task: Implement edit of task thread

This fixes an issue where, for task threads, if an agent has the thread edit
permission, the agent was neither able to edit his or her own entries, nor the
entries of other agents.

include/class.task.php

@@ -204,8 +204,24 @@ class TaskModel extends VerySimpleModel {
         return $this->setFlag(self::ISOPEN);
     }
 
-    function isAssigned() {
-        return ($this->isOpen() && ($this->getStaffId() || $this->getTeamId()));
+    function isAssigned($to=null) {
+        if (!$this->isOpen())
+            return false;
+
+        if (is_null($to))
+            return ($this->getStaffId() || $this->getTeamId());
+
+        switch (true) {
+        case $to instanceof Staff:
+            return ($to->getId() == $this->getStaffId() ||
+                    $to->isTeamMember($this->getTeamId()));
+            break;
+        case $to instanceof Team:
+            return ($to->getId() == $this->getTeamId());
+            break;
+        }
+
+        return false;
     }
 
     function isOverdue() {

include/class.thread_actions.php

@@ -138,6 +138,13 @@ class TEA_EditThreadEntry extends ThreadEntryAction {
                 && ($role = $thisstaff->getRole($T->getDeptId(), $T->isAssigned($thisstaff)))
                 && $role->hasPerm(ThreadEntry::PERM_EDIT)
             )
+            || ($T instanceof Task
+                && $T->getDept()->getManagerId() == $thisstaff->getId()
+            )
+            || ($T instanceof Task
+                && ($role = $thisstaff->getRole($T->getDeptId(), $T->isAssigned($thisstaff)))
+                && $role->hasPerm(ThreadEntry::PERM_EDIT)
+            )
         );
     }