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<?php

/**

 * @file

 * SQL helper for Date API.

 *

 * @TODO

 * Add experimental support for sqlite: http://www.sqlite.org/lang_datefunc.html

 * and Oracle (http://psoug.org/reference/date_func.html and

 * http://psoug.org/reference/datatypes.html) date/time functions.

 */

/**

 * A helper function to do cross-database concatation of date parts.

 *

 * @param array $array

 *   An array of values to be concatonated in sql.

 *

 * @return string

 *   Correct sql string for database type.

 */

function date_sql_concat($array) {

  switch (Database::getConnection()->databaseType()) {

    case 'mysql':

      return "CONCAT(" . implode(",", $array) . ")";

    case 'pgsql':

      return implode(" || ", $array);

  }

}

/**

 * Helper function to do cross-database NULL replacements

 *

 * @param array $array

 *   An array of values to test for NULL values.

 *

 * @return string

 *   SQL statement to return the first non-NULL value in the list.

 */

function date_sql_coalesce($array) {

  switch (Database::getConnection()->databaseType()) {

    case 'mysql':

    case 'pgsql':

      return "COALESCE(" . implode(',', $array) . ")";

  }

}

/**

 * A helper function to do cross-database padding of date parts.

 *

 * @param string $str

 *   A string to apply padding to

 * @param int $size

 *   The size the final string should be

 * @param string $pad

 *   The value to pad the string with

 * @param string $side

 *   The side of the string to pad

 */

function date_sql_pad($str, $size = 2, $pad = '0', $side = 'l') {

  switch ($side) {

    case 'r':

      return "RPAD($str, $size, '$pad')";

    default:

      return "LPAD($str, $size, '$pad')";

  }

}

/**

 * A class to manipulate date SQL.

 */

class date_sql_handler {

  var $db_type = NULL;

  var $date_type = DATE_DATETIME;

  // A string timezone name.

  var $db_timezone = 'UTC';

  // A string timezone name.

  var $local_timezone = NULL;

  // Use if the db timezone is stored in a field.

  var $db_timezone_field = NULL;

  // Use if the local timezone is stored in a field.

  var $local_timezone_field = NULL;

  // Use if the offset is stored in a field.

  var $offset_field = NULL;

  /**

   * The object constuctor.

   */

  function __construct($date_type = DATE_DATETIME, $local_timezone = NULL, $offset = '+00:00') {

    $this->db_type = Database::getConnection()->databaseType();

    $this->date_type = $date_type;

    $this->db_timezone = 'UTC';

    $this->local_timezone = isset($local_timezone) ? $local_timezone : date_default_timezone();

    $this->set_db_timezone($offset);

  }

  /**

   * See if the db has timezone name support.

   */

  function db_tz_support($reset = FALSE) {

    $has_support = variable_get('date_db_tz_support', -1);

    if ($has_support == -1 || $reset) {

      $has_support = FALSE;

      switch ($this->db_type) {

        case 'mysql':

          $test = db_query("SELECT CONVERT_TZ('2008-02-15 12:00:00', 'UTC', 'US/Central')")->fetchField();

          if ($test == '2008-02-15 06:00:00') {

            $has_support = TRUE;

          }

          break;

        case 'pgsql':

          $test = db_query("SELECT '2008-02-15 12:00:00 UTC' AT TIME ZONE 'US/Central'")->fetchField();

          if ($test == '2008-02-15 06:00:00') {

            $has_support = TRUE;

          }

          break;

      }

      variable_set('date_db_tz_support', $has_support);

    }

    return $has_support;

  }

  /**

   * Set the database timzone offset.

   *

   * Setting the db timezone to UTC is done to ensure consistency in date

   * handling whether or not the database can do proper timezone conversion.

   *

   * Views filters that not exposed are cached and won't set the timezone

   * so views date filters should add 'cacheable' => 'no' to their

   * definitions to ensure that the database timezone gets set properly

   * when the query is executed.

   *

   * @param string $offset

   *   An offset value to set the database timezone to. This will only

   *   set a fixed offset, not a timezone, so any value other than

   *   '+00:00' should be used with caution.

   */

  function set_db_timezone($offset = '+00:00') {

    static $already_set = FALSE;

    $type = Database::getConnection()->databaseType();

    if (!$already_set) {

      switch ($type) {

        case 'mysql':

          db_query("SET @@session.time_zone = '$offset'");

          break;

        case 'pgsql':

          db_query("SET TIME ZONE INTERVAL '$offset' HOUR TO MINUTE");

          break;

        case 'sqlsrv':

          // Issue #1201342, This is the wrong way to set the timezone, this

          // still needs to be fixed. In the meantime, commenting this out makes

          // SQLSRV functional.

