Transforms: add getAvailableTargetMimetypeList method

product/PortalTransforms/TransformEngine.py

@@ -30,6 +30,7 @@ from Products.PortalTransforms.transforms import initialize
 from Products.PortalTransforms.utils import log
 from Products.PortalTransforms.utils import TransformException
 from Products.PortalTransforms.utils import _www
+from Products.PortalTransforms.utils import parseContentType
 
 
 from ZODB.POSException import ConflictError
@@ -651,5 +652,44 @@ class TransformTool(UniqueObject, ActionProviderBase, Folder):
                     available_types.append(input)
         return available_types
 
+    security.declarePublic('getAvailableTargetMimetypeList')
+    def getAvailableTargetMimetypeList(self, source_mimetype):
+        """
+          Returns a list of mimetypes that can be used as target for
+          `source_mimetype` conversion.
+        """
+
+        # clean up mimetype from its useless characters
+        source_mimetype = parseContentType(source_mimetype)
+        source_mimetype = ";".join([source_mimetype.gettype()] + source_mimetype.getplist())
+
+        # fill dict that will contain all possible conversion for each mimetype
+        input_output_dict = {} # {"application/pdf": set(["text/html", "application/msword", ...])}
+        for obj in self.objectValues():
+            for input_ in obj.inputs:
+                if input_ in input_output_dict:
+                    input_output_dict[input_].add(obj.output)
+                else:
+                    input_output_dict[input_] = set([obj.output])
+
+        # browse mimetypes to fill result_set of available target mimetypes
+        result_set = set([source_mimetype])
+        browsing_list = [source_mimetype]
+        input_output_items = input_output_dict.items()
+        while len(browsing_list):
+            browsing_mimetype = browsing_list.pop()
+            for mimetype, output_mimetype_set in input_output_items:
+                if (browsing_mimetype == mimetype or
+                    (mimetype.endswith("/*") and
+                     browsing_mimetype[:len(mimetype[:-1])] == mimetype[:-1])
+                        ):
+                    for output_mimetype in output_mimetype_set:
+                        if output_mimetype not in result_set:
+                            result_set.add(output_mimetype)
+                            browsing_list.append(output_mimetype)
+
+        result_set.remove(source_mimetype)
+        return list(result_set)
+
 InitializeClass(TransformTool)
 registerToolInterface('portal_transforms', IPortalTransformsTool)

product/PortalTransforms/utils.py

@@ -2,6 +2,9 @@
 """some common utilities
 """
 
+import mimetools
+import cStringIO
+
 class TransformException(Exception):
     pass
 
@@ -25,3 +28,18 @@ def safeToInt(value):
         return int(value)
     except (TypeError, ValueError):
         return 0
+
+def parseContentType(content_type):
+  """Parses `text/plain;charset="utf-8"` to a mimetools.Message object.
+
+  Note: Content type or MIME type are built like `maintype/subtype[;params]`.
+
+      parsed_content_type = parseContentType('text/plain;charset="utf-8"')
+      parsed_content_type.gettype()  -> 'text/plain'
+      parsed_content_type.getmaintype()  -> 'text'
+      parsed_content_type.getsubtype()  -> 'plain'
+      parsed_content_type.getplist()  -> 'charset="utf-8"'
+      parsed_content_type.getparam('charset')  -> 'utf-8'
+      parsed_content_type.typeheader  -> 'text/plain;charset="utf-8"'
+  """
+  return mimetools.Message(cStringIO.StringIO("Content-Type:" + content_type.replace("\r\n", "\r\n\t")))