<?php
/**
 * This file contains the class that defines user defined functions for PDO library.
 * 
 * This file is for PHP 5.2.x or lesser. For PHP 5.3.x or later, functions.php is
 * loaded. PHP version is checked in the db.php and that will load the apropriate
 * one.
 * 
 * @package SQLite Integration
 * @author Kojima Toshiyasu
 *
 */

/**
 * This class defines user defined functions(UDFs) for PDO library.
 * 
 * These functions replace those used in the SQL statement with the PHP functions.
 * 
 * Usage:
 * 
 * <code>
 * new PDOSQLiteUDFS(ref_to_pdo_obj);
 * </code>
 * 
 * This automatically enables ref_to_pdo_obj to replace the function in the SQL statement
 * to the ones defined here.
 */
class PDOSQLiteUDFS {
	/**
	 * Constructor
	 * 
	 * Initialize the user defined functions to the PDO object with PDO::sqliteCreateFunction().
	 * 
	 * @param reference to PDO object $pdo
	 */
  public function __construct(&$pdo){
    foreach ($this->functions as $f=>$t) {
      $pdo->sqliteCreateFunction($f, array($this, $t));
    }
  }
	/**
	 * Array to associate MySQL function to the substituted one.
	 * 
	 * @var associative array
	 */
  private $functions = array(
      'month'          => 'month',
      'year'           => 'year',
      'day'            => 'day',
      'unix_timestamp' => 'unix_timestamp',
      'now'            => 'now',
      'char_length'    => 'char_length',
      'md5'            => 'md5',
      'curdate'        => 'curdate',
      'rand'           => 'rand',
      'substring'      => 'substring',
      'dayofmonth'     => 'day',
      'second'         => 'second',
      'minute'         => 'minute',
      'hour'           => 'hour',
      'date_format'    => 'dateformat',
      'from_unixtime'  => 'from_unixtime',
      'date_add'       => 'date_add',
      'date_sub'       => 'date_sub',
      'adddate'        => 'date_add',
      'subdate'        => 'date_sub',
      'localtime'      => 'now',
      'localtimestamp' => 'now',
      'isnull'         => 'isnull',
      'if'             => '_if',
      'regexpp'        => 'regexp',
      'concat'         => 'concat',
      'field'          => 'field',
      'log'            => 'log',
      'least'          => 'least',
  		'greatest'       => 'greatest',
      'get_lock'       => 'get_lock',
      'release_lock'   => 'release_lock',
      'ucase'          => 'ucase',
      'lcase'          => 'lcase',
      'inet_ntoa'      => 'inet_ntoa',
      'inet_aton'      => 'inet_aton',
      'datediff'       => 'datediff',
  		'locate'         => 'locate',
			'version'        => 'version'
  );
  /**
   * Method to extract the month value from the date.
   *
   * @param string representing the date formated as 0000-00-00.
   * @return string representing the number of the month between 1 and 12.
   */
  public function month($field){
    $t = strtotime($field);
    return date('n', $t);
  }
  /**
   * Method to extract the year value from the date.
   * 
   * @param string representing the date formated as 0000-00-00.
   * @return string representing the number of the year.
   */
  public function year($field){
    $t = strtotime($field);
    return date('Y', $t);
  }
  /**
   * Method to extract the day value from the date.
   * 
   * @param string representing the date formated as 0000-00-00.
   * @return string representing the number of the day of the month from 1 and 31.
   */
  public function day($field){
    $t = strtotime($field);
    return date('j', $t);
  }
  /**
   * Method to return the unix timestamp.
   * 
   * Used without an argument, it returns PHP time() function (total seconds passed
   * from '1970-01-01 00:00:00' GMT). Used with the argument, it changes the value
   * to the timestamp.
   * 
   * @param string representing the date formated as '0000-00-00 00:00:00'.
   * @return number of unsigned integer
   */
  public function unix_timestamp($field = null){
    return is_null($field) ? time() : strtotime($field);
  }
  /**
   * Method to emulate MySQL SECOND() function.
   * 
   * @param string representing the time formated as '00:00:00'.
   * @return number of unsigned integer
   */
  public function second($field){
    $t = strtotime($field);
    return intval( date("s", $t) );
  }
  /**
   * Method to emulate MySQL MINUTE() function.
