# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2023 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
import math
import enum
import json
import typing
from enum import StrEnum
from types import SimpleNamespace
from collections.abc import Sequence, Mapping
from typing import NewType, TypedDict, Protocol, NamedTuple, TYPE_CHECKING

if TYPE_CHECKING:
    from lveapi import PyLve


SerializedLveId = NewType('SerializedLveId', int)
LveId = NewType('LveId', int)
Timestamp = NewType('Timestamp', int)


class BurstingMultipliers(NamedTuple):
    cpu: float
    io: float


@enum.unique
class LveState(StrEnum):
    EXISTED = enum.auto()
    UNBURSTED = enum.auto()
    BURSTED = enum.auto()
    OVERUSING = enum.auto()

    def __str__(self) -> str:
        return self.name


class LveStats(Protocol):
    cpu: int
    io: int  # in KB
    reseller_id: int


empty_stats = typing.cast(LveStats, SimpleNamespace(
    cpu=0,
    cpu_usage=0,
    io=0,
    io_usage=0,
    reseller_id=0,
))


class LveUsage(Protocol):
    cpu_usage: int
    io_usage: int  # in bytes


empty_usage = typing.cast(LveUsage, SimpleNamespace(
    cpu_usage=0,
    io_usage=0,
))


class AdjustStepData(NamedTuple):
    now: Timestamp
    lve_active_ids: Sequence[SerializedLveId]
    stats: Mapping[SerializedLveId, LveStats]
    lve_usages_by_id: Mapping[SerializedLveId, LveUsage]


class LveLimits(TypedDict):
    cpu: int
    io: int


class InvalidStateError(RuntimeError):
    pass


class ApplyLveSettings(Protocol):
    def __call__(self, lve_id: LveId, lve_limits: LveLimits) -> None:
        ...


class GetNormalLimits(Protocol):
    def __call__(self) -> Mapping[LveId, LveLimits]:
        ...


def read_normal_limits_from_proc() -> Mapping[LveId, LveLimits]:
    with open('/var/run/cloudlinux/effective-normal-limits', 'r', encoding='utf-8') as f:
        result = json.load(f)
        result = {LveId(int(k)): v for k, v in result.items()}
        return result


class PyLveSettingsApplier:
    def __init__(self, pylve: 'PyLve') -> None:
        self._pylve = pylve

    def __call__(self, lve_id: LveId, lve_limits: LveLimits) -> None:
        if lve_id == 0:
            raise RuntimeError('Cannot alter LVE with id 0')

        lve_settings = self._pylve.liblve_settings()

        lve_settings.ls_io = int(lve_limits['io'])
        lve_settings.ls_cpu = int(lve_limits['cpu'])
        lve_settings.ls_cpus = int(lve_limits['ncpu'])
        lve_settings.ls_memory = int(lve_limits['mem'])
        lve_settings.ls_enters = int(lve_limits['ep'])
        lve_settings.ls_memory_phy = int(lve_limits['pmem'])
        lve_settings.ls_nproc = int(lve_limits['nproc'])
        lve_settings.ls_iops = int(lve_limits['iops'])

        self._pylve.lve_setup(
            lve_id,
            lve_settings,
            err_msg=f'Can`t setup lve with id {lve_id}; error code {{code}}',
        )


def infer_lve_state(
    stats: LveStats,
    normal_limits: LveLimits,
    usage: LveUsage,
) -> LveState:
    normal_cpu_limit = normal_limits['cpu']
    normal_io_limit = normal_limits['io'] * 1024  # to be in bytes

    kernel_cpu_limits = stats.cpu
    kernel_io_limits = stats.io * 1024  # to be in bytes

    current_cpu_usage = usage.cpu_usage
    current_io_usage = usage.io_usage  # in bytes

    if math.isclose(kernel_cpu_limits, normal_cpu_limit) and math.isclose(kernel_io_limits, normal_io_limit):
        assert current_cpu_usage <= normal_cpu_limit, 'CPU usage is not expected to be greater than CPU limit!'
        assert current_io_usage <= normal_io_limit, 'IO usage is not expected to be greater than IO limit!'
        return LveState.UNBURSTED
    elif current_cpu_usage < normal_cpu_limit and current_io_usage < normal_io_limit:
        return LveState.BURSTED
    else:
        return LveState.OVERUSING


def get_deserialized_lve_id(serialized_lve_id: SerializedLveId) -> LveId:
    # NOTE(vlebedev): This import requires some shared library to be present in order to succeed,
    #                 so deffer it until it's really needed to make unittests writing/running easier.
    from lvestats.lib.commons.func import deserialize_lve_id  # pylint: disable=import-outside-toplevel

    lve_id, _ = deserialize_lve_id(serialized_lve_id)

    return typing.cast(LveId, lve_id)


def calc_bursted_limits(normal_limits: LveLimits, bursting_multipliers: BurstingMultipliers) -> LveLimits:
    return {
        **normal_limits,
        'cpu': int(normal_limits['cpu'] * bursting_multipliers.cpu),
        'io': int(normal_limits['io'] * bursting_multipliers.io)
    }