Include a link to view or edit the activity when a copy of a case activity is emailed to an assignee (or other contact)

Modify the default message template for "Cases - Send Copy of an Activity" (HTML and Text versions) to conditionally include links to View and Edit the activity record. Links should be added based on the following rules:

If recipient has permission to edit this activity
include view and edit activity links
else if recipient has permission to view this activity
include view activity link
else
don't include links
end if

Links should be added above the fields output and below conditionally included "Your Case Role" line.
For TEXT part:

{ts}Edit this activity{/ts}: $editLink
For HTML part:
<tr><td colspan="2"><a href="$editLink" title="{ts}

Edit this activity

{/ts}">{ts}Edit this activity{/ts}

</a></td></tr>

(same format for view links)

NOTE: For case activities, the links should also include the caseId parameter so the activity is viewed or edited in the context of it's case.
URL pattern for VIEW is:
http://.../civicrm/case/activity/view?reset=1&aid=546&cid=102&caseID=1

... for EDIT:
http://.../civicrm/case/activity?reset=1&cid=102&caseid=1&action=update&id=546