<?php

/*
    This file is a part of myTinyTodo.
    (C) Copyright 2021,2022 Max Pozdeev <maxpozdeev@gmail.com>
    Licensed under the GNU GPL version 2 or any later. See file COPYRIGHT for details.
*/

class DBConnection
{
    protected static $instance;

    public static function init(Database_Abstract $instance) : Database_Abstract
    {
        self::$instance = $instance;
        return $instance;
    }

    public static function instance() : Database_Abstract
    {
        if (!isset(self::$instance)) {
            throw new Exception("DBConnection is not initialized");
        }
        return self::$instance;
    }

    public static function setTablePrefix($prefix)
    {
        $db = self::instance();
        $db->setPrefix($prefix);
    }
}

abstract class Database_Abstract
{
    protected static $readonlyProps = ['prefix', 'lastQuery'];

    /** @var string */
    protected $prefix = '';

    /** @var string */
    protected $lastQuery = '';

    abstract function connect($params);
    abstract function sq($query, $p = NULL);
    abstract function sqa($query, $p = NULL);
    abstract function dq($query, $p = NULL) : DatabaseResult_Abstract;
    abstract function ex($query, $p = NULL);
    abstract function affected();
    abstract function quote($s);
    abstract function quoteForLike($format, $s);
    abstract function lastInsertId($name = null);
    abstract function tableExists($table);
    abstract function tableFieldExists($table, $field): bool;

    function __get(string $propName) {
        if ( in_array($propName, self::$readonlyProps) ) {
            return $this->{$propName};
        }
        throw new Error("Attempt to read undefined property ". get_class($this). "::\$$propName");
    }

    function setPrefix(string $prefix) {
        if ($prefix != '' && !preg_match("/^[a-zA-Z0-9_]+$/", $prefix)) {
            throw new Exception("Incorrect table prefix");
        }
        $this->prefix = $prefix;
    }
}

abstract class DatabaseResult_Abstract
{
    abstract function fetchRow();
    abstract function fetchAssoc();
}