          // db_query('TimeZone.setDefault(TimeZone.getTimeZone("GMT"))');

          break;

      }

      $already_set = TRUE;

    }

  }

  /**

   * Return timezone offset for the date being processed.

   */

  function get_offset($comp_date = NULL) {

    if (!empty($this->db_timezone) && !empty($this->local_timezone)) {

      if ($this->db_timezone != $this->local_timezone) {

        if (empty($comp_date)) {

          $comp_date = date_now($this->db_timezone);

        }

        $comp_date->setTimezone(timezone_open($this->local_timezone));

        return date_offset_get($comp_date);

      }

    }

    return 0;

  }

  /**

   * Helper function to create cross-database SQL dates.

   *

   * @param string $field

   *   The real table and field name, like 'tablename.fieldname' .

   * @param string $offset

   *   The name of a field that holds the timezone offset or an

   *   offset value. If NULL, the normal Drupal timezone handling

   *   will be used, if $offset = 0 no adjustment will be made.

   *

   * @return string

   *   An appropriate SQL string for the db type and field type.

   */

  function sql_field($field, $offset = NULL, $comp_date = NULL) {

    if (strtoupper($field) == 'NOW') {

      // NOW() will be in UTC since that is what we set the db timezone to.

      $this->local_timezone = 'UTC';

      return $this->sql_offset('NOW()', $offset);

    }

    switch ($this->db_type) {

      case 'mysql':

        switch ($this->date_type) {

          case DATE_UNIX:

            $field = "FROM_UNIXTIME($field)";

            break;

          case DATE_ISO:

            $field = "STR_TO_DATE($field, '%Y-%m-%dT%T')";

            break;

          case DATE_DATETIME:

            break;

        }

        break;

      case 'pgsql':

        switch ($this->date_type) {

          case DATE_UNIX:

            $field = "$field::ABSTIME";

            break;

          case DATE_ISO:

            $field = "TO_DATE($field, 'FMYYYY-FMMM-FMDDTFMHH24:FMMI:FMSS')";

            break;

          case DATE_DATETIME:

            break;

        }

        break;

      case 'sqlite':

        switch ($this->date_type) {

          case DATE_UNIX:

            $field = "datetime($field, 'unixepoch')";

            break;

          case DATE_ISO:

          case DATE_DATETIME:

            $field = "datetime($field)";

            break;

        }

        break;

      case 'sqlsrv':

        switch ($this->date_type) {

          case DATE_UNIX:

            $field = "DATEADD(s, $field, '19700101 00:00:00:000')";

            break;

          case DATE_ISO:

          case DATE_DATETIME:

            $field = "CAST($field as smalldatetime)";

            break;

        }

        break;

      break;

    }

    // Adjust the resulting value to the right timezone/offset.

    return $this->sql_tz($field, $offset, $comp_date);

  }

  /**

   * Adjust a field value by an offset in seconds.

   */

  function sql_offset($field, $offset = NULL) {

    if (!empty($offset)) {

      switch ($this->db_type) {

        case 'mysql':

          return "ADDTIME($field, SEC_TO_TIME($offset))";

        case 'pgsql':

          return "($field + INTERVAL '$offset SECONDS')";;

        case 'sqlite':

          return "datetime($field, '$offset seconds')";

        case 'sqlsrv':

          return "DATEADD(second, $offset, $field)";

      }

    }

    return $field;

  }

  /**

   * Adjusts a field value by time interval.

   *

   * @param string $field

   *   The field to be adjusted.

   * @param string $direction

   *   Either ADD or SUB.

   * @param int $count

   *   The number of values to adjust.

   * @param string $granularity

   *   The granularity of the adjustment, should be singular,

   *   like SECOND, MINUTE, DAY, HOUR.

   */

  function sql_date_math($field, $direction, $count, $granularity) {

    $granularity = strtoupper($granularity);

    switch ($this->db_type) {

      case 'mysql':

        switch ($direction) {

          case 'ADD':

            return "DATE_ADD($field, INTERVAL $count $granularity)";

          case 'SUB':

            return "DATE_SUB($field, INTERVAL $count $granularity)";

        }

      case 'pgsql':

        $granularity .= 'S';

        switch ($direction) {

          case 'ADD':

            return "($field + INTERVAL '$count $granularity')";

          case 'SUB':

            return "($field - INTERVAL '$count $granularity')";

        }

      case 'sqlite':

        $granularity .= 'S';

        switch ($direction) {

          case 'ADD':

            return "datetime($field, '+$count $granularity')";

          case 'SUB':

            return "datetime($field, '-$count $granularity')";

        }

    }

    return $field;

  }

  /**

   * Select a date value from the database, adjusting the value

   * for the timezone.

