# -*- coding: utf-8 -*-
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from flask import g
from flask_appbuilder.security.sqla import models as sqla_models
from flask_appbuilder.security.sqla.manager import SecurityManager
from sqlalchemy import or_, and_

from airflow import models
from airflow.exceptions import AirflowException
from airflow.www_rbac.app import appbuilder
from airflow.utils.db import provide_session
from airflow.utils.log.logging_mixin import LoggingMixin


EXISTING_ROLES = {
    'Admin',
    'Viewer',
    'User',
    'Op',
    'Public',
}


class AirflowSecurityManager(SecurityManager, LoggingMixin):
    ###########################################################################
    #                               VIEW MENUS
    ###########################################################################
    VIEWER_VMS = {
        'Airflow',
        'DagModelView',
        'Browse',
        'DAG Runs',
        'DagRunModelView',
        'Task Instances',
        'TaskInstanceModelView',
        'SLA Misses',
        'SlaMissModelView',
        'Jobs',
        'JobModelView',
        'Logs',
        'LogModelView',
        'Docs',
        'Documentation',
        'Github',
        'About',
        'Version',
        'VersionView',
    }

    USER_VMS = VIEWER_VMS

    OP_VMS = {
        'Admin',
        'Configurations',
        'ConfigurationView',
        'Connections',
        'ConnectionModelView',
        'Pools',
        'PoolModelView',
        'Variables',
        'VariableModelView',
        'XComs',
        'XComModelView',
    }

    ###########################################################################
    #                               PERMISSIONS
    ###########################################################################

    VIEWER_PERMS = {
        'menu_access',
        'can_index',
        'can_list',
        'can_show',
        'can_chart',
        'can_dag_stats',
        'can_dag_details',
        'can_task_stats',
        'can_code',
        'can_log',
        'can_get_logs_with_metadata',
        'can_tries',
        'can_graph',
        'can_tree',
        'can_task',
        'can_task_instances',
        'can_xcom',
        'can_gantt',
        'can_landing_times',
        'can_duration',
        'can_blocked',
        'can_rendered',
        'can_pickle_info',
        'can_version',
    }

    USER_PERMS = {
        'can_dagrun_clear',
        'can_run',
        'can_trigger',
        'can_add',
        'can_edit',
        'can_delete',
        'can_paused',
        'can_refresh',
        'can_success',
        'muldelete',
        'set_failed',
        'set_running',
        'set_success',
        'clear',
        'can_clear',
    }

    OP_PERMS = {
        'can_conf',
        'can_varimport',
    }

    # global view-menu for dag-level access
    DAG_VMS = {
        'all_dags'
    }

    WRITE_DAG_PERMS = {
        'can_dag_edit',
    }

    READ_DAG_PERMS = {
        'can_dag_read',
    }

    DAG_PERMS = WRITE_DAG_PERMS | READ_DAG_PERMS

    ###########################################################################
    #                     DEFAULT ROLE CONFIGURATIONS
    ###########################################################################

    ROLE_CONFIGS = [
        {
            'role': 'Viewer',
            'perms': VIEWER_PERMS | READ_DAG_PERMS,
            'vms': VIEWER_VMS | DAG_VMS
        },
        {
            'role': 'User',
            'perms': VIEWER_PERMS | USER_PERMS | DAG_PERMS,
            'vms': VIEWER_VMS | DAG_VMS | USER_VMS,
        },
        {
            'role': 'Op',
            'perms': VIEWER_PERMS | USER_PERMS | OP_PERMS | DAG_PERMS,
            'vms': VIEWER_VMS | DAG_VMS | USER_VMS | OP_VMS,
        },
    ]

    def init_role(self, role_name, role_vms, role_perms):
        """
        Initialize the role with the permissions and related view-menus.

        :param role_name:
        :param role_vms:
        :param role_perms:
        :return:
        """
        pvms = self.get_session.query(sqla_models.PermissionView).all()
        pvms = [p for p in pvms if p.permission and p.view_menu]

        role = self.find_role(role_name)
        if not role:
            role = self.add_role(role_name)

        if len(role.permissions) == 0:
            self.log.info('Initializing permissions for role:%s in the database.', role_name)
            role_pvms = set()
            for pvm in pvms:
                if pvm.view_menu.name in role_vms and pvm.permission.name in role_perms:
                    role_pvms.add(pvm)
            role.permissions = list(role_pvms)
            self.get_session.merge(role)
            self.get_session.commit()
        else:
            self.log.debug('Existing permissions for the role:%s '
                           'within the database will persist.', role_name)

    def get_user_roles(self, user=None):
        """
        Get all the roles associated with the user.

