PHP & MySQL checker

checker.php

<?php

/**
 * Class Service_Checker
 * @author Mostafa Soufi
 */
class Service_Checker {
	/**
	 * @var array
	 */
	public $error_message = array();

	/**
	 * Service_Checker constructor.
	 *
	 * @param array $config
	 *
	 * @internal param array $db_config
	 */
	public function __construct( $config = array() ) {
		// Check php
		$this->php_checker();

		// Check MySQL
		$this->mysql_checker( $config );
	}

	/**
	 * PHP checker
	 */
	public function php_checker() {
		if ( ! function_exists( 'phpinfo' ) ) {
			$this->error_message[] = 'PHP is not running.';
		}
	}

	/**
	 * MySQL checker
	 *
	 * @param $config
	 *
	 * @internal param $host
	 * @internal param $username
	 * @internal param $password
	 */
	public function mysql_checker( $config ) {
		mysqli_report( MYSQLI_REPORT_STRICT );

		if ( ! function_exists( 'mysqli_connect' ) ) {
			$this->error_message[] = 'MySQLi is not running.';

			return;
		}

		try {
			$link = mysqli_connect( $config['host'], $config['username'], $config['password'], $config['db_name'], $config['port'] );

			if ( mysqli_connect_errno() ) {
				$this->error_message[] = "Mysql Error: " . mysqli_connect_error();

				return;
			}

			if ( ! mysqli_query( $link, "SHOW VARIABLES" ) === true ) {
				$this->error_message[] = 'MySQLi is not running.';

				return;
			}

			// Create table
			$check_table = mysqli_query( $link, "SHOW TABLES LIKE '" . $config['table_name'] . "'" );
			if ( ! $check_table->num_rows ) {
				// Create table
				mysqli_query( $link, "CREATE TABLE `" . $config['table_name'] . "` ( `ID` INT NOT NULL AUTO_INCREMENT , `meta_key` VARCHAR(255) NOT NULL , `value` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL , PRIMARY KEY (`ID`)) ENGINE = InnoDB CHARACTER SET utf8 COLLATE utf8_general_ci;" );
			}

			// Check insert
			$check_insert = mysqli_query( $link, "INSERT INTO `" . $config['table_name'] . "` (`ID`, `meta_key`, `value`) VALUES (NULL, 'name', 'michael');" );
			if ( ! $check_insert ) {
				$this->error_message[] = "Can't insert to database.";

				return;
			}

			// Check delete
			$check_delete = mysqli_query( $link, "DELETE FROM `" . $config['table_name'] . "`" );
			if ( ! $check_delete ) {
				$this->error_message[] = "Can't delete data from database.";

				return;
			}

		} catch ( Exception $e ) {
			$this->error_message[] = 'Mysql Error: ' . $e->getMessage();
		}
	}

	/**
	 * Do check
	 */
	public function check() {
		if ( $this->error_message ) {
			echo $this->json_response( $this->error_message, 300 );
		} else {
			echo $this->json_response( 'Everything is good!' );
		}
	}

	/**
	 * @param null $message
	 * @param int $code
	 *
	 * @return string
	 */
	private function json_response( $message = null, $code = 200 ) {
		// clear the old headers
		header_remove();

		// set the actual code
		http_response_code( $code );

		// set the header to make sure cache is forced
		header( "Cache-Control: no-transform,public,max-age=300,s-maxage=900" );

		// treat this as json
		header( 'Content-Type: application/json' );

		// return the encoded json
		return json_encode( array(
			'status'   => $code < 300, // success or not?
			'messages' => $message
		) );
	}
}

$db_config       = array(
	'host'       => 'localhost',
	'username'   => 'root',
	'password'   => '',
	'db_name'    => 'checker',
	'table_name' => 'checker',
	'port'       => 3306,
);
$service_checker = new Service_Checker( $db_config );
$service_checker->check();