# -------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for
# license information.
# --------------------------------------------------------------------------

import base64
import hashlib
import re
import random
from time import time
from io import SEEK_SET, UnsupportedOperation
import logging
import uuid
import types
import platform
from typing import Any, TYPE_CHECKING
from wsgiref.handlers import format_date_time
try:
    from urllib.parse import (
        urlparse,
        parse_qsl,
        urlunparse,
        urlencode,
    )
except ImportError:
    from urllib import urlencode # type: ignore
    from urlparse import ( # type: ignore
        urlparse,
        parse_qsl,
        urlunparse,
    )

from azure.core.pipeline.policies import (
    HeadersPolicy,
    SansIOHTTPPolicy,
    NetworkTraceLoggingPolicy,
    HTTPPolicy)
from azure.core.pipeline.policies.base import RequestHistory
from azure.core.exceptions import AzureError, ServiceRequestError, ServiceResponseError

from ..version import VERSION
from .models import LocationMode

try:
    _unicode_type = unicode # type: ignore
except NameError:
    _unicode_type = str

if TYPE_CHECKING:
    from azure.core.pipeline import PipelineRequest, PipelineResponse


_LOGGER = logging.getLogger(__name__)


def encode_base64(data):
    if isinstance(data, _unicode_type):
        data = data.encode('utf-8')
    encoded = base64.b64encode(data)
    return encoded.decode('utf-8')


def is_exhausted(settings):
    """Are we out of retries?"""
    retry_counts = (settings['total'], settings['connect'], settings['read'], settings['status'])
    retry_counts = list(filter(None, retry_counts))
    if not retry_counts:
        return False
    return min(retry_counts) < 0


def retry_hook(settings, **kwargs):
    if settings['hook']:
        settings['hook'](retry_count=settings['count'] - 1, location_mode=settings['mode'], **kwargs)


def is_retry(response, mode):
    """Is this method/status code retryable? (Based on whitelists and control
    variables such as the number of total retries to allow, whether to
    respect the Retry-After header, whether this header is present, and
    whether the returned status code is on the list of status codes to
    be retried upon on the presence of the aforementioned header)
    """
    status = response.http_response.status_code
    if 300 <= status < 500:
        # An exception occured, but in most cases it was expected. Examples could
        # include a 309 Conflict or 412 Precondition Failed.
        if status == 404 and mode == LocationMode.SECONDARY:
            # Response code 404 should be retried if secondary was used.
            return True
        if status == 408:
            # Response code 408 is a timeout and should be retried.
            return True
        return False
    if status >= 500:
        # Response codes above 500 with the exception of 501 Not Implemented and
        # 505 Version Not Supported indicate a server issue and should be retried.
        if status in [501, 505]:
            return False
        return True
    return False


def urljoin(base_url, stub_url):
    parsed = urlparse(base_url)
    parsed = parsed._replace(path=parsed.path + '/' + stub_url)
    return parsed.geturl()


class QueueMessagePolicy(SansIOHTTPPolicy):

    def on_request(self, request):
        message_id = request.context.options.pop('queue_message_id', None)
        if message_id:
            request.http_request.url = urljoin(
                request.http_request.url,
                message_id)


class StorageHeadersPolicy(HeadersPolicy):
    request_id_header_name = 'x-ms-client-request-id'

    def on_request(self, request):
        # type: (PipelineRequest, Any) -> None
        super(StorageHeadersPolicy, self).on_request(request)
        current_time = format_date_time(time())
        request.http_request.headers['x-ms-date'] = current_time

        custom_id = request.context.options.pop('client_request_id', None)
        request.http_request.headers['x-ms-client-request-id'] = custom_id or str(uuid.uuid1())

    def on_response(self, request, response):
        # raise exception if the echoed client request id from the service is not identical to the one we sent
        if self.request_id_header_name in response.http_response.headers:

            client_request_id = request.http_request.headers.get(self.request_id_header_name)

            if response.http_response.headers[self.request_id_header_name] != client_request_id:
                raise AzureError(
                    "Echoed client request ID: {} does not match sent client request ID: {}.  "
                    "Service request ID: {}".format(
                        response.http_response.headers[self.request_id_header_name], client_request_id,
                        response.http_response.headers['x-ms-request-id']),
                    response=response.http_response
                )


class StorageHosts(SansIOHTTPPolicy):

    def __init__(self, hosts=None, **kwargs):  # pylint: disable=unused-argument
        self.hosts = hosts
        super(StorageHosts, self).__init__()

    def on_request(self, request):
        # type: (PipelineRequest, Any) -> None
        request.context.options['hosts'] = self.hosts
        parsed_url = urlparse(request.http_request.url)