        :param user: the ab_user in FAB model.
        :return: a list of roles associated with the user.
        """
        if user is None:
            user = g.user
        if user.is_anonymous:
            public_role = appbuilder.config.get('AUTH_ROLE_PUBLIC')
            return [appbuilder.security_manager.find_role(public_role)] \
                if public_role else []
        return user.roles

    def get_all_permissions_views(self):
        """
        Returns a set of tuples with the perm name and view menu name
        """
        perms_views = set()
        for role in self.get_user_roles():
            perms_views.update({(perm_view.permission.name, perm_view.view_menu.name)
                                for perm_view in role.permissions})
        return perms_views

    def get_accessible_dag_ids(self, username=None):
        """
        Return a set of dags that user has access to(either read or write).

        :param username: Name of the user.
        :return: A set of dag ids that the user could access.
        """
        if not username:
            username = g.user

        if username.is_anonymous or 'Public' in username.roles:
            # return an empty set if the role is public
            return set()

        roles = {role.name for role in username.roles}
        if {'Admin', 'Viewer', 'User', 'Op'} & roles:
            return self.DAG_VMS

        user_perms_views = self.get_all_permissions_views()
        # return a set of all dags that the user could access
        return set([view for perm, view in user_perms_views if perm in self.DAG_PERMS])

    def has_access(self, permission, view_name, user=None):
        """
        Verify whether a given user could perform certain permission
        (e.g can_read, can_write) on the given dag_id.

        :param permission: permission on dag_id(e.g can_read, can_edit).
        :type permission: str
        :param view_name: name of view-menu(e.g dag id is a view-menu as well).
        :type permission: str
        :param user: user name
        :type permission: str
        :return: a bool whether user could perform certain permission on the dag_id.
        :rtype bool
        """
        if not user:
            user = g.user
        if user.is_anonymous:
            return self.is_item_public(permission, view_name)
        return self._has_view_access(user, permission, view_name)

    def _get_and_cache_perms(self):
        """
        Cache permissions-views
        """
        self.perms = self.get_all_permissions_views()

    def _has_role(self, role_name_or_list):
        """
        Whether the user has this role name
        """
        if not isinstance(role_name_or_list, list):
            role_name_or_list = [role_name_or_list]
        return any(
            [r.name in role_name_or_list for r in self.get_user_roles()])

    def _has_perm(self, permission_name, view_menu_name):
        """
        Whether the user has this perm
        """
        if hasattr(self, 'perms'):
            if (permission_name, view_menu_name) in self.perms:
                return True
        # rebuild the permissions set
        self._get_and_cache_perms()
        return (permission_name, view_menu_name) in self.perms

    def has_all_dags_access(self):
        """
        Has all the dag access in any of the 3 cases:
        1. Role needs to be in (Admin, Viewer, User, Op).
        2. Has can_dag_read permission on all_dags view.
        3. Has can_dag_edit permission on all_dags view.
        """
        return (
            self._has_role(['Admin', 'Viewer', 'Op', 'User']) or
            self._has_perm('can_dag_read', 'all_dags') or
            self._has_perm('can_dag_edit', 'all_dags'))

    def clean_perms(self):
        """
        FAB leaves faulty permissions that need to be cleaned up
        """
        self.log.info('Cleaning faulty perms')
        sesh = self.get_session
        pvms = (
            sesh.query(sqla_models.PermissionView)
            .filter(or_(
                sqla_models.PermissionView.permission == None,  # NOQA
                sqla_models.PermissionView.view_menu == None,  # NOQA
            ))
        )
        # Since FAB doesn't define ON DELETE CASCADE on these tables, we need
        # to delete the _object_ so that SQLA knows to delete the many-to-many
        # relationship object too. :(

        deleted_count = 0
        for pvm in pvms:
            sesh.delete(pvm)
            deleted_count += 1
        sesh.commit()
        if deleted_count:
            self.log.info('Deleted %s faulty permissions', deleted_count)

    def _merge_perm(self, permission_name, view_menu_name):
        """
        Add the new permission , view_menu to ab_permission_view_role if not exists.
        It will add the related entry to ab_permission
        and ab_view_menu two meta tables as well.

