<?php
// Applies the configured application timezone to PHP, and exposes the matching
// UTC offset so the database session can be pinned to the same zone.
//
// config.php has always defined $time_zone ("Asia/Bangkok"), but nothing ever
// called date_default_timezone_set() with it. PHP therefore ran on its ini
// default (UTC on this stack) while MySQL NOW() ran on the database server's
// zone (Bangkok). Every timestamp written from PHP — stock movement `date`
// above all — was stored 7 hours behind the real wall clock, so a stock-in
// created at 14:02 was listed as 07:02.
//
// Loaded from dbconn.php (covers every API engine, which is where writes
// happen) and from include_header.php (covers the rendered pages).

if (!defined('APP_TIMEZONE')) {

    $app_tz = $GLOBALS['time_zone'] ?? 'Asia/Bangkok';

    // An unknown identifier would leave PHP on UTC and silently reintroduce the
    // skew, so fall back to the documented project zone instead.
    try {
        $tz = new DateTimeZone($app_tz);
    } catch (Exception $e) {
        $app_tz = 'Asia/Bangkok';
        $tz     = new DateTimeZone($app_tz);
    }

    date_default_timezone_set($app_tz);
    define('APP_TIMEZONE', $app_tz);

    // "+07:00" — the form MySQL accepts without its named-timezone tables
    // having been loaded, which is the usual case on a stock install.
    $offset_seconds = $tz->getOffset(new DateTime('now', $tz));
    define('APP_TIMEZONE_OFFSET', sprintf(
        '%s%02d:%02d',
        $offset_seconds < 0 ? '-' : '+',
        intdiv(abs($offset_seconds), 3600),
        intdiv(abs($offset_seconds) % 3600, 60)
    ));
}