vzlogger/backend/lib/Model/Channel.php

<?php
/*
 * Copyright (c) 2010 by Justin Otherguy <justin@justinotherguy.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License (either version 2 or
 * version 3) as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * For more information on the GPL, please go to:
 * http://www.gnu.org/copyleft/gpl.html
 */

interface ChannelInterface {
	// data management
	public function addData($data);
	public function getData($from = NULL, $to = NULL, $groupBy = NULL);
	public function reset();

	// some statistical functions
	public function getMin($from = NULL, $to = NULL);
	public function getMax($from = NULL, $to = NULL);
	public function getAverage($from = NULL, $to = NULL);
}

/**
 * Channel class
 * 
 * @Entity
 * @Table(name="channels")
 */
abstract class Channel extends Entity implements ChannelInterface {
	/** @Column(type="string") */
	protected $type;
	
	/** @Column(type="integer") */
	protected $resolution;
	
	/** @Column(type="integer") */
	protected $cost;
	
	/** @Column(type="string") */
	protected $name;
	
	/** @Column(type="string") */
	protected $description;
	
	/*
	 * prune all data from database
	 */ 
	public function reset($from = 0, $to = NULL) {
		// TODO add timefilter
		$sql = 'DELETE FROM data WHERE channel_id = ' . (int) $this->id . ' && from to';
		
		// TODO delelte with doctrine dal
	}

	/*
	 * add a new data to the database
	 */
	public function addData($data) {
		$sql = 'INSERT INTO data (channel_id, timestamp, value) VALUES(' . $this->dbh->escape($this) . ', ' . $this->dbh->escape($data['timestamp']) . ', ' . $this->dbh->escape($data['value']) . ')';
		// TODO insert with doctrine dal
	}

	/*
	 * retrieve data from the database
	 * 
	 * If desired it groups it into packages ($groupBy parameter)
	 *
	 * @return array() Array with timestamps => value (sorted by timestamp from newest to oldest)
	 * @param $groupBy determines how readings are grouped. Possible values are: year, month, day, hour, minute or an integer for the desired size of the returned array
	 */
	public function getData($from = NULL, $to = NULL, $groupBy = NULL) {
		$ts = 'FROM_UNIXTIME(timestamp/1000)';	// just for saving space
		switch ($groupBy) {
			case 'year':
				$sqlGroupBy = 'YEAR(' . $ts . ')';
				break;

			case 'month':
				$sqlGroupBy = 'YEAR(' . $ts . '), MONTH(' . $ts . ')';
				break;

			case 'week':
				$sqlGroupBy = 'YEAR(' . $ts . '), WEEKOFYEAR(' . $ts . ')';
				break;

			case 'day':
				$sqlGroupBy = 'YEAR(' . $ts . '), DAYOFYEAR(' . $ts . ')';
				break;

			case 'hour':
				$sqlGroupBy = 'YEAR(' . $ts . '), DAYOFYEAR(' . $ts . '), HOUR(' . $ts . ')';
				break;

			case 'minute':
				$sqlGroupBy = 'YEAR(' . $ts . '), DAYOFYEAR(' . $ts . '), HOUR(' . $ts . '), MINUTE(' . $ts . ')';
				break;

			default:
				if (is_numeric($groupBy)) {
					$groupBy = (int) $groupBy;
				}
				$sqlGroupBy = false;
		}

		$sql = 'SELECT';
		$sql .= ($sqlGroupBy === false) ? ' timestamp, value' : ' MAX(timestamp) AS timestamp, SUM(value) AS value, COUNT(timestamp) AS count';
		$sql .= ' FROM data WHERE channel_id = ' . (int) $this->id . $this->buildFilterTime($from, $to);

		if ($sqlGroupBy !== false) {
			$sql .= ' GROUP BY ' . $sqlGroupBy;
		}
			
		$sql .= ' ORDER BY timestamp DESC';
		
		// TODO query with doctrine dal
		//$result = $this->dbh->query($sql);
		//$totalCount = $result->count();

		if (is_int($groupBy) && $groupBy < $totalCount) {	// return $groupBy values
			$packageSize = floor($totalCount / $groupBy);
			$packageCount = $groupBy;
		}
		else {												// return all values or grouped by year, month, week...
			$packageSize = 1;
			$packageCount = $totalCount;
		}

		$packages = array();
		$reading = $result->rewind();
		for ($i = 1; $i <= $packageCount; $i++) {
			$package = array('timestamp' => $reading['timestamp'],	// last timestamp in package
								'value' => (float) $reading['value'],		// sum of values
								'count' => ($sqlGroupBy === false) ? 1 : $reading['count']);						// total count of values or pulses in the package

			while ($package['count'] < $packageSize) {
				$reading = $result->next();

				$package['value'] += $reading['value'];
				$package['count']++;
			}

			$packages[] = $package;
			$reading = $result->next();
		}

		return array_reverse($packages);	// start with oldest ts and ends with newest ts (reverse array order due to descending order in sql statement)
	}
}