   * 
   * @param string representing the time formated as '00:00:00'.
   * @return number of unsigned integer
   */
  public function minute($field){
    $t = strtotime($field);
    return  intval(date("i", $t));
  }
  /**
   * Method to emulate MySQL HOUR() function.
   * 
   * @param string representing the time formated as '00:00:00'.
   * @return number
   */
  public function hour($time){
    list($hours, $minutes, $seconds) = explode(":", $time);
    return intval($hours);
  }
  /**
   * Method to emulate MySQL FROM_UNIXTIME() function.
   * 
   * @param integer of unix timestamp
   * @param string to indicate the way of formatting(optional)
   * @return string formatted as '0000-00-00 00:00:00'.
   */
  public function from_unixtime($field, $format=null){
    // $field is a timestamp
    //convert to ISO time
    $date = date("Y-m-d H:i:s", $field);
    //now submit to dateformat

    return is_null($format) ? $date : $self->dateformat($date, $format);
  }
  /**
   * Method to emulate MySQL NOW() function.
   * 
   * @return string representing current time formatted as '0000-00-00 00:00:00'.
   */
  public function now(){
    return date("Y-m-d H:i:s");
  }
  /**
   * Method to emulate MySQL CURDATE() function.
   * 
   * @return string representing current time formatted as '0000-00-00'.
   */
  public function curdate() {
    return date("Y-m-d");
  }
  /**
   * Method to emulate MySQL CHAR_LENGTH() function.
   * 
   * @param string
   * @return unsigned integer for the length of the argument.
   */
  public function char_length($field){
    return strlen($field);
  }
  /**
   * Method to emulate MySQL MD5() function.
   * 
   * @param string
   * @return string of the md5 hash value of the argument.
   */
  public function md5($field){
    return md5($field);
  }
  /**
   * Method to emulate MySQL RAND() function.
   * 
   * SQLite does have a random generator, but it is called RANDOM() and returns random
   * number between -9223372036854775808 and +9223372036854775807. So we substitute it
   * with PHP random generator.
   * 
   * This function uses mt_rand() which is four times faster than rand() and returns
   * the random number between 0 and 1.
   * 
   * @return unsigned integer
   */
  public function rand(){
    return mt_rand(0,1);
  }
  /**
   * Method to emulate MySQL SUBSTRING() function.
   * 
   * This function rewrites the function name to SQLite compatible substr().
   * 
   * @param string $text
   * @param integer $pos representing the start point.
   * @param integer $len representing the length of the substring(optional).
   * @return string
   */
  public function substring($text, $pos, $len=null){
  	return "substr($text, $pos, $len)";
  }
  /**
   * Method to emulate MySQL DATEFORMAT() function.
   * 
   * @param string date formatted as '0000-00-00' or datetime as '0000-00-00 00:00:00'.
   * @param string $format
   * @return string formatted according to $format
   */
  public function dateformat($date, $format){
    $mysql_php_dateformats = array ( '%a' => 'D', '%b' => 'M', '%c' => 'n', '%D' => 'jS', '%d' => 'd', '%e' => 'j', '%H' => 'H', '%h' => 'h', '%I' => 'h', '%i' => 'i', '%j' => 'z', '%k' => 'G', '%l' => 'g', '%M' => 'F', '%m' => 'm', '%p' => 'A', '%r' => 'h:i:s A', '%S' => 's', '%s' => 's', '%T' => 'H:i:s', '%U' => 'W', '%u' => 'W', '%V' => 'W', '%v' => 'W', '%W' => 'l', '%w' => 'w', '%X' => 'Y', '%x' => 'o', '%Y' => 'Y', '%y' => 'y', );
    $t = strtotime($date);
    $format = strtr($format, $mysql_php_dateformats);
    $output =  date($format, $t);
    return $output;
  }
  /**
   * Method to emulate MySQL DATE_ADD() function.
   * 
   * This function adds the time value of $interval expression to $date.
   * $interval is a single quoted strings rewritten by SQLiteQueryDriver::rewrite_query().
   * It is calculated in the private function deriveInterval().
   * 
   * @param string $date representing the start date.
   * @param string $interval representing the expression of the time to add.
