<?php
/*
** Zabbix
** Copyright (C) 2001-2021 Zabbix SIA
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
**/


class CLineGraphDraw extends CGraphDraw {

	public function __construct($type = GRAPH_TYPE_NORMAL) {
		parent::__construct($type);
		$this->yaxismin = null;
		$this->yaxismax = null;
		$this->triggers = [];
		$this->ymin_type = GRAPH_YAXIS_TYPE_CALCULATED;
		$this->ymax_type = GRAPH_YAXIS_TYPE_CALCULATED;
		$this->yaxisright = 0;
		$this->yaxisleft = 0;
		$this->skipLeftScale = 0; // in case if left axis should be drawn but doesn't contain any data
		$this->skipRightScale = 0; // in case if right axis should be drawn but doesn't contain any data
		$this->ymin_itemid = 0;
		$this->ymax_itemid = 0;
		$this->legendOffsetY = 90;
		$this->percentile = [
			'left' => [
				'percent' => 0, // draw percentage line
				'value' => 0 // calculated percentage value left y axis
			],
			'right' => [
				'percent' => 0, // draw percentage line
				'value' => 0 // calculated percentage value right y axis
			]
		];
		$this->m_showWorkPeriod = 1;
		$this->m_showTriggers = 1;
		$this->zero = [];
		$this->graphOrientation = [
			GRAPH_YAXIS_SIDE_LEFT => '',
			GRAPH_YAXIS_SIDE_RIGHT => ''
		];
		$this->grid = []; // vertical & horizontal grids params
		$this->gridLinesCount = []; // How many grids to draw
		$this->gridStep = []; // grid step
		$this->gridPixels = 30; // optimal grid size
		$this->gridPixelsVert = 40;
	}

	/********************************************************************************************************/
	// PRE CONFIG:	ADD / SET / APPLY
	/********************************************************************************************************/
	public function updateShifts() {
		if ($this->yaxisleft == 1 && $this->yaxisright == 1) {
			$this->shiftXleft = 85;
			$this->shiftXright = 85;
		}
		elseif ($this->yaxisleft == 1) {
			$this->shiftXleft = 85;
			$this->shiftXright = 30;
		}
		elseif ($this->yaxisright == 1) {
			$this->shiftXleft = 30;
			$this->shiftXright = 85;
		}
	}

	public function getShifts() {
		$shifts = [];
		$shifts['shiftXleft'] = $this->shiftXleft;
		$shifts['shiftXright'] = $this->shiftXright;
		$shifts['shiftY'] = $this->shiftY;
		$shifts['height'] = $this->sizeY;
		$shifts['width'] = $this->sizeX;
		return $shifts;
	}

	public function showWorkPeriod($value) {
		$this->m_showWorkPeriod = ($value == 1) ? 1 : 0;
	}

	public function showTriggers($value) {
		$this->m_showTriggers = ($value == 1) ? 1 : 0;
	}

	public function addItem($itemid, $axis = GRAPH_YAXIS_SIDE_DEFAULT, $calc_fnc = CALC_FNC_AVG, $color = null, $drawtype = null, $type = null) {
		if ($this->type == GRAPH_TYPE_STACKED) {
			$drawtype = GRAPH_ITEM_DRAWTYPE_FILLED_REGION;
		}

		// TODO: graphs shouldn't retrieve items and resolve macros themselves
		// all of the data must be passed as parameters
		$items = CMacrosResolverHelper::resolveItemNames([get_item_by_itemid($itemid)]);
		$item = reset($items);

		$item['name'] = $item['name_expanded'];

		$this->items[$this->num] = $item;

		$parser = new CItemDelayFlexParser($item['delay_flex']);
		$this->items[$this->num]['delay'] = getItemDelay($item['delay'], $parser->getFlexibleIntervals());
		$this->items[$this->num]['intervals'] = $parser->getIntervals();

		if (strpos($item['units'], ',') === false) {
			$this->items[$this->num]['unitsLong'] = '';
		}
		else {
			list($this->items[$this->num]['units'], $this->items[$this->num]['unitsLong']) = explode(',', $item['units']);
		}

		$host = get_host_by_hostid($item['hostid']);

		$this->items[$this->num]['host'] = $host['host'];
		$this->items[$this->num]['hostname'] = $host['name'];
		$this->items[$this->num]['color'] = is_null($color) ? 'Dark Green' : $color;
		$this->items[$this->num]['drawtype'] = is_null($drawtype) ? GRAPH_ITEM_DRAWTYPE_LINE : $drawtype;
		$this->items[$this->num]['axisside'] = is_null($axis) ? GRAPH_YAXIS_SIDE_DEFAULT : $axis;
		$this->items[$this->num]['calc_fnc'] = is_null($calc_fnc) ? CALC_FNC_AVG : $calc_fnc;
		$this->items[$this->num]['calc_type'] = is_null($type) ? GRAPH_ITEM_SIMPLE : $type;

		if ($this->items[$this->num]['axisside'] == GRAPH_YAXIS_SIDE_LEFT) {
			$this->yaxisleft = 1;
		}

		if ($this->items[$this->num]['axisside'] == GRAPH_YAXIS_SIDE_RIGHT) {
			$this->yaxisright = 1;
		}

		$this->num++;
	}

	public function setGraphOrientation($value, $axisside) {
		if ($value < 0) {
			$this->graphOrientation[$axisside] = '-';
		}
		elseif (zbx_empty($this->graphOrientation[$axisside]) && $value > 0) {
			$this->graphOrientation[$axisside] = '+';
		}
		return $this->graphOrientation[$axisside];
	}

	public function setYMinAxisType($yaxistype) {
		$this->ymin_type = $yaxistype;
	}

	public function setYMaxAxisType($yaxistype) {
		$this->ymax_type = $yaxistype;
	}

	public function setYAxisMin($yaxismin) {
		$this->yaxismin = $yaxismin;
	}

	public function setYAxisMax($yaxismax) {
		$this->yaxismax = $yaxismax;
	}

	public function setYMinItemId($itemid) {
		$this->ymin_itemid = $itemid;
	}

	public function setYMaxItemId($itemid) {
		$this->ymax_itemid = $itemid;
	}

	public function setLeftPercentage($percentile) {
		$this->percentile['left']['percent'] = $percentile;
	}

	public function setRightPercentage($percentile) {
		$this->percentile['right']['percent'] = $percentile;
	}

	protected function selectData() {
		$this->data = [];
		$now = time(null);

		if (!isset($this->stime)) {
			$this->stime = $now - $this->period;
		}

		$this->diffTZ = (date('Z', $this->stime) - date('Z', $this->stime + $this->period));
		$this->from_time = $this->stime; // + timeZone offset
		$this->to_time = $this->stime + $this->period; // + timeZone offset

		$p = $this->to_time - $this->from_time; // graph size in time
		$z = $p - $this->from_time % $p; // graphsize - mod(from_time,p) for Oracle...
		$x = $this->sizeX; // graph size in px

		$this->itemsHost = null;

		$config = select_config();

		for ($i = 0; $i < $this->num; $i++) {
			$item = get_item_by_itemid($this->items[$i]['itemid']);

			if ($this->itemsHost === null) {
				$this->itemsHost = $item['hostid'];
			}
			elseif ($this->itemsHost != $item['hostid']) {
				$this->itemsHost = false;
			}

			if (!isset($this->axis_valuetype[$this->items[$i]['axisside']])) {
				$this->axis_valuetype[$this->items[$i]['axisside']] = $item['value_type'];
			}
			elseif ($this->axis_valuetype[$this->items[$i]['axisside']] != $item['value_type']) {
				$this->axis_valuetype[$this->items[$i]['axisside']] = ITEM_VALUE_TYPE_FLOAT;
			}

			$type = $this->items[$i]['calc_type'];
			$from_time = $this->from_time;
			$to_time = $this->to_time;
			$calc_field = 'round('.$x.'*'.zbx_sql_mod(zbx_dbcast_2bigint('clock').'+'.$z, $p).'/('.$p.'),0)'; // required for 'group by' support of Oracle

			$sql_arr = [];

			// override item history setting with housekeeping settings
			if ($config['hk_history_global']) {
				$item['history'] = $config['hk_history'];
			}

			$trendsEnabled = $config['hk_trends_global'] ? ($config['hk_trends'] > 0) : ($item['trends'] > 0);

			if (!$trendsEnabled
					|| (($item['history'] * SEC_PER_DAY) > (time() - ($this->from_time + $this->period / 2))
						&& ($this->period / $this->sizeX) <= (ZBX_MAX_TREND_DIFF / ZBX_GRAPH_MAX_SKIP_CELL))) {
				$this->dataFrom = 'history';

				array_push($sql_arr,
					'SELECT itemid,'.$calc_field.' AS i,'.
						'COUNT(*) AS count,AVG(value) AS avg,MIN(value) as min,'.
						'MAX(value) AS max,MAX(clock) AS clock'.
					' FROM history '.
					' WHERE itemid='.zbx_dbstr($this->items[$i]['itemid']).
						' AND clock>='.zbx_dbstr($from_time).
						' AND clock<='.zbx_dbstr($to_time).
					' GROUP BY itemid,'.$calc_field
					,
					'SELECT itemid,'.$calc_field.' AS i,'.
						'COUNT(*) AS count,AVG(value) AS avg,MIN(value) AS min,'.
						'MAX(value) AS max,MAX(clock) AS clock'.
					' FROM history_uint '.
					' WHERE itemid='.zbx_dbstr($this->items[$i]['itemid']).
						' AND clock>='.zbx_dbstr($from_time).
						' AND clock<='.zbx_dbstr($to_time).
					' GROUP BY itemid,'.$calc_field
				);
			}
			else {
				$this->dataFrom = 'trends';

				array_push($sql_arr,
					'SELECT itemid,'.$calc_field.' AS i,'.
						'SUM(num) AS count,AVG(value_avg) AS avg,MIN(value_min) AS min,'.
						'MAX(value_max) AS max,MAX(clock) AS clock'.
					' FROM trends'.
					' WHERE itemid='.zbx_dbstr($this->items[$i]['itemid']).
						' AND clock>='.zbx_dbstr($from_time).
						' AND clock<='.zbx_dbstr($to_time).
					' GROUP BY itemid,'.$calc_field
					,
					'SELECT itemid,'.$calc_field.' AS i,'.
						'SUM(num) AS count,AVG(value_avg) AS avg,MIN(value_min) AS min,'.
						'MAX(value_max) AS max,MAX(clock) AS clock'.
					' FROM trends_uint '.
					' WHERE itemid='.zbx_dbstr($this->items[$i]['itemid']).
						' AND clock>='.zbx_dbstr($from_time).
						' AND clock<='.zbx_dbstr($to_time).
					' GROUP BY itemid,'.$calc_field
				);

				if (!$this->hasSchedulingIntervals($this->items[$i]['intervals']) || $this->items[$i]['delay'] != 0) {
					$this->items[$i]['delay'] = max($this->items[$i]['delay'], SEC_PER_HOUR);
				}
			}

			if (!isset($this->data[$this->items[$i]['itemid']])) {
				$this->data[$this->items[$i]['itemid']] = [];
			}

			if (!isset($this->data[$this->items[$i]['itemid']][$type])) {
				$this->data[$this->items[$i]['itemid']][$type] = [];
			}

			$curr_data = &$this->data[$this->items[$i]['itemid']][$type];

			$curr_data['count'] = null;
			$curr_data['min'] = null;
			$curr_data['max'] = null;
			$curr_data['avg'] = null;
			$curr_data['clock'] = null;

			foreach ($sql_arr as $sql) {
				$result = DBselect($sql);
				while ($row = DBfetch($result)) {
					$idx = $row['i'] - 1;
					if ($idx < 0) {
						continue;
					}

