<?php
abstract class Util_Db_Adapter_Pdo_Abstract extends Util_Db_Adapter_Abstract
{

    /**
     * Default class name for a DB statement.
     *
     * @var string
     */
    protected $_defaultStmtClass = 'Util_Db_Statement_Pdo';

    /**
     * Creates a PDO DSN for the adapter from $this->_config settings.
     *
     * @return string
     */
    protected function _dsn()
    {
        // baseline of DSN parts
        $dsn = $this->_config;

        // don't pass the username, password, charset, persistent and driver_options in the DSN
        unset($dsn['username']);
        unset($dsn['password']);
        unset($dsn['options']);
        unset($dsn['charset']);
        unset($dsn['persistent']);
        unset($dsn['driver_options']);

        // use all remaining parts in the DSN
        foreach ($dsn as $key => $val) {
            $dsn[$key] = "$key=$val";
        }

        return $this->_pdoType . ':' . implode(';', $dsn);
    }

    /**
     * Creates a PDO object and connects to the database.
     *
     * @return void
     * @throws Util_Db_Adapter_Exception
     */
    protected function _connect()
    {
        // if we already have a PDO object, no need to re-connect.
        if ($this->_connection) {
            
            // 2012/10/15 hf: 增加重新判断链接是否可用, 不可用则关闭MYSQL链接.
            if (! mysql_ping($this->_connection))
            {
                mysql_close($this->_connection);
            }
            else 
            {
                return;
            }
        }

        // get the dsn first, because some adapters alter the $_pdoType
        $dsn = $this->_dsn();

        // check for PDO extension
        if (!extension_loaded('pdo')) {
            /**
             * @see Util_Db_Adapter_Exception
             */
            // require_once 'Util/Db/Adapter/Exception.php';
            throw new Util_Db_Adapter_Exception('The PDO extension is required for this adapter but the extension is not loaded');
        }

        // check the PDO driver is available
        if (!in_array($this->_pdoType, PDO::getAvailableDrivers())) {
            /**
             * @see Util_Db_Adapter_Exception
             */
            // require_once 'Util/Db/Adapter/Exception.php';
            throw new Util_Db_Adapter_Exception('The ' . $this->_pdoType . ' driver is not currently installed');
        }

        // create PDO connection
        $q = $this->_profiler->queryStart('connect', Util_Db_Profiler::CONNECT);

        // add the persistence flag if we find it in our config array
        if (isset($this->_config['persistent']) && ($this->_config['persistent'] == true)) {
            $this->_config['driver_options'][PDO::ATTR_PERSISTENT] = true;
        }

        try {
            $this->_connection = new PDO(
                $dsn,
                $this->_config['username'],
                $this->_config['password'],
                $this->_config['driver_options']
            );

            $this->_profiler->queryEnd($q);

            // set the PDO connection to perform case-folding on array keys, or not
            $this->_connection->setAttribute(PDO::ATTR_CASE, $this->_caseFolding);

            // always use exceptions.
            $this->_connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        } catch (PDOException $e) {
            /**
             * @see Util_Db_Adapter_Exception
             */
            // require_once 'Util/Db/Adapter/Exception.php';
            throw new Util_Db_Adapter_Exception($e->getMessage(), $e->getCode(), $e);
        }

    }

    /**
     * Test if a connection is active
     *
     * @return boolean
     */
    public function isConnected()
    {
        return ((bool) ($this->_connection instanceof PDO));
    }

    /**
     * Force the connection to close.
     *
     * @return void
     */
    public function closeConnection()
    {
        $this->_connection = null;
    }

    /**
     * Prepares an SQL statement.
     *
     * @param string $sql The SQL statement with placeholders.
     * @param array $bind An array of data to bind to the placeholders.
     * @return PDOStatement
     */
    public function prepare($sql)
    {
        $this->_connect();
        $stmtClass = $this->_defaultStmtClass;
        $stmt = new $stmtClass($this, $sql);
        $stmt->setFetchMode($this->_fetchMode);
        return $stmt;
    }

    /**
     * Gets the last ID generated automatically by an IDENTITY/AUTOINCREMENT column.
     *
     * As a convention, on RDBMS brands that support sequences
     * (e.g. Oracle, PostgreSQL, DB2), this method forms the name of a sequence
     * from the arguments and returns the last id generated by that sequence.
     * On RDBMS brands that support IDENTITY/AUTOINCREMENT columns, this method
     * returns the last value generated for such a column, and the table name
     * argument is disregarded.
     *
     * On RDBMS brands that don't support sequences, $tableName and $primaryKey
     * are ignored.
     *
     * @param string $tableName   OPTIONAL Name of table.
     * @param string $primaryKey  OPTIONAL Name of primary key column.
     * @return string
     */
    public function lastInsertId($tableName = null, $primaryKey = null)
    {
        $this->_connect();
        return $this->_connection->lastInsertId();
    }