   * @return string date formated as '0000-00-00 00:00:00'.
   */
  public function date_add($date, $interval) {
    $interval = $this->deriveInterval($interval);
    switch (strtolower($date)) {
      case "curdate()":
        $objDate = new Datetime($this->curdate());
        $objDate->add(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d");
        break;
      case "now()":
        $objDate = new Datetime($this->now());
        $objDate->add(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d H:i:s");
        break;
      default:
        $objDate = new Datetime($date);
        $objDate->add(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d H:i:s");
    }
    return $returnval;
  }
  /**
   * Method to emulate MySQL DATE_SUB() function.
   * 
   * This function substracts the time value of $interval expression from $date.
   * $interval is a single quoted strings rewritten by SQLiteQueryDriver::rewrite_query().
   * It is calculated in the private function deriveInterval().
   * 
   * @param string $date representing the start date.
   * @param string $interval representing the expression of the time to substract.
   * @return string date formated as '0000-00-00 00:00:00'.
   */
  public function date_sub($date, $interval) {
    $interval = $this->deriveInterval($interval);
    switch (strtolower($date)) {
      case "curdate()":
        $objDate = new Datetime($this->curdate());
        $objDate->sub(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d");
        break;
      case "now()":
        $objDate = new Datetime($this->now());
        $objDate->sub(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d H:i:s");
        break;
      default:
        $objDate = new Datetime($date);
        $objDate->sub(new DateInterval($interval));
        $returnval = $objDate->format("Y-m-d H:i:s");
    }
    return $returnval;
  }
  /**
   * Method to calculate the interval time between two dates value.
   *
   * @access private
   * @param string $interval white space separated expression.
   * @return string representing the time to add or substract.
   */
	private function deriveInterval($interval){
		$interval = trim(substr(trim($interval), 8));
		$parts = explode(' ', $interval);
		foreach($parts as $part){
			if (!empty($part)){
				$_parts[] = $part;
			}
		}
		$type = strtolower(end($_parts));
		switch ($type){
			case "second":
			case "minute":
			case "hour":
			case "day":
			case "week":
			case "month":
			case "year":
        if (intval($_parts[0]) > 1){
          $type .= 's';
        }
        return "$_parts[0] $_parts[1]";
        break;
			case "minute_second":
        list($minutes, $seconds) = explode (':', $_parts[0]);
        $minutes = intval($minutes);
        $seconds = intval($seconds);
        $minutes = ($minutes > 1) ? "$minutes minutes" : "$minutes minute";
        $seconds = ($seconds > 1) ? "$seconds seconds" : "$seconds second";
        return "$minutes $seconds";
        break;
			
			case "hour_second":
        list($hours, $minutes, $seconds) = explode (':', $_parts[0]);
        $hours = intval($hours);
        $minutes = intval($minutes);
        $seconds = intval($seconds);
        $hours = ($hours > 1) ? "$hours hours" : "$hours hour";
        $minutes = ($minutes > 1) ? "$minutes minutes" : "$minutes minute";
        $seconds = ($seconds > 1) ? "$seconds seconds" : "$seconds second";
        return "$hours $minutes $seconds";
        break;
			case "hour_minute":
        list($hours, $minutes) = explode (':', $_parts[0]);
        $hours = intval($hours);
        $minutes = intval($minutes);
        $hours = ($hours > 1) ? "$hours hours" : "$hours hour";
        $minutes = ($minutes > 1) ? "$minutes minutes" : "$minutes minute";
        return "$hours $minutes";
        break;
			case "day_second":
        $days = intval($_parts[0]);
        list($hours, $minutes, $seconds) = explode (':', $_parts[1]);
        $hours = intval($hours);
        $minutes = intval($minutes);
        $seconds = intval($seconds);
        $days = $days > 1 ? "$days days" : "$days day";
        $hours = ($hours > 1) ? "$hours hours" : "$hours hour";
        $minutes = ($minutes > 1) ? "$minutes minutes" : "$minutes minute";
        $seconds = ($seconds > 1) ? "$seconds seconds" : "$seconds second";
        return "$days $hours $minutes $seconds";
        break;
			case "day_minute":
        $days = intval($_parts[0]);
        list($hours, $minutes) = explode (':', $_parts[1]);
        $hours = intval($hours);
        $minutes = intval($minutes);
        $days = $days > 1 ? "$days days" : "$days day";
        $hours = ($hours > 1) ? "$hours hours" : "$hours hour";
        $minutes = ($minutes > 1) ? "$minutes minutes" : "$minutes minute";
        return "$days $hours $minutes";
        break;	
			case "day_hour":
        $days = intval($_parts[0]);
        $hours = intval($_parts[1]);
        $days = $days > 1 ? "$days days" : "$days day";
        $hours = ($hours > 1) ? "$hours hours" : "$hours hour";
        return "$days $hours";
        break;	
			case "year_month":
        list($years, $months) = explode ('-', $_parts[0]);
        $years = intval($years);
        $months = intval($months);
        $years = ($years > 1) ? "$years years" : "$years year";
        $months = ($months > 1) ? "$months months": "$months month";
        return "$years $months";
        break;
      default:
        return false;
		}
	}
	/**
	 * Method to emulate MySQL DATE() function.