					/* --------------------------------------------------
						We are taking graph on 1px more than we need,
						and here we are skiping first px, because of MOD (in SELECT),
						it combines prelast point (it would be last point if not that 1px in begining)
						and first point, but we still losing prelast point :(
						but now we've got the first point.
					--------------------------------------------------*/
					$curr_data['count'][$idx] = $row['count'];
					$curr_data['min'][$idx] = $row['min'];
					$curr_data['max'][$idx] = $row['max'];
					$curr_data['avg'][$idx] = $row['avg'];
					$curr_data['clock'][$idx] = $row['clock'];
					$curr_data['shift_min'][$idx] = 0;
					$curr_data['shift_max'][$idx] = 0;
					$curr_data['shift_avg'][$idx] = 0;
				}

				$loc_min = is_array($curr_data['min']) ? min($curr_data['min']) : null;
				$this->setGraphOrientation($loc_min, $this->items[$i]['axisside']);
				unset($row);
			}
			$curr_data['avg_orig'] = is_array($curr_data['avg']) ? zbx_avg($curr_data['avg']) : null;

			// calculate missed points
			$first_idx = 0;

			/*
				first_idx - last existing point
				ci - current index
				cj - count of missed in one go
				dx - offset to first value (count to last existing point)
			*/
			for ($ci = 0, $cj = 0; $ci < $this->sizeX; $ci++) {
				if (!isset($curr_data['count'][$ci]) || ($curr_data['count'][$ci] == 0)) {
					$curr_data['count'][$ci] = 0;
					$curr_data['shift_min'][$ci] = 0;
					$curr_data['shift_max'][$ci] = 0;
					$curr_data['shift_avg'][$ci] = 0;
					$cj++;
					continue;
				}

				if ($cj == 0) {
					continue;
				}

				$dx = $cj + 1;
				$first_idx = $ci - $dx;

				if ($first_idx < 0) {
					$first_idx = $ci; // if no data from start of graph get current data as first data
				}

				for(; $cj > 0; $cj--) {
					if ($dx < ($this->sizeX / 20) && $this->type == GRAPH_TYPE_STACKED) {
						$curr_data['count'][$ci - ($dx - $cj)] = 1;
					}

					foreach (['clock', 'min', 'max', 'avg'] as $var_name) {
						$var = &$curr_data[$var_name];

						if ($first_idx == $ci && $var_name == 'clock') {
							$var[$ci - ($dx - $cj)] = $var[$first_idx] - (($p / $this->sizeX) * ($dx - $cj));
							continue;
						}

						$dy = $var[$ci] - $var[$first_idx];
						$var[$ci - ($dx - $cj)] = bcadd($var[$first_idx] , bcdiv(($cj * $dy) , $dx));
					}
				}
			}

			if ($cj > 0 && $ci > $cj) {
				$dx = $cj + 1;
				$first_idx = $ci - $dx;

				for(;$cj > 0; $cj--) {
					foreach (['clock', 'min', 'max', 'avg'] as $var_name) {
						$var = &$curr_data[$var_name];

						if ($var_name == 'clock') {
							$var[$first_idx + ($dx - $cj)] = $var[$first_idx] + (($p / $this->sizeX) * ($dx - $cj));
							continue;
						}
						$var[$first_idx + ($dx - $cj)] = $var[$first_idx];
					}
				}
			}
		}

		// calculate shift for stacked graphs
		if ($this->type == GRAPH_TYPE_STACKED) {
			for ($i = 1; $i < $this->num; $i++) {
				$curr_data = &$this->data[$this->items[$i]['itemid']][$this->items[$i]['calc_type']];

				if (!isset($curr_data)) {
					continue;
				}

				for ($j = $i - 1; $j >= 0; $j--) {
					if ($this->items[$j]['axisside'] != $this->items[$i]['axisside']) {
						continue;
					}

					$prev_data = &$this->data[$this->items[$j]['itemid']][$this->items[$j]['calc_type']];

					if (!isset($prev_data)) {
						continue;
					}

					for ($ci = 0; $ci < $this->sizeX; $ci++) {
						foreach (['min', 'max', 'avg'] as $var_name) {
							$shift_var_name = 'shift_'.$var_name;
							$curr_shift = &$curr_data[$shift_var_name];
							$curr_var = &$curr_data[$var_name];
							$prev_shift = &$prev_data[$shift_var_name];
							$prev_var = &$prev_data[$var_name];
							$curr_shift[$ci] = $prev_var[$ci] + $prev_shift[$ci];
						}
					}
					break;
				}
			}
		}
	}

	/********************************************************************************************************/
	// CALCULATIONS
	/********************************************************************************************************/
	protected function calcTriggers() {
		$this->triggers = [];
		if ($this->m_showTriggers != 1) {
			return;
		}

		$max = 3;
		$cnt = 0;

		foreach ($this->items as $inum => $item) {
			$db_triggers = DBselect(
				'SELECT DISTINCT h.host,tr.description,tr.triggerid,tr.expression,tr.priority,tr.value'.
				' FROM triggers tr,functions f,items i,hosts h'.
				' WHERE tr.triggerid=f.triggerid'.
					" AND f.function IN ('last','min','avg','max')".
					' AND tr.status='.TRIGGER_STATUS_ENABLED.
					' AND i.itemid=f.itemid'.
					' AND h.hostid=i.hostid'.
					' AND f.itemid='.zbx_dbstr($item['itemid']).
				' ORDER BY tr.priority'
			);
			while (($trigger = DBfetch($db_triggers)) && $cnt < $max) {
				$db_fnc_cnt = DBselect(
					'SELECT COUNT(*) AS cnt'.
					' FROM functions f'.
					' WHERE f.triggerid='.zbx_dbstr($trigger['triggerid'])
				);
				$fnc_cnt = DBfetch($db_fnc_cnt);

				if ($fnc_cnt['cnt'] != 1) {
					continue;
				}

				$trigger['expression'] = CMacrosResolverHelper::resolveTriggerExpressionUserMacro($trigger);

				if (!preg_match(
					'/^\{([0-9]+)\}\s*?([<>=]|[<>][=])\s*?([\-0-9\.]+)(['.ZBX_BYTE_SUFFIXES.ZBX_TIME_SUFFIXES.']?)$/',
						$trigger['expression'], $arr)) {
					continue;
				}

				$val = convert($arr[3].$arr[4]);

				$minY = $this->m_minY[$this->items[$inum]['axisside']];
				$maxY = $this->m_maxY[$this->items[$inum]['axisside']];

				$this->triggers[] = [
					'skipdraw' => ($val <= $minY || $val >= $maxY),
					'y' => $this->sizeY - (($val - $minY) / ($maxY - $minY)) * $this->sizeY + $this->shiftY,
					'color' => getSeverityColor($trigger['priority']),
					'description' => _('Trigger').NAME_DELIMITER.CMacrosResolverHelper::resolveTriggerName($trigger),
					'constant' => '['.$arr[2].' '.$arr[3].$arr[4].']'
				];
				++$cnt;
			}
		}
	}

	// calculates percentages for left & right Y axis
	protected function calcPercentile() {
		if ($this->type != GRAPH_TYPE_NORMAL) {
			return ;
		}

		$values = [
			'left' => [],
			'right'=> []
		];

		$maxX = $this->sizeX;

		// for each metric
		for ($item = 0; $item < $this->num; $item++) {
			$data = &$this->data[$this->items[$item]['itemid']][$this->items[$item]['calc_type']];

			if (!isset($data)) {
				continue;
			}

			// for each X
			for ($i = 0; $i < $maxX; $i++) { // new point
				if ($data['count'][$i] == 0 && $i != ($maxX - 1)) {
					continue;
				}

				$min = $data['min'][$i];
				$max = $data['max'][$i];
				$avg = $data['avg'][$i];

				switch ($this->items[$item]['calc_fnc']) {
					case CALC_FNC_MAX:
						$value = $max;
						break;
					case CALC_FNC_MIN:
						$value = $min;
						break;
					case CALC_FNC_ALL:
					case CALC_FNC_AVG:
					default:
						$value = $avg;
				}

				if ($this->items[$item]['axisside'] == GRAPH_YAXIS_SIDE_LEFT) {
					$values['left'][] = $value;
				}
				else {
					$values['right'][] = $value;
				}
			}
		}

		foreach ($this->percentile as $side => $percentile) {
			if ($percentile['percent'] > 0 && !empty($values[$side])) {
				sort($values[$side]);
				// Using "Nearest Rank" method: http://en.wikipedia.org/wiki/Percentile#Definition_of_the_Nearest_Rank_method
				$percent = (int) ceil($percentile['percent'] / 100 * count($values[$side]));
				// - 1 is necessary because array starts with the 0 index
				$this->percentile[$side]['value'] = $values[$side][$percent - 1];
				unset($values[$side]);
			}
		}
	}

	// calculation of minimum Y axis
	protected function calculateMinY($side) {
		if ($this->ymin_type == GRAPH_YAXIS_TYPE_FIXED) {
			return $this->yaxismin;
		}

		if ($this->ymin_type == GRAPH_YAXIS_TYPE_ITEM_VALUE) {
			$item = get_item_by_itemid($this->ymin_itemid);
			$history = Manager::History()->getLast([$item]);
			if (isset($history[$item['itemid']])) {
				return $history[$item['itemid']][0]['value'];
			}
		}

		$minY = null;
		for ($i = 0; $i < $this->num; $i++) {
			if ($this->items[$i]['axisside'] != $side) {
				continue;
			}

			if (!isset($this->data[$this->items[$i]['itemid']][GRAPH_ITEM_SIMPLE])) {
				continue;
			}

			$data = &$this->data[$this->items[$i]['itemid']][GRAPH_ITEM_SIMPLE];

			if (!isset($data)) {
				continue;
			}

			$calc_fnc = $this->items[$i]['calc_fnc'];

			switch ($calc_fnc) {
				case CALC_FNC_ALL:
				case CALC_FNC_MIN:
					$val = $data['min'];
					$shift_val = $data['shift_min'];
					break;
				case CALC_FNC_MAX:
					$val = $data['max'];
					$shift_val = $data['shift_max'];
					break;
				case CALC_FNC_AVG:
				default:
					$val = $data['avg'];
					$shift_val = $data['shift_avg'];
			}

			if (!isset($val)) {
				continue;
			}

			if ($this->type == GRAPH_TYPE_STACKED) {
				$min_val_shift = min(count($val), count($shift_val));
				for ($ci = 0; $ci < $min_val_shift; $ci++) {
					if ($shift_val[$ci] < 0) {
						$val[$ci] += bcadd($shift_val[$ci], $val[$ci]);
					}
				}
			}

			if (!isset($minY)) {
				if (isset($val) && count($val) > 0) {
					$minY = min($val);
				}
			}
			else {
				$minY = min($minY, min($val));
			}
		}

		return $minY;
	}

	// calculation of maximum Y of a side (left/right)
	protected function calculateMaxY($side) {
		if ($this->ymax_type == GRAPH_YAXIS_TYPE_FIXED) {
			return $this->yaxismax;
		}

		if ($this->ymax_type == GRAPH_YAXIS_TYPE_ITEM_VALUE) {
			$item = get_item_by_itemid($this->ymax_itemid);
			$history = Manager::History()->getLast([$item]);
			if (isset($history[$item['itemid']])) {
				return $history[$item['itemid']][0]['value'];
			}
		}