        # Detect what location mode we're currently requesting with
        location_mode = LocationMode.PRIMARY
        for key, value in self.hosts.items():
            if parsed_url.netloc == value:
                location_mode = key

        # See if a specific location mode has been specified, and if so, redirect
        use_location = request.context.options.pop('use_location', None)
        if use_location:
            # Lock retries to the specific location
            request.context.options['retry_to_secondary'] = False
            if use_location not in self.hosts:
                raise ValueError("Attempting to use undefined host location {}".format(use_location))
            if use_location != location_mode:
                # Update request URL to use the specified location
                updated = parsed_url._replace(netloc=self.hosts[use_location])
                request.http_request.url = updated.geturl()
                location_mode = use_location

        request.context.options['location_mode'] = location_mode


class StorageLoggingPolicy(NetworkTraceLoggingPolicy):
    """A policy that logs HTTP request and response to the DEBUG logger.

    This accepts both global configuration, and per-request level with "enable_http_logger"
    """

    def on_request(self, request):
        # type: (PipelineRequest, Any) -> None
        http_request = request.http_request
        options = request.context.options
        if options.pop("logging_enable", self.enable_http_logger):
            request.context["logging_enable"] = True
            if not _LOGGER.isEnabledFor(logging.DEBUG):
                return

            try:
                log_url = http_request.url
                query_params = http_request.query
                if 'sig' in query_params:
                    log_url = log_url.replace(query_params['sig'], "sig=*****")
                _LOGGER.debug("Request URL: %r", log_url)
                _LOGGER.debug("Request method: %r", http_request.method)
                _LOGGER.debug("Request headers:")
                for header, value in http_request.headers.items():
                    if header.lower() == 'authorization':
                        value = '*****'
                    elif header.lower() == 'x-ms-copy-source' and 'sig' in value:
                        # take the url apart and scrub away the signed signature
                        scheme, netloc, path, params, query, fragment = urlparse(value)
                        parsed_qs = dict(parse_qsl(query))
                        parsed_qs['sig'] = '*****'

                        # the SAS needs to be put back together
                        value = urlunparse((scheme, netloc, path, params, urlencode(parsed_qs), fragment))

                    _LOGGER.debug("    %r: %r", header, value)
                _LOGGER.debug("Request body:")

                # We don't want to log the binary data of a file upload.
                if isinstance(http_request.body, types.GeneratorType):
                    _LOGGER.debug("File upload")
                else:
                    _LOGGER.debug(str(http_request.body))
            except Exception as err:  # pylint: disable=broad-except
                _LOGGER.debug("Failed to log request: %r", err)

    def on_response(self, request, response):
        # type: (PipelineRequest, PipelineResponse, Any) -> None
        if response.context.pop("logging_enable", self.enable_http_logger):
            if not _LOGGER.isEnabledFor(logging.DEBUG):
                return

            try:
                _LOGGER.debug("Response status: %r", response.http_response.status_code)
                _LOGGER.debug("Response headers:")
                for res_header, value in response.http_response.headers.items():
                    _LOGGER.debug("    %r: %r", res_header, value)

                # We don't want to log binary data if the response is a file.
                _LOGGER.debug("Response content:")
                pattern = re.compile(r'attachment; ?filename=["\w.]+', re.IGNORECASE)
                header = response.http_response.headers.get('content-disposition')

                if header and pattern.match(header):
                    filename = header.partition('=')[2]
                    _LOGGER.debug("File attachments: %s", filename)
                elif response.http_response.headers.get("content-type", "").endswith("octet-stream"):
                    _LOGGER.debug("Body contains binary data.")
                elif response.http_response.headers.get("content-type", "").startswith("image"):
                    _LOGGER.debug("Body contains image data.")
                else:
                    if response.context.options.get('stream', False):
                        _LOGGER.debug("Body is streamable")
                    else:
                        _LOGGER.debug(response.http_response.text())
            except Exception as err:  # pylint: disable=broad-except
                _LOGGER.debug("Failed to log response: %s", repr(err))


class StorageUserAgentPolicy(SansIOHTTPPolicy):

