else:
                messages.error(self.request, str(e))
                self.has_unsaved_changes = True
                return self.render_to_response(self.get_context_data())

        if not self.expects_json_response:
            self.add_save_confirmation_message()

        if self.has_content_changes and "comments" in self.form.formsets:
            changes = self.get_commenting_changes()
            self.log_commenting_changes(changes, revision)
            self.send_commenting_notifications(changes)

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            if self.expects_json_response and not self.response_is_json(response):
                # Hook response is not suitable for a JSON response, so ignore it and just use
                # the standard one
                pass
            else:
                return response

        # Just saving - remain on edit page for further edits
        if self.expects_json_response:
            return JsonResponse(
                {
                    "success": True,
                    "pk": self.page.pk,
                    "revision_id": revision.pk,
                    "revision_created_at": revision.created_at.isoformat(),
                    "field_updates": dict(self.form.get_field_updates_for_resave()),
                    "comments": self.form.serialize_comments(self.request.user),
                    "html": self.render_partials(),
                }
            )
        else:
            return self.redirect_and_remain()

    def publish_action(self):
        self.page = self.form.save(commit=not self.page.live)
        self.subscription.save()

        # Save revision
        revision = self.page.save_revision(
            user=self.request.user,
            log_action=True,  # Always log the new revision on edit
            previous_revision=self.previous_revision,
        )

        # store submitted go_live_at for messaging below
        go_live_at = self.page.go_live_at

        response = self.run_hook("before_publish_page", self.request, self.page)
        if response:
            return response

        action = PublishPageRevisionAction(
            revision,
            user=self.request.user,
            changed=self.has_content_changes,
            previous_revision=self.previous_revision,
        )
        action.execute(skip_permission_checks=True)

        if self.has_content_changes and "comments" in self.form.formsets:
            changes = self.get_commenting_changes()
            self.log_commenting_changes(changes, revision)
            self.send_commenting_notifications(changes)

        # Need to reload the page because the URL may have changed, and we
        # need the up-to-date URL for the "View Live" button.
        self.page = self.page.specific_class.objects.get(pk=self.page.pk)

        response = self.run_hook("after_publish_page", self.request, self.page)
        if response:
            return response

        # Notifications
        if go_live_at and go_live_at > timezone.now():
            # Page has been scheduled for publishing in the future

            if self.is_reverting:
                message = _(
                    "Version from %(previous_revision_datetime)s "
                    "of page '%(page_title)s' has been scheduled for publishing."
                ) % {
                    "previous_revision_datetime": render_timestamp(
                        self.previous_revision.created_at
                    ),
                    "page_title": self.page.get_admin_display_title(),
                }
            else:
                if self.page.live:
                    message = _(
                        "Page '%(page_title)s' is live and this version has been scheduled for publishing."
                    ) % {"page_title": self.page.get_admin_display_title()}

                else:
                    message = _(
                        "Page '%(page_title)s' has been scheduled for publishing."
                    ) % {"page_title": self.page.get_admin_display_title()}

            messages.success(
                self.request, message, buttons=[self.get_edit_message_button()]
            )

        else:
            # Page is being published now

            if self.is_reverting:
                message = _(
                    "Version from %(datetime)s of page '%(page_title)s' has been published."
                ) % {
                    "datetime": render_timestamp(self.previous_revision.created_at),
                    "page_title": self.page.get_admin_display_title(),
                }
            else:
                message = _("Page '%(page_title)s' has been published.") % {
                    "page_title": self.page.get_admin_display_title()
                }

            buttons = []
            if self.page.url is not None:
                buttons.append(self.get_view_live_message_button())
            buttons.append(self.get_edit_message_button())
            messages.success(self.request, message, buttons=buttons)

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            return response

        # we're done here - redirect back to the explorer
        return self.redirect_away()

    def submit_action(self):
        self.page = self.form.save(commit=not self.page.live)
        self.subscription.save()

        # Save revision
        revision = self.page.save_revision(
            user=self.request.user,
            log_action=True,  # Always log the new revision on edit
            previous_revision=self.previous_revision,
        )

        if self.has_content_changes and "comments" in self.form.formsets:
            changes = self.get_commenting_changes()
            self.log_commenting_changes(changes, revision)
            self.send_commenting_notifications(changes)

        if (
            self.workflow_state
            and self.workflow_state.status == WorkflowState.STATUS_NEEDS_CHANGES
        ):
            # If the workflow was in the needs changes state, resume the existing workflow on submission
            self.workflow_state.resume(self.request.user)
        else:
            # Otherwise start a new workflow
            workflow = self.page.get_workflow()
            workflow.start(self.page, self.request.user)

        message = _("Page '%(page_title)s' has been submitted for moderation.") % {
            "page_title": self.page.get_admin_display_title()
        }

        messages.success(
            self.request,
            message,
            buttons=[
                self.get_view_draft_message_button(),
                self.get_edit_message_button(),
            ],
        )