		$maxY = null;
		for ($i = 0; $i < $this->num; $i++) {
			if ($this->items[$i]['axisside'] != $side) {
				continue;
			}

			if (!isset($this->data[$this->items[$i]['itemid']][GRAPH_ITEM_SIMPLE])) {
				continue;
			}

			$data = &$this->data[$this->items[$i]['itemid']][GRAPH_ITEM_SIMPLE];

			if (!isset($data)) {
				continue;
			}

			$calc_fnc = $this->items[$i]['calc_fnc'];

			switch ($calc_fnc) {
				case CALC_FNC_ALL:
				case CALC_FNC_MAX:
					$val = $data['max'];
					$shift_val = $data['shift_max'];
					break;
				case CALC_FNC_MIN:
					$val = $data['min'];
					$shift_val = $data['shift_min'];
					break;
				case CALC_FNC_AVG:
				default:
					$val = $data['avg'];
					$shift_val = $data['shift_avg'];
			}

			if (!isset($val)) {
				continue;
			}

			for ($ci = 0; $ci < min(count($val), count($shift_val)); $ci++) {
				if ($data['count'][$ci] == 0) {
					continue;
				}

				$val[$ci] = bcadd($shift_val[$ci], $val[$ci]);
			}

			if (!isset($maxY)) {
				if (isset($val) && count($val) > 0) {
					$maxY = max($val);
				}
			}
			else {
				$maxY = max($maxY, max($val));
			}
		}

		return $maxY;
	}

	/**
	 * Check if Y axis min value is larger than Y axis max value. Show error instead of graph if true.
	 *
	 * @param float $min		Y axis min value
	 * @param float $max		Y axis max value
	 */
	protected function validateMinMax($min, $max) {
		if (bccomp($min, $max) == 0 || bccomp($min, $max) == 1) {
			show_error_message(_('Y axis MAX value must be greater than Y axis MIN value.'));
			exit;
		}
	}

	protected function calcZero() {
		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_RIGHT])) {
			$sides[] = GRAPH_YAXIS_SIDE_RIGHT;
		}

		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_LEFT]) || !isset($sides)) {
			$sides[] = GRAPH_YAXIS_SIDE_LEFT;
		}

		foreach ($sides as $num => $side) {
			$this->unit2px[$side] = ($this->m_maxY[$side] - $this->m_minY[$side]) / $this->sizeY;
			if ($this->unit2px[$side] == 0) {
				$this->unit2px[$side] = 1;
			}

			if ($this->m_minY[$side] > 0) {
				$this->zero[$side] = $this->sizeY + $this->shiftY;
				if (bccomp($this->m_minY[$side], $this->m_maxY[$side]) == 1) {
					$this->oxy[$side] = $this->m_maxY[$side];
				}
				else {
					$this->oxy[$side] = $this->m_minY[$side];
				}
			}
			elseif ($this->m_maxY[$side] < 0) {
				$this->zero[$side] = $this->shiftY;
				if (bccomp($this->m_minY[$side], $this->m_maxY[$side]) == 1) {
					$this->oxy[$side] = $this->m_minY[$side];
				}
				else {
					$this->oxy[$side] = $this->m_maxY[$side];
				}
			}
			else {
				$this->zero[$side] = $this->sizeY + $this->shiftY - abs(bcdiv($this->m_minY[$side],
					$this->unit2px[$side]
				));
				$this->oxy[$side] = 0;
			}
		}
	}

	protected function calcMinMaxInterval() {
		// init intervals
		$intervals = [];
		foreach ([1, 2, 3, 4] as $num) {
			$dec = pow(0.1, $num);
			foreach ([1, 2, 5] as $int) {
				$intervals[] = bcmul($int, $dec);
			}
		}

		// check if items use B or Bps units
		$leftBase1024 = false;
		$rightBase1024 = false;

		for ($item = 0; $item < $this->num; $item++) {
			if ($this->items[$item]['units'] == 'B' || $this->items[$item]['units'] == 'Bps') {
				if ($this->items[$item]['axisside'] == GRAPH_YAXIS_SIDE_LEFT) {
					$leftBase1024 = true;
				}
				else {
					$rightBase1024 = true;
				}
			}
		}

		foreach ([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18] as $num) {
			$dec = bcpow(10, $num);
			foreach ([1, 2, 5] as $int) {
				$intervals[] = bcmul($int, $dec);
			}
		}

		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_RIGHT])) {
			$sides[] = GRAPH_YAXIS_SIDE_RIGHT;
		}

		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_LEFT]) || !isset($sides)) {
			$sides[] = GRAPH_YAXIS_SIDE_LEFT;
		}

		foreach ($sides as $snum => $side) {
			if (!isset($this->axis_valuetype[$side])) {
				continue;
			}

			if (($this->ymin_type != GRAPH_YAXIS_TYPE_FIXED || $this->ymax_type != GRAPH_YAXIS_TYPE_CALCULATED)
					&& $this->type == GRAPH_TYPE_STACKED) {
				$this->m_minY[$side] = min($this->m_minY[$side], 0);
				$this->validateMinMax($this->m_minY[$side], $this->m_maxY[$side]);

				continue;
			}

			if ($this->ymax_type == GRAPH_YAXIS_TYPE_FIXED) {
				$this->m_maxY[$side] = $this->yaxismax;
				if ($this->ymin_type == GRAPH_YAXIS_TYPE_CALCULATED
						&& ($this->m_minY[$side] == null || bccomp($this->m_maxY[$side], $this->m_minY[$side]) == 0
								|| bccomp($this->m_maxY[$side], $this->m_minY[$side]) == -1)) {
					if ($this->m_maxY[$side] == 0) {
						$this->m_minY[$side] = -1;
					}
					elseif ($this->m_maxY[$side] > 0) {
						$this->m_minY[$side] = bcmul($this->m_maxY[$side], 0.8);
					}
					else {
						$this->m_minY[$side] = bcmul($this->m_maxY[$side], 1.2);
					}
				}
			}

			if ($this->ymin_type == GRAPH_YAXIS_TYPE_FIXED) {
				$this->m_minY[$side] = $this->yaxismin;
				if ($this->ymax_type == GRAPH_YAXIS_TYPE_CALCULATED
						&& ($this->m_maxY[$side] == null || bccomp($this->m_maxY[$side], $this->m_minY[$side]) == 0
								|| bccomp($this->m_maxY[$side], $this->m_minY[$side]) == -1)) {
					if ($this->m_minY[$side] > 0) {
						$this->m_maxY[$side] = bcmul($this->m_minY[$side], 1.2);
					}
					else {
						$this->m_maxY[$side] = bcmul($this->m_minY[$side], 0.8);
					}
				}
			}

			$this->validateMinMax($this->m_minY[$side], $this->m_maxY[$side]);
		}

		$side = GRAPH_YAXIS_SIDE_LEFT;
		$other_side = GRAPH_YAXIS_SIDE_RIGHT;

		// invert sides and it bases, if left side not exist
		if (!isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_LEFT])) {
			$side = GRAPH_YAXIS_SIDE_RIGHT;
			$other_side = GRAPH_YAXIS_SIDE_LEFT;
			$tempBase = $leftBase1024;
			$leftBase1024 = $rightBase1024;
			$rightBase1024 = $tempBase;
		}

		if (!isset($this->m_minY[$side])) {
			$this->m_minY[$side] = 0;
		}
		if (!isset($this->m_maxY[$side])) {
			$this->m_maxY[$side] = 0;
		}

		if (!isset($this->m_minY[$other_side])) {
			$this->m_minY[$other_side] = 0;
		}
		if (!isset($this->m_maxY[$other_side])) {
			$this->m_maxY[$other_side] = 0;
		}

		$tmp_minY = $this->m_minY;
		$tmp_maxY = $this->m_maxY;

		// calc interval
		$columnInterval = bcdiv(bcmul($this->gridPixelsVert, (bcsub($this->m_maxY[$side], $this->m_minY[$side]))), $this->sizeY);

		$dist = bcmul(5, bcpow(10, 18));

		$interval = 0;
		foreach ($intervals as $int) {
			// we must get a positive number
			if (bccomp($int, $columnInterval) == -1) {
				$t = bcsub($columnInterval, $int);
			}
			else {
				$t = bcsub($int, $columnInterval);
			}

			if (bccomp($t, $dist) == -1) {
				$dist = $t;
				$interval = $int;
			}
		}

		// calculate interval, if left side use B or Bps
		if ($leftBase1024) {
			$interval = getBase1024Interval($interval, $this->m_minY[$side], $this->m_maxY[$side]);
		}

		$columnInterval = bcdiv(bcmul($this->gridPixelsVert, bcsub($this->m_maxY[$other_side], $this->m_minY[$other_side])), $this->sizeY);

		$dist = bcmul(5, bcpow(10, 18));

		$interval_other_side = 0;
		foreach ($intervals as $int) {
			// we must get a positive number
			if (bccomp($int, $columnInterval) == -1) {
				$t = bcsub($columnInterval, $int);
			}
			else {
				$t = bcsub($int, $columnInterval);
			}

			if (bccomp($t,$dist) == -1) {
				$dist = $t;
				$interval_other_side = $int;
			}
		}

		// calculate interval, if right side use B or Bps
		if ($rightBase1024) {
			$interval_other_side = getBase1024Interval($interval_other_side, $this->m_minY[$other_side],
				$this->m_maxY[$other_side]);
		}

		// save original min and max items values
		foreach ($sides as $graphSide) {
			$minY[$graphSide] = $this->m_minY[$graphSide];
			$maxY[$graphSide] = $this->m_maxY[$graphSide];
		}

		if (!isset($minY[$side])) {
			$minY[$side] = 0;
		}
		if (!isset($maxY[$side])) {
			$maxY[$side] = 0;
		}

		// correcting MIN & MAX
		$this->m_minY[$side] = bcmul(bcfloor(bcdiv($this->m_minY[$side], $interval)), $interval);
		$this->m_maxY[$side] = bcmul(bcceil(bcdiv($this->m_maxY[$side], $interval)), $interval);
		$this->m_minY[$other_side] = bcmul(bcfloor(bcdiv($this->m_minY[$other_side], $interval_other_side)), $interval_other_side);
		$this->m_maxY[$other_side] = bcmul(bcceil(bcdiv($this->m_maxY[$other_side], $interval_other_side)), $interval_other_side);

		// add intervals so min/max Y wouldn't be at the top
		foreach ($sides as $graphSide) {
			if ($graphSide == $side) {
				$tmpInterval = $interval;
			}
			else {
				$tmpInterval = $interval_other_side;
			}

			if (bccomp($this->m_minY[$graphSide], $minY[$side]) == 0
					&& $this->m_minY[$graphSide] != null && $this->m_minY[$graphSide] != 0) {
				$this->m_minY[$graphSide] = bcsub($this->m_minY[$graphSide], $tmpInterval);
			}

			if (bccomp($this->m_maxY[$graphSide], $maxY[$graphSide]) == 0
					&& $this->m_maxY[$graphSide] != null && $this->m_maxY[$graphSide] != 0) {
				$this->m_maxY[$graphSide] = bcadd($this->m_maxY[$graphSide], $tmpInterval);
			}
		}

		// calculate interval count for main and other side
		$this->gridLinesCount[$side] = bcceil(bcdiv(bcsub($this->m_maxY[$side], $this->m_minY[$side]), $interval));
		$this->gridLinesCount[$other_side] = bcceil(bcdiv(bcsub($this->m_maxY[$other_side], $this->m_minY[$other_side]), $interval_other_side));

