<?php

class DBConnectionFailure extends Exception {}

class DB extends PDO {
    function __construct() {
        $dsn = 'mysql:dbname=' . DBConfig::DBNAME . ';host=' . DBConfig::HOST;
        try {
            parent::__construct($dsn, DBConfig::USER, DBConfig::PASSWORD);
        }
        catch (PDOException $e) {
            throw new DBConnectionFailure();
        }
        $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $this->exec('SET NAMES ' . DBConfig::CHARSET);
    }

    static function i() {
        static $instance;
        if (!$instance) {
            $instance = new self;
        }
        return $instance;
    }

    function quoteIndent($str) {
        return '`' . str_replace('`', '``', $str) . '`';
    }

    function getFullTableName($table) {
        return $this->quoteIndent(DBConfig::TABLE_PREFIX . $table);
    }

    function pQuery($sql, $params = null) {
        // подставляем преффиксы таблицам
        $sql = str_replace('?_', DBConfig::TABLE_PREFIX, $sql);
        $stmt = $this->prepare($sql);
        $stmt->execute($params);
        return $stmt;
    }

    function single() {
        $args = func_get_args();
        $stmt = call_user_func_array(array($this, 'pQuery'), $args);
        return $stmt->fetchColumn();
    }

    function row() {
        $args = func_get_args();
        $stmt = call_user_func_array(array($this, 'pQuery'), $args);
        return $stmt->fetch();
    }

    function rows() {
        $args = func_get_args();
        $stmt = call_user_func_array(array($this, 'pQuery'), $args);
        return $stmt->fetchAll();
    }

    function assoc() {
        $args = func_get_args();
        $stmt = call_user_func_array(array($this, 'pQuery'), $args);
        $res = $stmt->fetchAll(PDO::FETCH_NUM);
        if (!is_array($res)) {
            return $res;
        }
        $ret = array();
        $total = count($res);
        for ($i = 0; $i < $total; ++$i) {
            $ret[$res[$i][0]] = $res[$i][1];
        }
        return $ret;
    }

    function insert($table, $data) {
        $sql = 'INSERT INTO' . $this->getFullTableName($table);
        $values = array_values($data);
        if ($values != $data) {
            $keys = array_keys($data);
            $sql .= '(' . implode(',', array_map(array($this, 'quoteIndent'), $keys)) . ')';
        }
        $sql .= 'VALUES(' . implode(',', array_fill(0, count($data), '?')) . ')';
        $this->pQuery($sql, $values);
        return $this->lastInsertId();
    }

    function update($table, $id, $data) {
        $sql = 'UPDATE' . $this->getFullTableName($table) . ' SET ';
        $temp = array();
        foreach (array_keys($data) as $v) {
            $temp[] = $this->quoteIndent($v) . '=?';
        }
        $sql .= implode(',', $temp) . 'WHERE id=' . intval($id);

        $stmt = $this->pQuery($sql, array_values($data));
        return $stmt->rowCount();
    }

    function delete($table, $id) {
        $sql = 'DELETE FROM' . $this->getFullTableName($table) . ' WHERE id=' . intval($id);
        $stmt = $this->pQuery($sql);
        return $stmt->rowCount();
    }
}