# -*- coding: utf-8 -*-
"""
Created on 2022-06-15
---------
@summary:  限制器
---------
@author: Dzr
"""

import inspect

from fastapi import FastAPI
from slowapi import Limiter, _rate_limit_exceeded_handler
from slowapi.errors import RateLimitExceeded

import db.redisdb as redis
import setting
from services.robot import send_msg
from services.utils import current_date

LIMITER_DATE = "lm_date"  # 当前日期
LIMITER_FORECAST_WARNING = "lm_forecast_warning"  # 上限预告
LIMITER_EXCEEDED_WARNING = "lm_exceeded_warning"  # 超限告警
PENV = setting.PLATFORM_ENVIRONMENT  # 当前运行环境

redis_db = redis.RedisDB()  # redis实例


def register_limiter(app: FastAPI):
    if not redis_db.exists_key(setting.LIMITER_REDIS_KEY):
        # 服务首次启动时初始化参数
        init_datas = [
            (LIMITER_DATE, current_date()),
            (LIMITER_FORECAST_WARNING, 1),
            (LIMITER_EXCEEDED_WARNING, 1)
        ]
        redis_db.hset_batch(setting.LIMITER_REDIS_KEY, init_datas)

    app.state.limiter = limiter
    app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)


class PayCaptchaLimiter(Limiter):

    def reset_warn(self):
        self.logger.debug("告警重置")
        # 开启上限预告
        redis_db.hset(setting.LIMITER_REDIS_KEY, LIMITER_FORECAST_WARNING, 1)
        # 开启超限告警
        redis_db.hset(setting.LIMITER_REDIS_KEY, LIMITER_EXCEEDED_WARNING, 1)

    def send_pre_warning(self, item, *identifiers):
        table = setting.LIMITER_REDIS_KEY
        limit_date = redis_db.hget(table, LIMITER_DATE)
        curr_date = current_date()
        if curr_date != limit_date:
            redis_db.hset(table, LIMITER_DATE, curr_date)
            self.reset_warn()
            self.reset()
            self.limiter.hit(item, *identifiers)

        usages_count = self._storage.get(item.key_for(*identifiers))
        val = '{:.2f}'.format(usages_count / item.amount * 100)
        if float(val) > 80 and int(redis_db.hget(table, LIMITER_FORECAST_WARNING)):
            tips = "".join([f"[{PENV}]", f"使用次数已超过{val}%"])
            send_msg("超级鹰", item.amount, usages_count, tips)
            redis_db.hset(table, LIMITER_FORECAST_WARNING, 0)

    def send_finished(self, limit):
        max_limit = setting.LIMITER_MAX_LIMIT  # 最大访问次数
        amount = limit.limit.amount
        self.logger.debug(f"今日接口调用次数 {amount} 已达上限！")
        if int(redis_db.hget(setting.LIMITER_REDIS_KEY, LIMITER_EXCEEDED_WARNING)):
            tips = "".join([f"[{PENV}]", "今日接口调用次数已达上限！\n 继续使用请点击"])
            send_msg("超级鹰", max_limit, amount, tips, allow_reset=True)
            # 关闭超限告警
            redis_db.hset(setting.LIMITER_REDIS_KEY, LIMITER_EXCEEDED_WARNING, 0)

    def __evaluate_limits(self, request, endpoint: str, limits) -> None:
        failed_limit = None
        limit_for_header = None
        for lim in limits:
            limit_scope = lim.scope or endpoint
            if lim.is_exempt:
                continue
            if lim.methods is not None and request.method.lower() not in lim.methods:
                continue
            if lim.per_method:
                limit_scope += ":%s" % request.method

            if "request" in inspect.signature(lim.key_func).parameters.keys():
                limit_key = lim.key_func(request)
            else:
                limit_key = lim.key_func()

            args = [limit_key, limit_scope]
            if all(args):
                if self._key_prefix:
                    args = [self._key_prefix] + args

                if not limit_for_header or lim.limit < limit_for_header[0]:
                    limit_for_header = (lim.limit, args)

                self.send_pre_warning(lim.limit, *args)  # 发送预警&自动重置
                if not self.limiter.hit(lim.limit, *args):
                    self.logger.warning(
                        "ratelimit %s (%s) exceeded at endpoint: %s",
                        lim.limit,
                        limit_key,
                        limit_scope,
                    )
                    failed_limit = lim
                    limit_for_header = (lim.limit, args)
                    break
            else:
                self.logger.error(
                    "Skipping limit: %s. Empty value found in parameters.",
                    lim.limit
                )
                continue
        request.state.view_rate_limit = limit_for_header

        if failed_limit:
            self.send_finished(failed_limit)  # 发送重置消息
            raise RateLimitExceeded(failed_limit)

    # 覆盖父类私有方法(不建议尝试做法，此处覆盖仅为了插入告警)
    _Limiter__evaluate_limits = __evaluate_limits


def get_usage_user_key(request):
    if "X_USER_TOKEN" in request.headers:
        key = request.headers["X_USER_TOKEN"]
    else:
        key = "PyCaptcha"
    return key


limiter = PayCaptchaLimiter(
    key_func=get_usage_user_key,
    storage_uri=setting.LIMITER_STORAGE_URI,
)  # 付费验证码限制器实例对象