		$this->m_maxY[$side] = bcadd($this->m_minY[$side], bcmul($interval, $this->gridLinesCount[$side]));
		$this->gridStep[$side] = $interval;

		if (isset($this->axis_valuetype[$other_side])) {
			// other side correction
			$dist = bcsub($this->m_maxY[$other_side], $this->m_minY[$other_side]);
			$interval = 1;

			foreach ($intervals as $int) {
				if (bccomp($dist, bcmul($this->gridLinesCount[$side], $int)) == -1) {
					$interval = $int;
					break;
				}
			}

			// correcting MIN & MAX
			$this->m_minY[$other_side] = bcmul(bcfloor(bcdiv($this->m_minY[$other_side], $interval)), $interval);
			$this->m_maxY[$other_side] = bcmul(bcceil(bcdiv($this->m_maxY[$other_side], $interval)), $interval);

			// if we lowered min more than highed max - need additional recalculating
			if (bccomp($tmp_maxY[$other_side], $this->m_maxY[$other_side]) == 1 || bccomp($tmp_minY[$other_side], $this->m_minY[$other_side]) == -1) {
				$dist = bcsub($this->m_maxY[$other_side], $this->m_minY[$other_side]);
				$interval = 0;
				foreach ($intervals as $int) {
					if (bccomp($dist, bcmul($this->gridLinesCount[$side], $int)) == -1) {
						$interval = $int;
						break;
					}
				}

				// recorrecting MIN & MAX
				$this->m_minY[$other_side] = bcmul(bcfloor(bcdiv($this->m_minY[$other_side], $interval)), $interval);
				$this->m_maxY[$other_side] = bcmul(bcceil(bcdiv($this->m_maxY[$other_side], $interval)), $interval);
			}

			// calculate interval, if right side use B or Bps
			if (isset($rightBase1024)) {
				$interval = getBase1024Interval($interval, $this->m_minY[$side], $this->m_maxY[$side]);
				// recorrecting MIN & MAX
				$this->m_minY[$other_side] = bcmul(bcfloor(bcdiv($this->m_minY[$other_side], $interval)), $interval);
				$this->m_maxY[$other_side] = bcmul(bcceil(bcdiv($this->m_maxY[$other_side], $interval)), $interval);
			}

			$this->gridLinesCount[$other_side] = $this->gridLinesCount[$side];
			$this->m_maxY[$other_side] = bcadd($this->m_minY[$other_side], bcmul($interval, $this->gridLinesCount[$other_side]));
			$this->gridStep[$other_side] = $interval;
		}

		foreach ($sides as $graphSide) {
			if (!isset($this->axis_valuetype[$graphSide])) {
				continue;
			}

			if ($this->type == GRAPH_TYPE_STACKED) {
				$this->m_minY[$graphSide] = bccomp($tmp_minY[GRAPH_YAXIS_SIDE_LEFT], 0) == -1 ? $tmp_minY[GRAPH_YAXIS_SIDE_LEFT] : 0;
			}

			if ($this->ymax_type == GRAPH_YAXIS_TYPE_FIXED) {
				$this->m_maxY[$graphSide] = $this->yaxismax;
			}
			elseif ($this->ymax_type == GRAPH_YAXIS_TYPE_ITEM_VALUE) {
				$this->m_maxY[$graphSide] = $tmp_maxY[$graphSide];
			}

			if ($this->ymin_type == GRAPH_YAXIS_TYPE_FIXED) {
				$this->m_minY[$graphSide] = $this->yaxismin;
			}
			elseif ($this->ymin_type == GRAPH_YAXIS_TYPE_ITEM_VALUE) {
				$this->m_minY[$graphSide] = $tmp_minY[$graphSide];
			}

			$this->validateMinMax($this->m_minY[$graphSide], $this->m_maxY[$graphSide]);
		}

		// division by zero
		$diff_val = bcsub($this->m_maxY[$side], $this->m_minY[$side]);
		if (bccomp($diff_val, 0) == 0) {
			$diff_val = 1;
		}

		$this->gridStepX[$side] = bcdiv(bcmul($this->gridStep[$side], $this->sizeY), $diff_val);

		if (isset($this->axis_valuetype[$other_side])) {
			$diff_val = bcsub($this->m_maxY[$other_side], $this->m_minY[$other_side]);
			if (bccomp($diff_val, 0) == 0) {
				$diff_val = 1;
			}
			$this->gridStepX[$other_side] = bcdiv(bcmul($this->gridStep[$other_side], $this->sizeY), $diff_val);
		}
	}

	/********************************************************************************************************/
	// DRAW ELEMENTS
	/********************************************************************************************************/
	public function drawXYAxisScale() {
		$gbColor = $this->getColor($this->graphtheme['gridbordercolor'], 0);

		if ($this->yaxisleft) {
			zbx_imageline(
				$this->im,
				$this->shiftXleft + $this->shiftXCaption,
				$this->shiftY - 5,
				$this->shiftXleft + $this->shiftXCaption,
				$this->sizeY + $this->shiftY + 4,
				$gbColor
			);

			imagefilledpolygon(
				$this->im,
				[
					$this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
					$this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
					$this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
				],
				3,
				$this->getColor('White')
			);

			/* draw left axis triangle */
			zbx_imageline($this->im, $this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
					$this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
					$gbColor);
			zbx_imagealine($this->im, $this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
					$this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
					$gbColor);
			zbx_imagealine($this->im, $this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
					$this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
					$gbColor);
		}
		else {
			dashedLine(
				$this->im,
				$this->shiftXleft + $this->shiftXCaption,
				$this->shiftY,
				$this->shiftXleft + $this->shiftXCaption,
				$this->sizeY + $this->shiftY,
				$this->getColor($this->graphtheme['gridcolor'], 0)
			);
		}

		if ($this->yaxisright) {
			zbx_imageline(
				$this->im,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption,
				$this->shiftY - 5,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption,
				$this->sizeY + $this->shiftY + 4,
				$gbColor
			);

			imagefilledpolygon(
				$this->im,
				[
					$this->sizeX + $this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
					$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
					$this->sizeX + $this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
				],
				3,
				$this->getColor('White')
			);

			/* draw right axis triangle */
			zbx_imageline($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
				$gbColor);
			zbx_imagealine($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption + 3, $this->shiftY - 5,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
				$gbColor);
			zbx_imagealine($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption - 3, $this->shiftY - 5,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption, $this->shiftY - 10,
				$gbColor);
		}
		else {
			dashedLine(
				$this->im,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption,
				$this->shiftY,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption,
				$this->sizeY + $this->shiftY,
				$this->getColor($this->graphtheme['gridcolor'], 0)
			);
		}

		zbx_imageline(
			$this->im,
			$this->shiftXleft + $this->shiftXCaption - 3,
			$this->sizeY + $this->shiftY + 1,
			$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5,
			$this->sizeY + $this->shiftY + 1,
			$gbColor
		);

		imagefilledpolygon(
			$this->im,
			[
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY - 2,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY + 4,
				$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 10, $this->sizeY + $this->shiftY + 1
			],
			3,
			$this->getColor('White')
		);

		/* draw X axis triangle */
		zbx_imageline($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY - 2,
			$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY + 4,
			$gbColor);
		zbx_imagealine($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY + 4,
			$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 10, $this->sizeY + $this->shiftY + 1,
			$gbColor);
		zbx_imagealine($this->im, $this->sizeX + $this->shiftXleft + $this->shiftXCaption + 10, $this->sizeY + $this->shiftY + 1,
			$this->sizeX + $this->shiftXleft + $this->shiftXCaption + 5, $this->sizeY + $this->shiftY - 2,
			$gbColor);
	}

	/**
	 * Draws Y scale grid.
	 */
	private function drawHorizontalGrid() {
		$yAxis = $this->yaxisleft ? GRAPH_YAXIS_SIDE_LEFT : GRAPH_YAXIS_SIDE_RIGHT;

		$stepY = $this->gridStepX[$yAxis];

		if ($this->gridLinesCount[$yAxis] < round($this->sizeY / $this->gridPixels)) {
			$stepY = $stepY / 2;
		}

		$xLeft = $this->shiftXleft;
		$xRight = $this->shiftXleft + $this->sizeX;
		$lineColor = $this->getColor($this->graphtheme['gridcolor'], 0);

		for ($y = $this->shiftY + $this->sizeY - $stepY; $y > $this->shiftY; $y -= $stepY) {
			dashedLine($this->im, $xLeft, $y, $xRight, $y, $lineColor);
		}
	}

	private function drawTimeGrid() {
		$time_format = (date('Y', $this->stime) != date('Y', $this->to_time))
			? DATE_FORMAT
			: DATE_TIME_FORMAT_SHORT;

		// Draw start date (and time) label.
		$this->drawStartEndTimePeriod($this->stime, $time_format, 0);

		$this->calculateTimeInterval();
		$this->drawDateTimeIntervals();

		// Draw end date (and time) label.
		$this->drawStartEndTimePeriod($this->to_time, $time_format, $this->sizeX);
	}

	/**
	 * Draw start or end date (and time) label.
	 *
	 * @param int $value		Unix time.
	 * @param sring $format		Date time format.
	 * @param int $position		Position on X axis.
	 */
	private function drawStartEndTimePeriod($value, $format, $position) {
		$point = zbx_date2str(_($format), $value);
		$element = imageTextSize(8, 90, $point);
		imageText(
			$this->im,
			8,
			90,
			$this->shiftXleft + $position + round($element['width'] / 2),
			$this->sizeY + $this->shiftY + $element['height'] + 6,
			$this->getColor($this->graphtheme['highlightcolor'], 0),
			$point
		);
	}

	/**
	 * Draw main period label in red color with 8px font size under X axis and a 2px dashed gray vertical line
	 * according to that label.
	 *
	 * @param string $value     Readable timestamp.
	 * @param int    $position  Position on X axis.
	 */
	private function drawMainPeriod($value, $position) {
		$dims = imageTextSize(8, 90, $value);

		imageText(
			$this->im,
			8,
			90,
			$this->shiftXleft + $position + round($dims['width'] / 2),
			$this->sizeY + $this->shiftY + $dims['height'] + 6,
			$this->getColor($this->graphtheme['highlightcolor'], 0),
			$value
		);

		dashedLine(
			$this->im,
			$this->shiftXleft + $position,
			$this->shiftY,
			$this->shiftXleft + $position,
			$this->sizeY + $this->shiftY,
			$this->getColor($this->graphtheme['maingridcolor'], 0)
		);
	}

	/**
	 * Draw main period label in black color with 7px font size under X axis and a 1px dashed gray vertical line
	 * according to that label.
	 *
	 * @param strimg $value     Readable timestamp.
	 * @param int    $position  Position on X axis.
	 */
	private function drawSubPeriod($value, $position) {
		$element = imageTextSize(7, 90, $value);

		imageText(
			$this->im,
			7,
			90,
			$this->shiftXleft + $position + round($element['width'] / 2),
			$this->sizeY + $this->shiftY + $element['height'] + 6,
			$this->getColor($this->graphtheme['textcolor'], 0),
			$value
		);

		dashedLine(
			$this->im,
			$this->shiftXleft + $position,
			$this->shiftY,
			$this->shiftXleft + $position,
			$this->sizeY + $this->shiftY,
			$this->getColor($this->graphtheme['gridcolor'], 0)
		);
	}

