# Software architecture

## Program flow

`init.php`
: Initializes common values

`router.php`
: Receives every external HTTP request from the web server, executes actions required in any case, executes matching code in `pg-act` if appropriate, and calls `view.php` either way.

`pg-act/`
: Executed when a form is submitted: checks that every parameter is valid and secure, then executes the feature of the page according to the parameters.

`view.php`
: Displays global HTML and includes matching file from `pg-view`.

`pg-view/`
: Displays the main page content (notably HTML forms), may sometimes display form output passed through the `$data` array.

The `output` function is used to return success or error messages and stop processing of the request.

## Other components

`fn/`
: Functions, grouped by concerned service

`jobs/`
: CLI scripts ; should be run as the same user as the rest of the program (e.g. `sudo -u servnest php /srv/servnest/core/jobs/something.php`)

`sftpgo-auth.php`
: When someone tries to log in over SFTP, SFTPGo sends username and password to this script, which queries the database and replies whether authentication succeeded or not.

`css/`
: Each `.css` file in this directory is declared in every page.

`db/`
: SQlite database, the only directory writable by the program

`locales/`
: Gettext translations, see [translation.md](translation.md)