Cleaner Fetcher interface

[paperdoorknob] / fetch.py

diff --git a/fetch.py b/fetch.py
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+++ b/fetch.py
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+# paperdoorknob: Print glowfic
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation, version 3.
+
+
+from abc import ABC, abstractmethod
+from contextlib import contextmanager
+from typing import Iterator
+
+import requests
+import requests_cache
+
+
+class Fetcher(ABC):
+    @abstractmethod
+    def fetch(self, url: str) -> bytes:
+        raise NotImplementedError()
+
+
+class _SessionFetcher(Fetcher):
+
+    def __init__(self, session: requests.Session, timeout: int) -> None:
+        self._session = session
+        self._timeout = timeout
+
+    def fetch(self, url: str) -> bytes:
+        with self._session.get(url, timeout=self._timeout) as r:
+            r.raise_for_status()
+            return r.content
+
+
+@contextmanager
+def DirectFetcher(timeout: int) -> Iterator[_SessionFetcher]:
+    with requests.session() as session:
+        yield _SessionFetcher(session, timeout)
+
+
+@contextmanager
+def CachingFetcher(cache_path: str, timeout: int) -> Iterator[_SessionFetcher]:
+    with requests_cache.CachedSession(cache_path, cache_control=True) as session:
+        yield _SessionFetcher(session, timeout)