from scrapy.core.downloader.handlers.http import HTTPDownloadHandler
from scrapy.exceptions import NotConfigured
from scrapy.utils.boto import is_botocore_available
from scrapy.utils.httpobj import urlparse_cached
from scrapy.utils.misc import create_instance


class S3DownloadHandler:

    def __init__(self, settings, *,
                 crawler=None,
                 aws_access_key_id=None, aws_secret_access_key=None,
                 aws_session_token=None,
                 httpdownloadhandler=HTTPDownloadHandler, **kw):
        if not is_botocore_available():
            raise NotConfigured('missing botocore library')

        if not aws_access_key_id:
            aws_access_key_id = settings['AWS_ACCESS_KEY_ID']
        if not aws_secret_access_key:
            aws_secret_access_key = settings['AWS_SECRET_ACCESS_KEY']
        if not aws_session_token:
            aws_session_token = settings['AWS_SESSION_TOKEN']

        # If no credentials could be found anywhere,
        # consider this an anonymous connection request by default;
        # unless 'anon' was set explicitly (True/False).
        anon = kw.get('anon')
        if anon is None and not aws_access_key_id and not aws_secret_access_key:
            kw['anon'] = True
        self.anon = kw.get('anon')

        self._signer = None
        import botocore.auth
        import botocore.credentials
        kw.pop('anon', None)
        if kw:
            raise TypeError(f'Unexpected keyword arguments: {kw}')
        if not self.anon:
            SignerCls = botocore.auth.AUTH_TYPE_MAPS['s3']
            self._signer = SignerCls(botocore.credentials.Credentials(
                aws_access_key_id, aws_secret_access_key, aws_session_token))

        _http_handler = create_instance(
            objcls=httpdownloadhandler,
            settings=settings,
            crawler=crawler,
        )
        self._download_http = _http_handler.download_request

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

    def download_request(self, request, spider):
        p = urlparse_cached(request)
        scheme = 'https' if request.meta.get('is_secure') else 'http'
        bucket = p.hostname
        path = p.path + '?' + p.query if p.query else p.path
        url = f'{scheme}://{bucket}.s3.amazonaws.com{path}'
        if self.anon:
            request = request.replace(url=url)
        else:
            import botocore.awsrequest
            awsrequest = botocore.awsrequest.AWSRequest(
                method=request.method,
                url=f'{scheme}://s3.amazonaws.com/{bucket}{path}',
                headers=request.headers.to_unicode_dict(),
                data=request.body)
            self._signer.add_auth(awsrequest)
            request = request.replace(
                url=url, headers=awsrequest.headers.items())
        return self._download_http(request, spider)