	 *
	 * @param string $date formatted as unix time.
	 * @return string formatted as '0000-00-00'.
	 */
  public function date($date){
    return date("Y-m-d", strtotime($date));
  }
  /**
   * Method to emulate MySQL ISNULL() function.
   *
   * This function returns true if the argument is null, and true if not.
   *
   * @param various types $field
   * @return boolean
   */
  public function isnull($field){
    return is_null($field);
  }
  /**
   * Method to emulate MySQL IF() function.
   *
   * As 'IF' is a reserved word for PHP, function name must be changed.
   *
   * @param unknonw $expression the statement to be evaluated as true or false.
   * @param unknown $true statement or value returned if $expression is true.
   * @param unknown $false statement or value returned if $expression is false.
   * @return unknown
   */
  public function _if($expression, $true, $false){
    return ($expression == true) ? $true : $false;
  }
  /**
   * Method to emulate MySQL REGEXP() function.
   *
   * @param string $field haystack
   * @param string $pattern: regular expression to match.
   * @return integer 1 if matched, 0 if not matched.
   */
  public function regexp($field, $pattern){
    $pattern = str_replace('/', '\/', $pattern);
    $pattern = "/" . $pattern ."/i";
    return preg_match ($pattern, $field);
  }
  /**
   * Method to emulate MySQL CONCAT() function.
   *
   * SQLite does have CONCAT() function, but it has a different syntax from MySQL.
   * So this function must be manipulated here.
   *
   * @param string
   * @return NULL if the argument is null | string conatenated if the argument is given.
   */
  public function concat() {
    $returnValue = "";
    $argsNum = func_num_args();
    $argsList = func_get_args();
    for ($i = 0; $i < $argsNum; $i++) {
      if (is_null($argsList[$i])) {
        return null;
      }
      $returnValue .= $argsList[$i];
    }
    return $returnValue;
  }
  /**
   * Method to emulate MySQL FIELD() function.
   *
   * This function gets the list argument and compares the first item to all the others.
   * If the same value is found, it returns the position of that value. If not, it
   * returns 0.
   *
   * @param variable number of string, integer or double
   * @return unsigned integer
   */
  public function field() {
    $numArgs = func_num_args();
    if ($numArgs < 2 or is_null(func_get_arg(0))) {
      return 0;
    }
    $arr = func_get_args();
    $searchString = strtolower(array_shift($arr));
    for ($i = 0; $i < $numArgs-1; $i++) {
      if ($searchString === strtolower($arr[$i])) return $i + 1;
    }
    return 0;
  }
  /**
   * Method to emulate MySQL LOG() function.
   *
   * Used with one argument, it returns the natural logarithm of X.
   * <code>
   * LOG(X)
   * </code>
   * Used with two arguments, it returns the natural logarithm of X base B.
   * <code>
   * LOG(B, X)
   * </code>
   * In this case, it returns the value of log(X) / log(B).
   *
   * Used without an argument, it returns false. This returned value will be
   * rewritten to 0, because SQLite doesn't understand true/false value.
   *
   * @param integer representing the base of the logarithm, which is optional.
   * @param double value to turn into logarithm.
