<?php

class dal {
    public $pdo;
    protected $queryCache = [];
    const FETCH_ALL = 1;
    const FETCH_ROW = 2;
    const FETCH_COLUMN = 4;
    // const D = 8;
    // const E = 16;
    // const F = 32;
    // const G = 64;
    // const H = 128;
    // const I = 256;
    // const J = 512;
    // const K = 1024;
    // const L = 2048;
    const FETCH_NUM = 4096;
    const FETCH_ASSOC = 8192;
    // const O = 16384;
    // const P = 32768;
    // const Q = 65536;
    // const R = 131072;
    // const S = 262144;
    // const T = 524288;
    // const U = 1048576;
    // const V = 2097152;
    // const W = 4194304;
    // const X = 8388608;
    // const Y = 16777216;
    // const Z = 33554432;
    const FETCH_BOTH = 12288; // 4096 | 8192

    public function __construct($dsn, $usr=null, $pswd=null, $args=null,
                                $charset='utf8')
    {
        try {
            $this->pdo = new PDO($dsn, $usr, $pswd, $args);
        }
        catch (PDOException $e) {
            die('Connection failed: ' . $e->getMessage());
        }

        $this->query("SET NAMES $charset");
    }

    public function query($query, array $params=null)
    {
        echo dump($query);
        $h = md5($query);
        // кешируем подготовленные выражения
        if (isset($this->queryCache[$h])) {
            echo 'Используем подготовленное выражение из кэша.<br>';
            $s = $this->queryCache[$h];
        }
        else {
            $s = $this->pdo->prepare($query);
            $this->queryCache[$h] = $s;
        }
        $s->execute($params);
        preg_match('/^\s*(\w+)/', $query, $m);
        $action = strtolower($m[1]);
        // var_dump($action);
        if ($action == 'insert') {
            return $this->lastInsertId();
        }
        if ($action == 'update' or $action == 'delete') {
            return $s->rowCount();
        }
        return $s;
    }

    public function get($query, array $params=null, $flags=self::FETCH_ALL)
    {
        $r = $this->query($query, $params);
        if ($flags & self::FETCH_ROW) {
            return $r->fetch();
        }
        if ($flags & self::FETCH_COLUMN) {
            return $r->fetchColumn();
        }
        return $r->fetchAll();
    }

    public function row($query, array $params=null, $add_flags=0)
    {
        return $this->get($query, $params, self::FETCH_ROW | $add_flagsPar);
    }

    public function column($query, array $params=null)
    {
        return $this->get($query, $params, self::FETCH_COLUMN);
    }

    public function count($table, $where=1, array $params=null)
    {
        return $this->column('SELECT COUNT(*) FROM ' .
                             $this->quoteid($table) . " WHERE $where",
                             $params);
    }

    public function insert($table, array $data)
    {
        $q = 'INSERT INTO ' . $this->quoteid($table);
        $fields = array_keys($data);
        $q .= ' (' .
              implode( ',', array_map([$this, 'quoteid'], $fields) ) .
              ') VALUES (';
        for ($i = 0, $c = count($fields); $i < $c; ++$i) {
            $q .= ($i ? ',' : '') . ':' . $fields[$i];
        }
        $q .= ')';
        return $this->query($q, $data);
    }

    public function update($table, array $data, $where=1, array $params=null)
    {
        is_null($params) and $params = [];
        $is_list_params = array_values($params) == $params;
        // var_dump($is_list_params);
        $params = array_merge($is_list_params ? array_values($data) : $data,
                              $params);
        $s = '';
        foreach ($data as $k => $v) {
            $s .= (strlen($s) ? ',' : '') . $this->quoteid($k) . '=' .
                  ($is_list_params ? '?' : ":$k");
        }
        // echo dump($params);
        return $this->query('UPDATE ' . $this->quoteid($table) .
                            " SET $s WHERE $where", $params);
    }

    public function delete($table, $where=1, array $params=null) {
        return $this->query('DELETE FROM ' . $this->quoteid($table) .
                            " WHERE $where", $params);
    }

    public function describe($table)
    {
        return $this->get( 'DESCRIBE ' . $this->quoteid($table) );
    }

    public function quoteid($s)
    {
        return '`' . str_replace('`', '``', $s) . '`';
    }

    public function lastInsertId()
    {
        return $this->pdo->lastInsertId();
    }
}

/* ---------------------------- 78 characters ----------------------------- */