<?php

/**
 * contains only class Dao
 *
 * @version 0.2
 * @author Artem Bykov <earthworm@i.ua>
 */

/**
 * Data Access Object class, works with database
 *
 * Connects to DB, can execute prepared statements
 */
class Dao
{
    /**
     * @var PDO DBH variable
     */
    private $db;

    /**
     * @var string server path
     */
    private $db_host;

    /**
     * @var string username
     */
    private $db_user;

    /**
     * @var string password
     */
    private $db_pass;

    /**
     * @var string data base name
     */
    private $db_name;

    /**
     * @var boolean
     */
    private $connected = false;

    /**
     * Constructor
     *
     * @param string $db_user Data Base username
     * @param string $db_pass Data Base user's password
     * @param string $db_name Data Base name
     * @param string $db_host Data Base server path
     */
    public function __construct(
    $db_user = 'root', $db_pass = '', $db_name = 'project222', $db_host = 'localhost'
    ) {
        $this->db_host = $db_host;
        $this->db_user = $db_user;
        $this->db_pass = $db_pass;
        $this->db_name = $db_name;

        $this->connect();
    }

    /**
     * Destructor
     *
     * Calls disconnect() method which unsets DBH variable
     */
    public function __destruct()
    {
        $this->disconnect();
    }

    /**
     * Connect method
     *
     * Creates PHP Data Object
     * Default server name, path, username, password
     *
     * @return boolean | string exception message
     */
    private function connect()
    {
        if (!$this->connected) {

            /**
             * try to connect to DB server on my localhost
             * 'mysql:host=localhost;dbname=project222', root, ''
             */
            try {
                $this->db = new PDO(
                        'mysql:host='.$this->db_host.';dbname='.$this->db_name, $this->db_user, $this->db_pass
                );

                $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                /**
                 * if not error cathed, must be connected already
                 */
                $this->connected = true;
                return true;
            } catch (PDOException $e) {
                return $e->getMessage();
            }
        } else {
            return true;
        }
    }

    /**
     * Disconnect function
     *
     * Unsets PDO variable
     *
     * @return void
     */
    private function disconnect()
    {
        if ($this->connected) {
            unset($this->db);
            $this->connected = false;
        }
    }

    /**
     * Executes query
     *
     * @deprecated since version 0.2
     *
     * @todo ненужная функция. это всё можно сделать настройкой PDO. то же самое и про другие подобные функции из этого класса. посмотри, как настраивается pdo
     * @param string $sql MySQL query
     * @return boolean
     */
    public function executeQuery($sql)
    {
        $raw_result = $this->db->query($sql);
        if (!$raw_result) {
            die('DB Access error: ' . $this->db->errorInfo());
        }
        return true;
    }

    /**
     * Executes query and returns array
     *
     * @deprecated since version 0.2
     *
     * @param string $sql MySQL query
     * @return array string[][]
     */
    public function selectQuery($sql)
    {
        $raw_result = $this->db->query($sql);
        if (!$raw_result) {
            die('DB Access error: ' . $this->db->errorInfo());
        }
        return $raw_result->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Prepared select
     *
     * Executes prepared statement with arguments
     * returns associated array
     *
     * @param string $sql Prepared MySQL statment
     * @param array $args arguments to execute with плохое название
     * @return array string[][]
     */
    public function preparedSelect($sql, $args)
    {
        $stmt = $this->db->prepare($sql);

        foreach ($args as $key => $value) {
            $stmt->bindValue($key, $value);
        }
        $stmt->execute();

        if (!$stmt) {
            die('DB Access error: ' . $this->db->errorInfo());
        }
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Prepared execute
     *
     * Executes prepared statement with arguments
     * returns true if success
     *
     * @param string $sql Prepared MySQL statment
     * @param array $args arguments to execute with
     * @return boolean
     */
    public function preparedExecute($sql, $args)
    {
        $stmt = $this->db->prepare($sql);

        foreach ($args as $key => $value) {
            $stmt->bindValue($key, $value);
        }
        $stmt->execute();

        if (!$stmt) {
            die('DB Access error: ' . $this->db->errorInfo());
        }
        return true;
    }
}