   *

   * Check whether database timezone conversion is supported in

   * this system and use it if possible, otherwise use an

   * offset.

   *

   * @param string $field

   *   The field to be adjusted.

   * @param bool $offset

   *   Set a fixed offset or offset field to use for the date.

   *   If set, no timezone conversion will be done and the

   *   offset will be used.

   */

  function sql_tz($field, $offset = NULL, $comp_date = NULL) {

    // If the timezones are values they need to be quoted, but

    // if they are field names they do not.

    $db_zone   = !empty($this->db_timezone_field) ? $this->db_timezone_field : "'{$this->db_timezone}'";

    $localzone = !empty($this->local_timezone_field) ? $this->local_timezone_field : "'{$this->local_timezone}'";

    // If a fixed offset is required, use it.

    if ($offset !== NULL) {

      return $this->sql_offset($field, $offset);

    }

    // If the db and local timezones are the same, make no adjustment.

    elseif ($db_zone == $localzone) {

      return $this->sql_offset($field, 0);

    }

    // If the db has no timezone support, adjust by the offset,

    // could be either a field name or a value.

    elseif (!$this->db_tz_support() || empty($localzone)) {

      if (!empty($this->offset_field)) {

        return $this->sql_offset($field, $this->offset_field);

      }

      else {

        return $this->sql_offset($field, $this->get_offset($comp_date));

      }

    }

    // Otherwise make a database timezone adjustment to the field.

    else {

      switch ($this->db_type) {

        case 'mysql':

          return "CONVERT_TZ($field, $db_zone, $localzone)";

        case 'pgsql':

          // WITH TIME ZONE assumes the date is using the system

          // timezone, which should have been set to UTC.

          return "$field::timestamp with time zone AT TIME ZONE $localzone";

      }

    }

  }

  /**

   * Helper function to create cross-database SQL date formatting.

   *

   * @param string $format

   *   A format string for the result, like 'Y-m-d H:i:s' .

   * @param string $field

   *   The real table and field name, like 'tablename.fieldname' .

   *

   * @return string

   *   An appropriate SQL string for the db type and field type.

   */

  function sql_format($format, $field) {

    switch ($this->db_type) {

      case 'mysql':

        $replace = array(

          'Y' => '%Y',

          'y' => '%y',

          'M' => '%b',

          'm' => '%m',

          'n' => '%c',

          'F' => '%M',

          'D' => '%a',

          'd' => '%d',

          'l' => '%W',

          'j' => '%e',

          'W' => '%v',

          'H' => '%H',

          'h' => '%h',

          'i' => '%i',

          's' => '%s',

          'A' => '%p',

          '\WW' => 'W%U',

        );

        $format = strtr($format, $replace);

        return "DATE_FORMAT($field, '$format')";

      case 'pgsql':

        $replace = array(

          'Y' => 'YYYY',

          'y' => 'YY',

          'M' => 'Mon',

          'm' => 'MM',

          // No format for Numeric representation of a month, without leading

          // zeros.

          'n' => 'MM',

          'F' => 'Month',

          'D' => 'Dy',

          'd' => 'DD',

          'l' => 'Day',

          // No format for Day of the month without leading zeros.

          'j' => 'DD',

          'W' => 'WW',

          'H' => 'HH24',

          'h' => 'HH12',

          'i' => 'MI',

          's' => 'SS',

          'A' => 'AM',

          '\T' => '"T"',

          // '\W' => // TODO, what should this be?

        );

        $format = strtr($format, $replace);

        return "TO_CHAR($field, '$format')";

      case 'sqlite':

        $replace = array(

          // 4 digit year number.

          'Y' => '%Y',

          // No format for 2 digit year number.

          'y' => '%Y',

          // No format for 3 letter month name.

          'M' => '%m',

          // Month number with leading zeros.

          'm' => '%m',

          // No format for month number without leading zeros.

          'n' => '%m',

          // No format for full month name.

          'F' => '%m',

          // No format for 3 letter day name.

          'D' => '%d',

          // Day of month number with leading zeros.

          'd' => '%d',

          // No format for full day name.

          'l' => '%d',

          // No format for day of month number without leading zeros.

          'j' => '%d',

          // ISO week number.

          'W' => '%W',

          // 24 hour hour with leading zeros.

          'H' => '%H',

          // No format for 12 hour hour with leading zeros.

          'h' => '%H',

          // Minutes with leading zeros.

          'i' => '%M',

          // Seconds with leading zeros.

          's' => '%S',

          // No format for AM/PM.

          'A' => '',

          // Week number.

