# Copyright (C) 2020 Linaro Limited
#
# Author: Stevan Radaković <stevan.radakovic@linaro.org>
#
# SPDX-License-Identifier: GPL-2.0-or-later

import contextlib

import yaml
from django.contrib.auth.models import Group, User
from django.core.management.base import BaseCommand
from django.db.models import Count, Q
from jinja2 import TemplateError as JinjaTemplateError
from jinja2.nodes import Assign as JinjaNodesAssign
from jinja2.nodes import Const as JinjaNodesConst
from jinja2.nodes import List as JinjaNodesList

from lava_common.exceptions import PermissionNameError
from lava_common.jinja import create_device_templates_env
from lava_common.yaml import yaml_safe_load
from lava_scheduler_app.environment import DEVICES_JINJA_ENV
from lava_scheduler_app.models import (
    Alias,
    Device,
    DeviceType,
    GroupDevicePermission,
    Tag,
    Worker,
)
from lava_server.files import File


class Command(BaseCommand):
    help = "Sync device dictionaries to db records"

    SYNC_KEY = "sync_to_lava"

    def _parse_sync_dict(self, sync_dict):
        ret = {}
        if hasattr(sync_dict, "items"):
            for pair in sync_dict.items:
                if isinstance(pair.value, JinjaNodesList):
                    ret[pair.key.value] = [
                        [sub_node.value for sub_node in node.items]
                        if isinstance(node, JinjaNodesList)
                        else node.value
                        for node in pair.value.items
                    ]
                elif isinstance(pair.value, JinjaNodesConst):
                    ret[pair.key.value] = pair.value.value
                else:  # Ignore all other nodes
                    continue
        return ret

    def _parse_config(self, hostname):
        # Will raise OSError if the file does not exist.
        # Will raise jinja2.TemplateError if the template cannot be parsed.
        jinja_config = File("device", hostname).read()

        env = create_device_templates_env()
        ast = env.parse(jinja_config)
        return ast

    def _get_sync_to_lava(self, hostname):
        # Fetches value of the 'sync_to_lava' variable set in dictionary.
        try:
            config = self._parse_config(hostname)
        except (OSError, JinjaTemplateError) as exc:
            return None, exc

        sync = list(config.find_all(JinjaNodesAssign))
        for node in sync:
            with contextlib.suppress(AttributeError):
                if node.target.name == self.SYNC_KEY:
                    return node.node, None
        return None, None

    def handle(self, *_, **options):
        dicts = File("device").list("*.jinja2")
        synced_devices = []
        self.stdout.write("Scanning devices:")
        for name in dicts:
            hostname = name.rsplit(".", 1)[0]

            # Get value of 'sync_to_lava' variable from template.
            sync_dict, exc = self._get_sync_to_lava(hostname)

            if exc:
                self.stdout.write(f"* {hostname} [SKIP]")
                self.stdout.write(f"  -> invalid jinja2 template")
                self.stdout.write(f"  -> {exc}")
                continue

            if sync_dict is None:
                self.stdout.write(f"* {hostname} [SKIP]")
                self.stdout.write(f"  -> missing '{self.SYNC_KEY}'")
                continue

            # Convert it to dictionary.
            sync_dict = self._parse_sync_dict(sync_dict)

            try:
                template = DEVICES_JINJA_ENV.get_template(name)
                yaml_safe_load(template.render())
            except JinjaTemplateError as exc:
                self.stdout.write(f"* {hostname} [SKIP]")
                self.stdout.write(f"  -> invalid jinja2 template")
                self.stdout.write(f"  -> {exc}")
                continue
            except yaml.YAMLError as exc:
                self.stdout.write(f"* {hostname} [SKIP]")
                self.stdout.write(f"  -> invalid yaml")
                self.stdout.write(f"  -> {exc}")
                continue

            # Check if this device is already manually created in db.
            with contextlib.suppress(Device.DoesNotExist):
                device = Device.objects.get(hostname=hostname)
                if not device.is_synced:
                    self.stdout.write(f"* {hostname} [SKIP]")
                    self.stdout.write(f"  -> created manually")
                    continue

            # Check keys
            if "device_type" not in sync_dict:
                self.stdout.write(f"* {hostname} [SKIP]")
                self.stdout.write(f"  -> 'device_type' is mandatory")
                continue

            # Add to managed devices list.
            self.stdout.write(f"* {hostname}")
            synced_devices.append(hostname)

