How convert text to TOC with use pattern Composite

Need make a TOC from next example String:
Input

`#` Sport
common text  
`##` Tennis  
`###` Table
`###` Ping Pong     
commontext  
`#` Dance

Output

 Sport 1  
 common text  
  Tennis 1.1  
   Table 1.1.1  
   Ping Pong 1.1.2  
   commontext  
 Dance 2
 etc

My one solution via Map and recursive substring Pastebin - https://pastebin.com/DqcsGKTu. But i think its may work with Composite design pattern cause its looks like tree. Someone have idea for it? First try to use tree structure https://pastebin.com/u54MQ88x - clien and logic, https://pastebin.com/fh4yVKXM - tree model. It doesnt work correctly cause printing Dance 1.2 not Dance 2.