    _USERAGENT = "User-Agent"

    def __init__(self, **kwargs):
        self._application = kwargs.pop('user_agent', None)
        storage_sdk = kwargs.pop('storage_sdk')
        self._user_agent = "azsdk-python-storage-{}/{} Python/{} ({})".format(
            storage_sdk,
            VERSION,
            platform.python_version(),
            platform.platform())
        super(StorageUserAgentPolicy, self).__init__()

    def on_request(self, request):
        existing = request.http_request.headers.get(self._USERAGENT, "")
        app_string = request.context.options.pop('user_agent', None) or self._application
        if app_string:
            request.http_request.headers[self._USERAGENT] = "{} {}".format(
                app_string, self._user_agent)
        else:
            request.http_request.headers[self._USERAGENT] = self._user_agent
        if existing:
            request.http_request.headers[self._USERAGENT] += " " + existing


class StorageRequestHook(SansIOHTTPPolicy):

    def __init__(self, **kwargs):  # pylint: disable=unused-argument
        self._request_callback = kwargs.get('raw_request_hook')
        super(StorageRequestHook, self).__init__()

    def on_request(self, request):
        # type: (PipelineRequest, **Any) -> PipelineResponse
        request_callback = request.context.options.pop('raw_request_hook', self._request_callback)
        if request_callback:
            request_callback(request)


class StorageResponseHook(HTTPPolicy):

    def __init__(self, **kwargs):  # pylint: disable=unused-argument
        self._response_callback = kwargs.get('raw_response_hook')
        super(StorageResponseHook, self).__init__()

    def send(self, request):
        # type: (PipelineRequest) -> PipelineResponse
        data_stream_total = request.context.get('data_stream_total') or \
            request.context.options.pop('data_stream_total', None)
        download_stream_current = request.context.get('download_stream_current') or \
            request.context.options.pop('download_stream_current', None)
        upload_stream_current = request.context.get('upload_stream_current') or \
            request.context.options.pop('upload_stream_current', None)
        response_callback = request.context.get('response_callback') or \
            request.context.options.pop('raw_response_hook', self._response_callback)

        response = self.next.send(request)
        will_retry = is_retry(response, request.context.options.get('mode'))
        if not will_retry and download_stream_current is not None:
            download_stream_current += int(response.http_response.headers.get('Content-Length', 0))
            if data_stream_total is None:
                content_range = response.http_response.headers.get('Content-Range')
                if content_range:
                    data_stream_total = int(content_range.split(' ', 1)[1].split('/', 1)[1])
                else:
                    data_stream_total = download_stream_current
        elif not will_retry and upload_stream_current is not None:
            upload_stream_current += int(response.http_request.headers.get('Content-Length', 0))
        for pipeline_obj in [request, response]:
            pipeline_obj.context['data_stream_total'] = data_stream_total
            pipeline_obj.context['download_stream_current'] = download_stream_current
            pipeline_obj.context['upload_stream_current'] = upload_stream_current
        if response_callback:
            response_callback(response)
            request.context['response_callback'] = response_callback
        return response


class StorageContentValidation(SansIOHTTPPolicy):
    """A simple policy that sends the given headers
    with the request.

    This will overwrite any headers already defined in the request.
    """
    header_name = 'Content-MD5'

    def __init__(self, **kwargs):  # pylint: disable=unused-argument
        super(StorageContentValidation, self).__init__()

    @staticmethod
    def get_content_md5(data):
        md5 = hashlib.md5()
        if isinstance(data, bytes):
            md5.update(data)
        elif hasattr(data, 'read'):
            pos = 0
            try:
                pos = data.tell()
            except:  # pylint: disable=bare-except
                pass
            for chunk in iter(lambda: data.read(4096), b""):
                md5.update(chunk)
            try:
                data.seek(pos, SEEK_SET)
            except (AttributeError, IOError):
                raise ValueError("Data should be bytes or a seekable file-like object.")
        else:
            raise ValueError("Data should be bytes or a seekable file-like object.")

        return md5.digest()

    def on_request(self, request):
        # type: (PipelineRequest, Any) -> None
        validate_content = request.context.options.pop('validate_content', False)
        if validate_content and request.http_request.method != 'GET':
            computed_md5 = encode_base64(StorageContentValidation.get_content_md5(request.http_request.data))
            request.http_request.headers[self.header_name] = computed_md5
            request.context['validate_content_md5'] = computed_md5
        request.context['validate_content'] = validate_content

    def on_response(self, request, response):
        if response.context.get('validate_content', False) and response.http_response.headers.get('content-md5'):
            computed_md5 = request.context.get('validate_content_md5') or \
                encode_base64(StorageContentValidation.get_content_md5(response.http_response.body()))
            if response.http_response.headers['content-md5'] != computed_md5:
                raise AzureError(
                    'MD5 mismatch. Expected value is \'{0}\', computed value is \'{1}\'.'.format(
                        response.http_response.headers['content-md5'], computed_md5),
                    response=response.http_response
                )