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            return response

        # we're done here - redirect back to the explorer
        return self.redirect_away()

    def restart_workflow_action(self):
        self.page = self.form.save(commit=not self.page.live)
        self.subscription.save()

        # save revision
        revision = self.page.save_revision(
            user=self.request.user,
            log_action=True,  # Always log the new revision on edit
            previous_revision=self.previous_revision,
        )

        if self.has_content_changes and "comments" in self.form.formsets:
            changes = self.get_commenting_changes()
            self.log_commenting_changes(changes, revision)
            self.send_commenting_notifications(changes)

        # cancel workflow
        self.workflow_state.cancel(user=self.request.user)
        # start new workflow
        workflow = self.page.get_workflow()
        workflow.start(self.page, self.request.user)

        message = _("Workflow on page '%(page_title)s' has been restarted.") % {
            "page_title": self.page.get_admin_display_title()
        }

        messages.success(
            self.request,
            message,
            buttons=[
                self.get_view_draft_message_button(),
                self.get_edit_message_button(),
            ],
        )

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            return response

        # we're done here - redirect back to the explorer
        return self.redirect_away()

    def perform_workflow_action(self):
        self.page = self.form.save(commit=not self.page.live)
        self.subscription.save()

        if self.has_content_changes:
            # Save revision
            revision = self.page.save_revision(
                user=self.request.user,
                log_action=True,  # Always log the new revision on edit
                previous_revision=(
                    self.previous_revision if self.is_reverting else None
                ),
            )

            if "comments" in self.form.formsets:
                changes = self.get_commenting_changes()
                self.log_commenting_changes(changes, revision)
                self.send_commenting_notifications(changes)

        extra_workflow_data_json = self.request.POST.get(
            "workflow-action-extra-data", "{}"
        )
        extra_workflow_data = json.loads(extra_workflow_data_json)
        self.page.current_workflow_task.on_action(
            self.page.current_workflow_task_state,
            self.request.user,
            self.workflow_action,
            **extra_workflow_data,
        )

        self.add_save_confirmation_message()

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            return response

        # we're done here - redirect back to the explorer
        return self.redirect_away()

    def cancel_workflow_action(self):
        self.workflow_state.cancel(user=self.request.user)
        self.page = self.form.save(commit=not self.page.live)
        self.subscription.save()

        # Save revision
        revision = self.page.save_revision(
            user=self.request.user,
            log_action=True,  # Always log the new revision on edit
            previous_revision=self.previous_revision,
        )

        if self.has_content_changes and "comments" in self.form.formsets:
            changes = self.get_commenting_changes()
            self.log_commenting_changes(changes, revision)
            self.send_commenting_notifications(changes)

        # Notifications
        self.add_cancel_workflow_confirmation_message()

        response = self.run_hook("after_edit_page", self.request, self.page)
        if response:
            return response

        # Just saving - remain on edit page for further edits
        return self.redirect_and_remain()

    def redirect_away(self):
        if self.next_url:
            # redirect back to 'next' url if present
            return redirect(self.next_url)
        else:
            # redirect back to the explorer
            return redirect("wagtailadmin_explore", self.page.get_parent().id)

    def redirect_and_remain(self):
        target_url = self.get_edit_url()
        if self.next_url:
            # Ensure the 'next' url is passed through again if present
            target_url += "?next=%s" % quote(self.next_url)
        return redirect(target_url)

    def form_invalid(self, form):
        # even if the page is locked due to not having permissions, the original submitter can still cancel the workflow
        if self.is_cancelling_workflow:
            self.workflow_state.cancel(user=self.request.user)
            self.add_cancel_workflow_confirmation_message()

            # Refresh the lock object as now WorkflowLock no longer applies
            self.lock = self.page.get_lock()
            self.locked_for_user = self.lock is not None and self.lock.for_user(
                self.request.user
            )
        elif self.locked_for_user:
            if self.expects_json_response:
                return self.json_error_response(
                    "locked", _("The page could not be saved as it is locked.")
                )
            else:
                messages.error(
                    self.request, _("The page could not be saved as it is locked.")
                )
        else:
            if self.expects_json_response:
                return self.json_error_response(
                    "validation_error",
                    _("There are validation errors, click save to highlight them."),
                )
            else:
                messages.validation_error(
                    self.request,
                    _("The page could not be saved due to validation errors."),
                    self.form,
                )
        self.errors_debug = repr(self.form.errors) + repr(
            [
                (name, formset.errors)
                for (name, formset) in self.form.formsets.items()
                if formset.errors
            ]
        )
        self.has_unsaved_changes = True