          '\WW' => '',

        );

        $format = strtr($format, $replace);

        return "strftime('$format', $field)";

      case 'sqlsrv':

        $replace = array(

          // 4 digit year number.

          'Y' => "' + CAST(DATEPART(year, $field) AS nvarchar) + '",

          // 2 digit year number.

          'y' => "' + RIGHT(DATEPART(year, $field), 2) + '",

          // 3 letter month name.

          'M' => "' + LEFT(DATENAME(month, $field), 3) + '",

          // Month number with leading zeros.

          'm' => "' + RIGHT('0' + CAST(DATEPART(month, $field) AS nvarchar), 2) + '",

          // Month number without leading zeros.

          'n' => "' + CAST(DATEPART(month, $field) AS nvarchar) + '",

          // Full month name.

          'F' => "' + DATENAME(month, $field) + '",

          // 3 letter day name.

          'D' => "' + LEFT(DATENAME(day, $field), 3) + '",

          // Day of month number with leading zeros.

          'd' => "' + RIGHT('0' + CAST(DATEPART(day, $field) AS nvarchar), 2) + '",

          // Full day name.

          'l' => "' + DATENAME(day, $field) + '",

          // Day of month number without leading zeros.

          'j' => "' + CAST(DATEPART(day, $field) AS nvarchar) + '",

          // ISO week number.

          'W' => "' + CAST(DATEPART(iso_week, $field) AS nvarchar) + '",

          // 24 hour with leading zeros.

          'H' => "' + RIGHT('0' + CAST(DATEPART(hour, $field) AS nvarchar), 2) + '",

          // 12 hour with leading zeros.

          // Conversion to 'mon dd yyyy hh:miAM/PM' format (corresponds to style

          // 100 in MSSQL).

          // Hour position is fixed, so we use SUBSTRING to extract it.

          'h' => "' + RIGHT('0' + LTRIM(SUBSTRING(CONVERT(nvarchar, $field, 100), 13, 2)), 2) + '",

          // Minutes with leading zeros.

          'i' => "' + RIGHT('0' + CAST(DATEPART(minute, $field) AS nvarchar), 2) + '",

          // Seconds with leading zeros.

          's' => "' + RIGHT('0' + CAST(DATEPART(second, $field) AS nvarchar), 2) + '",

          // AM/PM.

          // Conversion to 'mon dd yyyy hh:miAM/PM' format (corresponds to style

          // 100 in MSSQL).

          'A' => "' + RIGHT(CONVERT(nvarchar, $field, 100), 2) + '",

          // Week number.

          '\WW' => "' + CAST(DATEPART(week, $field) AS nvarchar) + '",

          '\T' => 'T',

          // MS SQL uses single quote as escape symbol.

          '\'' => '\'\'',

        );

        $format = strtr($format, $replace);

        $format = "'$format'";

        return $format;

    }

  }

  /**

   * Helper function to create cross-database SQL date extraction.

   *

   * @param string $extract_type

   *   The type of value to extract from the date, like 'MONTH'.

   * @param string $field

   *   The real table and field name, like 'tablename.fieldname'.

   *

   * @return string

   *   An appropriate SQL string for the db type and field type.

   */

  function sql_extract($extract_type, $field) {

    // Note there is no space after FROM to avoid db_rewrite problems

    // see http://drupal.org/node/79904.

    switch (strtoupper($extract_type)) {

      case 'DATE':

        return $field;

      case 'YEAR':

        return "EXTRACT(YEAR FROM($field))";

      case 'MONTH':

        return "EXTRACT(MONTH FROM($field))";

      case 'DAY':

        return "EXTRACT(DAY FROM($field))";

      case 'HOUR':

        return "EXTRACT(HOUR FROM($field))";

      case 'MINUTE':

        return "EXTRACT(MINUTE FROM($field))";

      case 'SECOND':

        return "EXTRACT(SECOND FROM($field))";

      // ISO week number for date.

      case 'WEEK':

        switch ($this->db_type) {

          case 'mysql':

            // WEEK using arg 3 in MySQl should return the same value as

            // Postgres EXTRACT.

            return "WEEK($field, 3)";

          case 'pgsql':

            return "EXTRACT(WEEK FROM($field))";

        }

      case 'DOW':

        switch ($this->db_type) {

          case 'mysql':

            // MySQL returns 1 for Sunday through 7 for Saturday, PHP date

            // functions and Postgres use 0 for Sunday and 6 for Saturday.

            return "INTEGER(DAYOFWEEK($field) - 1)";

          case 'pgsql':

            return "EXTRACT(DOW FROM($field))";

        }

      case 'DOY':

        switch ($this->db_type) {

          case 'mysql':

            return "DAYOFYEAR($field)";

          case 'pgsql':

            return "EXTRACT(DOY FROM($field))";

        }

    }

  }

  /**

   * Creates a where clause to compare a complete date field to a date value.

