import abc
import json
from urllib import error
from posixpath import join as urljoin

from uaclient import config
from uaclient import util
from uaclient import version

try:
    from typing import Optional, Type  # noqa
except ImportError:
    # typing isn't available on trusty, so ignore its absence
    pass


class UAServiceClient(metaclass=abc.ABCMeta):
    @property
    @abc.abstractmethod
    def api_error_cls(self) -> "Type[Exception]":
        """Set in subclasses to the type of API error raised"""
        pass

    @property
    @abc.abstractmethod
    def cfg_url_base_attr(self) -> str:
        """String in subclasses, the UAConfig attribute containing base url"""
        pass

    def __init__(self, cfg: "Optional[config.UAConfig]" = None) -> None:
        if not cfg:
            self.cfg = config.UAConfig()
        else:
            self.cfg = cfg

    def headers(self):
        return {
            "user-agent": "UA-Client/{}".format(version.get_version()),
            "accept": "application/json",
            "content-type": "application/json",
        }

    def request_url(self, path, data=None, headers=None, method=None):
        path = path.lstrip("/")
        if not headers:
            headers = self.headers()
        if headers.get("content-type") == "application/json" and data:
            data = json.dumps(data).encode("utf-8")
        url = urljoin(getattr(self.cfg, self.cfg_url_base_attr), path)
        try:
            response, headers = util.readurl(
                url=url, data=data, headers=headers, method=method
            )
        except error.URLError as e:
            if hasattr(e, "read"):
                try:
                    error_details = json.loads(e.read().decode("utf-8"))
                except ValueError:
                    error_details = None
                if error_details:
                    raise self.api_error_cls(e, error_details)
            raise util.UrlError(
                e, code=getattr(e, "code", None), headers=headers, url=url
            )
        return response, headers
