1 files changed, 135 insertions, 0 deletions
diff --git a/mediagoblin/workbench.py b/mediagoblin/workbench.py
new file mode 100644
index 00000000..d7252623
--- /dev/null
+++ b/mediagoblin/workbench.py
@@ -0,0 +1,135 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011 Free Software Foundation, Inc
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import shutil
+import tempfile
+
+
+DEFAULT_WORKBENCH_DIR = os.path.join(
+    tempfile.gettempdir(), u'mgoblin_workbench')
+
+
+# Exception(s)
+# ------------
+
+class WorkbenchOutsideScope(Exception):
+    """
+    Raised when a workbench is outside a WorkbenchManager scope.
+    """
+    pass
+
+
+# Actual workbench stuff
+# ----------------------
+
+class WorkbenchManager(object):
+    """
+    A system for generating and destroying workbenches.
+
+    Workbenches are actually just subdirectories of a temporary storage space
+    for during the processing stage.
+    """
+
+    def __init__(self, base_workbench_dir):
+        self.base_workbench_dir = os.path.abspath(base_workbench_dir)
+        if not os.path.exists(self.base_workbench_dir):
+            os.makedirs(self.base_workbench_dir)
+        
+    def create_workbench(self):
+        """
+        Create and return the path to a new workbench (directory).
+        """
+        return tempfile.mkdtemp(dir=self.base_workbench_dir)
+
+    def destroy_workbench(self, workbench):
+        """
+        Destroy this workbench!  Deletes the directory and all its contents!
+
+        Makes sure the workbench actually belongs to this manager though.
+        """
+        # just in case
+        workbench = os.path.abspath(workbench)
+
+        if not workbench.startswith(self.base_workbench_dir):
+            raise WorkbenchOutsideScope(
+                "Can't destroy workbench outside the base workbench dir")
+
+        shutil.rmtree(workbench)
+
+    def localized_file(self, workbench, storage, filepath,
+                       filename_if_copying=None,
+                       keep_extension_if_copying=True):
+        """
+        Possibly localize the file from this storage system (for read-only
+        purposes, modifications should be written to a new file.).
+
+        If the file is already local, just return the absolute filename of that
+        local file.  Otherwise, copy the file locally to the workbench, and
+        return the absolute path of the new file.
+
+        If it is copying locally, we might want to require a filename like
+        "source.jpg" to ensure that we won't conflict with other filenames in
+        our workbench... if that's the case, make sure filename_if_copying is
+        set to something like 'source.jpg'.  Relatedly, if you set
+        keep_extension_if_copying, you don't have to set an extension on
+        filename_if_copying yourself, it'll be set for you (assuming such an
+        extension can be extacted from the filename in the filepath).
+
+        Returns:
+          localized_filename
+
+        Examples:
+          >>> wb_manager.localized_file(
+          ...     '/our/workbench/subdir', local_storage,
+          ...     ['path', 'to', 'foobar.jpg'])
+          u'/local/storage/path/to/foobar.jpg'
+
+          >>> wb_manager.localized_file(
+          ...     '/our/workbench/subdir', remote_storage,
+          ...     ['path', 'to', 'foobar.jpg'])
+          '/our/workbench/subdir/foobar.jpg'
+
+          >>> wb_manager.localized_file(
+          ...     '/our/workbench/subdir', remote_storage,
+          ...     ['path', 'to', 'foobar.jpg'], 'source.jpeg', False)
+          '/our/workbench/subdir/foobar.jpeg'
+
+          >>> wb_manager.localized_file(
+          ...     '/our/workbench/subdir', remote_storage,
+          ...     ['path', 'to', 'foobar.jpg'], 'source', True)
+          '/our/workbench/subdir/foobar.jpg'
+        """
+        if storage.local_storage:
+            return storage.get_local_path(filepath)
+        else:
+            if filename_if_copying is None:
+                dest_filename = filepath[-1]
+            else:
+                orig_filename, orig_ext = os.path.splitext(filepath[-1])
+                if keep_extension_if_copying and orig_ext:
+                    dest_filename = filename_if_copying + orig_ext
+                else:
+                    dest_filename = filename_if_copying
+
+            full_dest_filename = os.path.join(
+                workbench, dest_filename)
+
+            # copy it over
+            storage.copy_locally(
+                filepath, full_dest_filename)
+
+            return full_dest_filename