            # Create device type. If not found, report an error and skip.
            device_type, created = DeviceType.objects.get_or_create(
                name=sync_dict["device_type"]
            )
            if created:
                self.stdout.write(f"  -> create device type: {device_type.name}")

            worker = None
            if "worker" in sync_dict:
                worker, created = Worker.objects.get_or_create(
                    hostname=sync_dict["worker"]
                )
                if created:
                    self.stdout.write(f"  -> create worker: {sync_dict['worker']}")

            # Create/update device.
            defaults = {
                "device_type": device_type,
                "description": "Created automatically by LAVA.",
                "worker_host": worker,
                "is_synced": True,
            }
            device, created = Device.objects.update_or_create(
                defaults, hostname=hostname
            )
            if created:
                Device.objects.filter(hostname=hostname).update(
                    health=Device.HEALTH_UNKNOWN
                )

            # Create aliases.
            for alias_name in sync_dict.get("aliases", []):
                Alias.objects.get_or_create(name=alias_name, device_type=device_type)
                self.stdout.write(f"  -> alias: {alias_name}")

            # Remove all tag relations first.
            device.tags.clear()
            # Create tags.
            for tag_name in sync_dict.get("tags", []):
                tag, _ = Tag.objects.get_or_create(name=tag_name)
                device.tags.add(tag)
                self.stdout.write(f"  -> tag: {tag_name}")

            # Link physical owner
            specified_owner = sync_dict.get("physical_owner", "")
            try:
                physical_owner = User.objects.get(username=specified_owner)
                device.physical_owner = physical_owner
                self.stdout.write(f"  -> user: {specified_owner}")
            except User.DoesNotExist:
                device.physical_owner = None
                if specified_owner:
                    self.stdout.write(f"  -> user '{specified_owner}' does not exist")
            finally:
                device.save()

            # Link physical group
            specified_group = sync_dict.get("physical_group", "")
            try:
                physical_group = Group.objects.get(name=specified_group)
                device.physical_group = physical_group
                self.stdout.write(f"  -> group: {specified_group}")
            except Group.DoesNotExist:
                device.physical_group = None
                if specified_group:
                    self.stdout.write(f"  -> group '{specified_group}' does not exist")
            finally:
                device.save()

            # Assign permission
            specified_permissions = sync_dict.get("group_device_permissions", [])
            for permission in specified_permissions:
                perm = permission[0]
                group = permission[1]

                try:
                    permission_group = Group.objects.get(name=group)
                    try:
                        GroupDevicePermission.objects.assign_perm(
                            perm, permission_group, device
                        )
                        self.stdout.write(
                            f"  -> add group permission: ({perm}, {group})"
                        )
                    except PermissionNameError:
                        self.stdout.write(f"  -> permission '{perm}' does not exist")
                except Group.DoesNotExist:
                    self.stdout.write(f"  -> group '{group}' does not exist")

            # Delete unused permission
            kwargs = {"device": device}
            obj_perm = GroupDevicePermission.objects.filter(**kwargs)
            for perm in obj_perm:
                if [
                    perm.permission.codename,
                    perm.group.name,
                ] not in specified_permissions:
                    GroupDevicePermission.objects.remove_perm(
                        perm.permission.codename, perm.group, perm.device
                    )
                    self.stdout.write(
                        f"  -> delete group permission: ({perm.permission.codename}, {perm.group.name})"
                    )

        # devices which have is_synced true if there's no device dict for them.
        Device.objects.filter(is_synced=True).exclude(
            hostname__in=synced_devices
        ).update(health=Device.HEALTH_RETIRED)

        # Device types which have all the devices synced and all of them retired
        # should become invisible.
        synced_retired_queryset = DeviceType.objects.annotate(
            not_synced_retired_count=Count(
                "device",
                filter=Q(device__is_synced=False)
                | ~Q(device__health=Device.HEALTH_RETIRED),
            )
        )
        synced_retired_queryset.filter(not_synced_retired_count=0).update(display=False)

        # Device types which have all the devices synced and some of them not
        # retired should become visible.
        synced_not_retired_queryset = DeviceType.objects.annotate(
            not_synced=Count(
                "device",
                filter=Q(device__is_synced=False),
            ),
            not_retired=Count(
                "device",
                filter=~Q(device__health=Device.HEALTH_RETIRED),
            ),
        )
        synced_not_retired_queryset.filter(not_synced=0).filter(
            not_retired__gt=0
        ).update(display=True)
