#!/usr/bin/env python
# coding:utf-8

__all__ = ('RetryAsyncHTTPClient', 'RequestException')

from tornado.httpclient import AsyncHTTPClient
from tornado.gen import coroutine, Return
from tornado import gen


class RequestException(Exception):
    pass

class RetryRequestException(RequestException):
    pass

class FailedRequestException(RequestException):
    pass



class RetryAsyncHTTPClient(object):
    """
    Usage:

    @coroutine
    def my_client():
        retry_client = RetryAsyncHTTPClient()
        try:
            response = yield retry_client.fetch("http://www.baidu.com")
        except FailedRequestException as e:
            pass
    """
    RETRY_ERROR_CODE = (400, 500)

    def __init__(self, http_client=None, max_retry=3, retry_timeout=0.5):
        """
        :param http_client: 可以自定义client
        :param max_retry:   最大尝试次数
        :param retry_timeout: 两次请求之间的时间间隔
        :return:
        """
        self.http_client = http_client if http_client else AsyncHTTPClient()
        self.max_retry = max_retry
        self.retry_timeout = retry_timeout

    @coroutine
    def _do_fetch(self, request, callback, raise_error, **kwargs):
        try:
            response = yield self.http_client.fetch(request, callback, raise_error, **kwargs)
        except Exception as e:
            raise RetryRequestException(e)
        else:
            raise Return(response)

    @coroutine
    def fetch(self, request, callback=None, raise_error=True, **kwargs):
        attempt = 0
        while True:
            try:
                response = yield self._do_fetch(request, callback, raise_error, **kwargs)
            except RequestException as e:
                attempt += 1
                if attempt > self.max_retry:
                    raise FailedRequestException("%s request failed, due to: %s" % (self.max_retry, e))
                yield gen.sleep(self.retry_timeout)
            except Exception as e:
                raise FailedRequestException("Failed due to: %s" % e)
            else:
                raise Return(response)