class StorageRetryPolicy(HTTPPolicy):
    """
    The base class for Exponential and Linear retries containing shared code.
    """

    def __init__(self, **kwargs):
        self.total_retries = kwargs.pop('retry_total', 10)
        self.connect_retries = kwargs.pop('retry_connect', 3)
        self.read_retries = kwargs.pop('retry_read', 3)
        self.status_retries = kwargs.pop('retry_status', 3)
        self.retry_to_secondary = kwargs.pop('retry_to_secondary', False)
        super(StorageRetryPolicy, self).__init__()

    def _set_next_host_location(self, settings, request):  # pylint: disable=no-self-use
        """
        A function which sets the next host location on the request, if applicable.

        :param ~azure.storage.models.RetryContext context:
            The retry context containing the previous host location and the request
            to evaluate and possibly modify.
        """
        if settings['hosts'] and all(settings['hosts'].values()):
            url = urlparse(request.url)
            # If there's more than one possible location, retry to the alternative
            if settings['mode'] == LocationMode.PRIMARY:
                settings['mode'] = LocationMode.SECONDARY
            else:
                settings['mode'] = LocationMode.PRIMARY
            updated = url._replace(netloc=settings['hosts'].get(settings['mode']))
            request.url = updated.geturl()

    def configure_retries(self, request):  # pylint: disable=no-self-use
        body_position = None
        if hasattr(request.http_request.body, 'read'):
            try:
                body_position = request.http_request.body.tell()
            except (AttributeError, UnsupportedOperation):
                # if body position cannot be obtained, then retries will not work
                pass
        options = request.context.options
        return {
            'total': options.pop("retry_total", self.total_retries),
            'connect': options.pop("retry_connect", self.connect_retries),
            'read': options.pop("retry_read", self.read_retries),
            'status': options.pop("retry_status", self.status_retries),
            'retry_secondary': options.pop("retry_to_secondary", self.retry_to_secondary),
            'mode': options.pop("location_mode", LocationMode.PRIMARY),
            'hosts': options.pop("hosts", None),
            'hook': options.pop("retry_hook", None),
            'body_position': body_position,
            'count': 0,
            'history': []
        }

    def get_backoff_time(self, settings):  # pylint: disable=unused-argument,no-self-use
        """ Formula for computing the current backoff.
        Should be calculated by child class.

        :rtype: float
        """
        return 0

    def sleep(self, settings, transport):
        backoff = self.get_backoff_time(settings)
        if not backoff or backoff < 0:
            return
        transport.sleep(backoff)

    def increment(self, settings, request, response=None, error=None):
        """Increment the retry counters.

        :param response: A pipeline response object.
        :param error: An error encountered during the request, or
            None if the response was received successfully.

        :return: Whether the retry attempts are exhausted.
        """
        settings['total'] -= 1

        if error and isinstance(error, ServiceRequestError):
            # Errors when we're fairly sure that the server did not receive the
            # request, so it should be safe to retry.
            settings['connect'] -= 1
            settings['history'].append(RequestHistory(request, error=error))

        elif error and isinstance(error, ServiceResponseError):
            # Errors that occur after the request has been started, so we should
            # assume that the server began processing it.
            settings['read'] -= 1
            settings['history'].append(RequestHistory(request, error=error))

        else:
            # Incrementing because of a server error like a 500 in
            # status_forcelist and a the given method is in the whitelist
            if response:
                settings['status'] -= 1
                settings['history'].append(RequestHistory(request, http_response=response))

        if not is_exhausted(settings):
            if request.method not in ['PUT'] and settings['retry_secondary']:
                self._set_next_host_location(settings, request)

            # rewind the request body if it is a stream
            if request.body and hasattr(request.body, 'read'):
                # no position was saved, then retry would not work
                if settings['body_position'] is None:
                    return False
                try:
                    # attempt to rewind the body to the initial position
                    request.body.seek(settings['body_position'], SEEK_SET)
                except (UnsupportedOperation, ValueError):
                    # if body is not seekable, then retry would not work
                    return False
            settings['count'] += 1
            return True
        return False

