Code editor like on wp?

Question

PHP

Hello.
Guys. Who can tell how to make a template editor (and not only. In terms of php and html).
That is:
For example, I open the edit.php page and select which file (php or html) I want to edit.
And I click on index.php and change the content of the code.
Such an example is implemented on WordPress (wp) and dle.
How to implement this or are there already ready-made scripts? Or the standard php methods can allow this to be done?

Answer 1

www.tinymce.com
https://codemirror.net/ace.c9.io/#nav=about
_

Answer 2

- Read the file and output the content to the form with textarea.
- Edit content.
- Submit the form, read the contents of the textarea in the function that receives the POST request from the form, and overwrite the file.
And that two functions, the elementary.