从目录树php获取json对象

I have a file structure like the following:

-problems
 - folder1.1
  -folder1.2
   -inputFolder
    -file.txt1
    -file2.txt2
   -outputFolder
   -file.txt1
   -file2.txt2
 -folder1.2
-folder2

And I have to convert it into two json objects like this:

  problems = {
          name: "someNameChosenByMe",
          id: "someIdChosenByMe",
          tests: {
              input: [], // array of strings with contents from text files in input
              output: "" // string from files in output
          }

    }

And this also

tree = [
    {
      id          : "12" id of element from the other json
      parent      : "someDir" parent directory name
      text        : "someTextChosenByMe"
      icon        : "somethingChosenFromMe" 
    },
    {
      id          : "12" id of element from the other json
      parent      : "someDir" parent directory name
      text        : "someTextChosenByMe"
      icon        : "somethingChosenFromMe" 
    },
];

... and so on. Basiclly I need to get the content from input and output folders for the first json. And for the second i need the id of the element from the first json and the parent directory. I tried a bunch of things but I don't know what the approach to this is and should be.

$path = 'problems/';
$files = [];
$di = new RecursiveDirectoryIterator($path, RecursiveDirectoryIterator::SKIP_DOTS);
$it = new RecursiveIteratorIterator($di);

foreach ($it as $file) {
    if (pathinfo($file, PATHINFO_EXTENSION) == "txt")
        $files[] = $file;
}

This gives me all the possible file paths. But I don't know if I continue this way if it will be best. So what is the approach to this. I dont want any code, just what to do in general. I need the second json to use it for jstree.js. http://www.jstree.com/docs/json