	/**
	 * Calculates the optimal size of time interval.
	 */
	private function calculateTimeInterval() {
		$time_interval = ($this->gridPixels * $this->period) / $this->sizeX;
		$intervals = [
			['main' => SEC_PER_MIN, 'sub' => SEC_PER_MIN / 60],			// minute and 1 second
			['main' => SEC_PER_MIN, 'sub' => SEC_PER_MIN / 12],			// minute and 5 seconds
			['main' => SEC_PER_MIN, 'sub' => SEC_PER_MIN / 6],			// 1 minute and 10 seconds
			['main' => SEC_PER_MIN, 'sub' => SEC_PER_MIN / 2],			// 1 minute and 30 seconds
			['main' => SEC_PER_HOUR, 'sub' => SEC_PER_MIN],				// 1 hour and 1 minute
			['main' => SEC_PER_HOUR, 'sub' => SEC_PER_MIN * 2],			// 1 hour and 2 minutes
			['main' => SEC_PER_HOUR, 'sub' => SEC_PER_MIN * 5],			// 1 hour and 5 minutes
			['main' => SEC_PER_HOUR, 'sub' => SEC_PER_MIN * 15],		// 1 hour and 15 minutes
			['main' => SEC_PER_HOUR, 'sub' => SEC_PER_MIN * 30],		// 1 hour and 30 minutes
			['main' => SEC_PER_DAY, 'sub' => SEC_PER_HOUR],				// 1 day and 1 hours
			['main' => SEC_PER_DAY, 'sub' => SEC_PER_HOUR * 3],			// 1 day and 3 hours
			['main' => SEC_PER_DAY, 'sub' => SEC_PER_HOUR * 6],			// 1 day and 6 hours
			['main' => SEC_PER_DAY, 'sub' => SEC_PER_HOUR * 12],		// 1 day and 12 hours
			['main' => SEC_PER_WEEK, 'sub' => SEC_PER_DAY],				// 1 week and 1 day
			['main' => SEC_PER_MONTH, 'sub' => SEC_PER_WEEK],			// 1 month and 1 week
			['main' => SEC_PER_MONTH, 'sub' => SEC_PER_WEEK * 2],		// 1 month and 2 weeks
			['main' => SEC_PER_YEAR, 'sub' => SEC_PER_MONTH],			// 1 year and 30 days
			['main' => SEC_PER_YEAR, 'sub' => SEC_PER_MONTH * 3],		// 1 year and 90 days
			['main' => SEC_PER_YEAR, 'sub' => SEC_PER_MONTH * 4],		// 1 year and 120 days
			['main' => SEC_PER_YEAR, 'sub' => SEC_PER_MONTH * 6],		// 1 year and 180 days
			['main' => SEC_PER_YEAR * 5, 'sub' => SEC_PER_YEAR],		// 5 years and 1 year
			['main' => SEC_PER_YEAR * 10, 'sub' => SEC_PER_YEAR * 2],	// 10 years and 2 years
			['main' => SEC_PER_YEAR * 15, 'sub' => SEC_PER_YEAR * 3],	// 15 years and 3 years
			['main' => SEC_PER_YEAR * 20, 'sub' => SEC_PER_YEAR * 5],	// 20 years and 5 years
			['main' => SEC_PER_YEAR * 30, 'sub' => SEC_PER_YEAR * 10],	// 30 years and 10 years
			['main' => SEC_PER_YEAR * 40, 'sub' => SEC_PER_YEAR * 20],	// 40 years and 20 years
			['main' => SEC_PER_YEAR * 60, 'sub' => SEC_PER_YEAR * 30],	// 60 years and 30 years
			['main' => SEC_PER_YEAR * 80, 'sub' => SEC_PER_YEAR * 40]	// 80 years and 40 years
		];

		// Default inteval values.
		$distance = SEC_PER_YEAR * 5;
		$this->grid['horizontal']['main']['interval'] = 0;
		$this->grid['horizontal']['sub']['interval'] = 0;

		foreach ($intervals as $interval) {
			$time = abs($interval['sub'] - $time_interval);

			if ($time < $distance) {
				$distance = $time;
				$this->grid['horizontal']['main']['interval'] = $interval['main'];
				$this->grid['horizontal']['sub']['interval'] = $interval['sub'];
			}
		}
	}

	/**
	 * Draw date and time intervals under the X axis.
	 */
	private function drawDateTimeIntervals() {
		$interval['sub'] = $this->grid['horizontal']['sub']['interval'];
		$interval['main'] = $this->grid['horizontal']['main']['interval'];

		// Sub interval title size.
		$element_size = imageTextSize(7, 90, 'WWW');

		$position = 0;
		$dt = [];
		$modifier = [];
		$format = [];

		foreach (['main', 'sub'] as $type) {
			$dt[$type] = new DateTime();
			$dt[$type]->setTimestamp($this->stime);

			if ($interval[$type] >= SEC_PER_YEAR) {
				$years = $interval[$type] / SEC_PER_YEAR;
				$year = (int) $dt[$type]->format('Y');
				$dt[$type]->modify('first day of January this year 00:00:00 -'.($year % $years).' year');
				$modifier[$type] = '+ '.$years.' year';
				$format[$type] = _x('Y', DATE_FORMAT_CONTEXT);
			}
			elseif ($interval[$type] >= SEC_PER_MONTH) {
				$months = $interval[$type] / SEC_PER_MONTH;
				$month = (int) $dt[$type]->format('m');
				$dt[$type]->modify('first day of this month 00:00:00 -'.(($month - 1) % $months).' month');
				$modifier[$type] = '+ '.$months.' month';
				$format[$type] = ($type == 'main') ? _('m-d') : _('M');
			}
			elseif ($interval[$type] >= SEC_PER_WEEK) {
				$weeks = $interval[$type] / SEC_PER_WEEK;
				$week = (int) $dt[$type]->format('W');
				$day_of_week = (int) $dt[$type]->format('w');
				$dt[$type]->modify('today -'.(($week - 1) % $weeks).' week -'.$day_of_week.' day');
				$modifier[$type] = '+ '.$weeks.' week';
				$format[$type] = _('m-d');
			}
			elseif ($interval[$type] >= SEC_PER_DAY) {
				$days = $interval[$type] / SEC_PER_DAY;
				$day = (int) $dt[$type]->format('d');
				$dt[$type]->modify('today -'.(($day - 1) % $days).' day');
				$modifier[$type] = '+ '.$days.' day';
				$format[$type] = _('m-d');
			}
			elseif ($interval[$type] >= SEC_PER_HOUR) {
				$hours = $interval[$type] / SEC_PER_HOUR;
				$hour = (int) $dt[$type]->format('H');
				$minute = (int) $dt[$type]->format('i');
				$second = (int) $dt[$type]->format('s');
				$dt[$type]->modify('-'.($hour % $hours).' hour -'.$minute.' minute -'.$second.' second');
				$modifier[$type] = '+ '.$hours.' hour';
				$format[$type] = TIME_FORMAT;
			}
			elseif ($interval[$type] >= SEC_PER_MIN) {
				$minutes = $interval[$type] / SEC_PER_MIN;
				$minute = (int) $dt[$type]->format('i');
				$second = (int) $dt[$type]->format('s');
				$dt[$type]->modify('-'.($minute % $minutes).' minute -'.$second.' second');
				$modifier[$type] = '+ '.$minutes.' min';
				$format[$type] = ($type == 'main') ? _('H:i:s') : TIME_FORMAT;
			}
			else {
				$seconds = $interval[$type];
				$second = (int) $dt[$type]->format('s');
				$dt[$type]->modify('-'.($second % $seconds).' second');
				$modifier[$type] = '+ '.$seconds.' second';
				$format[$type] = _('H:i:s');
			}
		}

		// It is necessary to align the X axis after the jump from winter to summer time.
		$prev_dst = (bool) $dt['sub']->format('I');
		$dst_offset = $dt['sub']->getOffset();
		$do_align = false;

		$prev_time = $this->stime;
		if ($interval['main'] == SEC_PER_MONTH) {
			$dt_start = new DateTime();
			$dt_start->setTimestamp($this->stime);
			$prev_month = (int) $dt_start->format('m');
		}

		while (true) {
			$dt['sub']->modify($modifier['sub']);

			if (SEC_PER_HOUR < $interval['sub'] && $interval['sub'] < SEC_PER_DAY) {
				if ($do_align) {
					$hours = $interval['sub'] / SEC_PER_HOUR;
					$hour = (int) $dt['sub']->format('H');
					if ($hour % $hours) {
						$dt['sub']->modify($dst_offset.' second');
					}

					$do_align = false;
				}

				$dst = (bool) $dt['sub']->format('I');

				if ($dst && $prev_dst != $dst) {
					$dst_offset -= $dt['sub']->getOffset();
					$do_align = $interval['sub'] > abs($dst_offset);
					$prev_dst = $dst;
				}
			}

			if ($dt['main'] < $dt['sub']) {
				$dt['main']->modify($modifier['main']);
			}

			if ($interval['main'] == SEC_PER_MONTH) {
				$month = (int) $dt['sub']->format('m');

				$draw_main = ($month != $prev_month);
				$prev_month = $month;
			}
			else {
				$draw_main = ($dt['main'] == $dt['sub']);
			}
			$time = $dt['sub']->format('U');

			$delta_x = bcsub($time, $prev_time) * $this->sizeX / $this->period;
			$position += $delta_x;

			// First element overlaping check.
			if ($prev_time != $this->stime || $delta_x > $element_size['width']) {
				// Last element overlaping check.
				if ($position > $this->sizeX - $element_size['width']) {
					break;
				}

				if ($draw_main) {
					$this->drawMainPeriod($dt['sub']->format($format['main']), $position);
				}
				else {
					$this->drawSubPeriod($dt['sub']->format($format['sub']), $position);
				}
			}

			$prev_time = $time;
		}
	}

	private function drawSides() {
		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_RIGHT])
				&& ($this->yaxisright != 0 || $this->skipRightScale != 1)) {
			$sides[] = GRAPH_YAXIS_SIDE_RIGHT;
		}

		if (((isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_LEFT]))
				&& ($this->yaxisleft != 0 || $this->skipLeftScale != 1)) || !isset($sides)) {
			$sides[] = GRAPH_YAXIS_SIDE_LEFT;
		}

		foreach ($sides as $side) {
			$minY = $this->m_minY[$side];
			$maxY = $this->m_maxY[$side];
			$units = null;
			$unitsLong = null;
			$byteStep = false;

			for ($item = 0; $item < $this->num; $item++) {
				if ($this->items[$item]['axisside'] == $side) {
					// check if items use B or Bps units
					if ($this->items[$item]['units'] == 'B' || $this->items[$item]['units'] == 'Bps') {
						$byteStep = true;
					}
					if (is_null($units)) {
						$units = $this->items[$item]['units'];
					}
					elseif ($this->items[$item]['units'] != $units) {
						$units = '';
					}
				}
			}

			if (is_null($units) || $units === false) {
				$units = '';
			}
			else {
				for ($item = 0; $item < $this->num; $item++) {
					if ($this->items[$item]['axisside'] == $side && !empty($this->items[$item]['unitsLong'])) {
						$unitsLong = $this->items[$item]['unitsLong'];
						break;
					}
				}
			}

			if (!empty($unitsLong)) {
				$dims = imageTextSize(9, 90, $unitsLong);

				$tmpY = $this->sizeY / 2 + $this->shiftY + $dims['height'] / 2;
				if ($tmpY < $dims['height']) {
					$tmpY = $dims['height'] + 6;
				}

				$tmpX = $side == GRAPH_YAXIS_SIDE_LEFT ? $dims['width'] + 8 : $this->fullSizeX - $dims['width'];

				imageText(
					$this->im,
					9,
					90,
					$tmpX,
					$tmpY,
					$this->getColor($this->graphtheme['textcolor'], 0),
					$unitsLong
				);
			}

			$step = $this->gridStep[$side];
			$hstr_count = $this->gridLinesCount[$side];