    /**
     * Special handling for PDO query().
     * All bind parameter names must begin with ':'
     *
     * @param string|Util_Db_Select $sql The SQL statement with placeholders.
     * @param array $bind An array of data to bind to the placeholders.
     * @return Util_Db_Statement_Pdo
     * @throws Util_Db_Adapter_Exception To re-throw PDOException.
     */
    public function query($sql, $bind = array())
    {
        if (empty($bind) && $sql instanceof Util_Db_Select) {
            $bind = $sql->getBind();
        }

        if (is_array($bind)) {
            foreach ($bind as $name => $value) {
                if (!is_int($name) && !preg_match('/^:/', $name)) {
                    $newName = ":$name";
                    unset($bind[$name]);
                    $bind[$newName] = $value;
                }
            }
        }

        try {
            return parent::query($sql, $bind);
        } catch (PDOException $e) {
            /**
             * @see Util_Db_Statement_Exception
             */
            // require_once 'Util/Db/Statement/Exception.php';
            throw new Util_Db_Statement_Exception($e->getMessage(), $e->getCode(), $e);
        }
    }

    /**
     * Executes an SQL statement and return the number of affected rows
     *
     * @param  mixed  $sql  The SQL statement with placeholders.
     *                      May be a string or Util_Db_Select.
     * @return integer      Number of rows that were modified
     *                      or deleted by the SQL statement
     */
    public function exec($sql)
    {
        if ($sql instanceof Util_Db_Select) {
            $sql = $sql->assemble();
        }

        try {
            $affected = $this->getConnection()->exec($sql);

            if ($affected === false) {
                $errorInfo = $this->getConnection()->errorInfo();
                /**
                 * @see Util_Db_Adapter_Exception
                 */
                // require_once 'Util/Db/Adapter/Exception.php';
                throw new Util_Db_Adapter_Exception($errorInfo[2]);
            }

            return $affected;
        } catch (PDOException $e) {
            /**
             * @see Util_Db_Adapter_Exception
             */
            // require_once 'Util/Db/Adapter/Exception.php';
            throw new Util_Db_Adapter_Exception($e->getMessage(), $e->getCode(), $e);
        }
    }

    /**
     * Quote a raw string.
     *
     * @param string $value     Raw string
     * @return string           Quoted string
     */
    protected function _quote($value)
    {
        if (is_int($value) || is_float($value)) {
            return $value;
        }
        $this->_connect();
        return $this->_connection->quote($value);
    }

    /**
     * Begin a transaction.
     */
    protected function _beginTransaction()
    {
        $this->_connect();
        $this->_connection->beginTransaction();
    }

    /**
     * Commit a transaction.
     */
    protected function _commit()
    {
        $this->_connect();
        $this->_connection->commit();
    }

    /**
     * Roll-back a transaction.
     */
    protected function _rollBack() {
        $this->_connect();
        $this->_connection->rollBack();
    }

    /**
     * Set the PDO fetch mode.
     *
     * @todo Support FETCH_CLASS and FETCH_INTO.
     *
     * @param int $mode A PDO fetch mode.
     * @return void
     * @throws Util_Db_Adapter_Exception
     */
    public function setFetchMode($mode)
    {
        //check for PDO extension
        if (!extension_loaded('pdo')) {
            /**
             * @see Util_Db_Adapter_Exception
             */
            // require_once 'Util/Db/Adapter/Exception.php';
            throw new Util_Db_Adapter_Exception('The PDO extension is required for this adapter but the extension is not loaded');
        }
        switch ($mode) {
            case PDO::FETCH_LAZY:
            case PDO::FETCH_ASSOC:
            case PDO::FETCH_NUM:
            case PDO::FETCH_BOTH:
            case PDO::FETCH_NAMED:
            case PDO::FETCH_OBJ:
                $this->_fetchMode = $mode;
                break;
            default:
                /**
                 * @see Util_Db_Adapter_Exception
                 */
                // require_once 'Util/Db/Adapter/Exception.php';
                throw new Util_Db_Adapter_Exception("Invalid fetch mode '$mode' specified");
                break;
        }
    }

    /**
     * Check if the adapter supports real SQL parameters.
     *
     * @param string $type 'positional' or 'named'
     * @return bool
     */
    public function supportsParameters($type)
    {
        switch ($type) {
            case 'positional':
            case 'named':
            default:
                return true;
        }
    }

    /**
     * Retrieve server version in PHP style
     *
     * @return string
     */
    public function getServerVersion()
    {
        $this->_connect();
        try {
            $version = $this->_connection->getAttribute(PDO::ATTR_SERVER_VERSION);
        } catch (PDOException $e) {
            // In case of the driver doesn't support getting attributes
            return null;
        }
        $matches = null;
        if (preg_match('/((?:[0-9]{1,2}\.){1,3}[0-9]{1,2})/', $version, $matches)) {
            return $matches[1];
        } else {
            return null;
        }
    }
}