        :param permission_name: Name of the permission.
        :type permission_name: str
        :param view_menu_name: Name of the view-menu
        :type view_menu_name: str
        :return:
        """
        permission = self.find_permission(permission_name)
        view_menu = self.find_view_menu(view_menu_name)
        pv = None
        if permission and view_menu:
            pv = self.get_session.query(self.permissionview_model).filter_by(
                permission=permission, view_menu=view_menu).first()
        if not pv and permission_name and view_menu_name:
            self.add_permission_view_menu(permission_name, view_menu_name)

    @provide_session
    def create_custom_dag_permission_view(self, session=None):
        """
        Workflow:
        1. Fetch all the existing (permissions, view-menu) from Airflow DB.
        2. Fetch all the existing dag models that are either active or paused. Exclude the subdags.
        3. Create both read and write permission view-menus relation for every dags from step 2
        4. Find out all the dag specific roles(excluded pubic, admin, viewer, op, user)
        5. Get all the permission-vm owned by the user role.
        6. Grant all the user role's permission-vm except the all-dag view-menus to the dag roles.
        7. Commit the updated permission-vm-role into db

        :return: None.
        """
        # todo(Tao): should we put this function here or in scheduler loop?
        self.log.info('Fetching a set of all permission, view_menu from FAB meta-table')

        def merge_pv(perm, view_menu):
            """Create permission view menu only if it doesn't exist"""
            if view_menu and perm and (view_menu, perm) not in all_pvs:
                self._merge_perm(perm, view_menu)

        all_pvs = set()
        for pv in self.get_session.query(self.permissionview_model).all():
            if pv.permission and pv.view_menu:
                all_pvs.add((pv.permission.name, pv.view_menu.name))

        # Get all the active / paused dags and insert them into a set
        all_dags_models = session.query(models.DagModel)\
            .filter(or_(models.DagModel.is_active, models.DagModel.is_paused))\
            .filter(~models.DagModel.is_subdag).all()

        # create can_dag_edit and can_dag_read permissions for every dag(vm)
        for dag in all_dags_models:
            for perm in self.DAG_PERMS:
                merge_pv(perm, dag.dag_id)

        # for all the dag-level role, add the permission of viewer
        # with the dag view to ab_permission_view
        all_roles = self.get_all_roles()
        user_role = self.find_role('User')

        dag_role = [role for role in all_roles if role.name not in EXISTING_ROLES]
        update_perm_views = []

        # need to remove all_dag vm from all the existing view-menus
        dag_vm = self.find_view_menu('all_dags')
        ab_perm_view_role = sqla_models.assoc_permissionview_role
        perm_view = self.permissionview_model
        view_menu = self.viewmenu_model

        all_perm_view_by_user = session.query(ab_perm_view_role)\
            .join(perm_view, perm_view.id == ab_perm_view_role
                  .columns.permission_view_id)\
            .filter(ab_perm_view_role.columns.role_id == user_role.id)\
            .join(view_menu)\
            .filter(perm_view.view_menu_id != dag_vm.id)
        all_perm_views = set([role.permission_view_id for role in all_perm_view_by_user])

        for role in dag_role:
            # Get all the perm-view of the role
            existing_perm_view_by_user = self.get_session.query(ab_perm_view_role)\
                .filter(ab_perm_view_role.columns.role_id == role.id)

            existing_perms_views = set([pv.permission_view_id
                                        for pv in existing_perm_view_by_user])
            missing_perm_views = all_perm_views - existing_perms_views

            for perm_view_id in missing_perm_views:
                update_perm_views.append({'permission_view_id': perm_view_id,
                                          'role_id': role.id})

        if update_perm_views:
            self.get_session.execute(ab_perm_view_role.insert(), update_perm_views)
        self.get_session.commit()

    def update_admin_perm_view(self):
        """
        Admin should has all the permission-views, except the dag views.
        because Admin have already have all_dags permission.
        Add the missing ones to the table for admin.