   *

   * @param string $type

   *   The type of value we're comparing to, could be another field

   *   or a date value.

   * @param string $field

   *   The db table and field name, like "$table.$field".

   * @param string $operator

   *   The db comparison operator to use, like '='.

   * @param int $value

   *   The value to compare the extracted date part to, could be a field name or

   *   a date string or NOW().

   *

   * @return string

   *   SQL for the where clause for this operation.

   */

  function sql_where_date($type, $field, $operator, $value, $adjustment = NULL) {

    $type = strtoupper($type);

    if (strtoupper($value) == 'NOW') {

      $value = $this->sql_field('NOW', $adjustment);

    }

    elseif ($type == 'FIELD') {

      $value = $this->sql_field($value, $adjustment);

    }

    elseif ($type == 'DATE') {

      $date = new DateObject($value, date_default_timezone(), DATE_FORMAT_DATETIME);

      if (!empty($adjustment)) {

        date_modify($date, $adjustment . ' seconds');

      }

      // When comparing a field to a date we can avoid doing timezone

      // conversion by altering the comparison date to the db timezone.

      // This won't work if the timezone is a field instead of a value.

      if (empty($this->db_timezone_field) && empty($this->local_timezone_field) && $this->db_timezone_field != $this->local_timezone_field) {

        $date->setTimezone(timezone_open($this->db_timezone));

        $this->local_timezone = $this->db_timezone;

      }

      $value = "'" . $date->format(DATE_FORMAT_DATETIME, TRUE) . "'";

    }

    if ($this->local_timezone != $this->db_timezone) {

      $field = $this->sql_field($field);

    }

    else {

      $field = $this->sql_field($field, 0);

    }

    return "$field $operator $value";

  }

  /**

   * Creates a where clause comparing an extracted date part to an integer.

   *

   * @param string $part

   *   The part to extract, YEAR, MONTH, DAY, etc.

   * @param string $field

   *   The db table and field name, like "$table.$field".

   * @param string $operator

   *   The db comparison operator to use, like '=' .

   * @param int $value

   *   The integer value to compare the extracted date part to.

   *

   * @return string

   *   SQL for the where clause for this operation.

   */

  function sql_where_extract($part, $field, $operator, $value, $adjustment = NULL) {

    if (empty($adjustment) && $this->local_timezone != $this->db_timezone) {

      $field = $this->sql_field($field);

    }

    else {

      $field = $this->sql_field($field, $adjustment);

    }

    return $this->sql_extract($part, $field) . " $operator $value";

  }

  /**

   * Create a where clause to compare a formated field to a formated value.

   *

   * @param string $format

   *   The format to use on the date and the value when comparing them.

   * @param string $field

   *   The db table and field name, like "$table.$field".

   * @param string $operator

   *   The db comparison operator to use, like '=' .

   * @param string $value

   *   The value to compare the extracted date part to, could be a

   *   field name or a date string or NOW().

   *

   * @return string

   *   SQL for the where clause for this operation.

   */

  function sql_where_format($format, $field, $operator, $value, $adjustment = NULL) {

    if (empty($adjustment) && $this->local_timezone != $this->db_timezone) {

      $field = $this->sql_field($field);

    }

    else {

      $field = $this->sql_field($field, $adjustment);

    }

    return $this->sql_format($format, $field) . " $operator '$value'";

  }

  /**

   * An array of all date parts,

   * optionally limited to an array of allowed parts.

   */

  function date_parts($limit = NULL) {

    $parts = array(

      'year' => t('Year', array(), array('context' => 'datetime')),

      'month' => t('Month', array(), array('context' => 'datetime')),

      'day' => t('Day', array(), array('context' => 'datetime')),

      'hour' => t('Hour', array(), array('context' => 'datetime')),

      'minute' => t('Minute', array(), array('context' => 'datetime')),

      'second' => t('Second', array(), array('context' => 'datetime')),

    );

    if (!empty($limit)) {

      $last = FALSE;

      foreach ($parts as $key => $part) {

        if ($last) {

          unset($parts[$key]);

        }

        if ($key == $limit) {

          $last = TRUE;

        }

      }

    }

    return $parts;

  }

  /**

   * Part information.

   *

   * @param string $op

   *   'min', 'max', 'format', 'sep', 'empty_now', 'empty_min', 'empty_max' .

   *   Returns all info if empty.

   * @param string $part

   *   'year', 'month', 'day', 'hour', 'minute', or 'second.