        return self.render_to_response(self.get_context_data())

    def get_preview_url(self):
        return reverse("wagtailadmin_pages:preview_on_edit", args=[self.page.id])

    def get_history_url(self):
        permissions = self.page.permissions_for_user(self.request.user)
        if permissions.can_view_revisions():
            return reverse("wagtailadmin_pages:history", args=[self.page.id])

    def get_side_panels(self):
        side_panels = [
            PageStatusSidePanel(
                self.page,
                self.request,
                show_schedule_publishing_toggle=self.form.show_schedule_publishing_toggle,
                live_object=self.real_page_record,
                scheduled_object=self.scheduled_page,
                locale=self.locale,
                translations=self.translations,
                parent_page=self.page.get_parent(),
            ),
        ]
        if not self.expects_json_response and self.page.is_previewable():
            side_panels.append(
                PreviewSidePanel(
                    self.page, self.request, preview_url=self.get_preview_url()
                )
            )
            # We don't need to re-render the checks panel when hydrating create view
            if not self.hydrate_create_view:
                side_panels.append(ChecksSidePanel(self.page, self.request))
        if (
            not self.expects_json_response
            and not self.hydrate_create_view
            and self.form.show_comments_toggle
        ):
            side_panels.append(CommentsSidePanel(self.page, self.request))
        return MediaContainer(side_panels)

    def get_editing_sessions(self):
        EditingSession.cleanup()
        content_type = get_default_page_content_type()
        session = EditingSession.objects.create(
            user=self.request.user,
            content_type=content_type,
            object_id=self.page.pk,
            last_seen_at=timezone.now(),
        )
        return EditingSessionsModule(
            session,
            reverse(
                "wagtailadmin_editing_sessions:ping",
                args=("wagtailcore", "page", self.page.pk, session.id),
            ),
            reverse(
                "wagtailadmin_editing_sessions:release",
                args=(session.id,),
            ),
            [],
            self.page.latest_revision_id,
            self.latest_revision_created_at,
        )

    def get_action_menu(self):
        return PageActionMenu(
            self.request,
            view="edit",
            page=self.page,
            lock=self.lock,
            locked_for_user=self.locked_for_user,
        )

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        user_perms = self.page.permissions_for_user(self.request.user)
        bound_panel = self.edit_handler.get_bound_panel(
            instance=self.page, request=self.request, form=self.form
        )
        action_menu = self.get_action_menu()
        side_panels = self.get_side_panels()

        js_context = JSContext()
        edit_handler_data = js_context.pack(bound_panel)

        media = MediaContainer(
            [bound_panel, self.form, action_menu, side_panels, js_context]
        ).media

        context.update(
            {
                "object": self.page,
                "page": self.page,
                "page_for_status": self.get_page_for_status(),
                "content_type": self.page_content_type,
                "edit_handler": bound_panel,
                "edit_handler_data": edit_handler_data,
                "errors_debug": self.errors_debug,
                "action_menu": action_menu,
                "side_panels": side_panels,
                "form": self.form,
                "next": self.next_url,
                "action_url": self.get_edit_url(),
                "history_url": self.get_history_url(),
                "has_unsaved_changes": self.has_unsaved_changes,
                "page_locked": self.locked_for_user,
                "workflow_state": self.workflow_state
                if self.workflow_state and self.workflow_state.is_active
                else None,
                "current_task_state": self.page.current_workflow_task_state,
                "publishing_will_cancel_workflow": self.workflow_tasks
                and getattr(settings, "WAGTAIL_WORKFLOW_CANCEL_ON_PUBLISH", True),
                "confirm_workflow_cancellation_url": reverse(
                    "wagtailadmin_pages:confirm_workflow_cancellation",
                    args=(self.page.id,),
                ),
                "user_can_lock": (not self.lock or isinstance(self.lock, WorkflowLock))
                and user_perms.can_lock(),
                "user_can_unlock": isinstance(self.lock, BasicLock)
                and user_perms.can_unlock(),
                "locale": self.locale,
                "media": media,
                "autosave_enabled": self.autosave_enabled,
                "autosave_interval": self.autosave_interval,
                "autosave_indicator": AutosaveIndicator(),
                "editing_sessions": self.get_editing_sessions(),
                "loaded_revision_created_at": self.latest_revision_created_at,
                "is_partial": self.expects_json_response or self.hydrate_create_view,
                "hydrate_create_view": self.hydrate_create_view,
            }
        )

        return context

    def get_translations(self):
        return [
            {
                "locale": translation.locale,
                "url": reverse("wagtailadmin_pages:edit", args=[translation.id]),
            }
            for translation in self.page.get_translations()
            .only("id", "locale", "depth")
            .select_related("locale")
            if translation.permissions_for_user(self.request.user).can_edit()
        ]
