Add abstract base class for story fetchers

fimfarchive/exceptions.py

@@ -26,3 +26,21 @@ class FimfarchiveError(Exception):
     """
     Base class for Fimfarchive exceptions.
     """
+
+
+class InvalidStoryError(FimfarchiveError):
+    """
+    Story does not exist.
+    """
+
+
+class StoryPermissionError(FimfarchiveError):
+    """
+    Story is password protected.
+    """
+
+
+class StorySourceError(FimfarchiveError):
+    """
+    Story source is unusable.
+    """

fimfarchive/fetchers.py

@@ -0,0 +1,97 @@
+"""
+Fetchers for Fimfarchive.
+"""
+
+
+#
+# Fimfarchive, preserves stories from Fimfiction
+# Copyright (C) 2015  Joakim Soderlund
+#
+# 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, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+
+class Fetcher:
+    """
+    Abstract base class for story fetchers.
+    """
+
+    def __enter__(self):
+        """
+        Returns self for use in with statements.
+        """
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        """
+        Closes the fetcher on exit in with statements.
+        """
+        self.close()
+
+    def close(self):
+        """
+        Closes file descriptors and frees memory.
+        """
+        raise NotImplementedError()
+
+    def fetch(self, pk):
+        """
+        Fetches story information.
+
+        Args:
+            pk: Primary key of the story.
+
+        Returns:
+            Story: A new `Story` object.
+
+        Raises:
+            InvalidStoryError: If a valid story is not found.
+            StoryPermissionError: If access to the story is denied.
+            StorySourceError: If source does not return any data.
+        """
+        raise NotImplementedError()
+
+    def fetch_data(self, pk):
+        """
+        Fetches story content data.
+
+        Args:
+            pk: Primary key of the story.
+
+        Returns:
+            bytes: Story content data.
+
+        Raises:
+            InvalidStoryError: If a valid story is not found.
+            StoryPermissionError: If access to the story is denied.
+            StorySourceError: If source does not return any data.
+        """
+        raise NotImplementedError()
+
+    def fetch_meta(self, pk):
+        """
+        Fetches story meta information.
+
+        Args:
+            pk: Primary key of the story.
+
+        Returns:
+            dict: Story meta information.
+
+        Raises:
+            InvalidStoryError: If a valid story is not found.
+            StoryPermissionError: If access to the story is denied.
+            StorySourceError: If source does not return any data.
+        """
+        raise NotImplementedError()