Velocity Test: XWiki Document tree

Background

In XWiki, documents are organized in spaces (the concept is somewhat similar to the directories on a file system; note that at this moment we cannot define spaces inside spaces, each space is top-level and contains only documents). The XWiki documents are identified by their fullName (composed of "<Space>.<PageName>") which is unique in the wiki. Each space should have a "WebHome" document (identified by "<Space>.WebHome").

A document hierarchy is defined in XWiki via the parent field of the document object. The parent field is normally the identifier (fullName) of another document in the wiki; note that it can be undefined (empty), and it may be invalid (pointing to a non-existing document).

Task
Write a velocity macro that displays all the documents in the wiki as a tree, where the hierarchy defined by the parent field. The documents whose parent field is undefined or invalid should be treated as follows:

• they are direct children of the "WebHome" document in their space if that document exists
• they are top-level nodes in the tree if they are the space's "WebHome" (their name is "<Space>.WebHome") or if the "WebHome" is missing