"""
HttpError Spider Middleware

See documentation in docs/topics/spider-middleware.rst
"""
import logging

from scrapy.exceptions import IgnoreRequest

logger = logging.getLogger(__name__)


class HttpError(IgnoreRequest):
    """A non-200 response was filtered"""

    def __init__(self, response, *args, **kwargs):
        self.response = response
        super(HttpError, self).__init__(*args, **kwargs)


class HttpErrorMiddleware:

    @classmethod
    def from_crawler(cls, crawler):
        return cls(crawler.settings)

    def __init__(self, settings):
        self.handle_httpstatus_all = settings.getbool('HTTPERROR_ALLOW_ALL')
        self.handle_httpstatus_list = settings.getlist('HTTPERROR_ALLOWED_CODES')

    def process_spider_input(self, response, spider):
        if 200 <= response.status < 300:  # common case
            return
        meta = response.meta
        if 'handle_httpstatus_all' in meta:
            return
        if 'handle_httpstatus_list' in meta:
            allowed_statuses = meta['handle_httpstatus_list']
        elif self.handle_httpstatus_all:
            return
        else:
            allowed_statuses = getattr(spider, 'handle_httpstatus_list', self.handle_httpstatus_list)
        if response.status in allowed_statuses:
            return
        raise HttpError(response, 'Ignoring non-200 response')

    def process_spider_exception(self, response, exception, spider):
        if isinstance(exception, HttpError):
            spider.crawler.stats.inc_value('httperror/response_ignored_count')
            spider.crawler.stats.inc_value(
                'httperror/response_ignored_status_count/%s' % response.status
            )
            logger.info(
                "Ignoring response %(response)r: HTTP status code is not handled or not allowed",
                {'response': response}, extra={'spider': spider},
            )
            return []
