from django.contrib import messages
from django.contrib.admin import helpers
from django.contrib.admin.utils import model_ngettext
from django.core.exceptions import PermissionDenied
from django.template.response import TemplateResponse

from documents.classifier import DocumentClassifier
from documents.models import Tag, Correspondent, DocumentType


def select_action(modeladmin, request, queryset, title, action, modelclass, success_message="", document_action=None, queryset_action=None):
    opts = modeladmin.model._meta
    app_label = opts.app_label

    if not modeladmin.has_change_permission(request):
        raise PermissionDenied

    if request.POST.get('post'):
        n = queryset.count()
        selected_object = modelclass.objects.get(id=request.POST.get('obj_id'))
        if n:
            for document in queryset:
                if document_action:
                    document_action(document, selected_object)
                document_display = str(document)
                modeladmin.log_change(request, document, document_display)
            if queryset_action:
                queryset_action(queryset, selected_object)

            modeladmin.message_user(request, success_message % {
                "selected_object": selected_object.name, "count": n, "items": model_ngettext(modeladmin.opts, n)
            }, messages.SUCCESS)

        # Return None to display the change list page again.
        return None

    context = dict(
        modeladmin.admin_site.each_context(request),
        title=title,
        queryset=queryset,
        opts=opts,
        action_checkbox_name=helpers.ACTION_CHECKBOX_NAME,
        media=modeladmin.media,
        action=action,
        objects=modelclass.objects.all(),
        itemname=model_ngettext(modelclass, 1)
    )

    request.current_app = modeladmin.admin_site.name

    return TemplateResponse(request, "admin/%s/%s/select_object.html" % (app_label, opts.model_name), context)


def simple_action(modeladmin, request, queryset, success_message="", document_action=None, queryset_action=None):
    if not modeladmin.has_change_permission(request):
        raise PermissionDenied

    n = queryset.count()
    if n:
        for document in queryset:
            if document_action:
                document_action(document)
            document_display = str(document)
            modeladmin.log_change(request, document, document_display)
        if queryset_action:
            queryset_action(queryset)
        modeladmin.message_user(request, success_message % {
            "count": n, "items": model_ngettext(modeladmin.opts, n)
        }, messages.SUCCESS)

    # Return None to display the change list page again.
    return None


def add_tag_to_selected(modeladmin, request, queryset):
    return select_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         title="Add tag to multiple documents",
                         action="add_tag_to_selected",
                         modelclass=Tag,
                         success_message="Successfully added tag %(selected_object)s to %(count)d %(items)s.",
                         document_action=lambda doc, tag: doc.tags.add(tag))
add_tag_to_selected.short_description = "Add tag to selected documents"


def remove_tag_from_selected(modeladmin, request, queryset):
    return select_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         title="Remove tag from multiple documents",
                         action="remove_tag_from_selected",
                         modelclass=Tag,
                         success_message="Successfully removed tag %(selected_object)s from %(count)d %(items)s.",
                         document_action=lambda doc, tag: doc.tags.remove(tag))
remove_tag_from_selected.short_description = "Remove tag from selected documents"


def set_correspondent_on_selected(modeladmin, request, queryset):
    return select_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         title="Set correspondent on multiple documents",
                         action="set_correspondent_on_selected",
                         modelclass=Correspondent,
                         success_message="Successfully set correspondent %(selected_object)s on %(count)d %(items)s.",
                         queryset_action=lambda qs, correspondent: qs.update(correspondent=correspondent))
set_correspondent_on_selected.short_description = "Set correspondent on selected documents"


def remove_correspondent_from_selected(modeladmin, request, queryset):
    return simple_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         success_message="Successfully removed correspondent from %(count)d %(items)s.",
                         queryset_action=lambda qs: qs.update(correspondent=None))
remove_correspondent_from_selected.short_description = "Remove correspondent from selected documents"


def set_document_type_on_selected(modeladmin, request, queryset):
    return select_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         title="Set document type on multiple documents",
                         action="set_document_type_on_selected",
                         modelclass=DocumentType,
                         success_message="Successfully set document type %(selected_object)s on %(count)d %(items)s.",
                         queryset_action=lambda qs, document_type: qs.update(document_type=document_type))
set_document_type_on_selected.short_description = "Set document type on selected documents"


def remove_document_type_from_selected(modeladmin, request, queryset):
    return simple_action(modeladmin=modeladmin, request=request, queryset=queryset,
                         success_message="Successfully removed document type from %(count)d %(items)s.",
                         queryset_action=lambda qs: qs.update(document_type=None))
remove_document_type_from_selected.short_description = "Remove document type from selected documents"


def run_document_classifier_on_selected(modeladmin, request, queryset):
    try:
        clf = DocumentClassifier.load_classifier()
        return simple_action(modeladmin=modeladmin, request=request, queryset=queryset,
                             success_message="Successfully applied document classifier to %(count)d %(items)s.",
                             document_action=lambda doc: clf.classify_document(doc, classify_correspondent=True, classify_tags=True, classify_document_type=True))
    except FileNotFoundError:
        modeladmin.message_user(request, "Classifier model file not found.", messages.ERROR)
        return None
run_document_classifier_on_selected.short_description = "Run document classifier on selected"