    def send(self, request):
        retries_remaining = True
        response = None
        retry_settings = self.configure_retries(request)
        while retries_remaining:
            try:
                response = self.next.send(request)
                if is_retry(response, retry_settings['mode']):
                    retries_remaining = self.increment(
                        retry_settings,
                        request=request.http_request,
                        response=response.http_response)
                    if retries_remaining:
                        retry_hook(
                            retry_settings,
                            request=request.http_request,
                            response=response.http_response,
                            error=None)
                        self.sleep(retry_settings, request.context.transport)
                        continue
                break
            except AzureError as err:
                retries_remaining = self.increment(
                    retry_settings, request=request.http_request, error=err)
                if retries_remaining:
                    retry_hook(
                        retry_settings,
                        request=request.http_request,
                        response=None,
                        error=err)
                    self.sleep(retry_settings, request.context.transport)
                    continue
                raise err
        if retry_settings['history']:
            response.context['history'] = retry_settings['history']
        response.http_response.location_mode = retry_settings['mode']
        return response


class NoRetry(StorageRetryPolicy):

    def __init__(self):
        super(NoRetry, self).__init__(retry_total=0)

    def increment(self, *args, **kwargs):  # pylint: disable=unused-argument,arguments-differ
        return False


class ExponentialRetry(StorageRetryPolicy):
    """Exponential retry."""

    def __init__(self, initial_backoff=15, increment_base=3, retry_total=3,
                 retry_to_secondary=False, random_jitter_range=3, **kwargs):
        '''
        Constructs an Exponential retry object. The initial_backoff is used for
        the first retry. Subsequent retries are retried after initial_backoff +
        increment_power^retry_count seconds. For example, by default the first retry
        occurs after 15 seconds, the second after (15+3^1) = 18 seconds, and the
        third after (15+3^2) = 24 seconds.

        :param int initial_backoff:
            The initial backoff interval, in seconds, for the first retry.
        :param int increment_base:
            The base, in seconds, to increment the initial_backoff by after the
            first retry.
        :param int max_attempts:
            The maximum number of retry attempts.
        :param bool retry_to_secondary:
            Whether the request should be retried to secondary, if able. This should
            only be enabled of RA-GRS accounts are used and potentially stale data
            can be handled.
        :param int random_jitter_range:
            A number in seconds which indicates a range to jitter/randomize for the back-off interval.
            For example, a random_jitter_range of 3 results in the back-off interval x to vary between x+3 and x-3.
        '''
        self.initial_backoff = initial_backoff
        self.increment_base = increment_base
        self.random_jitter_range = random_jitter_range
        super(ExponentialRetry, self).__init__(
            retry_total=retry_total, retry_to_secondary=retry_to_secondary, **kwargs)

    def get_backoff_time(self, settings):
        """
        Calculates how long to sleep before retrying.

        :return:
            An integer indicating how long to wait before retrying the request,
            or None to indicate no retry should be performed.
        :rtype: int or None
        """
        random_generator = random.Random()
        backoff = self.initial_backoff + (0 if settings['count'] == 0 else pow(self.increment_base, settings['count']))
        random_range_start = backoff - self.random_jitter_range if backoff > self.random_jitter_range else 0
        random_range_end = backoff + self.random_jitter_range
        return random_generator.uniform(random_range_start, random_range_end)


class LinearRetry(StorageRetryPolicy):
    """Linear retry."""

    def __init__(self, backoff=15, retry_total=3, retry_to_secondary=False, random_jitter_range=3, **kwargs):
        """
        Constructs a Linear retry object.

        :param int backoff:
            The backoff interval, in seconds, between retries.
        :param int max_attempts:
            The maximum number of retry attempts.
        :param bool retry_to_secondary:
            Whether the request should be retried to secondary, if able. This should
            only be enabled of RA-GRS accounts are used and potentially stale data
            can be handled.
        :param int random_jitter_range:
            A number in seconds which indicates a range to jitter/randomize for the back-off interval.
            For example, a random_jitter_range of 3 results in the back-off interval x to vary between x+3 and x-3.
        """
        self.backoff = backoff
        self.random_jitter_range = random_jitter_range
        super(LinearRetry, self).__init__(
            retry_total=retry_total, retry_to_secondary=retry_to_secondary, **kwargs)

    def get_backoff_time(self, settings):
        """
        Calculates how long to sleep before retrying.

        :return:
            An integer indicating how long to wait before retrying the request,
            or None to indicate no retry should be performed.
        :rtype: int or None
        """
        random_generator = random.Random()
        # the backoff interval normally does not change, however there is the possibility
        # that it was modified by accessing the property directly after initializing the object
        random_range_start = self.backoff - self.random_jitter_range \
            if self.backoff > self.random_jitter_range else 0
        random_range_end = self.backoff + self.random_jitter_range
        return random_generator.uniform(random_range_start, random_range_end)