   * @return double | NULL
   */
  public function log() {
    $numArgs = func_num_args();
    if ($numArgs == 1) {
      $arg1 = func_get_arg(0);
      return log($arg1);
    } else if ($numArgs == 2) {
      $arg1 = func_get_arg(0);
      $arg2 = func_get_arg(1);
      return log($arg1)/log($arg2);
    } else {
      return null;
    }
  }
  /**
   * Method to emulate MySQL LEAST() function.
   *
   * This function rewrites the function name to SQLite compatible function name.
   *
   * @return mixed
   */
  public function least() {
    $arg_list = func_get_args();
    return "min($arg_list)";
  }
  /**
   * Method to emulate MySQL GREATEST() function.
   *
   * This function rewrites the function name to SQLite compatible function name.
   *
   * @return mixed
   */
  public function greatest() {
  	$arg_list = func_get_args();
  	return "max($arg_list)";
  }
  /**
   * Method to dummy out MySQL GET_LOCK() function.
   * 
   * This function is meaningless in SQLite, so we do nothing.
   * 
   * @param string $name
   * @param integer $timeout
   * @return string
   */
  public function get_lock($name, $timeout) {
    return '1=1';
  }
  /**
   * Method to dummy out MySQL RELEASE_LOCK() function.
   * 
   * This function is meaningless in SQLite, so we do nothing.
   * 
   * @param string $name
   * @return string
   */
  public function release_lock($name) {
    return '1=1';
  }
  /**
   * Method to emulate MySQL UCASE() function.
   *
   * This is MySQL alias for upper() function. This function rewrites it
   * to SQLite compatible name upper().
   *
   * @param string
   * @return string SQLite compatible function name.
   */
  public function ucase($string) {
    return "upper($string)";
  }
  /**
   * Method to emulate MySQL LCASE() function.
   * 
   * This is MySQL alias for lower() function. This function rewrites it
   * to SQLite compatible name lower().
   * 
   * @param string
   * @return string SQLite compatible function name.
   */
  public function lcase($string) {
    return "lower($string)";
  }
  /**
   * Method to emulate MySQL INET_NTOA() function.
   *
   * This function gets 4 or 8 bytes integer and turn it into the network address.
   *
   * @param unsigned long integer
   * @return string
   */
  public function inet_ntoa($num) {
    return long2ip($num);
  }
  /**
   * Method to emulate MySQL INET_ATON() function.
   * 
   * This function gets the network address and turns it into integer.
   * 
   * @param string
   * @return unsigned long integer
   */
  public function inet_aton($addr) {
    $int_data = ip2long($addr);
    $unsigned_int_data = sprintf('%u', $address);
    return $unsigned_int_data;
  }
  /**
   * Method to emulate MySQL DATEDIFF() function.
   * 
   * This function compares two dates value and returns the difference.
   * 
   * PHP 5.3.2 has a serious bug in DateTime::diff(). So if users' PHP is that version,
   * we don't use that function. See https://bugs.php.net/bug.php?id=51184.
   * 
   * @param string start
   * @param string end
   * @return string
   */
  public function datediff($start, $end) {
    $start_date = strtotime($start);
    $end_date   = strtotime($end);
    $interval = floor(($end_date - $start_date)/(3600*24));
    return $interval;
  }
  /**
   * Method to emulate MySQL LOCATE() function.
   * 
   * This function returns the position if $substr is found in $str. If not,
   * it returns 0. If mbstring extension is loaded, mb_strpos() function is
   * used.
   * 
   * @param string needle
   * @param string haystack
   * @param integer position
   * @return integer
   */
  public function locate($substr, $str, $pos = 0) {
  	if (!extension_loaded('mbstring')) {
  		if (($val = stros($str, $substr, $pos)) !== false) {
  			return $val + 1;
  		} else {
  			return 0;
  		}
  	} else {
	  	if (($val = mb_strpos($str, $substr, $pos)) !== false) {
	  		return $val + 1;
	  	} else {
	  		return 0;
	  	}
  	}
  }
	/**
	 * Method to return MySQL version.
	 * 
	 * This function only returns WordPress $required_mysql_version, because it is
	 * meaningless for SQLite database.
	 * 
	 * @param none
	 * @return string representing the version number
	 */
	public function version() {
    global $required_mysql_version;
    return $required_mysql_version;
	}
}
?>