from django.conf import settings
from django.db.models import Subquery
from rest_framework.permissions import BasePermission, SAFE_METHODS

from api.permissions import ProjectMixin
from .models import RoleMapping, Role


class RolePermission(ProjectMixin, BasePermission):
    UNSAFE_METHODS = ('POST', 'PATCH', 'DELETE')
    unsafe_methods_check = True
    role_name = ''

    def has_permission(self, request, view):
        if request.user.is_superuser:
            return True

        if self.unsafe_methods_check and request.method in self.UNSAFE_METHODS:
            return request.user.is_superuser

        project_id = self.get_project_id(request, view)
        if not project_id and request.method in SAFE_METHODS:
            return True

        return is_in_role(self.role_name, request.user.id, project_id)


class IsProjectAdmin(RolePermission):
    unsafe_methods_check = False
    role_name = settings.ROLE_PROJECT_ADMIN


class IsAnnotatorAndReadOnly(RolePermission):
    role_name = settings.ROLE_ANNOTATOR


class IsAnnotator(RolePermission):
    unsafe_methods_check = False
    role_name = settings.ROLE_ANNOTATOR


class IsAnnotationApproverAndReadOnly(RolePermission):
    role_name = settings.ROLE_ANNOTATION_APPROVER


class IsAnnotationApprover(RolePermission):
    unsafe_methods_check = False
    role_name = settings.ROLE_ANNOTATION_APPROVER


def is_in_role(role_name, user_id, project_id):
    return RoleMapping.objects.filter(
        user_id=user_id,
        project_id=project_id,
        role_id=Subquery(Role.objects.filter(name=role_name).values('id')),
    ).exists()


IsInProjectReadOnlyOrAdmin = (IsAnnotatorAndReadOnly | IsAnnotationApproverAndReadOnly | IsProjectAdmin)
IsInProjectOrAdmin = (IsAnnotator | IsAnnotationApprover | IsProjectAdmin)