<?php


/* __ Defines _____________________________________________________________ */

require_once('config.php');

define('DATABASE_BACKEND', 'MySQL');


/* __ MySQL implementation ________________________________________________ */


/* 
 * 
 */
function ttdb_connect(&$connection)
{
    
    $connection = mysql_connect(DB_SERVER, DB_USER, DB_PASS);
    
    //echo "[connect: $connection] ";
    
    if (!mysql_select_db(DB_DATABASE)) 
        return false;   
    
    return true;
    
}

/* 
 * 
 */
function ttdb_close($connection)
{
    //echo "[close: $connection] ";
    if ($connection) 
        return mysql_close($connection);
}

/* 
 * 
 */
function ttdb_beginTransaction($connection)
{
    
    if ($connection) 
        return mysql_query("begin", $connection);
}

/* 
 * 
 */
function ttdb_commitTransaction($connection)
{
    if ($connection) 
        return mysql_query("commit", $connection);
}

/* 
 * 
 */
function ttdb_rollbackTransaction($connection)
{
    if ($connection) 
        return mysql_query("rollback", $connection);
}

/* 
 * 
 */
function ttdb_execQuery($connection, $query)
{
    //echo "[$query] ";
    
    $res = mysql_query($query, $connection);
    return $res; 
}

/* 
 * Params: resource is the query to get numrows from.
 */
function ttdb_getNumRows($resource)
{
    return mysql_num_rows($resource);
}

/* 
 * Params: resource is the query to get fields from.
 */
function ttdb_getNumFields($resource)
{
    return mysql_num_fields($resource);
}


/* 
 * Returns: an array of fields with the current row (field names are key values)
 */
function ttdb_getArray($resource)
{    
    return mysql_fetch_assoc($resource);    
}

/* 
 * Returns: an array of fields with the given row 
 * NOTE: this function is not implemented in every layer, and thus, not portable!!
 */
function ttdb_getArrayEx($resource, $rowNum)
{
    mysql_data_seek($resource, $rowNum);
    return mysql_fetch_assoc($resource);    
}


/* 
 * Returns: 
 */
function ttdb_getFieldName($resource, $field)
{
    return mysql_field_name($resource, $field);
}


/* 
 * Returns: 
 */
function ttdb_getFieldType($resource, $field)
{
    return mysql_field_type($resource, $field);
}


/*
 * Note: this one is portable between versions, as only uses calls
 *  from the abstraction layer.
 */
function ttdb_getSequenceValue($connection, $table)
{

    // Get current value from the DB

    $res = ttdb_execQuery($connection, "SELECT * FROM sequences WHERE stable = '$table'");    

    // This uses the new approach for retrieving records !!
    $fields = ttdb_getArray($res);
    
    if (!is_array($fields)) 
        return 0;           // Error, most likely table name didn´t exist 

    $currValue = $fields['inextval'];

    
    // Check correctness of the value
    
    if ($currValue > 0) 
        $result = $currValue;
    else 
        return 0;           // Error, should always be 1 or more

    
    // Increment for the next time and update in the sequences table
        
    $currValue++;
    
    $res = ttdb_execQuery($connection, "UPDATE sequences SET inextval = $currValue WHERE ".
            "stable = '$table'");
            
    if ($res == false) 
        return 0;         // Error updating
    else
        return $result;

}

?>