			// ignore milliseconds if  -1 <= maxY => 1 or -1 <= minY => 1
			$ignoreMillisec = (bccomp($maxY, -1) <= 0 || bccomp($maxY, 1) >= 0
					|| bccomp($minY, -1) <= 0 || bccomp($minY, 1) >= 0);

			$newPow = false;
			if ($byteStep) {
				$maxYPow = convertToBase1024($maxY, 1024);
				$minYPow = convertToBase1024($minY, 1024);
				$powStep = 1024;
			} else {
				$maxYPow = convertToBase1024($maxY);
				$minYPow = convertToBase1024($minY);
				$powStep = 1000;
			}

			if (abs($maxYPow['pow']) > abs($minYPow['pow']) && $maxYPow['value'] != 0) {
				$newPow = $maxYPow['pow'];
				if (abs(bcdiv($minYPow['value'], bcpow($powStep, $maxYPow['pow']))) > 1000) {
					$newPow = $minYPow['pow'];
				}
			}
			if (abs($maxYPow['pow']) < abs($minYPow['pow']) && $minYPow['value'] != 0) {
				$newPow = $minYPow['pow'];
				if (abs(bcdiv($maxYPow['value'], bcpow($powStep, $minYPow['pow']))) > 1000) {
					$newPow = $maxYPow['pow'];
				}
			}
			if ($maxYPow['pow'] == $minYPow['pow']) {
				$newPow = $maxYPow['pow'];
			}

			$maxLength = false;
			// get all values in y-axis if units != 's'
			if ($units != 's') {
				$calcValues = [];
				for ($i = 0; $i <= $hstr_count; $i++) {
					$hstr_count = ($hstr_count == 0) ? 1 : $hstr_count;

					$val = bcadd(bcmul($i, $step), $minY);

					if (bccomp(bcadd($val, bcdiv($step,2)), $maxY) == 1) {
						continue;
					}

					$calcValues[] = convert_units([
						'value' => $val,
						'convert' => ITEM_CONVERT_NO_UNITS,
						'byteStep' => $byteStep,
						'pow' => $newPow
					]);
				}

				$calcValues[] = convert_units([
					'value' => $maxY,
					'convert' => ITEM_CONVERT_NO_UNITS,
					'byteStep' => $byteStep,
					'pow' => $newPow
				]);

				$maxLength = calcMaxLengthAfterDot($calcValues);
			}

			for ($i = 0; $i <= $hstr_count; $i++) {
				$hstr_count = ($hstr_count == 0) ? 1 : $hstr_count;

				$val = bcadd(bcmul($i, $step), $minY);

				if (bccomp(bcadd($val, bcdiv($step, 2)), $maxY) == 1) {
					continue;
				}

				$str = convert_units([
					'value' => $val,
					'units' => $units,
					'convert' => ITEM_CONVERT_NO_UNITS,
					'byteStep' => $byteStep,
					'pow' => $newPow,
					'ignoreMillisec' => $ignoreMillisec,
					'length' => $maxLength
				]);

				if ($side == GRAPH_YAXIS_SIDE_LEFT) {
					$dims = imageTextSize(8, 0, $str);
					$posX = $this->shiftXleft - $dims['width'] - 9;
				}
				else {
					$posX = $this->sizeX + $this->shiftXleft + 12;
				}

				// marker Y coordinate
				$posY = $this->sizeY + $this->shiftY - $this->gridStepX[$side] * $i + 4;

				imageText(
					$this->im,
					8,
					0,
					$posX,
					$posY,
					$this->getColor($this->graphtheme['textcolor'], 0),
					$str
				);
			}

			$str = convert_units([
				'value' => $maxY,
				'units' => $units,
				'convert' => ITEM_CONVERT_NO_UNITS,
				'byteStep' => $byteStep,
				'pow' => $newPow,
				'ignoreMillisec' => $ignoreMillisec,
				'length' => $maxLength
			]);

			if ($side == GRAPH_YAXIS_SIDE_LEFT) {
				$dims = imageTextSize(8, 0, $str);
				$posX = $this->shiftXleft - $dims['width'] - 9;
				$color = $this->getColor(GRAPH_ZERO_LINE_COLOR_LEFT);
			}
			else {
				$posX = $this->sizeX + $this->shiftXleft + 12;
				$color = $this->getColor(GRAPH_ZERO_LINE_COLOR_RIGHT);
			}

			imageText(
				$this->im,
				8,
				0,
				$posX,
				$this->shiftY + 4,
				$this->getColor($this->graphtheme['textcolor'], 0),
				$str
			);

			if ($this->zero[$side] != $this->sizeY + $this->shiftY && $this->zero[$side] != $this->shiftY) {
				zbx_imageline(
					$this->im,
					$this->shiftXleft,
					$this->zero[$side],
					$this->shiftXleft + $this->sizeX,
					$this->zero[$side],
					$color
				);
			}
		}
	}

	protected function drawWorkPeriod() {
		imagefilledrectangle($this->im,
			$this->shiftXleft + 1,
			$this->shiftY,
			$this->sizeX + $this->shiftXleft-1, // -2 border
			$this->sizeY + $this->shiftY,
			$this->getColor($this->graphtheme['graphcolor'], 0)
		);

		if ($this->m_showWorkPeriod != 1) {
			return;
		}
		if ($this->period > 8035200) { // 31*24*3600*3 (3*month*3)
			return;
		}

		$db_work_period = DBselect('SELECT c.work_period FROM config c');
		$work_period = DBfetch($db_work_period);
		if (!$work_period) {
			return;
		}

		$periods = parse_period($work_period['work_period']);
		if (!$periods) {
			return;
		}

		imagefilledrectangle(
			$this->im,
			$this->shiftXleft + 1,
			$this->shiftY,
			$this->sizeX + $this->shiftXleft - 1, // -1 border
			$this->sizeY + $this->shiftY,
			$this->getColor($this->graphtheme['nonworktimecolor'], 0)
		);

		$now = time();
		if (isset($this->stime)) {
			$this->from_time = $this->stime;
			$this->to_time = $this->stime + $this->period;
		}
		else {
			$this->to_time = $now - SEC_PER_HOUR * $this->from;
			$this->from_time = $this->to_time - $this->period;
		}

		$from = $this->from_time;
		$max_time = $this->to_time;

		$start = find_period_start($periods, $from);
		$end = -1;
		while ($start < $max_time && $start > 0) {
			$end = find_period_end($periods, $start, $max_time);

			$x1 = round((($start - $from) * $this->sizeX) / $this->period) + $this->shiftXleft;
			$x2 = ceil((($end - $from) * $this->sizeX) / $this->period) + $this->shiftXleft;

			// draw rectangle
			imagefilledrectangle(
				$this->im,
				$x1,
				$this->shiftY,
				$x2 - 1, // -1 border
				$this->sizeY + $this->shiftY,
				$this->getColor($this->graphtheme['graphcolor'], 0)
			);

			$start = find_period_start($periods, $end);
		}
	}

	protected function drawPercentile() {
		if ($this->type != GRAPH_TYPE_NORMAL) {
			return ;
		}

		foreach ($this->percentile as $side => $percentile) {
			if ($percentile['percent'] > 0 && $percentile['value']) {
				if ($side == 'left') {
					$minY = $this->m_minY[GRAPH_YAXIS_SIDE_LEFT];
					$maxY = $this->m_maxY[GRAPH_YAXIS_SIDE_LEFT];

					$color = $this->graphtheme['leftpercentilecolor'];
				}
				else {
					$minY = $this->m_minY[GRAPH_YAXIS_SIDE_RIGHT];
					$maxY = $this->m_maxY[GRAPH_YAXIS_SIDE_RIGHT];

					$color = $this->graphtheme['rightpercentilecolor'];
				}

				$y = $this->sizeY - (($percentile['value'] - $minY) / ($maxY - $minY)) * $this->sizeY + $this->shiftY;
				zbx_imageline(
					$this->im,
					$this->shiftXleft,
					$y,
					$this->sizeX + $this->shiftXleft,
					$y,
					$this->getColor($color)
				);
			}
		}
	}

	protected function drawTriggers() {
		if ($this->m_showTriggers != 1) {
			return;
		}

		$oppColor = $this->getColor(GRAPH_TRIGGER_LINE_OPPOSITE_COLOR);

		foreach ($this->triggers as $tnum => $trigger) {
			if ($trigger['skipdraw']) {
				continue;
			}

			$triggerColor = $this->getColor($trigger['color']);
			$lineStyle = [$triggerColor, $triggerColor, $triggerColor, $triggerColor, $triggerColor, $oppColor, $oppColor, $oppColor];

			dashedLine(
				$this->im,
				$this->shiftXleft,
				$trigger['y'],
				$this->sizeX + $this->shiftXleft,
				$trigger['y'],
				$lineStyle
			);

			dashedLine(
				$this->im,
				$this->shiftXleft,
				$trigger['y'] + 1,
				$this->sizeX + $this->shiftXleft,
				$trigger['y'] + 1,
				$lineStyle
			);
		}
	}

	protected function drawLegend() {
		$leftXShift = 20;
		$units = ['left' => 0, 'right' => 0];

		// draw item legend
		$legend = new CImageTextTable($this->im, $leftXShift - 5, $this->sizeY + $this->shiftY + $this->legendOffsetY);
		$legend->color = $this->getColor($this->graphtheme['textcolor'], 0);
		$legend->rowheight = 14;
		$legend->fontsize = 9;

		// item legend table header
		$row = [
			['text' => '', 'marginRight' => 5],
			['text' => ''],
			['text' => ''],
			['text' => _('last'), 'align' => 1, 'fontsize' => 9],
			['text' => _('min'), 'align' => 1, 'fontsize' => 9],
			['text' => _('avg'), 'align' => 1, 'fontsize' => 9],
			['text' => _('max'), 'align' => 1, 'fontsize' => 9]
		];

		$legend->addRow($row);
		$rowNum = $legend->getNumRows();

		$i = ($this->type == GRAPH_TYPE_STACKED) ? $this->num - 1 : 0;
		while ($i >= 0 && $i < $this->num) {
			$color = $this->getColor($this->items[$i]['color'], GRAPH_STACKED_ALFA);
			switch ($this->items[$i]['calc_fnc']) {
				case CALC_FNC_MIN:
					$fncRealName = _('min');
					break;
				case CALC_FNC_MAX:
					$fncRealName = _('max');
					break;
				case CALC_FNC_ALL:
					$fncRealName = _('all');
					break;
				case CALC_FNC_AVG:
				default:
					$fncRealName = _('avg');
			}

			$data = &$this->data[$this->items[$i]['itemid']][$this->items[$i]['calc_type']];

			// draw color square
			if (function_exists('imagecolorexactalpha') && function_exists('imagecreatetruecolor') && @imagecreatetruecolor(1, 1)) {
				$colorSquare = imagecreatetruecolor(11, 11);
			}
			else {
				$colorSquare = imagecreate(11, 11);
			}

			imagefill($colorSquare, 0, 0, $this->getColor($this->graphtheme['backgroundcolor'], 0));
			imagefilledrectangle($colorSquare, 0, 0, 10, 10, $color);
			imagerectangle($colorSquare, 0, 0, 10, 10, $this->getColor('Black'));

			// caption
			$itemCaption = $this->itemsHost
				? $this->items[$i]['name_expanded']
				: $this->items[$i]['hostname'].NAME_DELIMITER.$this->items[$i]['name_expanded'];

			// draw legend of an item with data
			if (isset($data) && isset($data['min'])) {
				if ($this->items[$i]['axisside'] == GRAPH_YAXIS_SIDE_LEFT) {
					$units['left'] = $this->items[$i]['units'];
				}
				else {
					$units['right'] = $this->items[$i]['units'];
				}

