pferd/PFERD/downloaders.py

"""
General downloaders useful in many situations
"""

from dataclasses import dataclass, field
from typing import Any, Dict, List, Optional

import requests
import requests.auth

from .organizer import Organizer
from .tmp_dir import TmpDir
from .transform import Transformable
from .utils import stream_to_path


@dataclass
class HttpDownloadInfo(Transformable):
    """
    This class describes a single file to be downloaded.
    """

    url: str
    parameters: Dict[str, Any] = field(default_factory=dict)


class HttpDownloader:
    """A HTTP downloader that can handle HTTP basic auth."""

    def __init__(
            self,
            tmp_dir: TmpDir,
            organizer: Organizer,
            username: Optional[str],
            password: Optional[str],
    ):
        """Create a new http downloader."""
        self._organizer = organizer
        self._tmp_dir = tmp_dir
        self._username = username
        self._password = password
        self._session = self._build_session()

    def _build_session(self) -> requests.Session:
        session = requests.Session()
        if self._username and self._password:
            session.auth = requests.auth.HTTPBasicAuth(
                self._username, self._password
            )
        return session

    def download_all(self, infos: List[HttpDownloadInfo]) -> None:
        """
        Download multiple files one after the other.
        """

        for info in infos:
            self.download(info)

    def download(self, info: HttpDownloadInfo) -> None:
        """
        Download a single file.
        """

        with self._session.get(info.url, params=info.parameters, stream=True) as response:
            if response.status_code == 200:
                tmp_file = self._tmp_dir.new_path()
                stream_to_path(response, tmp_file, info.path.name)
                self._organizer.accept_file(tmp_file, info.path)
            else:
                # TODO use proper exception
                raise Exception(f"Could not download file, got response {response.status_code}")