   *   returns info for all parts if empty.

   */

  function part_info($op = NULL, $part = NULL) {

    $info = array();

    $info['min'] = array(

      'year' => 100,

      'month' => 1,

      'day' => 1,

      'hour' => 0,

      'minute' => 0,

      'second' => 0,

    );

    $info['max'] = array(

      'year' => 4000,

      'month' => 12,

      'day' => 31,

      'hour' => 23,

      'minute' => 59,

      'second' => 59,

    );

    $info['format'] = array(

      'year' => 'Y',

      'month' => 'm',

      'day' => 'd',

      'hour' => 'H',

      'minute' => 'i',

      'second' => 's',

    );

    $info['sep'] = array(

      'year' => '',

      'month' => '-',

      'day' => '-',

      'hour' => ' ',

      'minute' => ':',

      'second' => ':',

    );

    $info['empty_now'] = array(

      'year' => date('Y'),

      'month' => date('m'),

      'day' => min('28', date('d')),

      'hour' => date('H'),

      'minute' => date('i'),

      'second' => date('s'),

    );

    $info['empty_min'] = array(

      'year' => '1000',

      'month' => '01',

      'day' => '01',

      'hour' => '00',

      'minute' => '00',

      'second' => '00',

    );

    $info['empty_max'] = array(

      'year' => '9999',

      'month' => '12',

      'day' => '31',

      'hour' => '23',

      'minute' => '59',

      'second' => '59',

    );

    if (!empty($op)) {

      if (!empty($part)) {

        return $info[$op][$part];

      }

      else {

        return $info[$op];

      }

    }

    return $info;

  }

  /**

   * Create a complete datetime value out of an

   * incomplete array of selected values.

   *

   * For example, array('year' => 2008, 'month' => 05) will fill

   * in the day, hour, minute and second with the earliest possible

   * values if type = 'min', the latest possible values if type = 'max',

   * and the current values if type = 'now' .

   */

  function complete_date($selected, $type = 'now') {

    if (empty($selected)) {

      return '';

    }

    // Special case for weeks.

    if (array_key_exists('week', $selected)) {

      $dates = date_week_range($selected['week'], $selected['year']);

      switch ($type) {

        case 'empty_now':

        case 'empty_min':

        case 'min':

          return date_format($dates[0], 'Y-m-d H:i:s');

        case 'empty_max':

        case 'max':

          return date_format($dates[1], 'Y-m-d H:i:s');

        default:

          return;

      }

    }

    $compare = array_merge($this->part_info('empty_' . $type), $selected);

    // If this is a max date, make sure the last day of

    // the month is the right one for this date.

    if ($type == 'max') {

      $compare['day'] = date_days_in_month($compare['year'], $compare['month']);

    }

    $value = '';

    $separators = $this->part_info('sep');

    foreach ($this->date_parts() as $key => $name) {

      $value .= $separators[$key] . (!empty($selected[$key]) ? $selected[$key] : $compare[$key]);

    }

    return $value;

  }

  /**

   * Converts a format string into help text, i.e. 'Y-m-d' becomes 'YYYY-MM-DD'.

   *

   * @param string $format

   *   A date format string.

   *

   * @return string

   *   The conveted help text.

   */

  function format_help($format) {

    $replace = array(

      'Y' => 'YYYY',

      'm' => 'MM',

      'd' => 'DD',

      'H' => 'HH',

      'i' => 'MM',

      's' => 'SS',

      '\T' => 'T',

    );

    return strtr($format, $replace);

  }

  /**

   *  A function to test the validity of various date parts

   */

  function part_is_valid($value, $type) {

    if (!preg_match('/^[0-9]*$/', $value)) {

      return FALSE;

    }

    $value = intval($value);

    if ($value <= 0) {

      return FALSE;

    }

    switch ($type) {

      case 'year':

        if ($value < DATE_MIN_YEAR) {

          return FALSE;

        }

        break;

      case 'month':

        if ($value < 0 || $value > 12) {

          return FALSE;

        }

        break;

      case 'day':

        if ($value < 0 || $value > 31) {

          return FALSE;

        }

        break;

      case 'week':

        if ($value < 0 || $value > 53) {

          return FALSE;

        }

        break;

    }

    return TRUE;

  }

  /**

   * @todo.

   */

  function views_formats($granularity, $type = 'sql') {

    if (empty($granularity)) {

      return DATE_FORMAT_ISO;

    }

    $formats = array('display', 'sql');

    // Start with the site long date format and add seconds to it.