				$legend->addCell($rowNum, ['image' => $colorSquare, 'marginRight' => 5]);
				$legend->addCell($rowNum, ['text' => $itemCaption]);
				$legend->addCell($rowNum, ['text' => '['.$fncRealName.']']);
				$legend->addCell($rowNum, [
					'text' => convert_units([
						'value' => $this->getLastValue($i),
						'units' => $this->items[$i]['units'],
						'convert' => ITEM_CONVERT_NO_UNITS
					]),
					'align' => 2
				]);
				$legend->addCell($rowNum, [
					'text' => convert_units([
						'value' => min($data['min']),
						'units' => $this->items[$i]['units'],
						'convert' => ITEM_CONVERT_NO_UNITS
					]),
					'align' => 2
				]);
				$legend->addCell($rowNum, [
					'text' => convert_units([
						'value' => $data['avg_orig'],
						'units' => $this->items[$i]['units'],
						'convert' => ITEM_CONVERT_NO_UNITS
					]),
					'align' => 2
				]);
				$legend->addCell($rowNum, [
					'text' => convert_units([
						'value' => max($data['max']),
						'units' => $this->items[$i]['units'],
						'convert' => ITEM_CONVERT_NO_UNITS
					]),
					'align' => 2
				]);
			}
			// draw legend of an item without data
			else {
				$legend->addCell($rowNum, ['image' => $colorSquare, 'marginRight' => 5]);
				$legend->addCell($rowNum, ['text' => $itemCaption]);
				$legend->addCell($rowNum, ['text' => '['._('no data').']']);
			}

			$rowNum++;

			// legends for stacked graphs are written in reverse order so that the order of items
			// matches the order of lines on the graphs
			if ($this->type == GRAPH_TYPE_STACKED) {
				$i--;
			}
			else {
				$i++;
			}
		}

		$legend->draw();

		// if graph is small, we are not drawing percent line and trigger legends
		if ($this->sizeY < ZBX_GRAPH_LEGEND_HEIGHT) {
			return true;
		}

		$legend = new CImageTextTable(
			$this->im,
			$leftXShift + 10,
			$this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY
		);
		$legend->color = $this->getColor($this->graphtheme['textcolor'], 0);
		$legend->rowheight = 14;
		$legend->fontsize = 9;

		// draw percentile
		if ($this->type == GRAPH_TYPE_NORMAL) {
			foreach ($this->percentile as $side => $percentile) {
				if ($percentile['percent'] > 0 && $percentile['value']) {
					$percentile['percent'] = (float) $percentile['percent'];
					$convertedUnit = convert_units([
						'value' => $percentile['value'],
						'units' => $units[$side]
					]);
					$legend->addCell($rowNum, [
						'text' => $percentile['percent'].'th percentile: '.$convertedUnit.' ('.$side.')',
						ITEM_CONVERT_NO_UNITS
					]);
					if ($side == 'left') {
						$color = $this->graphtheme['leftpercentilecolor'];
					}
					else {
						$color = $this->graphtheme['rightpercentilecolor'];
					}

					imagefilledpolygon(
						$this->im,
						[
							$leftXShift + 5, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
							$leftXShift - 5, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
							$leftXShift, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY - 10
						],
						3,
						$this->getColor($color)
					);

					imagepolygon(
						$this->im,
						[
							$leftXShift + 5, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
							$leftXShift - 5, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
							$leftXShift, $this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY - 10
						],
						3,
						$this->getColor('Black No Alpha')
					);
					$rowNum++;
				}
			}
		}

		$legend->draw();

		$legend = new CImageTextTable(
			$this->im,
			$leftXShift + 10,
			$this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY + 5
		);
		$legend->color = $this->getColor($this->graphtheme['textcolor'], 0);
		$legend->rowheight = 14;
		$legend->fontsize = 9;

		// draw triggers
		foreach ($this->triggers as $trigger) {
			imagefilledellipse(
				$this->im,
				$leftXShift,
				$this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
				10,
				10,
				$this->getColor($trigger['color'])
			);

			imageellipse(
				$this->im,
				$leftXShift,
				$this->sizeY + $this->shiftY + 14 * $rowNum + $this->legendOffsetY,
				10,
				10,
				$this->getColor('Black No Alpha')
			);

			$legend->addRow([
				['text' => $trigger['description']],
				['text' => $trigger['constant']]
			]);
			$rowNum++;
		}

		$legend->draw();
	}

	protected function limitToBounds(&$value1, &$value2, $min, $max, $drawtype) {
		// fixes graph out of bounds problem
		if ((($value1 > ($max + $min)) && ($value2 > ($max + $min))) || ($value1 < $min && $value2 < $min)) {
			if (!in_array($drawtype, [GRAPH_ITEM_DRAWTYPE_FILLED_REGION, GRAPH_ITEM_DRAWTYPE_GRADIENT_LINE])) {
				return false;
			}
		}

		$y_first = $value1 > ($max + $min) || $value1 < $min;
		$y_second = $value2 > ($max + $min) || $value2 < $min;

		if ($y_first) {
			$value1 = ($value1 > ($max + $min)) ? $max + $min : $min;
		}

		if ($y_second) {
			$value2 = ($value2 > ($max + $min)) ? $max + $min : $min;
		}

		return true;
	}

	protected function drawElement(&$data, $from, $to, $minX, $maxX, $minY, $maxY, $drawtype, $max_color, $avg_color, $min_color, $minmax_color, $calc_fnc, $axisside) {
		if (!isset($data['max'][$from]) || !isset($data['max'][$to])) {
			return;
		}

		$oxy = $this->oxy[$axisside];
		$zero = $this->zero[$axisside];
		$unit2px = $this->unit2px[$axisside];

		$shift_min_from = $shift_min_to = 0;
		$shift_max_from = $shift_max_to = 0;
		$shift_avg_from = $shift_avg_to = 0;

		if (isset($data['shift_min'][$from])) {
			$shift_min_from = $data['shift_min'][$from];
		}
		if (isset($data['shift_min'][$to])) {
			$shift_min_to = $data['shift_min'][$to];
		}

		if (isset($data['shift_max'][$from])) {
			$shift_max_from = $data['shift_max'][$from];
		}
		if (isset($data['shift_max'][$to])) {
			$shift_max_to = $data['shift_max'][$to];
		}

		if (isset($data['shift_avg'][$from])) {
			$shift_avg_from = $data['shift_avg'][$from];
		}
		if (isset($data['shift_avg'][$to])) {
			$shift_avg_to = $data['shift_avg'][$to];
		}

		$min_from = $data['min'][$from] + $shift_min_from;
		$min_to = $data['min'][$to] + $shift_min_to;

		$max_from = $data['max'][$from] + $shift_max_from;
		$max_to = $data['max'][$to] + $shift_max_to;

		$avg_from = $data['avg'][$from] + $shift_avg_from;
		$avg_to = $data['avg'][$to] + $shift_avg_to;

		$x1 = $from + $this->shiftXleft - 1;
		$x2 = $to + $this->shiftXleft;

		$y1min = $zero - ($min_from - $oxy) / $unit2px;
		$y2min = $zero - ($min_to - $oxy) / $unit2px;

		$y1max = $zero - ($max_from - $oxy) / $unit2px;
		$y2max = $zero - ($max_to - $oxy) / $unit2px;

		$y1avg = $zero - ($avg_from - $oxy) / $unit2px;
		$y2avg = $zero - ($avg_to - $oxy) / $unit2px;

		switch ($calc_fnc) {
			case CALC_FNC_MAX:
				$y1 = $y1max;
				$y2 = $y2max;
				$shift_from = $shift_max_from;
				$shift_to = $shift_max_to;
				break;
			case CALC_FNC_MIN:
				$y1 = $y1min;
				$y2 = $y2min;
				$shift_from = $shift_min_from;
				$shift_to = $shift_min_to;
				break;
			case CALC_FNC_ALL:
				// max
				$y1x = (($y1max > ($this->sizeY + $this->shiftY)) || $y1max < $this->shiftY);
				$y2x = (($y2max > ($this->sizeY + $this->shiftY)) || $y2max < $this->shiftY);

				if ($y1x) {
					$y1max = ($y1max > ($this->sizeY + $this->shiftY)) ? $this->sizeY + $this->shiftY : $this->shiftY;
				}
				if ($y2x) {
					$y2max = ($y2max > ($this->sizeY + $this->shiftY)) ? $this->sizeY + $this->shiftY : $this->shiftY;
				}

				// min
				$y1n = (($y1min > ($this->sizeY + $this->shiftY)) || $y1min < $this->shiftY);
				$y2n = (($y2min > ($this->sizeY + $this->shiftY)) || $y2min < $this->shiftY);

				if ($y1n) {
					$y1min = ($y1min > ($this->sizeY + $this->shiftY)) ? $this->sizeY + $this->shiftY : $this->shiftY;
				}
				if ($y2n) {
					$y2min = ($y2min > ($this->sizeY + $this->shiftY)) ? $this->sizeY + $this->shiftY : $this->shiftY;
				}

				$a[0] = $x1;
				$a[1] = $y1max;
				$a[2] = $x1;
				$a[3] = $y1min;
				$a[4] = $x2;
				$a[5] = $y2min;
				$a[6] = $x2;
				$a[7] = $y2max;

			// don't use break, avg must be drawn in this statement
			case CALC_FNC_AVG:

			// don't use break, avg must be drawn in this statement
			default:
				$y1 = $y1avg;
				$y2 = $y2avg;
				$shift_from = $shift_avg_from ;
				$shift_to = $shift_avg_to;
		}

		$shift_from -= ($shift_from != 0) ? $oxy : 0;
		$shift_to -= ($shift_to != 0) ? $oxy : 0;

		$y1_shift = $zero - $shift_from / $unit2px;
		$y2_shift = $zero - $shift_to / $unit2px;

		if (!$this->limitToBounds($y1, $y2, $this->shiftY, $this->sizeY, $drawtype)) {
			return true;
		}
		if (!$this->limitToBounds($y1_shift, $y2_shift, $this->shiftY, $this->sizeY, $drawtype)) {
			return true;
		}

		// draw main line
		switch ($drawtype) {
			case GRAPH_ITEM_DRAWTYPE_BOLD_LINE:
				if ($calc_fnc == CALC_FNC_ALL) {
					imagefilledpolygon($this->im, $a, 4, $minmax_color);
					if (!$y1x || !$y2x) {
						zbx_imagealine($this->im, $x1, $y1max, $x2, $y2max, $max_color, LINE_TYPE_BOLD);
					}

					if (!$y1n || !$y2n) {
						zbx_imagealine($this->im, $x1, $y1min, $x2, $y2min, $min_color, LINE_TYPE_BOLD);
					}
				}

				zbx_imagealine($this->im, $x1, $y1, $x2, $y2, $avg_color, LINE_TYPE_BOLD);
				break;
			case GRAPH_ITEM_DRAWTYPE_LINE:
				if ($calc_fnc == CALC_FNC_ALL) {
					imagefilledpolygon($this->im, $a, 4, $minmax_color);
					if (!$y1x || !$y2x) {
						zbx_imagealine($this->im, $x1, $y1max, $x2, $y2max, $max_color);
					}
					if (!$y1n || !$y2n) {
						zbx_imagealine($this->im, $x1, $y1min, $x2, $y2min, $min_color);
					}
				}

				zbx_imagealine($this->im, $x1, $y1, $x2, $y2, $avg_color);
				break;
			case GRAPH_ITEM_DRAWTYPE_FILLED_REGION:
				$a[0] = $x1;
				$a[1] = $y1;
				$a[2] = $x1;
				$a[3] = $y1_shift;
				$a[4] = $x2;
				$a[5] = $y2_shift;
				$a[6] = $x2;
				$a[7] = $y2;

				imagefilledpolygon($this->im, $a, 4, $avg_color);
				break;
			case GRAPH_ITEM_DRAWTYPE_DOT:
				imagefilledrectangle($this->im, $x1 - 1, $y1 - 1, $x1, $y1, $avg_color);
				break;
			case GRAPH_ITEM_DRAWTYPE_BOLD_DOT:
				imagefilledrectangle($this->im, $x2 - 1, $y2 - 1, $x2 + 1, $y2 + 1, $avg_color);
				break;
			case GRAPH_ITEM_DRAWTYPE_DASHED_LINE:
				if (function_exists('imagesetstyle')) {
					// use imagesetstyle+imageline instead of bugged imagedashedline
					$style = [$avg_color, $avg_color, IMG_COLOR_TRANSPARENT, IMG_COLOR_TRANSPARENT];
					imagesetstyle($this->im, $style);
					zbx_imageline($this->im, $x1, $y1, $x2, $y2, IMG_COLOR_STYLED);
				}
				else {
					imagedashedline($this->im, $x1, $y1, $x2, $y2, $avg_color);
				}
				break;
			case GRAPH_ITEM_DRAWTYPE_GRADIENT_LINE:
				imageLine($this->im, $x1, $y1, $x2, $y2, $avg_color); // draw the initial line
				imageLine($this->im, $x1, $y1 - 1, $x2, $y2 - 1, $avg_color);