        :return: None.
        """
        all_dag_view = self.find_view_menu('all_dags')
        dag_perm_ids = [self.find_permission('can_dag_edit').id, self.find_permission('can_dag_read').id]
        pvms = self.get_session.query(sqla_models.PermissionView).filter(~and_(
            sqla_models.PermissionView.permission_id.in_(dag_perm_ids),
            sqla_models.PermissionView.view_menu_id != all_dag_view.id)
        ).all()

        pvms = [p for p in pvms if p.permission and p.view_menu]

        admin = self.find_role('Admin')
        admin.permissions = list(set(admin.permissions) | set(pvms))

        self.get_session.commit()

    def sync_roles(self):
        """
        1. Init the default role(Admin, Viewer, User, Op, public)
           with related permissions.
        2. Init the custom role(dag-user) with related permissions.

        :return: None.
        """
        self.log.info('Start syncing user roles.')
        # Create global all-dag VM
        self.create_perm_vm_for_all_dag()

        # Create default user role.
        for config in self.ROLE_CONFIGS:
            role = config['role']
            vms = config['vms']
            perms = config['perms']
            self.init_role(role, vms, perms)
        self.create_custom_dag_permission_view()

        # init existing roles, the rest role could be created through UI.
        self.update_admin_perm_view()
        self.clean_perms()

    def sync_perm_for_dag(self, dag_id, access_control=None):
        """
        Sync permissions for given dag id. The dag id surely exists in our dag bag
        as only / refresh button or cli.sync_perm will call this function

        :param dag_id: the ID of the DAG whose permissions should be updated
        :type dag_id: str
        :param access_control: a dict where each key is a rolename and
            each value is a set() of permission names (e.g.,
            {'can_dag_read'}
        :type access_control: dict
        :return:
        """
        for dag_perm in self.DAG_PERMS:
            perm_on_dag = self.find_permission_view_menu(dag_perm, dag_id)
            if perm_on_dag is None:
                self.add_permission_view_menu(dag_perm, dag_id)

        if access_control:
            self._sync_dag_view_permissions(dag_id, access_control)

    def _sync_dag_view_permissions(self, dag_id, access_control):
        """Set the access policy on the given DAG's ViewModel.

        :param dag_id: the ID of the DAG whose permissions should be updated
        :type dag_id: str
        :param access_control: a dict where each key is a rolename and
            each value is a set() of permission names (e.g.,
            {'can_dag_read'}
        :type access_control: dict
        """
        def _get_or_create_dag_permission(perm_name):
            dag_perm = self.find_permission_view_menu(perm_name, dag_id)
            if not dag_perm:
                self.log.info("Creating new permission '{}' on view '{}'".format(
                    perm_name,
                    dag_id
                ))
                dag_perm = self.add_permission_view_menu(perm_name, dag_id)

            return dag_perm

        def _revoke_stale_permissions(dag_view):
            existing_dag_perms = self.find_permissions_view_menu(dag_view)
            for perm in existing_dag_perms:
                non_admin_roles = [role for role in perm.role
                                   if role.name != 'Admin']
                for role in non_admin_roles:
                    target_perms_for_role = access_control.get(role.name, {})
                    if perm.permission.name not in target_perms_for_role:
                        self.log.info("Revoking '{}' on DAG '{}' for role '{}'".format(
                            perm.permission,
                            dag_id,
                            role.name
                        ))
                        self.del_permission_role(role, perm)

        dag_view = self.find_view_menu(dag_id)
        if dag_view:
            _revoke_stale_permissions(dag_view)

        for rolename, perms in access_control.items():
            role = self.find_role(rolename)
            if not role:
                raise AirflowException(
                    "The access_control mapping for DAG '{}' includes a role "
                    "named '{}', but that role does not exist".format(
                        dag_id,
                        rolename))

            perms = set(perms)
            invalid_perms = perms - self.DAG_PERMS
            if invalid_perms:
                raise AirflowException(
                    "The access_control map for DAG '{}' includes the following "
                    "invalid permissions: {}; The set of valid permissions "
                    "is: {}".format(dag_id,
                                    (perms - self.DAG_PERMS),
                                    self.DAG_PERMS))

            for perm_name in perms:
                dag_perm = _get_or_create_dag_permission(perm_name)
                self.add_permission_role(role, dag_perm)

    def create_perm_vm_for_all_dag(self):
        """
        Create perm-vm if not exist and insert into FAB security model for all-dags.
        """
        # create perm for global logical dag
        for dag_vm in self.DAG_VMS:
            for perm in self.DAG_PERMS:
                self._merge_perm(permission_name=perm,
                                 view_menu_name=dag_vm)