    $short = str_replace(':i', ':i:s', variable_get('date_format_short', 'l, F j, Y - H:i'));

    switch ($granularity) {

      case 'year':

        $formats['display'] = 'Y';

        $formats['sql'] = 'Y';

        break;

      case 'month':

        $formats['display'] = date_limit_format($short, array('year', 'month'));

        $formats['sql'] = 'Y-m';

        break;

      case 'day':

        $formats['display'] = date_limit_format($short, array('year', 'month', 'day'));

        $formats['sql'] = 'Y-m-d';

        break;

      case 'hour':

        $formats['display'] = date_limit_format($short, array('year', 'month', 'day', 'hour'));

        $formats['sql'] = 'Y-m-d\TH';

        break;

      case 'minute':

        $formats['display'] = date_limit_format($short, array('year', 'month', 'day', 'hour', 'minute'));

        $formats['sql'] = 'Y-m-d\TH:i';

        break;

      case 'second':

        $formats['display'] = date_limit_format($short, array('year', 'month', 'day', 'hour', 'minute', 'second'));

        $formats['sql'] = 'Y-m-d\TH:i:s';

        break;

      case 'week':

        $formats['display'] = 'F j Y (W)';

        $formats['sql'] = 'Y-\WW';

        break;

    }

    return $formats[$type];

  }

  /**

   * @todo.

   */

  function granularity_form($granularity) {

    $form = array(

      '#title' => t('Granularity'),

      '#type' => 'radios',

      '#default_value' => $granularity,

      '#options' => $this->date_parts(),

      );

    return $form;

  }

  /**

   * Parse date parts from an ISO date argument.

   *

   * Based on ISO 8601 date duration and time interval standards.

   *

   * Parses a value like 2006-01-01--2006-01-15, or 2006-W24, or @P1W.

   * Separate start and end dates or date and period with a double hyphen (--).

   *

   * The 'end' portion of the argument can be eliminated if it is the same as

   * the 'start' portion. Use @ instead of a date to substitute in the current

   * date and time.

   *

   * Use periods (P1H, P1D, P1W, P1M, P1Y) to get next hour/day/week/month/year

   * from now. Use date before P sign to get next hour/day/week/month/year from

   * that date. Use period then date to get a period that ends on the date.

   *

   * @see http://en.wikipedia.org/wiki/ISO_8601#Week_dates

   * @see http://en.wikipedia.org/wiki/ISO_8601#Duration

   */

  function arg_parts($argument) {

    $values = array();

    // Keep mal-formed arguments from creating errors.

    if (empty($argument) || is_array($argument)) {

      return array('date' => array(), 'period' => array());

    }

    $fromto = explode('--', $argument);

    foreach ($fromto as $arg) {

      $parts = array();

      if ($arg == '@') {

        $date = date_now();

        $parts['date'] = $date->toArray();

      }

      elseif (preg_match('/(\d{4})?-?(W)?(\d{1,2})?-?(\d{1,2})?[T\s]?(\d{1,2})?:?(\d{1,2})?:?(\d{1,2})?/', $arg, $matches)) {

        $date = array();

        if (!empty($matches[1])) {

          $date['year'] = $matches[1];

        }

        if (!empty($matches[3])) {

          if (empty($matches[2])) {

            $date['month'] = $matches[3];

          }

          else {

            $date['week'] = $matches[3];

          }

        }

        if (!empty($matches[4])) {

          $date['day'] = $matches[4];

        }

        if (!empty($matches[5])) {

          $date['hour'] = $matches[5];

        }

        if (!empty($matches[6])) {

          $date['minute'] = $matches[6];

        }

        if (!empty($matches[7])) {

          $date['second'] = $matches[7];

        }

        $parts['date'] = $date;

      }

      if (preg_match('/^P(\d{1,4}[Y])?(\d{1,2}[M])?(\d{1,2}[W])?(\d{1,2}[D])?([T]{0,1})?(\d{1,2}[H])?(\d{1,2}[M])?(\d{1,2}[S])?/', $arg, $matches)) {

        $period = array();

        if (!empty($matches[1])) {

          $period['year'] = str_replace('Y', '', $matches[1]);

        }

        if (!empty($matches[2])) {

          $period['month'] = str_replace('M', '', $matches[2]);

        }

        if (!empty($matches[3])) {

          $period['week'] = str_replace('W', '', $matches[3]);

        }

        if (!empty($matches[4])) {

          $period['day'] = str_replace('D', '', $matches[4]);

        }

        if (!empty($matches[6])) {

          $period['hour'] = str_replace('H', '', $matches[6]);

        }

        if (!empty($matches[7])) {

          $period['minute'] = str_replace('M', '', $matches[7]);

        }

        if (!empty($matches[8])) {

          $period['second'] = str_replace('S', '', $matches[8]);

        }

        $parts['period'] = $period;

      }

      $values[] = $parts;

    }

    return $values;

  }

  /**

   * Convert strings like '+1 day' to the ISO equivalent, like 'P1D' .