				$bitmask = 255;
				$blue = $avg_color & $bitmask;

				// $blue_diff = 255 - $blue;
				$bitmask = $bitmask << 8;
				$green = ($avg_color & $bitmask) >> 8;

				// $green_diff = 255 - $green;
				$bitmask = $bitmask << 8;
				$red = ($avg_color & $bitmask) >> 16;
				// $red_diff = 255 - $red;

				// note: though gradients on the chart looks ok, the formula used is completely incorrect
				// if you plan to fix something here, it would be better to start from scratch
				$maxAlpha = 110;
				$startAlpha = 50;
				$alphaRatio = $maxAlpha / ($this->sizeY - $startAlpha);

				$diffX = $x1 - $x2;
				for ($i = 0; $i <= $diffX; $i++) {
					$Yincr = ($diffX > 0) ? (abs($y2 - $y1) / $diffX) : 0;

					$gy = ($y1 > $y2) ? ($y2 + $Yincr * $i) : ($y2 - $Yincr * $i);
					$steps = $this->sizeY + $this->shiftY - $gy + 1;

					for ($j = 0; $j < $steps; $j++) {
						if (($gy + $j) < ($this->shiftY + $startAlpha)) {
							$alpha = 0;
						}
						else {
							$alpha = 127 - abs(127 - ($alphaRatio * ($gy + $j - $this->shiftY - $startAlpha)));
						}

						$color = imagecolorexactalpha($this->im, $red, $green, $blue, $alpha);
						imagesetpixel($this->im, $x2 + $i, $gy + $j, $color);
					}
				}
			break;
		}
	}

	public function draw() {
		$start_time = microtime(true);

		set_image_header();

		$this->selectData();

		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_RIGHT])) {
			$sides[] = GRAPH_YAXIS_SIDE_RIGHT;
		}

		if (isset($this->axis_valuetype[GRAPH_YAXIS_SIDE_LEFT]) || !isset($sides)) {
			$sides[] = GRAPH_YAXIS_SIDE_LEFT;
		}

		foreach ($sides as $graphSide) {
			$this->m_minY[$graphSide] = $this->calculateMinY($graphSide);
			$this->m_maxY[$graphSide] = $this->calculateMaxY($graphSide);

			if ($this->m_minY[$graphSide] === null) {
				$this->m_minY[$graphSide] = 0;
			}
			if ($this->m_maxY[$graphSide] === null) {
				$this->m_maxY[$graphSide] = 1;
			}

			if ($this->m_minY[$graphSide] == $this->m_maxY[$graphSide]) {
				if ($this->graphOrientation[$graphSide] == '-') {
					$this->m_maxY[$graphSide] = 0;
				}
				elseif ($this->m_minY[$graphSide] == 0) {
					$this->m_maxY[$graphSide] = 1;
				}
				else {
					$this->m_minY[$graphSide] = 0;
				}
			}
			elseif ($this->m_minY[$graphSide] > $this->m_maxY[$graphSide]) {
				if ($this->graphOrientation[$graphSide] == '-') {
					$this->m_minY[$graphSide] = bcmul($this->m_maxY[$graphSide], 0.2);
				}
				else {
					$this->m_minY[$graphSide] = 0;
				}
			}

			// If max Y-scale bigger min Y-scale only for 10% or less, then we don't allow Y-scale duplicate
			if ($this->m_maxY[$graphSide] && $this->m_minY[$graphSide]) {
				if ($this->m_minY[$graphSide] < 0) {
					$absMinY = bcmul($this->m_minY[$graphSide], '-1');
				}
				else {
					$absMinY = $this->m_minY[$graphSide];
				}
				if ($this->m_maxY[$graphSide] < 0) {
					$absMaxY = bcmul($this->m_maxY[$graphSide], '-1');
				}
				else {
					$absMaxY = $this->m_maxY[$graphSide];
				}

				if ($absMaxY < $absMinY) {
					$oldAbMaxY = $absMaxY;
					$absMaxY = $absMinY;
					$absMinY = $oldAbMaxY;
				}

				if (bcdiv((bcsub($absMaxY, $absMinY)), $absMaxY) <= 0.1) {
					if ($this->m_minY[$graphSide] > 0) {
						$this->m_minY[$graphSide] = bcmul($this->m_minY[$graphSide], 0.95);
					}
					else {
						$this->m_minY[$graphSide] = bcmul($this->m_minY[$graphSide], 1.05);
					}
					if ($this->m_maxY[$graphSide] > 0) {
						$this->m_maxY[$graphSide] = bcmul($this->m_maxY[$graphSide], 1.05);
					}
					else {
						$this->m_maxY[$graphSide] = bcmul($this->m_maxY[$graphSide], 0.95);
					}
				}
			}
		}

		$this->calcMinMaxInterval();
		$this->updateShifts();
		$this->calcTriggers();
		$this->calcZero();
		$this->calcPercentile();

		$this->fullSizeX = $this->sizeX + $this->shiftXleft + $this->shiftXright + 1;
		$this->fullSizeY = $this->sizeY + $this->shiftY + $this->legendOffsetY;

		if ($this->drawLegend) {
			$this->fullSizeY += 14 * ($this->num + 1 + (($this->sizeY < 120) ? 0 : count($this->triggers))) + 8;
		}

		// if graph height is big enough, we reserve space for percent line legend
		if ($this->sizeY >= ZBX_GRAPH_LEGEND_HEIGHT) {
			foreach ($this->percentile as $percentile) {
				if ($percentile['percent'] > 0 && $percentile['value']) {
					$this->fullSizeY += 14;
				}
			}
		}

		if (function_exists('imagecolorexactalpha') && function_exists('imagecreatetruecolor') && @imagecreatetruecolor(1, 1)) {
			$this->im = imagecreatetruecolor($this->fullSizeX, $this->fullSizeY);
		}
		else {
			$this->im = imagecreate($this->fullSizeX, $this->fullSizeY);
		}

		$this->initColors();
		$this->drawRectangle();
		$this->drawHeader();
		$this->drawWorkPeriod();
		$this->drawTimeGrid();
		$this->drawHorizontalGrid();
		$this->drawXYAxisScale();

		$maxX = $this->sizeX;

		// for each metric
		for ($item = 0; $item < $this->num; $item++) {
			$minY = $this->m_minY[$this->items[$item]['axisside']];
			$maxY = $this->m_maxY[$this->items[$item]['axisside']];

			$data = &$this->data[$this->items[$item]['itemid']][$this->items[$item]['calc_type']];

			if (!isset($data)) {
				continue;
			}

			if ($this->type == GRAPH_TYPE_STACKED) {
				$drawtype = $this->items[$item]['drawtype'];
				$max_color = $this->getColor('ValueMax', GRAPH_STACKED_ALFA);
				$avg_color = $this->getColor($this->items[$item]['color'], GRAPH_STACKED_ALFA);
				$min_color = $this->getColor('ValueMin', GRAPH_STACKED_ALFA);
				$minmax_color = $this->getColor('ValueMinMax', GRAPH_STACKED_ALFA);

				$calc_fnc = $this->items[$item]['calc_fnc'];
			}
			else {
				$drawtype = $this->items[$item]['drawtype'];
				$max_color = $this->getColor('ValueMax', GRAPH_STACKED_ALFA);
				$avg_color = $this->getColor($this->items[$item]['color'], GRAPH_STACKED_ALFA);
				$min_color = $this->getColor('ValueMin', GRAPH_STACKED_ALFA);
				$minmax_color = $this->getColor('ValueMinMax', GRAPH_STACKED_ALFA);

				$calc_fnc = $this->items[$item]['calc_fnc'];
			}

			// for each X
			$prevDraw = true;
			for ($i = 1, $j = 0; $i < $maxX; $i++) { // new point
				if ($data['count'][$i] == 0 && $i != ($maxX - 1)) {
					continue;
				}

				$delay = $this->items[$item]['delay'];

				if ($this->items[$item]['type'] == ITEM_TYPE_TRAPPER
						|| ($this->hasSchedulingIntervals($this->items[$item]['intervals']) && $delay == 0)) {
					$draw = true;
				}
				else {
					$diff = abs($data['clock'][$i] - $data['clock'][$j]);
					$cell = ($this->to_time - $this->from_time) / $this->sizeX;

					if ($cell > $delay) {
						$draw = ($diff < (ZBX_GRAPH_MAX_SKIP_CELL * $cell));
					}
					else {
						$draw = ($diff < (ZBX_GRAPH_MAX_SKIP_DELAY * $delay));
					}
				}

				if (!$draw && !$prevDraw) {
					$draw = true;
					$valueDrawType = GRAPH_ITEM_DRAWTYPE_BOLD_DOT;
				}
				else {
					$valueDrawType = $drawtype;
					$prevDraw = $draw;
				}

				if ($draw) {
					$this->drawElement(
						$data,
						$i,
						$j,
						0,
						$this->sizeX,
						$minY,
						$maxY,
						$valueDrawType,
						$max_color,
						$avg_color,
						$min_color,
						$minmax_color,
						$calc_fnc,
						$this->items[$item]['axisside']
					);
				}

				$j = $i;
			}
		}

		$this->drawSides();

		if ($this->drawLegend) {
			$this->drawTriggers();
			$this->drawPercentile();
			$this->drawLegend();
		}

		$this->drawLogo();

		$str = sprintf('%0.2f', microtime(true) - $start_time);
		$str = _s('Data from %1$s. Generated in %2$s sec.', $this->dataFrom, $str);
		$strSize = imageTextSize(6, 0, $str);
		imageText($this->im, 6, 0, $this->fullSizeX - $strSize['width'] - 5, $this->fullSizeY - 5, $this->getColor('Gray'), $str);

		unset($this->items, $this->data);

		imageOut($this->im);
	}

	/**
	 * Checks if item intervals has at least one scheduling interval.
	 *
	 * @param array $intervals
	 *
	 * @return bool
	 */
	private function hasSchedulingIntervals($intervals) {
		foreach ($intervals as $interval) {
			if ($interval['type'] == ITEM_DELAY_FLEX_TYPE_SCHEDULING) {
				return true;
			}
		}

		return false;
	}
}
