Creating a regex for mongoose URI -

I am trying to figure out how to fix the peanut urine with regex. My current rezux is:

  ^ (mongodb: \ / 2}) (\ w *?): {0,1} (\ W *?) @ {0,1} (\ w +?): (\ D +) \ / (\ w +?)  

I should know that enter the username and password has been, ie

  mongodb: username: password @ Sthaniyhost: 27107 / mydatabasename  

so I required in the case are invalid:

  mongodb: // username: Sthaniyhost: 27107 / adfaeadf mongodb: // username: @ Loklh Trust: 27107 / adfaeadf mongodb: //: password @ localhost: 27107 / adfaeadf  

But these cases are valid:

  mongodb: // localhost: 27107 / mydatabasename mongodb: // @ localhost: 27107 / mydatabasename mongodb: // localhost: 27107 / mydatabasename mongodb: username: password @ Sthaniyhost: 27107 / mydatabasename   
 Any help would be appreciated 
 

  ^ (MongoDB: (: \ / {2}?)) ((\ W +?): (\ W +?) @ | ???? @) (\ W +): (\ d +) \ / (\ w +) $  

for clarification

for your final link, "mongodb : "Should be after" // "? Regex will match it in any way.