   */

  function arg_replace($arg) {

    if (!preg_match('/([+|-])\s?([0-9]{1,32})\s?([day(s)?|week(s)?|month(s)?|year(s)?|hour(s)?|minute(s)?|second(s)?]{1,10})/', $arg, $results)) {

      return str_replace('now', '@', $arg);

    }

    $direction = $results[1];

    $count = $results[2];

    $item = $results[3];

    $replace = array(

      'now' => '@',

      '+' => 'P',

      '-' => 'P-',

      'years' => 'Y',

      'year' => 'Y',

      'months' => 'M',

      'month' => 'M',

      'weeks' => 'W',

      'week' => 'W',

      'days' => 'D',

      'day' => 'D',

      'hours' => 'H',

      'hour' => 'H',

      'minutes' => 'M',

      'minute' => 'M',

      'seconds' => 'S',

      'second' => 'S',

      '  ' => '',

      ' ' => '',

      );

    $prefix = in_array($item, array('hours', 'hour', 'minutes', 'minute', 'seconds', 'second')) ? 'T' : '';

    return $prefix . strtr($direction, $replace) . $count . strtr($item, $replace);

  }

  /**

   * Use the parsed values from the ISO argument to determine the

   * granularity of this period.

   */

  function arg_granularity($arg) {

    $granularity = '';

    $parts = $this->arg_parts($arg);

    $date = !empty($parts[0]['date']) ? $parts[0]['date'] : (!empty($parts[1]['date']) ? $parts[1]['date'] : array());

    foreach ($date as $key => $part) {

      $granularity = $key;

    }

    return $granularity;

  }

  /**

   * Use the parsed values from the ISO argument to determine the

   * min and max date for this period.

   */

  function arg_range($arg) {

    // Parse the argument to get its parts.

    $parts = $this->arg_parts($arg);

    // Build a range from a period-only argument (assumes the min date is now.)

    if (empty($parts[0]['date']) && !empty($parts[0]['period']) && (empty($parts[1]))) {

      $min_date = date_now();

      $max_date = clone($min_date);

      foreach ($parts[0]['period'] as $part => $value) {

        date_modify($max_date, "+$value $part");

      }

      date_modify($max_date, '-1 second');

      return array($min_date, $max_date);

    }

    // Build a range from a period to period argument.

    if (empty($parts[0]['date']) && !empty($parts[0]['period']) && !empty($parts[1]['period'])) {

      $min_date = date_now();

      $max_date = clone($min_date);

      foreach ($parts[0]['period'] as $part => $value) {

        date_modify($min_date, "+$value $part");

      }

      date_modify($min_date, '-1 second');

      foreach ($parts[1]['period'] as $part => $value) {

        date_modify($max_date, "+$value $part");

      }

      date_modify($max_date, '-1 second');

      return array($min_date, $max_date);

    }

    if (!empty($parts[0]['date'])) {

      $value = $this->complete_date($parts[0]['date'], 'min');

      $min_date = new DateObject($value, date_default_timezone(), DATE_FORMAT_DATETIME);

      // Build a range from a single date-only argument.

      if (empty($parts[1]) || (empty($parts[1]['date']) && empty($parts[1]['period']))) {

        $value = $this->complete_date($parts[0]['date'], 'max');

        $max_date = new DateObject($value, date_default_timezone(), DATE_FORMAT_DATETIME);

        return array($min_date, $max_date);

      }

      // Build a range from start date + period.

      elseif (!empty($parts[1]['period'])) {

        foreach ($parts[1]['period'] as $part => $value) {

          $max_date = clone($min_date);

          date_modify($max_date, "+$value $part");

        }

        date_modify($max_date, '-1 second');

        return array($min_date, $max_date);

      }

    }

    // Build a range from start date and end date.

    if (!empty($parts[1]['date'])) {

      $value = $this->complete_date($parts[1]['date'], 'max');

      $max_date = new DateObject($value, date_default_timezone(), DATE_FORMAT_DATETIME);

      if (isset($min_date)) {

        return array($min_date, $max_date);

      }

    }

    // Build a range from period + end date.

    if (!empty($parts[0]['period'])) {

      $min_date = date_now();

      foreach ($parts[0]['period'] as $part => $value) {

        date_modify($min_date, "$value $part");

      }

      return array($min_date, $max_date);

    }

     // Intercept invalid info and fall back to the current date.

    $now = date_now();

    return array($now, $now);

  }

}