# Copyright 2022 Webull
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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# to you under the Apache License, Version 2.0 (the
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# coding=utf-8

"""
This file borrowed some of its methods from a  modified fork of the
https://github.com/aliyun/aliyun-openapi-python-sdk/blob/master/aliyun-python-sdk-core/aliyunsdkcore/retry/backoff_strategy.py
which was part of Alibaba Group.
"""

import random
from webullsdkcore.retry.retry_condition import RetryCondition

class BackoffStrategy(object):
    def compute_delay_before_next_retry(self, retry_policy_context):
        """Compute delay for request need to be retried, in milliseconds"""
        pass

class FixedDelayStrategy(BackoffStrategy):
    def __init__(self, fixed_delay):
        self.fixed_delay = fixed_delay
        
    def compute_delay_before_next_retry(self, retry_policy_context):
        return self.fixed_delay

class NoDelayStrategy(FixedDelayStrategy): 
    def __init__(self):
        FixedDelayStrategy.__init__(self, 0)

class ExponentialBackoffStrategy(BackoffStrategy): 
    MAX_RETRY_LIMIT = 30   # to avoid integer overflow during delay calculation

    def __init__(self, base_delay_in_milliseconds, max_delay_in_milliseconds):
        self.base_delay_in_milliseconds = base_delay_in_milliseconds
        self.max_delay_in_milliseconds = max_delay_in_milliseconds

    def compute_delay_before_next_retry(self, retry_policy_context):
        retries = min(self.MAX_RETRY_LIMIT, retry_policy_context.retries_attempted)
        delay = min(self.max_delay_in_milliseconds, self.base_delay_in_milliseconds << retries)
        return delay

class JitteredExponentialBackoffStrategy(ExponentialBackoffStrategy):
    def compute_delay_before_next_retry(self, retry_policy_context):
        delay = ExponentialBackoffStrategy.compute_delay_before_next_retry(self, retry_policy_context)
        return delay / 2 + random.randint(0, int(delay / 2))

class DefaultMixedBackoffStrategy(BackoffStrategy):
    
    # in milliseconds
    SDK_DEFAULT_BASE_DELAY = 100
    SDK_DEFAULT_TROTTLED_BASE_DELAY = 500
    SDK_DEFAULT_MAX_BACKOFF = 20 * 1000

    def __init__(self):
        self._default_backoff_strategy = ExponentialBackoffStrategy(
            self.SDK_DEFAULT_BASE_DELAY,
            self.SDK_DEFAULT_MAX_BACKOFF
        )
        self._default_throttled_backoff_strategy = JitteredExponentialBackoffStrategy(
            self.SDK_DEFAULT_TROTTLED_BASE_DELAY,
            self.SDK_DEFAULT_MAX_BACKOFF
        )

    def compute_delay_before_next_retry(self, retry_policy_context):
        retryable = retry_policy_context.retryable
        if retryable & RetryCondition.SHOULD_RETRY_WITH_THROTTLING_BACKOFF:
            return self._default_throttled_backoff_strategy.compute_delay_before_next_retry(
                retry_policy_context)
        else:
            return self._default_backoff_strategy.compute_delay_before_next_retry(
                retry_policy_context)