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<?php
class Db {
private static ?Db $instance = null;
private ?PDO $pdo = null;
function __construct() {
ORM::configure(self::get_dsn());
ORM::configure('username', Config::get(Config::DB_USER));
ORM::configure('password', Config::get(Config::DB_PASS));
ORM::configure('return_result_sets', true);
}
/**
* @param int $delta adjust generated timestamp by this value in seconds (either positive or negative)
* @return string
*/
static function NOW(int $delta = 0): string {
return date("Y-m-d H:i:s", time() + $delta);
}
private function __clone() {
//
}
public static function get_dsn(): string {
$db_port = Config::get(Config::DB_PORT) ? ';port=' . Config::get(Config::DB_PORT) : '';
$db_host = Config::get(Config::DB_HOST) ? ';host=' . Config::get(Config::DB_HOST) : '';
return Config::get(Config::DB_TYPE) . ':dbname=' . Config::get(Config::DB_NAME) . $db_host . $db_port;
}
// this really shouldn't be used unless a separate PDO connection is needed
// normal usage is Db::pdo()->prepare(...) etc
public function pdo_connect() : PDO {
try {
$pdo = new PDO(self::get_dsn(),
Config::get(Config::DB_USER),
Config::get(Config::DB_PASS));
} catch (Exception $e) {
print "<pre>Exception while creating PDO object:" . $e->getMessage() . "</pre>";
exit(101);
}
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->query("set client_encoding = 'UTF-8'");
$pdo->query("set datestyle = 'ISO, european'");
$pdo->query("set TIME ZONE 0");
$pdo->query("set cpu_tuple_cost = 0.5");
return $pdo;
}
public static function instance() : Db {
if (self::$instance == null)
self::$instance = new self();
return self::$instance;
}
public static function pdo() : PDO {
if (self::$instance == null)
self::$instance = new self();
if (empty(self::$instance->pdo)) {
self::$instance->pdo = self::$instance->pdo_connect();
}
return self::$instance->pdo;
}
public static function sql_random_function(): string {
return "RANDOM()";
}
/**
* Helper to build a query part comparing a field against a past datetime (determined by "$now - $some_interval")
*
* The example below could be read as "last_digest_sent is older than 1 day ago".
* ```php
* Db::past_comparison_qpart('last_digest_sent', '<', 1, 'day');
* ```
*
* @todo validate value of $unit and fail if invalid (or massage if practical)?
* @link https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-INTERVAL-INPUT
* @param string $field the table field being checked
* @param '<'|'>'|'<='|'>='|'=' $operator the comparison operator
* @param positive-int $quantity the amount of $unit
* @param 'year'|'month'|'week'|'day'|'hour'|'minute'|'second' $unit the unit of time for $quantity (see links for more info)
* @return string the query part string
*/
static function past_comparison_qpart(string $field, string $operator, int $quantity, string $unit): string {
return "$field $operator NOW() - INTERVAL '$quantity $unit' ";
}
}
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